WO2003024855A1

WO2003024855A1 - A device and a method for driving an elevator door

Info

Publication number: WO2003024855A1
Application number: PCT/KR2002/000947
Authority: WO
Inventors: Dong-Joon Sim; Ji-Taek Yoon
Original assignee: Emt International Co., Ltd.
Priority date: 2001-07-31
Filing date: 2002-05-20
Publication date: 2003-03-27
Also published as: KR100422730B1; KR20030012278A; CN1701034A

Abstract

A device and a method for driving an elevator door which uses a brushless DC motor for providing sliding force.

Description

[DESCRIPTION]

[TITLE]

A Device and A Method for Driving An Elevator Door

[TECHNICAL FILED]

The present invention relates to a device and a method for driving an

elevator door. More particularly, the present invention relates to a device and a

method for driving an elevator door which is installed to be opened and closed

automatically on an elevator.

[BACKGROUND ART]

In general, an elevator includes an elevator car and a pair of doors at a

landing site on each floor. A door driving device for driving the doors is installed

at a predetermined portion of the elevator car. When the elevator car arrives at

the landing site of each floor, a pair of doors of the elevator car and the pair of

doors of the landing site are engaged with each other and opened or closed by

the door driving device installed in the elevator car. An elevator door system is

defined to be devices including the door driving device as described hereinafter

and other mechanical or electrical elements for opening or closing the door.

Referring to Fig. 1 , an example of a widely known door driving device of

an elevator is described. Fig. 1 shows a schematic block diagram of a

conventional elevator door system and a conventional door driving device included in the system.

As shown in Fig. 1, the conventional elevator door system 1 includes a

door driving device 100 for controlling doors 30a or 30b to be placed at a

predetermined position with electric powers supplied from a power source 10,

pulleys 16a and 16b and an arm 18 for transferring torques provided from the

door driving device 100 to the doors 30a or 30b, and at least two limit

switches 20a and 20b turned on or off according to the position of the doors

30a or 30b.

In addition, the door driving device 100 of the conventional elevator door

system 1 includes a motor 14 for providing torques and a motor controller 12 for

driving the motor 14 in response to outputted signals from the limit switches 20a

and 20b. Examples of the motor 14 used for the conventional door driving

device 100 may includes a DC motor, a one-phase induction motor, a three-

phase induction motor, etc.

Control characteristics for driving an elevator door, as described above,

include;

1) to drive the doors repeatedly moving within a predetermined distance,

2) in control of door opening or closing velocity and door position,

2-1) that it is not required to achieve a very precise position

control of a so-called "servo-level control", in other words, that it is

allowable to have position control tolerance of several millimeters.

2-2) that sudden accelerating or decelerating operation should be prevented while the door is opened or closed.

According to the conventional door driving device 100 used in the

conventional elevator door system 1 , since driving operation of the motor 14 is

totally dependent on on or off state of the limit switches 20a or 20b, there is a

problem that smooth driving is difficult to open or close the door.

Further, in case additional parts are attached to compensate control

precision, it causes problems of increase of cost, energy consumption, number

of control elements, difficulty in control stability, etc.

[DISCLOSURE OF INVENTION]

The present invention is suggested in order to fix the aforementioned

' problems, and the object of the present invention is providing a device and a

method for driving an elevator door appropriate and stable to satisfy control

characteristics of an elevator door.

[DETAILED DESCRIPTION]

In order to accomplish the object, the present invention provides a door

driving device, which includes a power source for supplying electric power, a

door moving a predetermined driving distance reciprocally, and a power

transferring unit for transforming rotating motion into linear motion in order to

open or close the door, including: a brushless DC motor for providing torque for

driving the door and outputting a rotor's position signal (pr); and a controller for determining operation state of the door on the basis of the rotor's position signal

outputted from the brushless DC motor and driving the brushless DC motor in

response to the determined operation state of the door.

Further, the present invention also provides a door driving method of an

elevator door system, which includes a power source for supplying electric

power, a door moving a predetermined driving distance reciprocally, a brushless

DC motor for providing torque for driving the door and outputting a rotor's

position signal (p_r) and a power transferring unit for transferring torque of the

brushless DC motor to the door, the method including steps of: receiving a door

driving command from a controlling device of the elevator system; receiving the

rotor's position signal (p_r) outputted from the brushless DC motor; determining

operation state of the door on the basis of the received rotor's position signal

(p_r); and driving the brushless DC motor on the basis of the determined

operation state of the door.

