U.S. patent application number 09/928997 was filed with the patent office on 2002-03-07 for drive control for elevator.
Invention is credited to Takahashi, Toru, Tauchi, Shigeaki.
Application Number | 20020027047 09/928997 |
Document ID | / |
Family ID | 27761462 |
Filed Date | 2002-03-07 |
United States Patent
Application |
20020027047 |
Kind Code |
A1 |
Tauchi, Shigeaki ; et
al. |
March 7, 2002 |
Drive control for elevator
Abstract
A drive machine for elevators comprises a rotatable drive sheave
(16) over which a main cable (18) for hanging an elevator cage is
wound, a stationary shaft (9) for supporting rotation of the drive
sheave and bearing a load applied to the drive sheave from the main
cable, a field magnet (14) attached to the drive sheave,
constituting a part of an electric motor, and comprising at least
one pair of magnetic poles, an armature (11, 12) attached to the
stationary shaft in a facing relation to the field magnet and
constituting another part of the motor, and a field magnetic pole
detector (27) for detecting the predetermined magnetic pole of the
field magnet rotated together with the drive sheave.
Inventors: |
Tauchi, Shigeaki; (Aichi,
JP) ; Takahashi, Toru; (Tokyo, JP) |
Correspondence
Address: |
LEYDIG VOIT & MAYER, LTD
700 THIRTEENTH ST. NW
SUITE 300
WASHINGTON
DC
20005-3960
US
|
Family ID: |
27761462 |
Appl. No.: |
09/928997 |
Filed: |
August 15, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09928997 |
Aug 15, 2001 |
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09381197 |
Sep 17, 1999 |
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09381197 |
Sep 17, 1999 |
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PCT/JP97/00877 |
Mar 18, 1997 |
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Current U.S.
Class: |
187/391 |
Current CPC
Class: |
H02K 7/1016 20130101;
H02K 29/08 20130101; H02K 7/14 20130101; B66B 1/3492 20130101; B66B
11/08 20130101 |
Class at
Publication: |
187/391 |
International
Class: |
B66B 001/34; B66B
003/00 |
Claims
1. A drive machine for elevators, comprising: a rotatable drive
sheave over which a main cable for hanging an elevator cage is
wound, a stationary shaft for supporting rotation of said drive
sheave and bearing a load applied to said drive sheave from said
main cable, a field magnet attached to said drive sheave,
constituting a part of an electric motor, and comprising at least
one pair of magnetic poles, an armature attached to said stationary
shaft in a facing relation to said field magnet and constituting
another part of said motor, and a field magnetic pole detector for
detecting the predetermined magnetic pole of said field magnet
rotated together with said drive sheave.
2. A drive machine for elevators according to claim 1, wherein said
field magnet comprises a permanent magnet.
3. A drive machine for elevators according to claim 1 or 2, wherein
said field magnetic pole detector comprises a magnetic sensor
attached to the stationary side in a close and facing relation to
said field magnet.
4. A drive machine for elevators according to claim 1, wherein a
detected portion indicating the position of the magnetic pole
disposed on said drive sheave is provided on said drive sheave in a
facing relation to said field magnetic pole detector, and the
position of the predetermined magnetic pole is recognized with said
field magnetic pole detector detecting said detected portion.
5. A drive machine for elevators according to claim 4, wherein said
detected portion comprises a convex or concave portion formed on or
in the surface of said drive sheave corresponding to the position
of the predetermined magnetic pole.
6. A drive machine for elevators according to claim 1, wherein said
field magnetic pole detector is provided at least three at a pitch
equal to 1/3 of the pitch of one pair of the field magnetic
poles.
7. A drive machine for elevators according to claim 2 or 6, further
comprising a rotation detector for detecting rotation of said drive
sheave with respect to said stationary shaft as a reference, and
drive control means for executing drive control of said motor in
accordance with results detected by said rotation detector and said
field magnetic pole detector, wherein said drive control means
starts up said motor in accordance with an imaginary field magnetic
pole position when the magnetic pole position of said field magnet
attached to said drive sheave is not known at the start-up of said
elevator, and executes the drive control in accordance with the
results detected by said field magnetic pole detector and said
rotation detector after the field magnetic pole position has been
recognized upon operation of said field magnetic pole detector.
8. A drive machine for elevators according to claim 1, further
comprising a rotation detector for detecting rotation of said drive
sheave with respect to said stationary shaft as a reference,
detection difference calculating means for detecting the difference
between the rotation of said drive sheave detected by said rotation
detector and the rotation of said drive sheave detected by said
field magnetic pole detector, and anomaly determining means for
determining the occurrence of an anomaly when a value of the
difference determined by said detection difference calculating
means exceeds a predetermined value.
9. A drive machine for elevators according to claim 8, further
comprising drive control means for executing drive control of said
motor in accordance with results detected by said rotation detector
and said field magnetic pole detector, wherein when said value of
the difference determined by said detection difference calculating
means does not exceed the predetermined value, said drive control
means executes the control while correcting an output value of said
rotation detector in accordance with said value of the
difference.
10. A drive machine for elevators according to claim 1, further
comprising a rotation detector for detecting rotation of said drive
sheave with respect to said stationary shaft as a reference, memory
means for storing an output of said rotation detector in a
corresponding relation to the position detected by said field
magnetic pole detector while said field magnetic pole detector is
detecting the field magnetic pole position with the rotation of
said drive sheave, and drive control means for executing drive
control of said motor in accordance with results detected by said
rotation detector and said field magnetic pole detector, wherein
said drive control means utilizes values stored in said memory
means for phase control of electric power supplied to said
armature.
