EP1918239A1

EP1918239A1 - Elevator device

Info

Publication number: EP1918239A1
Application number: EP05780959A
Authority: EP
Inventors: Takaharu Ueda
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2005-08-25
Filing date: 2005-08-25
Publication date: 2008-05-07
Anticipated expiration: 2025-08-25
Also published as: CN101044081A; EP1918239A4; JPWO2007023550A1; JP5026073B2; WO2007023550A1; CN101044081B; EP1918239B1

Abstract

Provided is an elevator apparatus in which a car is raised and lowered by driving forces of a plurality of driving machines. The driving machines have driving sheaves, motors for rotating the driving sheaves, and brake devices for braking the rotation of the driving sheaves. Each brake device has a plurality of brake main bodies belonging to a plurality of different groups. At the time of emergency braking, the brake devices generate braking forces by means of the brake main bodies with timings differing from group to group.

Description

TECHNICAL FIELD

The present invention relates to an elevator apparatus for raising and lowering a car by driving forces of a plurality of driving machines.

BACKGROUND ART

In a conventional elevator apparatus, a car is raised and lowered by a first driving machine and a second driving machine which are provided in an upper portion of a hoistway. The car is provided with a sensor for detecting an inclination of the car. During traveling of the car, the first and second driving machines are controlled so as to cancel the inclination of the car according to signals from the sensor (see, for example, Patent Document 1) .
Patent Document 1: WO 2004/026749 A1

DISCLOSURE OF THE INVENTION

PROBLEM TO BE SOLVED BY THE INVENTION

In the conventional elevator apparatus as described above, when braking timings of brake devices of a first driving machine and a second driving machine are deviated from each other at the time of emergency braking, an inclination of the car is generated, so there is a fear of the passenger in the car experiencing discomfort.
The present invention has been made with a view toward solving the above-mentionedproblem. It is an object of the present invention to provide an elevator apparatus capable of restraining generation of an inclination of the car at the time of emergency braking.

MEANS FOR SOLVING THE PROBLEM

An elevator apparatus according to the present invention includes: a plurality of driving machines; a car that is raised and lowered by driving forces of the driving machines; and a plurality of brake devices for braking the ascent and descent of the car, in which the brake devices have a plurality of brake main bodies belonging to a plurality of different groups, and in which, at the time of emergency braking, the brake devices generate braking forces by the brake main bodies with timings deviated from group to group.

BRIEF DESCRIPTION OF THE DRAWINGS

[Fig. 1] Fig. 1 is a schematic view of an elevator apparatus according to Embodiment 1 of the present invention.
[Fig. 2] Fig. 2 is a circuit diagram showing driving circuits for first through sixth electromagnetic coils of Fig. 1.
[Fig. 3] Fig. 3 is an explanatory view illustrating a difference in operation between brake main bodies due to a difference in electric resistance value between resistors of Fig. 2.
[Fig. 4] Fig. 4 is a circuit diagram showing driving circuits for first through sixth electromagnetic coils of an elevator apparatus according to Embodiment 2 of the present invention.
[Fig. 5] Fig. 5 is a block diagram showing a control portion for controlling first through sixth selection switches of Fig. 4.
[Fig. 6] Fig. 6 is a block diagram showing a control portion for controlling first through sixth selection switches of an elevator apparatus according to Embodiment 3 of the present invention.
[Fig. 7] Fig. 7 is a circuit diagram showing driving circuits for first through sixth electromagnetic coils of an elevator apparatus according to Embodiment 4 of the present invention.
[Fig. 8] Fig. 8 is an explanatory view showing a difference in contact opening operation between electromagnetic switch devices due to a difference in electric resistance value between resistors of Fig. 7.

BEST MODE FOR CARRYING OUT THE INVENTION

In the following, preferred embodiments of the present invention will be described with reference to the drawings.