[BRIEF DESCRIPTION OF DRAWINGS]

Fig. 1 shows a schematic block diagram of a conventional elevator door

system and a conventional door driving device included in the system.

Fig. 2 shows a block diagram of an embodiment of an elevator door

driving device according to the present invention and an elevator door system

including the elevator door driving device.

Fig. 3a shows examples of waveforms of position signals of a rotor in the brushless DC motor provided in the door driving device shown in Fig. 2.

Fig. 3b shows a data table of binary-codes of waveforms shown in Fig.

3a.

Fig. 4 is a flow chart showing operation processes of the door driving

device shown in Fig. 2 according to an embodiment of the present invention.

Fig. 5 shows a functional block diagram of a controller used for the door

driving device shown in Fig. 2.

Fig. 6 shows a schematic block diagram of an elevator door driving

device according to another embodiment of the present invention.

*Explanation of symbols of some parts in the drawing

1 , 2: an elevator door system 10: a power source 30a, 30b: doors

100a, 100b, 200: a door driving device

16, 18: a power transferring unit

[BEST MODE FOR CARRYING OUT THE INVENTION]

In the following, preferred embodiments of the present invention are

described in detail with reference to attached drawings.

Referring to Fig. 2, Fig. 2 shows a block diagram of an embodiment of

the elevator door driving device according to the present invention and a

elevator door system including the elevator door driving device. As shown in Fig.

2, the elevator door system 2 including the door driving device 200 of the

present invention includes a power source 10 for supplying electric power, a pair of doors 30a and 30b which are opened or closed by moving reciprocally in a

predetermined moving distance, a door driving device 200 for driving the doors

30a and 30b by using supplied power from the power source 10, and a power

transferring unit, namely pulley 16 and arm 18, for transferring torque from the

door driving device 200 to the doors 30a and 30b.

Details, modifications, and applications of the power source 10, the

doors 30a and 30b, and the power transferring unit 16 and 18 are already widely

known in the art, and thus may be omitted.

The door driving device 200 of the present invention especially includes

a brushless DC motor 214 for providing torque to drive the doors 30a and 30b

and outputting position signal (p_r) of a rotor thereof. Characteristics and usages

of the rotor's position signal (p_r) produced by the brushless DC motor 214 will be

described in more detail, later.

Further, the door driving device 200 determines operation state of the

doors 30a and/or 30b on the basis of the rotor's position signal (p_r) outputted

from the brushless DC motor 214, and includes a controller 212 for driving the

brushless DC motor 214 on the basis of the operation state of the doors 30a

and/or 30b.

Now, an examplary embodiment of the rotor's position signal (p_r)

provided by the brushless DC motor 214, which is widely known at the present

time, is described in detail. Fig. 3a shows waveforms of the rotor's position

signals (p_r) of a three-phase brushless DC motor 214 included in the door driving device 200 shown in Fig. 2. Fig. 3b shows a data table formed by binary-

coding the waveforms shown in Fig. 3a.

The three-phase brushless DC motor 214 includes three Hall sensors,

one of which is representatively designated by 216 in Fig. 2, installed at intervals

of 120 degrees of electric angle in order to be corresponded to predetermined

positions of a stator thereof, so that each of the Hall sensors 216 detects a

rotor's position and outputs the rotor's position signal (p_r) as shown in Fig. 3a.

The controller 212 drives the three-phase brushless DC motor 214 by using the

rotor's position signals (p_r) according to a predetermined rule. Each of the rotor's

position signals (p_r), as shown in Fig. 3a, has high and low outputs alternately at

every 180-degree in the electrical angle (θ), and there are three kinds of

position signals having phase differences of 120 degrees among one another.

Therefore, it is possible to acquire an identifiable output at every 60-degree in

the electrical angle by using the rotor's position signal (p_r).

