Turn valve control system for a rotary screw compressor

Claim 1

In a rotary screw compressor having an inlet port for receiving a low pressure fluid to be compressed and a discharge port for discharging the compressed fluid at a predetermined pressure, an apparatus for regulating the fluid throughput of the rotary screw compressor from a full capacity operating condition to a desired, predetermined capacity operating condition, the apparatus comprising: an inlet valve flow connected with the inlet port; positioning means for positioning the inlet valve in a predetermined orientation, the inlet valve positioning means positioning the inlet valve in discrete, predetermined, angular steps; position sensing means, operably connected to the inlet valve, for detecting the angular orientation of the inlet valve; pressure sensing means for detecting fluid pressure at the compressor inlet port; a rotatable valve disposed in fluid communication with the low pressure fluid; rotatable valve positioning means for positioning the rotatable valve in a predetermined orientation, the rotatable valve positioning means positioning the rotatable valve in discrete, predetermined, angular steps; position sensing means, operably connected to the rotatable valve, for detecting the angular orientation of the rotatable valve; pressure sensing means for detecting a compressor service pressure; and electronic control means, responsive to the inlet valve and rotatable valve position sensing means and to the inlet port pressure and service pressure sensing means, for controlling the inlet valve positioning means and the rotatable valve positioning means to orient the inlet valve and the rotatable valve in a respective, predetermined position thereby regulating a fluid throughput of the rotary screw compressor from a full capacity to a predetermined capacity during compressor operation.