Embodiment 1

Fig. 1 is a schematic view of an elevator apparatus according to Embodiment 1 of the present invention. In the drawing, first and second driving machines (i.e., hoists) 1 and 2 are installed in an upper portion of a hoistway. The first driving machine 1 has a first driving sheave 3, a first motor 4 for rotating the first driving sheave 3, a first brake drum 5, which is a brake rotary member to be rotated integrally with the first driving sheave 3, and a first brake device 6 for braking the rotation of the first brake drum 5.
The second driving machine 2 has a second driving sheave 7, a second motor 8 for rotating the second driving sheave 7, a second brake drum 9, which is a brake rotary member to be rotated integrally with the second driving sheave 7, and a second brake device 10 for braking the rotation of the second brake drum 9.
A plurality of first main ropes 11 (only one of which is shown in the drawing) are wound around the first driving sheave 3. A plurality of second main ropes 12 (only one of which is shown in the drawing) are wound around the second driving sheave 7.
A car 13 is connected to first end portions of the first and second main ropes 11 and 12. A first counterweight 14 is connected to second end portions of the first main ropes 11. A second counterweight 15 is connected to second end portions of the second main ropes 12. That is, the car 13 and the first and second counterweights 14 and 15 are suspended in the hoistway by the first and second main ropes 11 and 12 through a 1:1 roping system, and are raised and lowered in the hoistway by the driving forces of the first and second driving devices 1 and 2.
Provided on the car 13 are a first rope connecting portion 13a and a second rope connecting portion 13b arranged on the opposite side of the first rope connecting portion 13a with respect to the center of gravity of the car 13. In a vertical projection plane, the first and second rope connecting portions 13a and 13b are arranged symmetrically with respect to the center of gravity of the car 13. The first main ropes 11 are connected to the first rope connecting portion 13a, and the second main ropes 12 are connected to the second rope connecting portion 13b.
The first brake device 6 has first through third brake main bodies 16a through 16c belonging to a plurality of different groups (here, first through third groups) . The second brake device 10 has fourth through sixth brake main bodies 16d through 16f belonging toapluralityofdifferentgroups (here, first through third groups) .
To be more specific, the first and fourth brake main bodies 16a and 16d belong to the first group, the second and fifth brake main bodies 16b and 16e belong to the second group, and the third and sixth brake main bodies 16c and 16f belong to the third group.
The first brake main body 16a has a first brake shoe 17a to be brought into and out of contact with the braking surface of the first brake drum 5, a first brake spring (i.e., mechanical spring) 18a for pressing the first brake shoe 17a against the first brake drum 5, a first iron core 19a fixed to the first brake shoe 17a, and a first electromagnetic coil 20a for attracting the first iron core 19a to thereby separate the first brake shoe 17a from the first brake drum 5.
Like the first brake main body 16a, the second through sixth brake main bodies 16b through 16f have brake shoes 17b through 17f, brake springs 18b through 18f, iron cores 19b through 19f, and electromagnetic coils 20b through 20f, respectively.
Fig. 2 is a circuit diagram showing driving circuits for the first through sixth electromagnetic coils 20a through 20f. Electric currents from first through sixth brake attraction amplifiers 21a through 21f are supplied to the electromagnetic coils 20a through 20f through an electromagnetic switch device 22, respectively.
The electromagnetic switch device 22 has first through sixth contacts 22a through 22f connected between the brake attraction amplifiers 21a through 21f and the electromagnetic coils 20a through 20f, respectively, and an opening/closing drive portion 22g for opening and closing the contacts 22a through 22f. The opening/closing drive portion 22g has an iron core 22h, a switch coil 22i wound around the iron core 22h, and a resistor 22j and a diode 22k connected in parallel to the switch coil 22i.
The contacts 22a through 22f are normally closed. However, when an emergency stop command signal is input to the opening/closing drive portion 22g, the contacts 22a through 22f are opened. This causes the electric currents supplied to the electromagnetic coils 20a through 20f of the brake main bodies 16a through 16f to be cut off simultaneously.
First through sixth corresponding resistors 23a through 23f and first through sixth corresponding diodes 24a through 24f are connected in parallel to the first through sixth electromagnetic coils 20a through 20f. The diodes 24a through 24f are connected in series to the corresponding resistors 23a through 23f.