Fig. 3b shows a data table acquired by binary-coding the outputted

position signal of each phase by mapping a high output to "1" and a low output

to "0" with 60-degree in the electrical angle as a unit. As shown, considering the

data acquired from A, B and C phase position signals as 3-unit binary coded

data, the rotor's position signals (p_r) provided by the 3-phase brushless DC

motor are in the format of gray codes.

Therefore, since outputs are identifiable at every 60-degree in the

electrical angle, a possible maximum error in position control is equal to or less than 60 degrees in the electrical angle, and is equal to or less than 120 degrees

per number of poles in mechanical angle domain. In general, a small brushless

DC motor adopts 4, 6 or 8 poles, and the mechanical possible maximum error

may be 30, 20 or 15 degrees, respectively, in case of the conventional small

brushless DC motor.

In order for a better understanding, this maximum possible error, or

resolution, can be converted into distance by using the equation of

{(circumference of motor shaft)/(a constant x number of poles)}, thereby the

maximum possible errors in distance are 2.5, 1.67 and 1.25 millimeters,

respectively, in case of motors having 4, 6 and 8 poles with shafts of

circumferences of 30 millimeters. In this way, it is possible to achieve a sufficient

level of precision to control positions of the elevator doors.

Further, in case the rotor rotates in an opposite direction to the case

described above, order of signals outputted in each phase is opposite to that in

the above described case so that rotating direction of the motor 214 can be

detected by using this fact.

Of course, type or size, etc. of the brushless DC motor 214 is not limited

if it is appropriate to be used for the door driving device 200 of the present

invention. On the other hand, the most effective method for using the 3-phase

brushless DC motor has been explained in the above, but it should be

understood that a method for using a rotor's position signal (p_r) of a brushless

DC motor is not limited to that described above. For instance, it may also be used to detect rotating direction based on signals of two phases and velocity

based on signals of the other phase, or to detect both velocity and rotating

direction based on signals of only two phases, etc.

The door driving device 200 of the present invention performs following

operations using the rotor's position signal (p_r) produced by the brushless DC

motor 214 having the waveform as described above. Hereinafter, there will be

described an embodiment of a method for using the rotor's position signal (p_r) of

the 3-phase brushless DC motor 214.

If the rotor's position signal (p_r) of waveforms as described above is

used, operations performed by the end-limit switch of the conventional elevator

can be embodied as a software program, and thus the doors 30a and 30b can

be driven precisely and easily without an extra hardware like the end-limit switch.

In order to embody this, the door driving device 200 of the present invention

performs an operation for measuring a door driving distance when it is first

installed, an operation for outputting an end-limit signal and an operation for

initializing at power-on, etc. Detailed description will follow.

First of all, the operation for measuring a door driving distance at

installation is to measure a distance (defined as "a driving distance" in the

present specification) from a location where the doors 30a and 30b are fully

opened to a location where the doors 30a and 30b are tightly closed.

That is to say, the elevator doors 30a and 30b are driven to be fully

opened (or tightly closed) at the first installation, then a moving distance of each of the doors 30a and 30b is measured until each of the doors 30a and 30b is

tightly closed (or fully opened), namely the door 30a or 30b does not move any

further, in the opposite direction at a low speed from the above locations as

starting points.

Next, this moving distance of each of the doors 30a and 30b is stored in

the controller 212 as a driving distance of the doors 30a and 30b to which the

door driving device 200 is installed. Herein, in order to minimize an error which

may be caused by belt slip, etc., it is preferred that the doors 30a and 30b are

driven at as slow speed as possible.

Calculation (or measurement) of the moving distance may be performed

by multiplying the number of the rotor's position signals (p_r), which are inputted

during the first driving of the doors 30a and 30b, to the resolution of the

brushless DC motor 214, and determined by the following equation. That is to

say,

[Equation 1]

a moving distance = (number of the rotor's position signals) x

[ (circumference of shaft) / (number of poles x number of phases)]

Of course, the method for calculating the moving distance may be

changed according to selection of rotor's position signals (p_r). But, the new

method is not quite different from the case of the Equation 1 , and the selection is

just one of design options in embodiments, thus detailed description about them

is omitted. By setting door driving patterns, such as a maximum velocity,

accelerating or decelerating time after the driving distance is measured as

described above, a moving distance of the door 30a or 30b, which means

present location of the door 30a or 30b, can be known and velocity of the door

30a or 30b can be calculated from the moving distance and time of the door 30a

and 30b. Therefore, the doors 30a and 30b can be driven smoothly by

controlling the rotating velocity of the motor 214 precisely without any extra

velocity detector.

