Pumps – Condition responsive control of pump drive motor – Responsive to pump lubricant – sealant – or coolant condition
Reexamination Certificate
2000-11-14
2002-05-28
Walberg, Teresa (Department: 3742)
Pumps
Condition responsive control of pump drive motor
Responsive to pump lubricant, sealant, or coolant condition
C417S032000, C417S018000
Reexamination Certificate
active
06394758
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus and method of controlling an air compressor and, more particularly, to an apparatus and method of smoothly and effectively controlling the operation of such an air compressor while maintaining a desired target pressure of resulting compressed air and conserving electric power required for the operation of the compressor.
2. Description of the Prior Art
As well known to those skilled in the art, conventional air compressors have been typically controlled through a loading/offloading process or a suction air controlling process to maintain a desired target pressure of resulting compressed air. In such a conventional loading/offloading process, a predetermined load is applied to an air compressor, thus allowing the compressor to perform a desired compressing operation, the load being, thereafter, removed from the compressor when necessary, thus allowing the compressor to stop its compressing operation. It is thus possible for the compressor to maintain the desired target pressure of resulting compressed air. On the other hand, in the suction air controlling process, the desired target pressure of resulting compressed air is maintained by controlling the amount of suction air so as to finally control the amount of the resulting compressed air.
However, the conventional loading/offloading process is problematic in that the desired target pressure of resulting compressed air is accomplished by discharging surplus compressed air into the atmosphere, thus regrettably consuming excessive electric power to generate such surplus compressed air. On the other hand, the suction air controlling process is problematic in that it reduces the operational efficiency of an air compressor in addition to regrettably consuming excessive electric power while maintaining the target pressure of resulting compressed air.
SUMMARY OF THE INVENTION
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide an apparatus and method of controlling air compressors, which smoothly and effectively controls the operation of an air compressor.
Another object of the present invention is to provide an apparatus and method of controlling air compressors, which controls the operation of an air compressor while maintaining a desired target pressure of resulting compressed air.
A further object of the present invention is to provide an apparatus and method of controlling air compressors, which controls the operation of an air compressor while conserving electric power.
In its embodiment, the present invention provides an apparatus for controlling an air compressor, comprising: a controller for controlling the operation of the apparatus; an inverter circuit interfaced between the controller and the air compressor and used for modulating the frequency of a drive signal for the air compressor in response to a control signal output from the controller, and outputting the modulated drive signal to the air compressor so as to control the operation of the air compressor and to control the rpm of the air compressor; a temperature sensor connected to the controller and used for sensing the temperature of lubrication oil of the compressor and outputting a temperature signal to the controller; a main air tank connected to the air compressor through an air pipeline and used for storing compressed air supplied from the air compressor; and a pressure sensor connected to the controller and used for sensing the pressure of compressed air stored within the air tank and outputting a pressure signal to the controller.
The present invention also provides a method of controlling an air compressor, comprising the steps of: (a) starting the operation of the air compressor, thus allowing the compressor to supply compressed air to a main air tank through an air pipeline; (b) sensing the temperature of the lubrication oil in the air compressor using a temperature sensor; (c) determining whether the sensed lubrication oil temperature is higher than a preset reference temperature stored in the memory of the controlling mechanism; (d) primarily sensing the pressure of the compressed air within the air tank when the sensed lubrication oil temperature is not higher than the preset reference temperature; (e) determining whether the primarily sensed pressure of the compressed air within the air tank is higher than a preset minimum pressure stored in the memory; (f) lowering the frequency of a drive signal for the air compressor and outputting the regulated drive signal to the air compressor so as to operate the air compressor at a low rpm when the primarily sensed pressure of the compressed air is higher than the preset minimum pressure; (g) secondarily sensing the pressure of compressed air within the air tank using the pressure sensor; (h) determining whether the secondarily sensed pressure of the compressed air within the air tank is higher than a preset maximum pressure stored in the memory; (i) operating the air compressor at a minimum rpm and discharging the compressed air from the air tank into the atmosphere when the secondarily sensed pressure of the compressed air within the air tank is higher than the preset maximum pressure; (j) thirdly sensing the pressure of compressed air within the air tank using the pressure sensor; (k) determining whether the thirdly sensed pressure of the compressed air within the air tank is higher than a preset stop pressure stored in the memory; and (l) stopping the operation of the air compressor when the thirdly sensed pressure of the compressed air within the air tank is higher than the preset stop pressure.
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patent: 6093975 (2000-07-01), Peticolas
patent: 6236183 (2001-05-01), Schroeder
patent: 6281595 (2001-08-01), Sinha et al.
Han Yu Sang
Lee Jae Young
Lee Jae Young
Rothwell Figg Ernst & Manbeck
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