Here, the electric resistance values of the resistors 23a through 23f connected to the electromagnetic coils 20a through 20f belonging to the same group are set to be the same. To be more specific, the electric resistance value R1 of the first resistor 23a is the same as the electric resistance value R4 of the fourth resistor 23d (i.e., R1 = R4), the electric resistance value R2 of the second resistor 23b is the same as the electric resistance value R5 of the fifth resistor 23e (i.e., R2 = R5), and the electric resistance value R3 of the third resistor 23c is the same as the electric resistance value R6 of the sixth resistor 23f (i.e., R3 = R6).
The electric resistance values of the resistors 23a through 23f connected to the electromagnetic coils 20a through 20f belonging to different groups are set to be different. To be more specific, the electric resistance value R1 of the first resistor 23a is larger than the electric resistance value R2 of the second resistor 23b (i.e., R1 > R2), and the electric resistance value R2 of the second resistor 23b is larger than the electric resistance value R3 of the third resistor 23c (i.e., R2 > R3).
Next, the operation of this embodiment will be described. During normal operation, the first and second motors 4 and 8 are driven in synchronism with each other, whereby the first and the second sheaves 3 and 7 are rotated simultaneously, and the car 13 and the counterweights 14 and 15 are raised and lowered in the hoistway. During traveling of the car 13, the brake shoes 17a through 17f are kept away from the brake drums 5 and 9 by the electromagnetic actuators composed of the iron cores 19a through 19f and the electromagnetic coils 20a through 20f against the forces of the brake springs 18a through 18f.
When the car 13 is at rest, the electromagnetic coils 20a through 20f are in a non-energized state, and the brake shoes 17a through 17f are pressed against the brake drums 5 and 9 by the spring forces of the brake springs 18a through 18f, thus keeping the car 13 at rest.
When the car 13 is to be brought to an emergency stop during traveling of the car 13, the electricity supply to the motors 4 and 8 is cut off, and an emergency stop signal is input to the opening/closing drive portion 22g, opening the contacts 22a through 22f simultaneously. As a result, the electricity supply to the electromagnetic coils 20a through 20f is also forcibly cut off, and the brake shoes 17a through 17f are pressed against the drums 5 and 9 by the spring forces of the brake springs 18a through 18f. As a result, frictional forces are generated between the brake shoes 17a through 17f and the brake drums 5 and 9, and the rotation of the brake drums 5 and 9 and the driving sheaves 3 and 7 is stopped, whereby the car 13 is stopped abruptly.
At this point, the electric resistance values of the resistors 23a through 23f connected in parallel to the electromagnetic coils 20a through 20f are set as described above, so the timings with which the braking forces are generated by the brake main bodies 16a through 16f are slightly deviated from group to group. That is, the brake main bodies 16a through 16f are grouped in terms of brake operation timing.
Here, Fig. 3 is an explanatory view showing a difference in operation between the brake main bodies 16a through 16f due to a difference in electric resistance value between the resistors 23a through 23f of Fig. 2. The period of time between the moment when the power supply to the electromagnetic coils 20a through 20f is cut off by the emergency stop command and the moment when the electric current flowing through the electromagnetic coils 20a through 20f is reduced to 0 is shortened when the electric resistance values of the resistors 23a through 23f are increased. Thus, the larger the electric resistance values of the resistors 23a through 23f, the quicker the shoe gaps (i.e., the gaps between the brake shoes 17a through 17f and the brake drums 5 and 9) are reduced to 0. That is, the larger the electric resistance values of the resistors 23a through 23f, the earlier the braking forces are generated and exerted.
Thus, in the case where the electric resistance values of the resistors 23a through 23f are set as stated above, the braking forces are generated in the order: the first and fourth brake main bodies 16a and 16d, the second and fifth brake main bodies 16b and 16e, and the third and sixth brake main bodies 16c and 16f.
In such the elevator apparatus, at the time of emergency braking, the timings with which the braking forces are generated by the brake main bodies 16a through 16f are deviated from group to group, so it is possible to prevent an excessive deceleration frombeing applied to the car 13. Further, since the braking forces are applied to the first and second brake drums 5 and 9 a plurality of times, so if there should be a slight deviation in braking timing between the right and left sides, the difference in braking force is small. Thus, it is possible to prevent generation of an inclination of the car 13 at the time of emergency braking.

