Winding – tensioning – or guiding – Tension control or brake – Supply controlled
Reexamination Certificate
1999-08-13
2001-02-13
Mansen, Michael R. (Department: 3653)
Winding, tensioning, or guiding
Tension control or brake
Supply controlled
C242S14700M, C242S15500M, 36, 36, C318S432000
Reexamination Certificate
active
06186434
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a tension apparatus having an electromagnetic brake for applying a tension to a material in continuous form such as a fibrous yarn, or a wire or tape of metal material or the like in winding or stretching the material in continuous form.
A tension apparatus used in textile machinery generally comprises an electromagnetic brake actuated as a thread such as a yarn, twist yarn, or double yarn travels, a tension roller fitted on the rotating shaft of the electromagnetic brake, on which a thread is spirally wound, and a pair of large-diameter tenser discs having cooperative surfaces which oppose each other and sandwich the thread between them. A thread handling area is formed from the inlet guide to the outlet guide through the pair of tenser discs and tension roller.
Conventionally, in a tension apparatus of this type, a tension is applied to a material in continuous form such as a thread using a built-in contact or non-contact electromagnetic brake in winding or stretching the material in continuous form. The output torque of the electromagnetic brake is generated in correlation to the exciting current to the electromagnetic brake. A tension based on the product of the output torque of the electromagnetic brake and the radius of the tension roller having the shape of a winding disc or column acts on the material in continuous form. The tension to the material in continuous form is increased/decreased by changing the output torque generated by the electromagnetic brake, i.e., the exciting current to the electromagnetic brake.
This tension apparatus incorporates a D/A converter of a PWM (Pulse Width Modulation) scheme. The D/A converter of the PWM scheme smoothes a PWM signal with a duty ratio corresponding to an input tension instruction value and supplies the PWM signal to a constant current driving circuit. The constant current driving circuit generates an exciting current corresponding to the voltage value of the smoothed PWM signal from the D/A converter and supplies the exciting current to an electromagnetic brake.
According to such a tension apparatus, however, when the PWM signal to the D/A converter is stopped, no voltage is output to the constant current driving circuit. For this reason, the PWM signal to the D/A converter must be continuously output, and a single microcomputer cannot time-divisionally perform PWM control of the electromagnetic brake simultaneously with other communication control or rotation pulse detection processing. Hence, a dedicated PWM controller is required, resulting in an increase in component mounted area or cost of components.
When a microcomputer having a PWM control function capable of independent PWM control is used, the dedicated PWM controller need not be used. However, since the dedicated microcomputer is expensive and cannot be made compact, the component mounted area or cost of components inevitably increases.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a tension apparatus capable of time-divisionally performing PWM control of an electromagnetic brake together with other communication control or rotation pulse detection processing using a single microcomputer.
In order to achieve the above object, according to the present invention, there is provided a tension apparatus comprising a mechanical section having an electromagnetic brake driven by an exciting current to generate an output torque, the mechanical section applying a tension to a material in continuous form which is being wounded and stretched by the output torque of the electromagnetic brake, signal output means for repeatedly outputting a PWM (Pulse Width Modulation) signal having a duty ratio corresponding to an input tension instruction value before and after a predetermined stop period, smoothing means for smoothing the PWM signal from the signal output means, maximum value holding means for holding a maximum voltage value of the smoothed PWM signal, exciting current supply means for supplying an exciting current corresponding to the held maximum voltage value to the electromagnetic brake, and reset means for resetting holding operation of the maximum value holding means on the basis of a magnitude comparison result between a current tension instruction value and a previous tension instruction value.
REFERENCES:
patent: 3034744 (1962-05-01), Bancroft
patent: 4480799 (1984-11-01), Yano et al.
patent: 4891764 (1990-01-01), McIntosh
patent: 6029923 (2000-02-01), Ishimaru et al.
patent: 5-44739 (1993-02-01), None
patent: 7-37745 (1995-02-01), None
Blakely & Sokoloff, Taylor & Zafman
Mansen Michael R.
Ogura Clutch Co., Ltd
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