11. A drive machine for elevators according to claim 1, further
comprising a rotation detector for detecting rotation of said drive
sheave with respect to said stationary shaft as a reference, and
drive control means for executing drive control of said motor in
accordance with results detected by said rotation detector and said
field magnetic pole detector, wherein the amount of change in value
detected by said rotation detector is determined at the start-up of
said elevator while said field magnetic pole detector detects one
pair of the field magnetic poles, and said drive control means
executes phase control of said motor by setting said amount of
change as a reference value of a phase signal for one pair of the
field magnetic poles since then.
Description
TECHNICAL FIELD
[0001] The present invention relates to an elevator apparatus, and
more particularly to a drive machine for elevators which employs an
outer rotor motor.
BACKGROUND ART
[0002] FIGS. 11 and 12 show a conventional elevator apparatus
disclosed in, for example, Japanese Unexamined Patent Publication
No. 7-117957. The disclosed elevator apparatus is of the traction
sheave type wherein a main cable is wound over a drive sheave, and
a cage and a counterweight are moved up and down in opposite
directions. The elevator apparatus employs, as a winder, an outer
rotor motor. FIG. 11 is a perspective view of the elevator
apparatus, and FIG. 12 is an enlarged sectional view of a drive
machine shown in FIG. 11.
[0003] Referring to FIGS. 11 and 12, denoted by numeral 1 is an
elevator pit, 2 is a cage, 3 is a cage guide rail vertically
provided in pair within the elevator pit 1 for guiding both sides
of the cage 2 so that the cage moves up and down along a
predetermined path, 4 is a counterweight, 5 is a counterweight
guide rail vertically provided in pair within the elevator pit 1
for guiding both sides of the counterweight 4 so that the
counterweight moves up and down along a predetermined path, and 6
is a braking device associated with the counterweight 4 and tightly
pressed against the counterweight guide rails 5 for applying a
brake as the occasion requires. Numeral 7 denotes a support beam
provided at the top of the elevator pit 1, and 8 denotes a winder
comprising an outer rotor motor provided at the top of the elevator
pit 1.
[0004] As shown in FIG. 12, the winder 8 mainly comprises a
stationary shaft 9 having opposite ends supported by and fixed to
the support beams 7, an armature iron-core 11 fixed to the shaft 9
and having armature coils 10 wound over the same, and a rotor 12
rotatably supported by the shaft 9 and constituting a drive
sheave.
[0005] The rotor 12 includes a field iron-core 13, a field
permanent magnet 14, a drive sheave 16 having cable grooves formed
in its outer periphery, and bearings 17 disposed between the rotor
and the shaft 9 for rotatably supporting the former relative to the
latter. Numeral 18 denotes an elevator main cable wound along the
sheave groove 15, the main cable having one end coupled to the cage
2 and the other end coupled to the counterweight 4. Numeral 19
denotes a braking device associated with the rotor 12 for stopping
the rotor 12.
[0006] Numeral 20 denotes an absolute value encoder in the form of
a ring. The absolute value encoder 20 is arranged such that it
surrounds a projected flange of the rotor 12, is joined to the
projected flange of the rotor 12 through a baring 21 for free
rotation of the rotor 12, and is fixed through a mounting fixture
23 to an encoder holder 22 which is secured to the shaft 9. Numeral
24 denotes a supporting fixture provided on each of the support
beams 7 on both sides for supporting the shaft 9.
[0007] In the drive machine thus constructed, the magnetic pole
position of the field permanent magnet 14 is detected by the
absolute value encoder 20, and the phases of currents supplied to
the armature coils 10 are controlled in accordance with the
detected result. Also, the rotating speed and the rotating
direction of the rotor 12 and hence the drive sheave 16 are
detected by the absolute value encoder 20 in order to control the
rising/lowering speed and the moving direction of the cage 2.
[0008] In not only such a synchronous motor using a field permanent
magnet, but also other electric motors such as the so-called
three-phase induction motor, it is important to detect the
rotational angle of a rotor with respect to a field magnet in a
circuit driving control for any of those motors.
[0009] The above-described conventional drive machine for elevators
has problems below. Supposing, for example, that the absolute value
encoder 20 directly attached to the shaft of the winder
malfunctions and has to be replaced, because the absolute value
encoder 20 is in the ring form, it is required to dismount the
entirety of the winder 8 by moving the shaft 9 upward so as to be
withdrawn from the supporting fixtures 24 fixed to the support
beams 7, thus resulting in troublesome work. In addition, when the
winder 8 is mounted at the top of the elevator pit 1, scaffolding
must be temporarily built up, which renders the replacement work
more troublesome.
[0010] Further, because the absolute value encoder 20 is in the
ring form and arranged in a surrounding relation to the projected
flange of the rotor 12, its inner diameter is so large that an
inexpensive absolute value encoder, which is usually employed in
general motors having rotary shafts, is not usable. This raises
another problem that the absolute value encoder 20 must be a custom
and expensive product.
[0011] Still another problem is that because the magnetic pole
position of the field magnet is indirectly determined by the
absolute value encoder 20 surrounding the projected flange of the
rotor 12, the accurate magnetic pole position of the field magnet
cannot be obtained.
