EP2360112A1

EP2360112A1 - Elevator safety circuit device

Info

Publication number: EP2360112A1
Application number: EP08878754A
Authority: EP
Inventors: Jun Hashimoto; Takaharu Ueda; Masunori Shibata
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2008-12-12
Filing date: 2008-12-12
Publication date: 2011-08-24
Anticipated expiration: 2028-12-12
Also published as: KR20110039385A; KR101219230B1; JP5220126B2; EP2360112B1; EP2360112A4; CN102177082A; WO2010067455A1; JPWO2010067455A1; CN102177082B

Abstract

In a safety circuit device for an elevator a failure detecting section detects faulty opening corresponding to opening of a first safety switch due to a failure based on a state of the first safety switch and a state of a second safety switch. A switching device connects a first safety circuit to a brake device and disconnects a second safety circuit from the brake device at normal time, and switches a circuit to be connected to the brake device from the first safety circuit to the second safety circuit when the faulty opening is detected by the failure detecting section. A circuit switching time period by the switching device is set shorter than a time period from the opening of the first safety switch to start of a braking operation of the brake device.

Description

Technical Field

The present invention relates to a safety circuit device for an elevator, which includes a safety circuit for detecting an abnormal state based on opening of a safety switch to generate a car stop command to a brake device.

Background Art

In a conventional elevator controller, switches having the same configuration as that of lower limit switches are also provided to a floor just above a lowermost floor. In case of flooding in a pit, switching between limit switches to be used is performed to prevent degradation in elevator service at the time of flooding in the pit (for example, see Patent Document 1).

Patent Document 1: JP 05-32382 A

Disclosure of the Invention

Problem to Be Solved by the Invention

In the conventional elevator controller as described above, it is necessary to switch a part of the safety circuit so as to switch between the limit switches to be used. Thus, there is a fear in that the service is degraded due to an operation of the safety circuit, which is caused by the switching operation.
The present invention has been made to solve the problem described above, and has an objet to provide a safety circuit device for an elevator, which is capable of controlling the elevator to travel without bringing a car to a sudden stop when faulty opening of a safety switch is detected.

Means for Solving the Problem

A safety circuit device for an elevator according to the present invention includes: a first safety circuit including at least one first safety switch, for detecting an abnormal state based on opening of the at least one first safety switch to generate a car stop command to a brake device; a second safety circuit including at least one second safety switch, for detecting the same type of abnormal state as the abnormal state detected by the first safety circuit based on opening of the at least one second safety switch to generate a car stop command to the brake device; a failure detecting section for detecting faulty opening corresponding to the opening of the at least one first safety switch due to a failure based on a state of the at least one first safety switch and a state of the at least one second safety switch; and a switching device for connecting the first safety circuit to the brake device and disconnecting the second safety circuit from the brake device at normal time and for switching a circuit to be connected to the brake device from the first safety circuit to the second safety circuit when the faulty opening is detected by the failure detecting section, in which a circuit switching time period by the switching device is set shorter than a time period from the opening of the at least one first safety switch to start of a braking operation of the brake device.
Further, a safety circuit device for an elevator according to the present invention includes: a first safety circuit including at least one first safety switch, for detecting an abnormal state based on opening of the at least one first safety switch to generate a car stop command to a brake device; a second safety circuit including at least one second safety switch, for detecting the same type of abnormal state as the abnormal state detected by the first safety circuit based on opening of the at least one second safety switch to generate a car stop command to the brake device; a failure detecting section for detecting faulty opening corresponding the opening of the at least one first safety switch due to a failure based on a state of the at least one first safety switch and a state of the at least one second safety switch; and a switching device for connecting the first safety circuit to the brake device and disconnecting the second safety circuit from the brake device at normal time and for switching a circuit to be connected to the brake device from the first safety circuit to the second safety circuit when the faulty opening is detected by the failure detecting section, in which the switching device connects the second safety circuit to the brake device and then disconnects the first safety circuit from the brake device when the faulty opening is detected by the failure detecting section.

