Electricity: motive power systems – Automatic and/or with time-delay means – With respect to a fixed standard – master or reference device
Patent
1995-03-27
1997-04-08
Sircus, Brian
Electricity: motive power systems
Automatic and/or with time-delay means
With respect to a fixed standard, master or reference device
70282, E05C 306
Patent
active
056191103
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a safety ensuring apparatus for ensuring the safety of operators working at factories and the like.
BACKGROUND ART
With equipment requiring for example, maintenance of mechanical moving parts, or coordinated (alternate) operation between an operator and a mechanical moving part, measures to ensure operator safety are extremely important.
In situations for example, where an operator approaches a danger region wherein it is possible to touch a mechanical moving part, conventional methods of ensuring safety when the mechanical moving part is in a movable condition, involve first shutting off the motor power supply in the case of motor driven mechanical moving parts, or shutting off the pressure supply in the case of pressure driven mechanical moving parts. The operator then verifies that the mechanical moving part has stopped, before approaching the mechanical moving part.
In practice however, there is the case wherein the operator approaches the mechanical moving part with the judgment that it will soon stop although it has not completely stopped. There is also the case wherein the operator mistakenly approaches while the mechanical moving part is moving. Furthermore, there is the case wherein the mechanical moving part which normally stops after a predetermined time interval, does not stop within the normal period due to a fault in the mechanical side (for example a fault in the braking).
It is therefore necessary to implement some type of safety measure. Conventional methods involve surrounding the mechanical moving part with a safety enclosure. There is also the case which adopt an arrangement for shutting off the drive power source to the mechanical moving part when the door to the safety enclosure is opened.
However, even though the drive power source to the mechanical moving part may for example be shut off by opening the door, since the mechanical moving part cannot stop instantaneously, there is the possibility of the operator approaching the mechanical moving part inside the safety enclosure before it has completely stopped.
Here an interlock system can be considered with a door lock incorporating a solenoid, provided in the door of the safety enclosure, so that the lock is released when the solenoid is excited. With this interlock system, the solenoid is excited when the mechanical moving part inside the safety enclosure stops, thereby releasing the lock only after the mechanical moving part has stopped.
Such an interlock system, necessitates a sensor which detects the stopping of the mechanical moving part, and stops the solenoid. An example, of such a sensor for detecting the stopping of the mechanical moving part and exciting the solenoid is shown in FIG. 1.
In FIG. 1, a rotation body 3 is provided by way of a speed reducing mechanism 2 on a motor 1 which is used to drive a mechanical moving part. A rotation disc 4 having a plurality of apertures 4a around a periphery thereof, is attached to the rotation body 3. A light emitting element 5 and a light receiving element 6 of a photo-interrupter are positioned opposite each other on either side of the rotation disc 4.
When the motor 1 is rotating, the light beam from the light emitting element 5 is received intermittently by the light receiving element 6 through the apertures 4a, depending on the rotation of the rotation disc 4. An alternating current signal as shown in FIG. 1 is therefore output from the light receiving element 6. This is amplified by an AC amplifier 7 and rectified by a rectifying circuit 8 to produce a direct current output signal. When the motor 1 is not rotating however, the light beam from the light emitting element 5 is either shut off by the rotation disc 4 so as not to reach the light receiving element 6, or continuously received by the light receiving element 6 by way of the apertures 4a. The output of the light receiving element 6 is therefore either a zero or a constant level direct current output. Hence a direct current output is not produced by the rectifying circui
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Futsuhara Koichi
Mihira Ritsuo
Sakai Masayoshi
Sugimoto Noboru
Suzuki Masatoshi
Kao Corporation
Sircus Brian
The Nippon Signal Co. Ltd.
Yamatake & Co., Ltd.
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