[0012] The present invention has been accomplished with the view of
solving the problems set forth above, and its object is to provide
a drive machine for elevators which can determine the accurate
magnetic pole position of a field magnet, and can facilitate
maintenance work for a detecting unit to detect the magnetic pole
position, the rotating speed and the rotating direction of the
field magnet.
DISCLOSURE OF THE INVENTION
[0013] A first aspect of the present invention resides in a drive
machine for elevators, which comprises a rotatable drive sheave
over which a main cable for hanging an elevator cage is wound, a
stationary shaft for supporting rotation of the drive sheave and
bearing a load applied to the drive sheave from the main cable, a
field magnet attached to the drive sheave, constituting a part of
an electric motor, and comprising at least one pair of magnetic
poles, an armature attached to the stationary shaft in a facing
relation to the field magnet and constituting another part of the
motor, and a field magnetic pole detector for detecting the
predetermined magnetic pole of the field magnet rotated together
with the drive sheave.
[0014] A second aspect of the present invention resides in, on the
basis of the drive machine for elevators according to the first
aspect, that the field magnet comprises a permanent magnet.
[0015] A third aspect-of the present invention resides in, on the
basis of the drive machine for elevators according to the first or
second aspect, that the field magnetic pole detector comprises a
magnetic sensor attached to the stationary side in a close and
facing relation to the field magnet.
[0016] A fourth aspect of the present invention resides in, on the
basis of the drive machine for elevators according to the first
aspect, that a detected portion indicating the position of the
magnetic pole disposed on the drive sheave is provided on the drive
sheave in a facing relation to the field magnetic pole detector,
and the position of the predetermined magnetic pole is recognized
with the field magnetic pole detector detecting the detected
portion.
[0017] A fifth aspect of the present invention resides in, on the
basis of the drive machine for elevators according to the fourth
aspect, that the detected portion comprises a convex or concave
portion formed on or in the surface of the drive sheave
corresponding to the position of the predetermined magnetic
pole.
[0018] A sixth aspect of the present invention resides in, on the
basis of the drive machine for elevators according to the first
aspect, that the field magnetic pole detector is provided at least
three at a pitch equal to 1/3 of the pitch of one pair of the field
magnetic poles.
[0019] A seventh aspect of the present invention resides in, on the
basis of the drive machine for elevators according to the second or
sixth aspect, further comprising a rotation detector for detecting
rotation of the drive sheave with respect to the stationary shaft
as a reference, and drive control means for executing drive control
of the motor in accordance with results detected by the rotation
detector and the field magnetic pole detector, wherein the drive
control means starts up the motor in accordance with an imaginary
field magnetic pole position when the magnetic pole position of the
field magnet attached to the drive sheave is not known at the
start-up of the elevator, and executes the drive control in
accordance with the results detected by the field magnetic pole
detector and the rotation detector after the field magnetic pole
position has been recognized upon operation of the field magnetic
pole detector.
[0020] An eighth aspect of the present invention resides in, on the
basis of the drive machine for elevators according to the first
aspect, further comprising a rotation detector for detecting
rotation of the drive sheave with respect to the stationary shaft
as a reference, detection difference calculating means for
detecting the difference between the rotation of the drive sheave
detected by the rotation detector and the rotation of the drive
sheave detected by the field magnetic pole detector, and anomaly
determining means for determining the occurrence of an anomaly when
a value of the difference determined by the detection difference
calculating means exceeds a predetermined value.
[0021] A ninth aspect of the present invention resides in, on the
basis of the drive machine for elevators according to the eighth
aspect, further comprising drive control means for executing drive
control of the motor in accordance with results detected by the
rotation detector and the field magnetic pole detector, wherein
when the value of the difference determined by the detection
difference calculating means does not exceed the predetermined
value, the drive control means executes the control while
correcting an output value of the rotation detector in accordance
with the value of the difference.
[0022] A tenth aspect of the present invention resides in, on the
basis of the drive machine for elevators according to the first
aspect, further comprising a rotation detector for detecting
rotation of the drive sheave with respect to the stationary shaft
as a reference, memory means for storing an output of the rotation
detector in a corresponding relation to the position detected by
the field magnetic pole detector while the field magnetic pole
detector is detecting the field magnetic pole position with the
rotation of the drive sheave, and drive control means for executing
drive control of the motor in accordance with results detected by
the rotation detector and the field magnetic pole detector, wherein
the drive control means utilizes values stored in the memory means
for phase control of electric power supplied to the armature.
[0023] An eleventh aspect of the present invention resides in, on
the basis of the drive machine for elevators according to the first
aspect, further comprising a rotation detector for detecting
rotation of the drive sheave with respect to the stationary shaft
as a reference, and drive control means for executing drive control
of the motor in accordance with results detected by the rotation
detector and the field magnetic pole detector, wherein the amount
of change in value detected by the rotation detector is determined
at the start-up of the elevator while the field magnetic pole
detector detects one pair of the field magnetic poles, and the
drive control means executes phase control of the motor by setting
the amount of change as a reference value of a phase signal for one
pair of the field magnetic poles since then.
BRIEF DESCRTPTION OF THE DRAWINGS
[0024] FIG. 1 is a sectional view showing a structure of a drive
machine for elevators according to Embodiment 1 of the present
invention.
[0025] FIG. 2 is a sectional view taken along the line A-A of FIG.
1.
[0026] FIG. 3 is a chart showing the correlation between the
positions of proximity switches shown in FIG. 2 and signals from
the proximity switches.
