Electricity: motive power systems – Miscellaneous
Patent
1996-10-07
1997-12-30
Ro, Bentsu
Electricity: motive power systems
Miscellaneous
256 1, 49 31, 361 1, 192129R, F16P 308, F16P 310
Patent
active
057034524
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a safety ensuring apparatus that allows an operator to approach a movable section of a machine after the movable section, which is driven by a motor or the like, has stopped rotating or moving. The safety ensuring apparatus according to the present invention is particularly suited for constituting a guard system in which the movable section of a machine is surrounded by a fence with a door having a locking device provided at a portion of the fence so that, when the locking device of the door is released, the movable section within the fence can be approached.
BACKGROUND ART
A safety ensuring apparatus of this type is disclosed in PCT/JP93/00758. Also, a sensor for verifying that the rotation or movement of a movable portion has stopped is disclosed in International Publication WO94/23303. In addition, a device for detecting that rotation is at a specific rate or lower is also required in an apparatus that includes a movable portion driven by a motor or the like, i.e. , a robot or the like, as a safety device that allows the operator to approach the apparatus only after the movable portion has completely stopped its operation, in order to assure the safety of the operator who must approach the apparatus. Such safety devices include the motor rotation stop detecting device disclosed in International Publication WO94/23303, which is capable of reliably detecting that the rotation of a motor has stopped, including rotation under inertia, and operates toward safety when the apparatus has had a failure, thereby providing a high degree of safety. However, the device disclosed in this prior art publication has problems yet to be solved, i.e., a delay in issuing notification of the stop that occurs because the device is not provided with a function for detecting the rotation rate and, since a bridge circuit is employed in a rotation sensor, adjustment of the bridge circuit is required.
These problems are eliminated in PCT/JP95/00165, for which an application was submitted by the applicant. However, PCT/JP95/00165 only discloses the technology for issuing notification of movable portion stop, and the disclosure does not encompass the use of the movable portion stop signal as a signal for assuring safety of the operator against the movable portion.
In addition, PCT/JP95/00243 discloses a safety securing device which uses a movable portion stop signal for a signal for assuring the safety of the operator against the mechanical movable portion. To be more specific, the publication discloses a device that assures safety by using a movable portion stop signal and a movable portion rotation signal as signals for assuring safety of the operator against the mechanical movable portion when constituting a guard system in which the mechanical movable portion is enclosed by a fence, with a door having a locking device provided at a portion of the fence and the operator is allowed to approach the mechanical movable portion within the fence when the locking device at the door is released. However, PCT/JP95/00243 carries the danger of the locking device being released if the operating switch is turned on in order to drive the mechanical movable portion when the operator does not realize that the sensor has gone down.
DISCLOSURE OF THE INVENTION
Accordingly, it is an object of the present invention to provide an apparatus that assures the safety of the operator by using a movable section stop signal and a movable section rotation signal as signals for assuring the safety of the operator against the movable section of a machine when constituting a guard system in which the movable section of a machine is enclosed by a fence provided with a door having a locking device at a portion of the fence and the movable section of a machine within the fence can be approached when the locking device of the door is released.
It is a further object of the present invention to provide a safety ensuring apparatus in which the locking device does not become released even if the operating switch
REFERENCES:
patent: 4386341 (1983-05-01), Yamamoto
patent: 4870592 (1989-09-01), Lampi et al.
Ro Bentsu
The Nippon Signal Co. Ltd.
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