Embodiment 2

Next, Fig. 4 is a circuit diagram showing driving circuits for the first through sixth electromagnetic coils 20a through 20f of an elevator apparatus according to Embodiment 2 of the present invention. The overall construction of the elevator apparatus is the same as that of Embodiment 1 (shown in Fig. 1). In the drawing, two first resistors 23a1 and 23a2 are provided in a circuit in parallel with the first electromagnetic coil 20a. The first resistors 23a1 and 23a2 are connected in parallel to each other, and are connected in series to the first diode 24a.
Between the first diode 24a and the first resistors 23a1 and 23a2, there is connected a first selection switch 25a selectively connecting one of the first resistors 23a1 and 23a2 to the first diode 24a. As in the first electromagnetic coil 20a, in the second through sixth electromagnetic coils 20b through 20f also, there are connected second through sixth resistors 23b1 through 23f2 and second through sixth selection switches 25b through 25f, respectively.
The electric resistance value of the first resistor 23a1 is set to be slightly larger than the electric resistance value of the first resistor 23a2 . The electric resistance value of the second resistor 23b1 is set to be slightly larger than the electric resistance value of the second resistor 23b2. The electric resistance value of the third resistor 23c1 is set to be slightly larger than the electric resistance value of the third resistor 23c2. The electric resistance value of the fourth resistor 23d1 is set to be slightly larger than the electric resistance value of the fourth resistor 23d2. The electric resistance value of the fifth resistor 23e1 is set to be slightly larger than the electric resistance value of the fifth resistor 23e2. The electric resistance value of the sixth resistor 23f 1 is set to be slightly larger than the electric resistance value of the sixth resistor 23f2.
The electric resistance value of the first resistor 23a1 is equal to the electric resistance value of the fourth resistor 23d1. The electric resistance value of the first resistor 23a2 is equal to the electric resistance value of the fourth resistor 23d2. The electric resistance value of the second resistor 23b1 is equal to the electric resistance value of the fifth resistor 23e1. The electric resistance value of the second resistor 23b2 is equal to the electric resistance value of the fifth resistor 23e2. The electric resistance value of the third resistor 23c1 is equal to the electric resistance value of the sixth resistor 23f1. The electric resistance value of the third resistor 23c2 is equal to the electric resistance value of the sixth resistor 23f2.
Further, the electric resistance values of the first resistors 23a1 and 23a2 are larger than the electric resistance values of the second resistors 23b1 and 23b2. The electric resistance values of the second resistors 23b1 and 23b2 are larger than the electric resistance values of the third resistors 23c1 and 23c2.
Fig. 5 is a block diagram showing a control portion for controlling the first through sixth selection switches 25a through 25f of Fig. 4. First and second weighing devices 26 and 27 output signals corresponding to the load of the car 13. The first weighing device 26 is provided at the first rope connecting portion 13a. The second weighing device 27 is provided at the second rope connecting portion 13b. To be more specific, the weighing devices 26 and 27 output signals corresponding to the respective tensions of the main ropes 11 and 12, through expansion and contraction of built-in elastic bodies.
The signals from the weighing devices 26 and 27 are input to a comparing portion 28. The comparing portion 28 compares the signals from the weighing devices 26 and 27 with each other, thereby detecting an imbalance between the tension of the first main ropes 11 and the tension of the secondmain ropes 12. A command generating portion 29 generates a command signal for operating the selection switches 25a through 25f according to the imbalance detection result obtained by the comparing portion 28.
The command generating portion 29 performs switching operation on the selection switches 25a through 25f so as to deviate the braking force generating timings of the brake main bodies 16a through 16f belonging to the same group from each other according to the difference in tension between the first and second main ropes 11 and 12. For example, when the tension of the first main ropes 11 is higher than the tension of the second main ropes 12, the first through third resistors 23a1, 23b1, and 23c1 and the fourth through sixth resistors 23d2, 23e2, and 23f are selected.
As a result, in the first group, the fourth brake main body 16d generates a braking force slightly earlier than the first brake main body 16a. In the second group, the fifth brake main body 16e generates a braking force slightly earlier than the second brake main body 16b. In the third group, the sixth brake main body 16f generates a braking force slightly earlier than the third brake main body 16c.
The comparing portion 28 and the command generating portion 29 may be formed by computers performing operations on the signals from the weighing devices 26 and 27 converted to digital signals, or by analog circuits using analog signals from the weighing devices 26 and 27 as they are.
In such the elevator apparatus, at the time of emergency braking, the braking force generating timings of the brake main bodies 16a through 16f belonging to the same group are deviated from each other to cancel the difference in tension between the first and second main ropes 11 and 12, so it is possible to more effectively restrain generation of an inclination of the car 13 at the time of emergency braking.