[0027] FIG. 4 is a sectional view showing a structure of a drive
machine for elevators according to Embodiment 2 of the present
invention.
[0028] FIG. 5 is a sectional view taken along the line B-B of FIG.
4.
[0029] FIG. 6 is a block diagram showing inverter control in drive
machine according to Embodiments 3 and 4 of the present
invention.
[0030] FIG. 7 is a waveform chart for explaining the operation of
Embodiment 3 of the present invention.
[0031] FIG. 8 is a waveform chart for explaining another operation
of Embodiment 3 of the present invention.
[0032] FIG. 9 is a waveform chart for explaining still another
operation of Embodiment 3 of the present invention.
[0033] FIG. 10 is a waveform chart for explaining the operation of
Embodiment 4 of the present invention.
[0034] FIG. 11 is a perspective view of a conventional elevator
apparatus including a winder which comprises an outer rotor.
[0035] FIG. 12 is a sectional view showing a structure of a
conventional drive machine for elevators which comprises an outer
rotor.
BEST MODE FOR CARRYING OUT THE INVENTION
[0036] First Embodiment
[0037] FIG. 1 is a sectional view showing a structure of a drive
machine for elevators according to one embodiment of the present
invention. In FIG. 1, the same or corresponding parts as or to
those in the conventional drive machine described above are denoted
by the same symbols.
[0038] A winder 8 mainly comprises a stationary shaft 9 having
opposite ends supported by supporting fixtures 24, an armature
iron-core 11 (armature) having armature coils 10 wound over the
same, and a rotor 12 rotatably supported by the shaft 9 and
constituting a drive sheave 16. Note that O denotes an axis of the
shaft 9.
[0039] The rotor 12 includes a field permanent magnet 14 (field
magnet) disposed inside the rotor to face the armature iron-core
11, cable grooves 15 formed in an outer periphery of the rotor for
receiving a main cable 18 wound over the rotor, and machined
portions 30 (detected portions) in the form of recesses which are
used to detect the magnetic pole position of the field permanent
magnet 14. Additionally, bearings 17 are disposed between the rotor
12 and the shaft 9.
[0040] While the winder utilizing the permanent magnet 14 as a
field magnet is described here, the present invention is also
similarly applicable to another type of winder wherein an iron core
having coils wound around the same is disposed (not shown) in place
of the permanent magnet, and electric power is supplied to the
coils through a slip ring, thereby generating a magnetic field as
with the permanent magnet.
[0041] Further, around the winder 8, there are provided proximity
switches 27 as field magnetic pole detectors for detecting the
position of each machined portion 30 in the form of a recess, and a
rotary encoder 29 serving as a rotation detector and including a
roller 28 held pressed against the outer periphery of the rotor 12
for detecting the rotating speed and the rotating direction of the
rotor 12. Numeral 25 denotes a mounting stand for the rotary
encoder 29. The proximity switches 27 may be attached to the
mounting stand 25, or may be attached to a dedicated mounting stand
(not shown) which is provided separately.
[0042] FIG. 2 is a sectional view taken along the line A-A of FIG.
1, showing the positional relationship among the machined portion
30 in the form of a recess, the field permanent magnet 14, and the
proximity switches 27a-27c. Referring to FIG. 2, the outer
periphery of the rotor 12 is machined to have a recess (30) in a
position coincident with the position of each N pole of the field
permanent magnet 14 where the pole is fixed to the rotor 12, as
viewed from the center LO of the rotating shaft in the radial
direction, while the rotor outer periphery is not machined to have
a recess in a position coincident with the position of each S pole
where it is fixed to the rotor 12.
[0043] To detect the positions of the concave and convex machined
portions 30 formed in the outer periphery of the rotor 12, three
proximity switches 27a-27c are mounted in a close relation to the
concave and convex machined portions 30. Supposing that an angle
occupied by one pair of N and S poles of the field permanent magnet
14 is .alpha., the proximity switches 27a-27c are arranged along
the outer periphery of the rotor 12 in such positions that the
interval (pitch) between the proximity switches is .alpha./3.
[0044] Next, how respective signals from the proximity switches
27a-27c change depending on their relative positions to the concave
and convex machined portions 30 will be described in conjunction
with FIG. 3. For the convenience of explanation, the positions of
the concave and convex portions and the magnets, and the mount
positions of the proximity switches are represented in the linear
form.
[0045] When the concave and convex portions are moved from the
position shown in FIG. 3 in the direction of arrow S, the signals
from the proximity switches 27a-27c change as shown, namely change
in six combinations P1-P6, while the rotor moves through-the angle
a corresponding to one pair of the concave and convex portions.
After that, the signals from the proximity switches 27a-27c change
in the same manner repeatedly. Since the concave and convex
portions are positioned in a one-to-one relation to the magnetic
poles, .alpha. is given by 360 degrees representing one cycle of
the magnetic pole phase, and therefore P1 to P6 each represent a
range of 60 degrees. In other words, the magnetic pole position can
be determined based on the combinations in state of the signals
from the proximity switches 27a-27c with resolution of 60
degrees.