Brief Description of the Drawings

FIG. 1 is a configuration diagram illustrating an elevator according to a first embodiment of the present invention.
FIG. 2 is a circuit diagram illustrating a safety circuit device for the elevator illustrated in FIG. 1.
FIG. 3 is a timing chart illustrating an operation of a brake contactor when a circuit switching time period by a switching device illustrated in FIG. 2 is longer than a time period required for the brake contactor to cut off a brake coil current.
FIG. 4 is a timing chart illustrating the operation of the brake contactor when the circuit switching time period by the switching device illustrated in FIG. 2 is shorter than the time period required for the brake contactor to cut off the brake coil current.
FIG. 5 is a timing chart illustrating a circuit switching operation of a safety circuit device for an elevator according to a second embodiment of the present invention.

Best Modes for Carrying Out the Invention

Hereinafter, preferred embodiments of the present invention are described referring to the drawings.

First Embodiment

FIG. 1 is a configuration diagram illustrating an elevator according to a first embodiment of the present invention. In the drawing, a car 1 and a counterweight 2 are suspended in a hoistway by suspension means 3, and are raised and lowered in the hoistway by a driving force of a hoisting machine 4. As the suspension means 3, a plurality of ropes or a plurality of belts are used.
The hoisting machine 4 includes a driving sheave 5 around which the suspension means 3 is looped, a hoisting-machine motor 6 corresponding to a driving device for rotating the driving sheave 5, and a brake device 7 for braking the rotation of the driving sheave 5. The brake device 7 includes a brake drum 8 connected to the driving sheave 5 so as to be coaxial therewith, a brake shoe 9 brought into contact with and separated away from the brake drum 8, a brake spring (not shown) for pressing the brake shoe 9 against the brake drum 8 to apply a braking force thereto, and an electromagnetic magnet (not shown) for separating the brake shoe 9 away from the brake drum 8 against the brake spring to release the braking force.
In an upper part of the hoistway, an upper pulley 10 is provided. In a lower part of the hoistway, a lower pulley 11 is provided. A governor rope 12 is looped around the upper pulley 10 and the lower pulley 11. Both ends of the governor rope 12 are connected to the car 1. The governor rope 12 is circulated with the ascent/descent of the car 1. As a result, the upper pulley 10 is rotated at a speed according to a running speed of the car 1. The upper pulley 10 is provided with a governor encoder 13 for generating a signal according to the speed of rotation of the upper pulley 10.
The hoisting-machine motor 6 and the brake device 7 are controlled by a travel controller 14. Specifically, a travel of the car 1 is controlled by the travel controller 14. The travel controller 14 controls the hoisting-machine motor 6 to raise and lower the car 1 and maintains a stationary state of the car 1 on a target floor by the brake device 7. Moreover, the travel controller 14 includes a microcomputer in which a program for the travel of the car 1 is stored.
A signal from the governor encoder 13 is input to a safety controller (electronic safety controller) 15. The safety controller 15 monitors the occurrence of abnormality in the elevator, independently of the travel controller 14. The safety controller 15 includes a microcomputer. In the microcomputer of the safety controller 15, a program for controlling electric power supply to the hoisting-machine motor 6 and the brake device 7 according to the type of the detected abnormality is stored. The safety controller 15 may alternatively include a logic circuit.
FIG. 2 is a circuit diagram illustrating a safety circuit device for the elevator illustrated in FIG. 1. The electromagnetic magnet of the brake device 7 includes a brake coil 21. The safety controller 15 controls energization of the brake coil 21 to control the braking force of the brake device 7. For example, the safety controller 15 controls the braking force of the brake device 7 by intermittently applying the braking force of the brake device 7 so that a deceleration of the car 1 does not become excessively high when the car 1 is brought to an emergency stop. However, a circuit configuration for performing the control on the braking force as described above is omitted in FIG. 2.
