Electricity: motive power systems – Braking – Friction braking
Patent
1990-02-22
1992-10-20
Smith, Jr., David
Electricity: motive power systems
Braking
Friction braking
112275, H02P 324
Patent
active
051573075
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a sewing machine drive apparatus having a power source circuit for driving a solenoid of a sewing machine for industrial use.
BACKGROUND ART
A conventional example is shown in FIG. 4 and elucidated.
Numeral 1 designates an AC power source, numeral 6 designates a sewing machine control circuit, numeral 7 designates a rectifying-smoothing circuit, numeral 9 designates a solenoid drive circuit, numeral 10 designates a solenoid, numeral 11 designates a transformer, and numeral 12 designates a chopping control circuit.
With regard to the sewing machine drive apparatus constituted as mentioned above, its operation is described referring to FIG. 5.
The AC power source 1 is transformed to a rated input voltage of the solenoid 10 by the transformer 11. The output of transformer 11 is smoothed by the rectifying-smoothing circuit 7, thereby a solenoid power source is made. A solenoid drive signal of the sewing machine control circuit 6 is received by the solenoid drive circuit 9. The solenoid 10 is driven by taking said solenoid power source as an input. After an elaspe of a time period, a chopping signal of a certain frequency from said sewing machine control circuit 6 is received by the chopping control circuit 12; and thereby, output voltage of the solenoid 10 is controlled and output current of the solenoid is reduced.
However, in the convention power source above, after driving and holding the solenoid, when chopping control is executed on the output voltage by the chopping control circuit 12 for holding the solenoid by the chopping control circuit 12, an acoustic noise of chopping sound (frequency of the chopping signal) is generated giving unpleasant feeling to a user.
DISCLOSURE OF THE INVENTION
The purpose of the present invention is, to provide a sewing machine drive apparatus which eliminates acoustic noise and can set a voltage for holding a solenoid.
This purpose is achieved by apparatus in accordance with the present invention which has an output voltage of a DC/DC converter solenoid power source circuit used as a power source of a solenoid, uses a DC power source direct rectification and smoothing of an AC power source as an input, and controls the voltage of the power source by a voltage control signal from a sewing machine control circuit.
The present invention can, by constituting the solenoid power source circuit by DC/DC type converter, control the voltage control signal of the sewing machine control circuit freely by an output voltage control circuit in the solenoid power source circuit.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of a sewing machine drive apparatus in a first embodiment in accordance with the present invention.
FIG. 2 is a time chart showing drive characteristics of solenoid of the sewing machine drive apparatus in accordance with the present invention.
FIG. 3 is a block diagram of a sewing machine drive apparatus in a second embodiment in accordance with the present invention.
FIG. 4 is the block diagram of the conventional sewing machine drive apparatus.
FIG. 5 is the time chart of deriving characteristics of the solenoid of the conventional sewing machine drive apparatus.
BEST MODE FOR EMBODYING THE INVENTION
Hereafter, a first embodiment in accordance with the present invention is described referring to the drawings.
FIG. 1 shows a sewing machine drive apparatus in the first embodiment in accordance with the present invention.
In FIG. 1, numeral 1 designates an AC power source, numeral 2 designates a first rectifying-smoothing circuit, numeral 3 designates a motor drive circuit, numeral 4 designates a synchronous motor, numeral 5 designates a sewing machine, numeral 6 designates a sewing machine control circuit having a voltage control circuit for controlling the output voltage of the solenoid power source circuit 8, numeral 7 designates a second rectifying-smoothing circuit, numeral 8 designates a DC/DC converter/solenoid power source circuit, numeral 9 designates a solenoid drive circuit, and num
REFERENCES:
patent: 4161919 (1979-07-01), Nishida et al.
patent: 4351254 (1982-09-01), Brown
patent: 4403563 (1983-09-01), Shinozaki et al.
patent: 4627370 (1986-12-01), Nakamura
patent: 4714039 (1987-12-01), Shimada
Matsushita Electric - Industrial Co., Ltd.
Smith Jr. David
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