[0046] As well known, a synchronous motor of the type employing a
permanent magnet cannot start up unless the magnetic pole position
of a fled magnet is known at the time of start-up. With the method
according to this Embodiment, the magnetic pole position can be
detected with an angular range of 60 degrees. Assuming that the
magnetic pole position locates at the middle of the 60-degree
range, an error between the actual magnetic pole position and the
measured magnetic pole position is .+-.30 degrees at maximum. When
the synchronous motor of the type employing a permanent magnet is
operated under vector control, a torque reduction of 13% occurs at
a maximum error because of cos30.degree.=0.87, but a sufficient
torque for the start-up can be generated. Once the rotor 12 is
rotated and a level of the signal from any-one of the proximity
switches 27a-27c is changed over, the magnetic pole position can be
precisely detected at that time, and current phase control can be
performed with a highly-accurate magnetic pole position signal
since then.
[0047] When later-described drive control means for the winder 8 in
the form of a motor, shown in FIG. 6, cannot know in which position
the motor locates relative to the corresponding field magnetic pole
at the start-up, i.e., when it is not known how far the motor has
rotated, before stopping, from the changing-over point of the
magnetic pole to be detected, an imaginary position in the field
magnet is introduced and phase control is performed in accordance
with the imaginary position in the field magnet until the first
field magnetic pole detector starts operation. By so doing, the
drive sheave can be started up even if the position in the field
magnet is not known at the start-up.
[0048] Further, since the changing-over point between the concave
and convex portions is coincident with the changing-over point
between the magnetic poles, this provides such an advantage that
the changing-over point between the magnetic poles can be directly
read based on the signals from the proximity switches 27a-27c. On
the other hand, the rotating direction and the rotating speed of
the rotor 12 are determined based on a signal from the rotary
encoder 29.
[0049] The concave and convex machined portions may be provided in
any other suitable locations than the outer periphery of the rotor.
A similar operating effect as described above can be obtained if
the concave and convex machined portions are located in coincidence
with the positions of the magnetic poles of the field magnet as
viewed from the center of the rotating shaft in the radial
direction. The similar operating effect can also be obtained by
attaching a ring with concave and convex portions in coincidence
with the magnetic pole positions rather than directly machining the
rotor (drive sheave) to have the concave and convex portions.
[0050] As described above, since the proximity switches 27a-27c
serving as field magnetic pole detectors and the rotary encoder 29
serving as a rotation detector are arranged as separate components
in an easily detachable manner, it is easy to carry out check and
displacement in the event of failure.
[0051] Moreover, since the field magnetic pole position is directly
detected from the concave and convex machined portions 30 precisely
corresponding to the field permanent magnet 14 which provides field
magnetic poles, the winder can be controlled with good
accuracy.
[0052] Second Embodiment
[0053] FIG. 4 is a sectional view showing a structure of a drive
machine for elevators according to another embodiment of the
present invention, and FIG. 5 is a sectional view taken along the
line B-B of FIG. 4. A principal part of this embodiment is the same
as shown in FIGS. 1 and 2. This embodiment employs, as field
magnetic pole detectors, three magnetic sensors 70a-70c provided in
the proximity of the field permanent magnet 14. Numeral 71 denotes
a mounting fixture for the magnetic sensors 70a-70c. The magnetic
sensors 70a-70c obtain information about the position in a field
magnet, i.e., the field magnetic pole position, by directly
detecting the magnetic field generated by the field permanent
magnet 14.
[0054] With such an arrangement, since the magnetism generated by
the field magnet is directly detected by the magnetic sensors, the
construction is simplified and the magnetic pole position can be
more precisely obtained. In addition, by combining the magnetic
sensors with a permanent magnet to provide field magnetic poles,
the position in the field magnet can be roughly detected from the
magnitude of detected magnetic flux even while the rotor is
stopped.
[0055] Third Embodiment
[0056] A phase control method used in the case of detecting the
rotation of the winder 8 by the rotary encoder 29 using the roller
28, and detecting the magnetic pole position by separate magnetic
pole position detectors, as described in the above First and Second
Embodiments, will be described below with reference to FIGS. 6 and
7. FIG. 6 is a control block diagram of an inverter for driving the
winder 8 which comprises a synchronous motor of the outer rotor
type employing a permanent magnet as a field magnet. Note that an
elevator control section, a position control section, etc., which
are not directly related to the present invention, are omitted from
the drawing.
[0057] In FIG. 6, the same or corresponding parts as or to those in
the above Embodiments are denoted by the same symbols. Numeral 43
denotes an inverter for driving the winder 8 which comprises an
outer rotor motor, 27 denotes a proximity switch for detecting the
field magnetic pole position within the winder 8, and 29 denotes a
rotary encoder for detecting the rotation of the winder 8 through
the roller 28. Further, denoted by numeral 40 is a power supply, 41
is a converter, 42 is a smoothing capacitor, 2 is an elevator cage,
and 4 is a counterweight.
[0058] Numeral 45 denotes a speed detecting section for determining
the speed based on a signal from the rotary encoder 29, 46 denotes
a phase detecting section for determining the current phase based
on a signal from the rotary encoder 29, 47 denotes a magnetic pole
position detecting section for determining the magnetic pole
position based on signals from the proximity switches 27, 49
denotes a speed control section for combining a speed command and a
speed feedback signal w to calculate a torque current command iq,
50 denotes a current command creating section for calculating a
current command from an excitation current command id, the torque
current command iq and a phase signal .theta., and 51 denotes a
current control section for combining the current command and a
current detection signal from a current sensor 44 to output a
control signal to the inverter 43.