The brake device 7 further includes a brake contactor 22 for supplying the electric power and cutting off the electric power supply to the brake coil 21.
A first safety circuit (main safety circuit) 23 is connected between the brake contactor 22 and a power supply. The first safety circuit 23 includes at least one first safety switch 25 connected in series.
The first safety circuit 23 detects an abnormal state based on opening of the first safety switch 25 to generate a car stop command to the brake device 7. Specifically, when the at least one first safety switch 25 is opened while the car 1 is running, the brake contactor 22 is de-energized. As a result, the hoisting-machine motor 6 is de-energized and the brake coil 21 is also de-energized to bring the car to a sudden stop.
A second safety circuit (auxiliary safety circuit) 24 is provided between the brake contactor 22 and the power supply so as to be in parallel to the first safety circuit 23. The brake contactor 22 and the second safety circuit 24 are disconnected from each other at normal time. The second safety circuit 24 includes at least one second safety switch 26 connected in series.
The second safety circuit 24 detects the same type of abnormal state as that detected by the first safety circuit 23 based on opening of the second safety switch 26 to generate a car stop command to the brake device 7. At the normal time, however, the second safety circuit 24 is disconnected from the brake contactor 22 and placed in a standby state. Therefore, the car stop command is not transmitted to the brake contactor 22.
The first safety switch 25 and the second safety switch 26 corresponding thereto, specifically, the second safety switch 26 which has the same target to monitor, are always in the same open/closed state unless a failure occurs in the first and second safety switches.
Examples of the first safety switch 25 and the second safety switch 26 include an upper hoistway switch, a lower hoistway switch, a car door opening detection switch, a landing door opening detection switch, and an overspeed detection switch.
A safety circuit to be connected to the brake contactor 22 is switched between the first safety circuit 23 and the second safety circuit 24 by a switching device 27. The switching device 27 includes an electromagnetic relay 28 and a semiconductor switch 29 which is an electric switch connected in series to the electric relay 28.
The electromagnetic relay 28 is provided between the first safety circuit 23 and the brake contactor 22, and between the second safety circuit 24 and the brake contactor 22, to selectively connect the first safety circuit 23 and the second safety circuit 24 to the brake contactor 22. The semiconductor switch 29 energizes and de-energizes a coil of the electromagnetic relay 28.
The semiconductor switch 29 is controlled to be turned ON/OFF by a failure detecting section 30. The failure detecting section 30 detects faulty opening which corresponds to opening of the first safety switch 25 due to a failure, based on the state of the first safety switch 25 and the state of the second safety switch 26. Specifically, the failure detecting section 30 compares the states of the first safety switch 25 and the second safety switch 26 (which have the same target to monitors), which are opened when the same type of abnormal state occurs, and detects a state in which the first safety switch 25 is opened while the second safety switch 26 is closed as the faulty opening.
At the normal time, a current does not flow through the second safety circuit 24. Therefore, it is conceivable that an ON failure due to energization does not occur in the second safety switch 26. Therefore, a state in which the first safety switch 25 is opened while the second safety switch 26 is closed is considered as the faulty opening of the first safety switch 25.
The failure detecting section 30 is provided to the safety controller 15. Functions of the failure detecting section 30 are realized by the microcomputer or the logic circuit of the safety controller 15.
At the normal time, the switching device 27 connects the first safety circuit 23 to the brake contactor 22 and disconnects the second safety circuit 24 from the brake contactor 22. When the faulty opening is detected by the failure detecting section 30, however, the switching device 27 switches the circuit to be connected to the brake contactor 22 from the first safety circuit 23 to the second safety circuit 24.