Embodiment 3

Next, Fig. 6 is a block diagram showing a control portion for controlling the first through sixth selection switches 25a through 25f of an elevator apparatus according to Embodiment 3 of the present invention. In this embodiment, instead of the weighing devices 26 and 27, a command generating portion 31 generates a command for performing switching on the selection switches 25a through 25f according to a signal from a car inclination sensor 30 adapted to output a signal corresponding to an inclination of the car 13. The command generating portion 31 outputs a command signal to the selection switches 25a through 25f so as to deviate the braking force generating timings of the brake main bodies 16a through 16f belonging to the same group to thereby cancel the inclination of the car 13.
For example, when the car 13 is inclined in such a direction that the second rope connecting portion 13b is lower than the first rope connecting portion 13a, the braking force of the fourth brake main body 16d is generated slightly earlier than that of the first brake main body 16a, the braking force of the fifth brake main body 16e is generated slightly earlier than that of the second brake main body 16b, and the braking force of the sixth brake main body 16f is generated slightly earlier than that of the third brake main body 16c. Other than the points described above, this embodiment has the same construction as Embodiment 2.
In such the elevator apparatus, at the time of emergency braking, the braking force generating timings of the brake main bodies 16a through 16f belonging to the same group are deviated from each other so as to cancel the inclination of the car 13, so it is possible to more effectively restrain generation of an inclination of the car 13 at the time of emergency braking.

Embodiment 4

Next, Fig. 7 is a circuit diagram showing driving circuits for the first through sixth electromagnetic coils 20a through 20f of an elevator apparatus according to Embodiment 4 of the present invention. The construction of the elevator apparatus as a whole is the same as that of Embodiment 1 (shown in Fig. 1). Electric currents from the first and fourth brake attraction amplifiers 21a and 21d are supplied to the first and fourth electromagnetic coils 20a and 20d, respectively, which belong to the first group, through a first electromagnetic switch device 32.
The first electromagnetic switch device 32 has the contacts 22a and 22d connected between the brake attraction amplifiers 21a and 21d and the electromagnetic coils 20a and 20d, and a first opening/closing drive portion 32a for opening and closing the contacts 22a and 22d. The first opening/closing drive portion 32a has a first iron core 32b, a first switch coil 32c wound around the first iron core 32b, and a first resistor 32d and a first diode 32e, which are connected in parallel to the first switch coil 32c.
Electric currents from the second and fifth brake attraction amplifiers 21b and 21e are supplied to the second and fifth electromagnetic coils 20b and 20e, respectively, which belong to the second group, through a second electromagnetic switch device 33. The second electromagnetic switch device 33 has the contacts 22b and 22e, and a second opening/closing drive portion 33a. The second opening/closing drive portion 33a has a second iron core 33b, a second switch coil 33c, a second resistor 33d, and a second diode 33e.
Electric currents from the third and sixth brake attraction amplifiers 21c and 21f are supplied to the third and sixth electromagnetic coils 20c and 20f, respectively, which belong to the third group, through a third electromagnetic switch device 34. The third electromagnetic switch device 34 has the contacts 22c and 22f, and a third opening/closing drive portion 34a. The third opening/closing drive portion 34a has a third iron core 34b, a third switch coil 34c, a third resistor 34d, and a third diode 34e.
The contacts 22a through 22f are normally closed. However, when an emergency stop command signal is input to the opening/closing drive portions 32 through 34, the contacts 22a through 22f are opened, whereby the electric currents supplied to the electromagnetic coils 20a through 20f of the brake main bodies 16a through 16f are cut off.
The respective electric resistance values of the resistors 32d, 33d, and 34d, which belong to different groups, are different from one another. To be more specific, the electric resistance value of the first resistor 32d is larger than the electric resistance value of the second resistor 33d, and the electric resistance value of the second resistor 33d is larger than the electric resistance value of the third resistor 34d.
Here, Fig. 8 is an explanatory view showing a difference in contact opening operation between the electromagnetic switch devices 32 through 34 due to the difference in electric resistance value between the resistors 32d, 33d, and 34d of Fig. 7. The period of time between the moment when an emergency stop command signal is input to the opening/ closing drive portions 32a, 33a, and 34a (i.e., when the voltage of the command signal is reduced to 0) and the moment when the contacts 22a through 22f are actually opened is shortened when the electric resistance values of the resistors 32d, 33d, and 34d are increased.
Thus, when the electric resistance values of the resistors 23a through 23f are set as described above, the braking forces are generated in the order: the first and fourth brake main bodies 16a and 16d, the second and fifth brake main bodies 16b and 16e, and the third and sixth brake main bodies 16c and 16f.
In such the elevator apparatus, at the time of emergency braking, the timings with which the braking forces are generated by the brake main bodies 16a through 16f are deviated from group to group, so it is possible to prevent an excessive deceleration frombeing applied to the car 13. Further, since the braking forces are applied to the first and second brake drums 5 and 9 a plurality of times, it is possible to restrain generation of an inclination of the car 13 at the time of emergency braking.
While one brake device is provided with three brake main bodies in the examples described above, it is also possible for one brake device to be provided with two or four or more brake main bodies.
Further, while all the brake main bodies provided in one brake device belong to different groups from one another in the examples described above, it is also possible for a plurality of brake main bodies to belong to the same group. For example, when providing four brake main bodies in one brake device, it is possible for the four brake main bodies to be divided into two groups each including two brake main bodies.
Further, while two driving machines are used in the examples described above, the number of driving machines may be three or more.
Furthermore, while two counterweights are used in the examples described above, the number of counterweights may be one or three or more.
Further, while the timings with which the braking operations are started are deviated from group to group of the brake main bodies 16a through 16f in the examples described above, it is also possible to divide the brake main bodies into a plurality of groups, with intermittent or continuous control methods for the braking forces differing from group to group.
Further, while the present invention is applied to a brake device for braking the rotation of a driving sheave in the examples described above, the present invention is also applicable to a brake device for braking the ascent/descent of a car by some other method. For example, the present invention may also be applied to a plurality of car brake devices mounted to the car, for braking the ascent and descent of a car by holding braking members in press contact with car guide rails. In this case, each car brake device is provided with a plurality of brake main bodies belonging to a plurality of different groups. The present invention may also be applied to a plurality of rope brake devices provided in a hoistway or on a support member supporting a driving machine and adapted to brake the ascent and descent of a car through braking of the movement of main ropes. In this case also, each rope brake device is provided with a plurality of brake main bodies belonging to a plurality of different groups.