[0059] Numeral 55 denotes memory means for storing, in a correlated
manner, the current phase, i.e., the position in the field magnet,
determined by the phase detecting section 46 based on the signal
from the rotary encoder 29, and the magnetic pole position
recognized by the magnetic pole position detecting section 47 based
on the signals detected by the proximity switches 27. Numeral 56
denotes detection difference calculating means for determining the
difference between the magnetic pole position recognized by the
magnetic pole position detecting section 47 based on the signals
detected by the proximity switches 27 and the magnetic pole
position determined by the phase detecting section 46 based on the
signal from the rotary encoder 29. Numeral 57 denotes anomaly
determining means for generating an abnormal signal upon
determining the occurrence of an anomaly if the difference or
deviation in the magnetic pole position resulted from the different
detectors and determined by the detection difference calculating
means 56 exceeds a predetermined value.
[0060] A manner of determining the phase signal .theta. will now be
described with reference to FIG. 7. In FIG. 7, alphabet A
represents an initial state immediately after power-on, and the
phase signal .theta. is set to a phase signal .theta.A that is
determined from a combination of the signals from the three
proximity switches 27 in accordance with the above-described
method. Subsequently, when the winder 8 is rotated and a pulse
signal is outputted from the rotary encoder 29 with the rotation of
the winder 8, the phase detecting section 46 counts the number of
the pulses, and outputs the phase signal .theta. after multiplying
the counted number by a phase angle corresponding to one pulse.
Further, in the synchronous motor, the current phase signal .theta.
must be coincident with the cycle of the magnetic pole position of
the field magnet.
[0061] To that end, the phase signal .theta. is reset to be
coincident with 0 degree, for example, at the changing-over point
from the S to N pole of the magnetic pole position signal
determined based on the signals from the proximity switches 27, as
shown in FIG. 7.
[0062] As shown in FIG. 8, however, the length of one cycle of each
detector signal may change due to errors in machining of the
concave machined portions 30 serving as the detected portions in
Embodiment 1, or errors in installation of the proximity switches
27a-27c used in Embodiment 1 and the magnetic sensors 70a-70c used
in Embodiment 2 which serves as the field magnetic pole detectors.
If the length of one cycle is shortened, for example, the phase
signal .theta. is reset to 0 degree before reaching 360 degrees.
Conversely, if the length of one cycle is prolonged, the phase
signal .theta. is reset midway the succeeding cycle. This results
in that the phase signal .theta. becomes not consistent and the
motor cannot rotate smoothly.
[0063] To cope with the above-mentioned problem, the length
corresponding to each cycle of the magnetic poles is stored as the
difference in counted value of the output pulses from the rotation
detector (rotary encoder 29) over the entire circumference of the
winder 8. Thus, a time period (a) in FIG. 8 is represented by a
value of C2-C1, a time period (b) by a value of C3-C2, and a time
period (c) by a value of C4-C3.
[0064] In a shorter time period, e.g., the time period (b), than
the standard one (a), the amount of change in value of the phase
signal .theta. corresponding to one count of the output pulses from
the rotation detector is calculated from the stored pulse counted
values, and is set to be larger than in the standard time period to
modify the value of the phase signal .theta. so that one cycle
completes at 360 degrees. Conversely, in a longer time period,
e.g., the time period (c), than the standard one (a), the amount of
change in value of the phase signal .theta. is set to be smaller
than in the standard time period to modify the value of the phase
signal .theta. so that one cycle completes at 360 degrees. Stated
otherwise, as shown in FIG. 8, while the phase signal .theta. has
the same slope for each time period in the unmodified case, the
slope of the phase signal .theta. is changed depending on the
stored length of one cycle in the modified case. With such a
modification, the value of the phase signal .theta. is kept from
becoming inconsistent, and smooth phase control can be
achieved.
[0065] The operation in the above case will be described below with
reference to FIG. 6. After the winder 8 has started up, the
magnetic pole position detecting section 47 detects the
changing-over point in the cycle of the magnetic poles, and assigns
the successive number to each cycle from the first cycle over a
full turn. At the same time, the assigned numbers and the
difference in counted value of the output pulses from the rotary
encoder 29 for each cycle are stored in the storage means 55. After
that, the magnetic pole position detecting section 47 outputs, to
the phase detecting section 46, information indicating in what
number of magnetic pole cycle the winder 8 is positioned at this
moment. In accordance with the indicated number of magnetic pole
cycle, the phase detecting section 46 reads the difference in
counted value of the corresponding magnetic pole cycle from the
storage means 55, and determines the length of the cycle. Then, in
consideration of correspondence between the signal newly inputted
from the rotary encoder 29 and the length of the cycle, the phase
detecting section 46 modifies and calculates the phase signal
.theta. so that one cycle completes at 360 degrees. The modified
phase signal .theta. is outputted to the current command creating
section 50.
[0066] On the other hand, because the rotation of the winder 8 is
detected by the rotary encoder 29 using the roller 28, there is a
possibility that slippage of the roller may occur. The function of
detecting such a slippage and the function of generating an
abnormal signal will now be described with reference to FIG. 9.