Moreover, a circuit switching time period T1 for switching between the first safety circuit 23 and the second safety circuit 24 by the switching device 27 is set shorter than a time period T2 from the opening of the first safety switch 25 to the actual start of a braking operation of the brake device 7 (T1<T2). Specifically, T2 is generally about 50 to 100 milliseconds depending on the specifications of the brake contactor 22. With respect to T2, T1 is set so as to satisfy T1<T2 in consideration of an error. For setting T1, the electromagnetic relay 28 is selected based on an estimate value of a time period required for the detection performed by the failure detecting section 30 and operation specifications of the semiconductor switch 29.
Next, an operation is described. At the normal time, the second safety circuit 24 is disconnected from the brake contactor 22, whereas the first safety circuit 23 is placed in a valid state. Then, when the at least one first safety switch 25 is opened due to some abnormality occurring in the elevator, the hoisting-machine motor 6 is de-energized and the brake coil 21 is also de-energized to bring the car 1 to a sudden stop.
On the other hand, the failure detecting section 30 always monitors whether or not the faulty opening of the first safety switch 25 occurs. Then, when the faulty opening is detected, the semiconductor switch 29 is turned OFF to de-energize the electromagnetic relay 28. In this manner, the circuit to be connected to the brake contactor 22 is instantaneously switched from the first safety circuit 23 to the second safety circuit 24.
At this time, when the circuit switching time period T1 by the switching device 27 is longer than the time period T2 required for the brake contactor 22 to cut off the brake coil current as illustrated in FIG. 3, the electric power supply to the brake contractor 22 is temporarily cut off. Therefore, the car 1 is rapidly decelerated by the braking force of the brake device 7 and is suddenly stopped in some cases depending on the length of T1.
On the other hand, with the safety circuit device for the elevator according to the first embodiment, as illustrated in FIG. 4, by setting T1<T2, the elevator can travel without bringing the car 1 to a sudden stop even when the faulty opening of the first safety switch 25 is detected. Specifically, even when a failure occurs in the first safety circuit 23 which is in operation, the switching to the second safety circuit 24 which is in a standby state is instantaneously performed. Therefore, a safety travel can be performed without bringing the car 1 to a sudden stop.
Moreover, the failure detecting section 30 compares the states of the first safety circuit 25 and the second safety circuit 26, which are opened when the same type of abnormal state occurs, and detects the state in which the first safety circuit 25 is opened while the second safety switch 26 is closed as the faulty opening. Therefore, the failure of the first safety circuit 23 can be detected with high accuracy.
Further, when the abnormality occurring in the elevator is detected, the brake contactor 22 is de-energized so that the hoisting-machine motor 6 and the brake coil 21 are de-energized by a mechanical switch. Therefore, the car 1 can be more reliably stopped.
Further, when the faulty opening is detected by the failure detecting section 30, the semiconductor switch 29 is turned OFF. Thus, the switching between the circuits can be performed at a high speed.
The operation of the elevator can be continued after the switching to the second safety circuit 24. However, it is preferred that the operation of the elevator be interrupted to perform inspection work after a maintenance center or the like is notified of the failure of the first safety circuit 23 and the car 1 is stopped at a predetermine floor.
Alternatively, after the switching to the second safety circuit 24 is performed and the maintenance center or the like is then notified of the failure of the first safety circuit 23, the elevator may be operated while the second safety circuit 24 is operated only until the inspection work is started by a maintenance worker.
Further, the first safety switch 25 and the second safety switch 26 are not necessarily required to correspond to each other exactly on a one-to-one basis. For example, the number of the second safety switches 26 may be larger than that of the first safety switches 25. Specifically, the number of targets to be monitored by the second safety circuit 24 may be larger than that of targets to be monitored by the first safety circuit 23. In this case, a part of the targets to be monitored may be allocated to the safety controller 15 at the normal time so as to be monitored.