In order to drive the elevator system safely, in general, the controller of

the elevator system is designed to receive end-point signals indicating that the

door 30a or 30b reaches a predetermined stop position.

In the conventional elevator door system 1 , output of the end-limit switch

out of the limit switches 20a and 20b is transmitted directly to the controller of

the elevator system as an end-point signal. But, the limit switches 20a and 20b

produce signals by physically contacting the doors 30a and 30b, and thus there

are problems like malfunction, breakdown, etc. mainly resulted from being

deteriorated by long use.

On the contrary, the door driving device 200 of the present invention

removes the needs for using the conventional end-limit switches by performing

the end-point signal outputting operation as described hereinafter. That is to say,

in case the doors 30a and 30b are determined to be in the state where they are

fully opened or tightly closed, the door driving device 200 produces the end- point signal by itself and transmits the produced signal to the controller (not

shown) of the elevator system.

A method for determining whether or not the door is in the fully opened

state (or the tightly closed state) is, for example, that the moving distance of the

doors 30a or 30b is calculated in real-time, and doors 30a and 30b are

determined to be in its fully opened state (or the tightly closed state) when

calculated moving distance is equal to the driving distance. In case the above

described method is used, an error may be occurred due to, for example, belt

slip, etc. Therefore, the method may be modified to determine whether or not the

door 30a or 30b is in its fully opened state (or the tightly closed state) when

output of the rotor's position signal (p_r) does not change for a predetermined

time.

As described above, according to the end-point signal outputting

operation of the door driving device 200 of the present invention, an extra

hardware like the end-limit switch is not required, thereby the installation of the

door driving device 200 is much easier than the conventional case, and it is

possible to remove or decrease the possibility of malfunction or breakdown

caused by mechanical friction or deterioration.

Finally, the initialization driving operation at the time of power-on is

described in detail. This operation is to move the doors 30a and 30b to an initial

location which can be a temporary reference point, because there might not be

information on a present location of the doors 30a and 30b at the time of power- on of the door driving device 200. The initial location can be the above described

fully opened state or the tightly closed state of the doors 30a and 30b. That is to

say, the door driving device 200 drives the doors 30a and 30b in the closing (or

opening) direction, and the doors 30a and 30b are determined to be in its fully

opened state (or the tightly closed state) if the rotor's position signal (p_r) does

not change for a predetermined time, then the end-point signal is produced and

transmitted to the controller (not shown) of the elevator system. By this, it is

possible to acquire information on the present position of the doors 30a and 30b.

Now, referring to Fig. 4, the door driving operation, which is performed

by the controller 212 included in the door driving device 200 in order to open or

close the doors 30a and 30b after the initial installing operation including the

driving distance measuring operation, etc. are completed and a power for

ordinary driving is applied, is described in detail. Fig. 4 is a flow chart showing

operation processes of the door driving device 200 shown in Fig. 2 according to

an embodiment of the present invention.

First of all, if the power source is applied to the elevator door system 2

(step 400), the door driving device 200 performs the initializing operation (step

402).

Next, after the initializing operation is performed, the door driving device

200 enters a stand-by state (step 404), and waits for a door opening or closing

command (hereinafter, collectively called as "door driving command") from the

controller (not shown) of the elevator system. Then, it is determined whether or not the door driving command is

provided (step 406). As described above, the door driving command is either

one of the door opening or closing command. In case any door driving command

is not provided, the door driving device 200 remains in the stand-by state.

Next, in case a door driving command is provided, the brushless DC

motor is driven according to type of the provided door driving command (step

408). The door opening or closing command can be interpreted as a command

to rotate in the right or left direction for the brushless DC motor 214. Therefore,

the brushless DC motor 214 is driven according to a predetermined operation

rule by determining a rotating direction with type of determined command and

analyzing the rotor's position signal (p_r).

