Motor stopped verification apparatus

Details Motor stopped verification apparatus Motor stopped verification apparatus

1996-05-29

1998-02-10

Ip, Paul

Electricity: motive power systems

Braking

'plugging' or application of reverse power to motor

318282, 318254, 318439, 340648, G01P 1300, H02P 624

Patent

active

057173028

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to a fail-safe motor stopped verification apparatus which can verify if a motor has stopped rotating by reliably distinguishing between a motor rotating condition (including rotation under inertia) and a motor stopped condition. In particular the invention relates to technology for rotation sensors for sampling motor rotating and stopped detection outputs.


BACKGROUND ART

Heretofore, to ensure operator safety when using motor driven apparatus, it has been necessary to have a safety device which can detect a sudden unintentional start up of a stopped motor, and give a warning. As such a safety device, the present applicant has proposed (refer to PCT/JP93/00411) a motor stopped verification apparatus having a high degree of safety, which can reliably detect that a motor has stopped rotating (including rotation under inertia) and which has excellent fail-safe characteristics at the time of a fault in the apparatus.
The operation of such a rotation stopped verification apparatus is described hereunder.
With this apparatus, the construction includes a sensor section (rotation sensor) incorporating a bridge circuit having a transducer coil on one side for converting a motor rotating or stopped condition into an electrical signal, which converts a detection output for the rotation or non-rotation of motor into a change in the imbalance output signal (alternating current signal) of the bridge circuit and outputs, and a rotation judgement circuit incorporating a fail-safe window comparator, previously known for example from U.S. Pat. No. 4,661,880, wherein a logical value output from the window comparator based on the detection output from the sensor section, is made a judgement output for the rotation or non-rotation of motor.
In this judgement operation, the detection output from the sensor becomes constant when the motor is stopped. When this constant level detection output is input from the sensor section to the rotation judgement circuit, an output signal of logic value "1" indicating that the motor has stopped (corresponding to the safe condition) is generated from the window comparator of the rotation judgement circuit. On the other hand, when the motor is rotating (including rotation under inertia) the detection output from the sensor changes periodically corresponding to the rotation. When this periodically changing detection output is input from the sensor section to the rotation judgement circuit, an output signal of logic value "0" indicating that the motor is rotating (corresponding to a danger condition) is generated from the window comparator of the rotation judgement circuit. Furthermore the construction is fail-safe in that, if a fault occurs in the sensor section or the rotation judgement circuit, the output from the window comparator becomes a logic value "0" indicating danger.
However, with the rotation stopped verification apparatus of the conventional technology, since a bridge circuit is used in the sensor section the following problems arise:
One problem is that when a motor exciting winding is used as the transducer coil connected to the one side of the bridge circuit, then the impedance of the exciting winding differs depending on the motor used. Moreover, when a pick-up coil for detecting rotation of the motor from changes due to recesses and protrusions around the periphery of a motor driven metal rotation body is used as the transducer coil, then the size of the pick-up coil differs depending on the shape of the metal rotation body. Therefore, an adjustment is necessary for appropriately setting the imbalance output signal from the bridge circuit each time there is a change in the detection object being used for detecting the rotation or non-rotation. That is to say, it is necessary to adjust the imbalance output signal level of the bridge circuit to match the detection object, so that the imbalance output signal level is within the range (window) of the upper limit and lower limit threshold values of the window comparator when the motor

REFERENCES:
patent: 4105903 (1978-08-01), Shaw et al.
patent: 4236604 (1980-12-01), Warner
patent: 4661880 (1987-04-01), Futsuhara
patent: 4734673 (1988-03-01), Murata et al.
patent: 4926101 (1990-05-01), Enomoto et al.
patent: 4977375 (1990-12-01), Toth
patent: 5027114 (1991-06-01), Kawashima et al.
patent: 5493188 (1996-02-01), Yoshikawa et al.
patent: 5568131 (1996-10-01), Sakai et al.
patent: 5619110 (1997-04-01), Sugimoto et al.

Affiliated with

Also associated with

Rating

Motor stopped verification apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Motor stopped verification apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Motor stopped verification apparatus will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2079738