Second Embodiment

Next, a second embodiment of the present invention is described. A configuration of a safety circuit device for an elevator according to the second embodiment is basically the same as that of the first embodiment. In the second embodiment, when faulty opening is detected by the failure detecting section 30, the switching device 27 connects the second safety circuit 24 to the brake contactor 22 and then disconnects the first safety circuit 23 from the brake contactor 22, as illustrated in FIG. 5. Specifically, the switching device 27 performs switching between the first safety circuit 23 and the second safety circuit 24 so that the circuits are not simultaneously placed in a standby state.
Even with the safety circuit device described above, the elevator can travel without bringing the car 1 to a sudden stop even when the faulty opening of the first safety switch 25 is detected.
In the above-mentioned examples, the brake device 7 which brakes the rotation of the driving sheave 5 to brake the car 1 is described. However, the brake device is not limited thereto. For example, a brake (rope brake) for gripping the suspension means 3 to brake the car 1, a brake (car brake) mounted to the car 1, which is engaged with a guide rail so as to brake the car 1, or the like may be used.
The number of brake devices is not limited to one. A plurality of the brake devices may be used.
Further, in the above-mentioned examples, although the car 1 is raised and lowered by the single hoisting machine 4, the elevator may use a plurality of hoisting machines.

Claims

A safety circuit device for an elevator, comprising:
a first safety circuit including at least one first safety switch, for detecting an abnormal state based on opening of the at least one first safety switch to generate a car stop command to a brake device;

a second safety circuit including at least one second safety switch, for detecting the same type of abnormal state as the abnormal state detected by the first safety circuit based on opening of the at least one second safety switch to generate a car stop command to the brake device;

a failure detecting section for detecting faulty opening corresponding to the opening of the at least one first safety switch due to a failure based on a state of the at least one first safety switch and a state of the at least one second safety switch; and

a switching device for connecting the first safety circuit to the brake device and disconnecting the second safety circuit from the brake device at normal time and for switching a circuit to be connected to the brake device from the first safety circuit to the second safety circuit when the faulty opening is detected by the failure detecting section,

wherein a circuit switching time period by the switching device is set shorter than a time period from the opening of the at least one first safety switch to start of a braking operation of the brake device.
A safety circuit device for an elevator according to claim 1, wherein the failure detecting section compares the state of the at least one first safety switch and the state of the at least one second safety switch, each of the at least one first safety switch and the at least one second safety switch being opened when the same type of abnormal state occurs, with each other, and detects a state in which the at least one first safety switch is opened while the at least one second safety switch is closed as the faulty opening.
A safety circuit device for an elevator according to claim 1, wherein:
the first safety circuit and the second safety circuit are connected in parallel between the brake device and a power supply; and

the switching device is provided between the first safety circuit and the brake device, and between the second safety circuit and the brake device, and includes a changeover switch section for selectively connecting the first safety circuit and the second safety circuit to the brake device.
A safety circuit device for an elevator according to claim 1, wherein:
the switching device includes an electromagnetic relay for selectively connecting the first safety circuit and the second safety circuit to the brake device and an electric switch for energizing and de-energizing a coil of the electromagnetic relay; and

the electric switch is controlled to be turned ON/OFF by the failure detecting section.
A safety circuit device for an elevator, comprising:
a first safety circuit including at least one first safety switch, for detecting an abnormal state based on opening of the at least one first safety switch to generate a car stop command to a brake device;

a second safety circuit including at least one second safety switch, for detecting the same type of abnormal state as the abnormal state detected by the first safety circuit based on opening of the at least one second safety switch to generate a car stop command to the brake device;

a failure detecting section for detecting faulty opening corresponding the opening of the at least one first safety switch due to a failure based on a state of the at least one first safety switch and a state of the at least one second safety switch; and

a switching device for connecting the first safety circuit to the brake device and disconnecting the second safety circuit from the brake device at normal time and for switching a circuit to be connected to the brake device from the first safety circuit to the second safety circuit when the faulty opening is detected by the failure detecting section,

wherein the switching device connects the second safety circuit to the brake device and then disconnects the first safety circuit from the brake device when the faulty opening is detected by the failure detecting section.