Next, if the brushless DC motor 214 starts to rotate, the number of the

rotor's position signals (p_r) inputted from the brushless DC motor 214 to the

driving device 200 is counted (step 410). Herein, it is preferred that unit of the

rotor's position signals (p_r) counted is 3-bit binary-code generated by binary-

coding outputs of each phase at every 60-degree in electrical angle, as shown in

Fig. 3b. As described above, however, outputs from only one phase may be

used according to practical applications and, in this case, counting inputted

signal may be performed so that one signal gets inputted whenever the output

voltage level is changed from high to low or low to high.

Next, for instance, moving distance of the doors 30a and 30b are

calculated by using the Equation 1 according to counted number of the rotor's position signals (p_r) (step 412).

Next, if the calculated distance becomes equal to the driving distance

stored in advance, it is determined that the doors 30a and 30b reach the stop

position (step 414) and operation stops (step 416).

In general, the door driving device 200 performs its operations by

receiving the door opening or closing command from the controller (not shown)

of the elevator system but, according to applications, in case an input is

provided from, for example, an opening button, a hall button, a door safety bar,

etc., the door driving device 200 should process this input by itself. Those skilled

in the art can embody this process easily, and thus detail is omitted.

As a result of determination in step 414, if it is determined that the doors

30a and 30b does not yet reach the stop position, or the fully opened or tightly

closed state, the door driving device 200 continues to drive the brushless DC

motor 214 by returning its control to the step 408, and repeats steps 410 to 414.

Next, with reference to a functional block diagram shown in Fig. 5, the

controller 212 of the door driving device 200 according to an embodiment of the

present invention is described in detail. Preferably, the controller 212 included in

the door driving device 200 of the present invention is embodied by

programming a widely known micro-processor (not shown) and combining it with

an appropriate hardware like a widely known driver circuitry (not shown) for the

brushless DC motor. Fig. 5 shows an examplary functional block diagram

including functional blocks performed by the programmed microprocessor and other hardware. There can be various combinations of functional blocks

according to practical design options.

As shown in Fig. 5, the controller 212 according to the present invention

includes a door driving command operating unit 402 for receiving the door

opening command to open the doors 30a and 30b or the door closing command

to close the doors 30a and 30b and storing it temporarily, a door operating state

processing unit 404 for receiving the rotor's position signal (p_r) from the

brushless DC motor 214 and determining operation state of the doors 30a and

30b by analyzing received rotor's position signal (p_r), and a motor driving unit

406 for driving the brushless DC motor 214 on the basis of the door opening or

closing command received from the door driving command operating unit 402

and the doors' operation state determined by the door operation state

processing unit 404. The door driving command operating unit 402 receives the

door opening or closing command produced by a door open button, a door close

button, a hall button, a door safety bar, etc. installed in the elevator door system

2. And, the door driving command operating unit 402 stores it temporarily and

transmits it to the motor driving unit 406.

The door operating state processing unit 404 stores all of constants and

variables, such as the driving distance, etc., necessary to drive the doors, and

calculates the moving distance and velocity of the doors 30a or 30b by analyzing

the rotor's position signal (p_r) produced from the brushless DC motor 214.

Further, it is determined on the basis of theses constants and variables whether or not the doors 30a and 30b reach the stop position. And, the end-point signal

is produced as a result of the determination.

The motor driving unit 406 controls rotation, rotating direction, rotating

velocity, etc. of the brushless DC motor 214 on the basis of commands and/or

a nalyzed data provided by the door operating state processing unit 404.

Next, referring to Fig. 6, Fig. 6 shows a schematic block diagram of

another embodiment of the elevator door system 2 to which the door driving

device 200 of the present invention is applied. As shown in Fig. 6, the elevator

door system 2 is configured to improve control precision of the door driving

device 200 according to the present invention by using two-stage pulleys 16a

and 16b for transferring torque from the brushless DC motor 214 to the doors

30a and 30b.

According to the present embodiment, control precision of the door

driving device 200 according to the present invention increases proportionally to

the ratio of shaft diameter of the second pulley 16b to that of the first pulley 16a.

