Pumps – Condition responsive control of pump drive motor – By controlling free piston internal combustion engine
Reexamination Certificate
1998-07-30
2001-01-09
Thorpe, Timothy S. (Department: 2838)
Pumps
Condition responsive control of pump drive motor
By controlling free piston internal combustion engine
C417S032000, C417S045000
Reexamination Certificate
active
06171063
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to a control circuit for vibrating compressors, and more specifically to a control circuit for vibrating compressors having a vibrating drive coil in a magnetic field, which protects the vibrating compressor when an overrun of the vibrating compressor piston might cause a damage to the valve by generating an a-c voltage of a reduced voltage level to prevent the valve from being damaged.
BACKGROUND OF THE INVENTION
Conventional types of control circuit for vibrating compressors are such that the d-c voltage of a battery, etc. is converted into an a-c voltage, which is applied to the vibrating compressor. In converting a d-c voltage into an a-c voltage, an a-c voltage of a frequency agreeing with the mechanical vibration of the vibrating compressor is generated and applied to the vibrating compressor.
Conventional types of control circuit for vibrating compressors have heretofore used a circuit configuration in which a switching element, such as a MOS-FET transistor, converts the d-c voltage of a battery into an a-c voltage, which is in turn applied directly to the vibrating compressor.
For this reason, the battery voltage during or immediately after the charging of the battery is normally higher than the predetermined voltage, and accordingly the converted a-c voltage of a frequency agreeing with the mechanical vibration of the vibrating compressor also tends to be higher, causing or threatening to cause a damage to the valve due to the overrun of the vibrating compressor piston.
If the ambient temperature of the vibrating compressor drops, the delivery pressure of the vibrating compressor also drops, causing the stroke of the vibrating compressor piston to increase. As a result, when the ambient temperature of the vibrating compressor is lower than a predetermined temperature, a damage is caused or threatens to be caused to the valve due to the overrun of the vibrating compressor piston even when a predetermined voltage is applied to the vibrating compressor.
SUMMARY OF THE INVENTION
To overcome the aforementioned problems, it is an object of this invention to protect the valve of a vibrating compressor from being damaged due to the overrun of the vibrating compressor piston by providing a control circuit that converts a d-c voltage into an a-c voltage to supply to the vibrating compressor.
It is another object of this invention to protect the valve of a vibrating compressor from being damaged due to the overrun of the vibrating compressor piston by providing a control circuit that detects an input voltage to be input into the vibrating compressor at a timing at which the voltage is restored to a level close to 0 volts, and reduces the input voltage when the input voltage is higher than a predetermined voltage.
It is a further object of this invention to protect the valve of a vibrating compressor from being damaged due to the overrun of the vibrating compressor piston by providing a control circuit that detects the ambient temperature of the vibrating compressor instead of detecting a high input voltage to the vibrating compressor, or simultaneously with the detection of a high input voltage, and reduces the input voltage when the ambient temperature is lower than a predetermined temperature.
It is still a further object of this invention to protect a MOS-FET transistor due to the malfunction of a control circuit by providing a capacitor on the gate of the MOS-FET transistor to cut d-c components.
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Akazawa Naoki
Namai Masao
Evora Robert Z.
McGlew and Tuttle , P.C.
Sawafuji Electric Co. Ltd.
Thorpe Timothy S.
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