[0067] If the rotation of the rotary encoder 29 becomes slower than
the rotation of the winder 8 due to slippage of the roller 28
during the operation, the phase signal .theta. deviates by a large
amount from 360 degrees at the changing-over point of the magnetic
pole position signal as indicated by X in FIG. 9. In view of such a
problem, at the changing-over point from the S to N pole of the
magnetic pole position signal from the magnetic pole position
detecting section 47, the detection difference calculating means 56
determines how far the phase signal .theta. from the phase
detecting section 46 deviates from 0 degree or 360 degrees. Then,
the anomaly determining means 57 sets an angle of a certain width d
at the changing-over point from the S to N pole of the magnetic
pole position signal from the magnetic pole position detecting
section 47 as shown in FIG. 9, and monitors whether the angle of
the phase signal .theta. from the phase detecting section 46
deviates over the angle d not, thereby outputting an abnormal
signal if the deviation over the angle d occurs. The width of d is
set to about 10 degrees in terms of phase angle, taking into
account that a torque reduction should not be so increased and that
a speed detection error should not be so enlarged.
[0068] Further, when the rotation of the winder 8 is sped up, there
also occurs an error in the magnetic pole position signal due to a
delay in operation of the proximity switches 27. Since this error
is proportional to the speed, the speed feedback signal .omega. is
applied to the magnetic pole position detecting section 47 which
creates the magnetic pole position signal after compensating for
the error in accordance with the speed feedback signal .omega..
This process increases the accuracy in detecting slippage of the
roller. On the other hand,-a response speed of the rotary encoder
29 is sufficiently high and a delay in operation thereof is
negligible.
[0069] Fourth Embodiment
[0070] When the rotation of the winder 8 is detected by the rotary
encoder 29 using the roller 28 like the above Embodiment 1, the
roller 28 may be abraded to cause a change of configuration over
time and hence to produce an error in the phase signal .theta..
Supposing, for example, that the roller 28 has a diameter of 100 mm
and the length of one pair of magnetic poles of the field permanent
magnet 14 is exactly equal to 1/2 of the outer circumference of the
roller 28, if the roller 28 is abraded 0.1 mm and the diameter is
changed to 99.8 mm, the phase signal .theta. would shift 90 degrees
in terms of the magnetic pole phase after only 62.5 rotations of
the roller 28. The 90-degree shift of the magnetic pole phase means
that the torque applied to the winder 8 becomes zero.
[0071] To cope with that problem, as shown in FIG. 10, immediately
after the start-up of the winder 8, the number of output pulses
from the rotary encoder 29 is counted (a value given by PB-PA in
the drawing) for one cycle of the signal from the proximity switch
27 (indicated by the signal from 27a in the drawing), and the
counted value is used as a reference value for one cycle of the
magnetic pole phase in the subsequent phase calculation until the
winder 8 is stopped. Since the length of one pair of magnetic poles
of the field permanent magnet 14 is fixed regardless of the roller
abrasion, the pulse count for one cycle of the magnetic pole phase
can be correctly detected even if the roller diameter varies due to
a change of configuration over time. As an alternative, counting
the number of pulses over several cycles and calculating an average
of the counted numbers as a standard value further increases the
accuracy. Such a modification can be easily implemented, for
example, by adding a correcting section 46a, which has the
calculating and storing functions and the temporarily storing
function required for the modified process, to the phase detector
46 shown in FIG. 6.
INDUSTRIAL APPLICABILITY
[0072] As described above, according to the first aspect of the
present invention, a drive machine for elevators comprises a
rotatable drive sheave over which a main cable for hanging an
elevator cage is wound, a stationary shaft for supporting rotation
of the drive sheave and bearing a load applied to the drive sheave
from the main cable, a field magnet attached to the drive sheave,
constituting a part of an electric motor, and comprising at least
one pair of magnetic poles, an armature attached to the stationary
shaft in a facing relation to the field magnet and constituting
another part of the motor, and a field magnetic pole detector for
detecting the predetermined magnetic pole of the field magnet
rotated together with the drive sheave. With the provision of the
field magnetic pole detector capable of directly and precisely
detecting the position in the field magnet, rotational angle
control of the drive sheave and control of the motor can be
implemented with good accuracy.
[0073] According to the second aspect of the present invention, on
the basis of the first aspect, the field magnet comprises a
permanent magnet. If a field magnet using winding coils is attached
to the rotatable drive sheave, a special device such as a slip ring
is required to supply excitation currents to the coils. By
contrast, the use of a permanent magnet eliminates the need of such
a special device.
[0074] According to the third aspect of the present invention, on
the basis of the first or second aspect, the field magnetic pole
detector comprises a magnetic sensor attached to the stationary
side in a close and facing relation to the field magnet. Therefore,
the magnetism generated by the field magnet can be directly
detected by the magnetic sensor, and hence the construction is
simplified. In addition, by combining the magnetic sensor with the
use of the above permanent magnet, the position in the field
magnetic can be roughly detected from the magnitude of detected
magnetic flux even while the motor is stopped.
[0075] According to the fourth aspect of the present invention, on
the basis of the first aspect, a detected portion indicating the
position of the magnetic pole disposed on the drive sheave is
provided on the drive sheave in a facing relation to the field
magnetic pole detector, and the position of the predetermined
magnetic pole is recognized with the field magnetic pole detector
detecting the detected portion. With this feature, an optimum
detected portion adapted for the field magnetic pole detector can
be provided on the drive sheave, and the detecting position can be
set with good accuracy and high flexibility.
[0076] According to the fifth aspect of the present invention, on
the basis of the fourth aspect, the detected portion comprises a
convex or concave portion formed on or in the surface of the drive
sheave corresponding to the position of the predetermined magnetic
pole. By simply machining a portion of a body of the drive sheave
in synch with the magnetic pole position of the field magnet
attached to the drive sheave, therefore, the detected portion can
be formed without intricate machining and additional parts to
constitute special detected means.
