Brakes – Operators – Spring
Reexamination Certificate
2002-12-10
2004-06-01
Lavinder, Jack (Department: 3683)
Brakes
Operators
Spring
C188S163000
Reexamination Certificate
active
06742634
ABSTRACT:
TECHNICAL FIELD
This invention relates to a magnetic brake system capable of detecting a trouble of a magnetic brake controlled by an electric current fed through a coil, and also to an elevator trouble detection system using the above magnetic brake system as an elevator drive motor.
BACKGROUND ART
As a brake for an elevator, a magnetic brake is generally used. This magnetic brake is constructed such that feeding of an electric current through a coil attracts an armature to separate a lining from a disc for permitting running of a car and cut-off of the electric current causes the armature to return to bring the lining into contact with the disc for applying braking force.
A magnetic brake of such a construction may be locked for various reasons so that the above-mentioned attraction of an armature may be troubled. As occurrence of such a trouble leads to a loss of normal braking force, a serious accident may take place. It is, therefore, required to detect a trouble of a magnetic brake without failure.
As disclosed in JP-A-11222371, for example, it has conventionally been proposed to measure the temperature of the lining by a temperature sensor and, when the measurement value is higher than a criterion, to determine that the gap between the lining and the disc is not normal and abnormal frictional heat is being produced, and to transmit trouble information to a supervision center by which an elevator is supervised at a remote location.
In the above-mentioned conventional art, the determination of a trouble in the magnetic brake is performed based on a comparison between the temperature measured by the temperature sensor and the criterion. However, the air temperature of a location at which an elevator is installed varies depending upon the geographical location or the season, so that measurement values obtained by the temperature sensor also deviate due to variations in air temperature. For accurate detection of a trouble, it is, therefore, necessary to adjust the criterion depending upon the geographical location or the season. However, irksome labor is required for resetting the criterion. Further, a magnetic brake is structurally arranged adjacent an elevator drive motor. Heat produced by the motor is hence transferred to the magnetic brake, leading to a rise in the temperature of the magnetic brake. Depending upon the installation site of an elevator, however, the operation rate of the elevator varies and the quantity of heat produced by its motor also differs. It is, therefore, also necessary to take into consideration the heat to be transferred from the motor upon setting the above-described criterion.
With the foregoing circumstances of the conventional art in view, the present invention has as primary objects thereof the provision of a magnetic brake system capable of detecting a trouble with accuracy and an elevator trouble detection system making use of the magnetic brake system.
DISCLOSURE OF THE INVENTION
To achieve these objects, the present invention, in a first aspect thereof, provides a magnetic brake system for performing braking action by cancellation of energization of a coil, said magnetic brake system comprising a magnetic brake provided with a disc connected to a shaft of a motor and also with an armature responsive to energization of the coil for being attracted to separate the disc from a lining, wherein the magnetic brake system comprises: a temperature detection means for detecting a temperature of the magnetic brake; a temperature comparison means for comparing a first temperature, which is detected by the temperature detection means when the coil is energized to release the magnetic brake, specifically, shortly after the coil is energized to release the magnetic brake, with a second temperature which is detected by the temperature detection means shortly when the energization of the coil is cancelled, specifically, shortly before the energization of the coil is cancelled to actuate the magnetic brake; and a control means for determining on a basis of a result of the comparison by the temperature comparison means whether or not the magnetic brake has developed any trouble.
The present invention, in a second aspect thereof, provides a magnetic brake system for performing braking action by, said magnetic brake system comprising a magnetic brake provided with a disc connected to a shaft of a motor and also with an armature responsive to energization of the coil for being attracted to separate the disc from a lining, wherein the magnetic brake system comprises: a temperature detection means for detecting a temperature of the magnetic brake; a temperature comparison means for comparing a first temperature, which is detected by the temperature detection means shortly before the energization of the coil is cancelled to actuate the magnetic brake, with a second temperature which is detected by the temperature detection means after a predetermined time is elapsed in continuous actuation of the magnetic brake over the predetermined time since the actuation of the magnetic brake; and a control means for determining on a basis of results of the comparison by the temperature comparison means whether or not the magnetic brake has developed any trouble.
The present invention, in a third aspect thereof, provides a magnetic brake system for performing braking action by cancellation of energization of a coil, said magnetic brake system comprising a magnetic brake provided with a disc connected to a shaft of a motor and also with an armature responsive to energization of the coil for being attracted to separate the disc from a lining, wherein the magnetic brake system comprises: a first temperature detection means for detecting a temperature of the magnetic brake; a second temperature detection means for detecting an air temperature of an environment in which the magnetic brake is installed; a temperature comparison means for comparing a first temperature, which is detected by the first temperature detection means, with a second temperature detected by the second temperature detection means; and a control means for determining on a basis of a result of the comparison by the temperature comparison means whether or not the magnetic brake has developed any trouble.
The present invention, in a fourth aspect thereof, provides a magnetic brake system as described above in connection with the first or third aspect, wherein, when a temperature difference between the first temperature and the second temperature as determined by the temperature comparison means is greater than a predetermined value, the control means determines that the magnetic brake has developed a trouble.
The present invention, in a fifth aspect thereof, provides a magnetic brake system as described above in connection with any one of the first to fourth aspects, further comprising an informing means for informing that the magnetic brake has developed the trouble, wherein, when the magnetic brake is determined to have developed the trouble, the control means informs accordingly by the informing means.
The present invention, in a sixth aspect thereof, provides an elevator trouble detection system for detecting a trouble of a magnetic brake for a drive motor of an elevator, said magnetic brake being provided with an armature attractable by energization of a coil in response to a brake release command to separate a lining from a disc for permitting running of a car and returnable by cancellation of the energization in response to a brake actuation command to bring the lining into contact with the disc for applying braking force, wherein the elevator trouble detection system comprises: a temperature detection means for detecting a temperature of the magnetic brake; a temperature comparison means for comparing a first temperature, which is detected by the temperature detection means when the armature has been attracted responsive to the brake release command, with a second temperature which is detected before the armature returns responsive to the brake actuation command; and a control means for determining on
Ishida Yuki
Kiyosugi Hiroshi
Matsuo Toshiaki
Nakai Mikio
Sekiya Takashi
Crowell & Moring LLP
Hitachi Building Systems Co., Ltd.
Lavinder Jack
Torres Melanie
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