[INDUSTRIAL APPLICABILITY]

According to the present invention, it is possible to provide a device and

a method for driving an elevator door, which can meet control characteristics of

the elevator door, by utilizing the rotor's position signal (p_r) of the brushless DC

motor 200 directly.

In addition, according to the present invention, it is also possible to provide a device and a method for driving an elevator door driving device which

not only performs necessary and sufficient control ability to satisfy control

characteristics for the elevator doors, but also improves effectiveness of power

consumption and control stability.

Claims

[CLAIMS]

1. A door driving device, which comprises a power source for supplying

electric power, a door moving a predetermined driving distance reciprocally, and

a power transferring unit for transforming rotating motion into linear motion in

order to open or close said door, comprising:

a brushless DC motor for providing torque for driving said door and

outputting a rotor's position signal (p_r); and

a controller for determining operation state of said door on the basis of

said rotor's position signal outputted from said brushless DC motor and driving

said brushless DC motor in response to the determined operation state of said

door.

2. A door driving device as claimed in claim 1 , wherein said controller

performs:

a driving distance measuring operation for measuring a distance from a

location of said door, which is fully opened at said location, to another location of

said door, which is tightly closed at said another location, and storing measured

distance as a driving distance at a first installation;

an end-point signal outputting operation for producing an end-point

signal indicating that said door reaches a stopping position in case said door is

determined to be at said location where said door is fully opened or at said

another location where said door is tightly closed by detecting said rotor's position signal (p_r); and

a door driving operation for rotating said brushless DC motor in a

predetermined direction in response to a door opening command or a door

closing command, calculating moving distance of said door on the basis of said

rotor's position signal (p_r) inputted from said brushless DC motor, and stopping

driving of said brushless DC motor by determining that said door reaches a

stopping position as said calculated moving distance becomes substantially

equal to said driving distance.

3. A door driving device as claimed in claim 2, wherein said controller

comprises:

a door driving command operating unit for receiving and at least

temporarily storing said door opening command or said door closing command;

a door operation state processing unit for receiving said rotor's position

signal (p_r) from said brushless DC motor and determining operation state of said

door by analyzing received said rotor's position signal; and

a motor driving unit for driving said brushless DC motor on the basis of

said door opening command or said door closing command received from said

door driving command operating unit and said operation state of said door

determined by said door operation state processing unit.

4. A door driving device as claimed in claim 3, wherein said door operation state processing unit stores one or more of constants and/or variables

necessary to drive said door, calculates moving distance and/or velocity of said

door by analyzing said rotor's position signal (p_r) produced from said brushless

DC motor, determines on the basis of said one or more of constants and/or

variables if said door reaches said stopping position, and produces said end-

point signal as a result of said determination.

5. A door driving method of an elevator door system, which comprises a

power source for supplying electric power, a door moving a predetermined

driving distance reciprocally, a brushless DC motor for providing torque for

driving said door and outputting a rotor's position signal (p_r) and a power

transferring unit for transferring torque of said brushless DC motor to said door,

said method comprising steps of:

receiving a door driving command from a controlling device of said

elevator system;

receiving said rotor's position signal (p_r) outputted from said brushless

DC motor;

determining operation state of said door on the basis of said received

rotor's position signal (p_r); and

driving said brushless DC motor on the basis of said determined

operation state of said door.

6. A door driving method as claimed in claim 5 further comprising a step of

performing a driving distance measuring operation for measuring a distance

from a location of said door, which is fully opened at said location, to another

location of said door, which is tightly closed at said another location, and storing

measured distance as a driving distance at a first installation

7. A door driving method as claimed in claim 5 further comprising a step of

performing an end-point signal outputting operation for producing an end-point

determined to be at said location where said door is fully opened or at said

another location where said door is tightly closed by detecting said rotor's

position signal (p_r).

8. A door driving method as claimed in claim 5 further comprising a step of

performing an initializing operation for setting up a present position of said door

by moving said door to a predetermined initial location.

9. A door driving method as claimed in any one of claims 5 to 8, wherein

said step of determining operation state of said door comprises steps of:

calculating moving distance of said door on the basis of said rotor's

position signal (p_r) inputted from said brushless DC motor; and

determining that said door reaches a stopping position as said calculated moving distance becomes substantially equal to said driving distance.