[0077] According to the sixth aspect of the present invention, on
the basis of the-first aspect, the field magnetic pole detector is
provided at least three at a pitch equal to 1/3 of the pitch of one
pair of the field magnetic poles. Therefore, the field magnetic
pole position can be recognized with resolution of 60 degrees by
only the field magnetic pole detectors. In other words, the field
magnetic pole position can be detected by a small number of field
magnetic pole detectors. In addition, even the resolution of 60
degrees corresponds to a torque error less than 15% in control of
the motor, and is within the allowable range from the viewpoint of
control capability.
[0078] According to the seventh aspect of the present invention, on
the basis of second or sixth aspect, the drive machine for
elevators further comprises a rotation detector for detecting
rotation of the drive sheave with respect to the stationary shaft
as a reference, and drive control means for executing drive control
of the motor in accordance with results detected by the rotation
detector and the field magnetic pole detector, wherein the drive
control means starts up the motor in accordance with an imaginary
field magnetic pole position when the magnetic pole position of the
field magnet attached to the drive sheave is not known at the
start-up of the elevator, and executes the drive control in
accordance with the results detected by the field magnetic pole
detector and the rotation detector after the field magnetic
pole-position has been recognized upon operation of the field
magnetic pole detector. With this feature, when the drive control
means cannot know in which position the motor locates relative to
the corresponding field magnetic pole at the start-up, i.e., when
it is not known how far the motor has rotated, before stopping,
from the point to be detected (the changing-over point of the field
magnetic pole), the imaginary field magnetic pole position is
introduced and phase control is performed in accordance with the
imaginary field magnetic pole position until the first field
magnetic pole detector starts operation. Thus, the drive sheave can
be started up even if the position in the field magnet is not known
at the start-up.
[0079] According to the eighth aspect of the present invention, on
the basis of the first aspect, the drive machine for elevators
further comprises a rotation detector for detecting rotation of the
drive sheave with respect to the stationary shaft as a reference,
detection difference calculating means for detecting the difference
between the rotation of the drive sheave detected by the rotation
detector and the rotation of the drive sheave detected by the field
magnetic pole detector, and anomaly determining means for
determining the occurrence of an anomaly when a value of the
difference determined by the detection difference calculating means
exceeds a predetermined value. It is therefore possible to early
find an anomaly in the rotation detector, the field magnetic pole
detector, or the detected portion.
[0080] According to the ninth aspect of the present invention, on
the basis of the eighth aspect, the drive machine for elevators
further comprises drive control means for executing drive control
of the motor in accordance with results detected by the rotation
detector and the field magnetic pole detector, wherein when the
value of the difference determined by the detection difference
calculating means does not exceed the predetermined value, the
drive control means executes the control while correcting an output
value of the rotation detector in accordance with the value of the
difference. Accordingly, if there occurs a slight anomaly such as
abrasion of a roller over time, the elevator can continue the
operation for the present just by slightly correcting a detected
value of the rotation detector. As a result, a rest time of the
elevator attributable to the detection of anomaly can be
minimized.
[0081] According to the tenth aspect of the present invention, on
the basis of the first aspect, the drive machine for elevators
further comprises a rotation detector for detecting rotation of the
drive sheave with respect to the stationary shaft as a reference,
memory means for storing an output of the rotation detector in a
corresponding relation to the position detected by the field
magnetic pole detector while the field magnetic pole detector is
detecting the field magnetic pole position with the rotation of the
drive sheave, and drive control means for executing drive control
of the motor in accordance with results detected by the rotation
detector and the field magnetic pole detector, wherein the drive
control means utilizes values stored in the memory means for phase
control of electric power supplied to the armature. The accuracy in
installation of the field magnetic pole detector or the
corresponding detected portion may affect phase control for one
rotation of the drive sheave. Further, it is not always ensured
that the pitch of the pair of field magnetic poles is divided so as
to evenly cover one rotation. Storing values detected by each field
magnetic pole detector and values detected by the rotation detector
makes it possible to implement the phase control with good accuracy
by referring to the stored value and utilizing them in a combined
manner for effective compensation.
[0082] According to the eleventh aspect of the present invention,
on the basis of the first aspect, the drive machine for elevators
further comprises a rotation detector for detecting rotation of the
drive sheave with respect to the stationary shaft as a reference,
and drive control means for executing drive control of the motor in
accordance with results detected by the rotation detector and the
field magnetic pole detector, wherein the amount of change in value
detected by the rotation detector is determined at the start-up of
the elevator while the field magnetic pole detector detects one
pair of the field magnetic poles, and the drive control means
executes phase control of the motor by setting the above amount of
change as a reference value of a phase signal for one pair of the
field magnetic poles since then. When the values detected by the
rotation detector are neither sure nor definite with respect to the
field magnetic poles, the amount of change in value detected by the
rotation detector while the field magnetic pole detector detects
the first pair of field magnetic poles is set as a temporary
reference and is utilized in subsequent calculation for the phase
control. Even if the position in the field magnet is not known
since then, the phase calculation can be relatively precisely
implemented. Once the drive sheave makes a turn under the drive
control based on the temporary reference, the subsequent phase
control can be implemented with good accuracy by precisely
recognizing the mutual positions detected by each field magnetic
pole detector and the rotation detector during the turn as with the
above tenth aspect of the present invention.
* * * * *