Claims

An elevator apparatus comprising:
a plurality of driving machines;

a car that is raised and lowered by driving forces of the driving machines; and

a plurality of brake devices for braking the ascent and descent of the car,
wherein the brake devices have a plurality of brake main bodies belonging to a plurality of different groups, and
wherein, at the time of emergency braking, the brake devices generate braking forces by the brake main bodies with timings deviated from group to group.
An elevator apparatus according to Claim 1, wherein the driving machines have driving sheaves, motors for rotating the driving sheaves, and the brake devices for braking the rotation of the driving sheaves, and
wherein the car is suspended by a plurality of main ropes wound around the driving sheaves.
An elevator apparatus according to Claim 2, wherein the car has a first rope connecting portion, and a second rope connecting portion arranged on the opposite side of the first rope connecting portion with respect to the center of gravity of the car,
wherein the main ropes include a first main rope connected to the first rope connecting portion, and a secondmain rope connected to the second rope connecting portion, and
wherein the brake devices detect a difference in tension between the first and second main ropes, and deviates, at the time of emergency braking, the timings with which the braking forces of the brake main bodies of the same group are generated according to the difference in tension.
An elevator apparatus according to Claim 1, wherein the brake devices detect an inclination of the car, and deviate the timings with which the braking forces of the brake main bodies of the same group are generated according to the inclination of the car.
An elevator apparatus according to Claim 2, wherein the brake main bodies have brake shoes to be brought into and out of contact with brake rotary members rotated integrally with the driving sheaves, brake springs for pressing the brake shoes against the brake rotary members, electromagnetic coils for generating electromagnetic forces for separating the brake shoes from the brake rotary members against forces of the brake springs, and resistors connected in parallel to the electromagnetic coils, and
wherein the resistors have electric resistance values differing from group to group.
An elevator apparatus according to Claim 2, wherein the brake main bodies have brake shoes to be brought into and out of contact with brake rotarymembers rotated integrally with the driving sheaves, brake springs for pressing the brake shoes against the brake rotary members, and electromagnetic coils for generating electromagnetic forces for separating the brake shoes from the brake rotary members against forces of the brake springs, and
wherein, at the time of emergency braking, electricity supply to the electromagnetic coils is cut off with timings differing from group to group.
An elevator apparatus according to Claim 6, further comprising a plurality of electromagnetic switches for switching between supply and cut-off of an electric current to the electromagnetic coils,
wherein the electromagnetic switch devices have contacts connected to the electromagnetic coils, switch coils for opening and closing the contacts, and resistors connected in parallel to the switch coils, and
wherein the resistors have electric resistance values differing from group to group.