Control device for a motor-compressor

Claim 2

A control assembly for a motor and compressor in which the working medium is progressively compressed in a plurality of stages and the power output transmitted from the motor to the compressor is varied in dependence of a change above a predetermined value of the outlet medium Pressure at the delivery side of the compressor, said control assembly comprising: a. a power control mechanism adapted to control the input power to the motor, b. said power control mechanism including an adjusting means for actuating said control mechanism in response to an interstage pressure of the compressor, c. a pressure converter arranged to amplify the pressure medium increase above the predetermined value at the delivery side of the compressor to provide a control pressure which is a multiple of said pressure increase, and d. said pressure converter being connected to said adjusting means for countering said interstage pressure with the control pressure so that the power input to said motor is reduced in response to an increase of the control pressure.

Claim 3

A control assembly as defined in claim 1 wherein said adjusting means includes a spring means arranged to aid said control pressure in countering said interstage pressure.

Claim 4

A control assembly as defined in claim 1 which includes an unloading mechanism adapted to be connected to the delivery side of said compressor for relieving the outlet medium pressure, and a control valve operatively connected to said unloading mechanism and responsive to said control pressure whereby said unloading mechanism is actuated to relieve the outlet medium pressure from said delivery side of said compressor when the control pressure reaches a certain value.

Claim 5

A control assembly for a motor-compressor in which the working medium is progressively compressed in a plurality of stages and the motor drive power to the compressor is varied in dependence upon a pressure change above a predetermined value of the outlet medium pressure at the delivery side of the compressor, said control assembly comprising: a. a power control means adapted to change the input power to the motor so as to vary the motor drive power to the compressor, b. said power control means including adjusting means for actuating said power control means responsive to an interstage pressure of the compressor, and spring means disposed to counter said interstage pressure on said adjusting means, c. pressure sensing means for sensing the outlet medium pressure and providing a control pressure to the adjusting means when said outlet medium pressure exceeds said predetermined value, d. said adjusting means being responsive to said control pressure to aid said spring means in countering the interstage pressure whereby the input power to said motor is reduced in response to an increase in the output medium pressure from said compressor.

Claim 6

A control assembly for a motor-compressor in which the working medium is progressively compressed in a plurality of stages and the motor drive power to the compressor is varied in dependence upon a pressure change above a predetermined value of the outlet medium pressure at the delivery side of the compressor, said control assembly comprising: a. a power control means adapted to change the input power to the motor so as to vary the motor drive power to the compressor, b. said power control means including adjusting means for actuating said power control means responsive to an interstage pressure of the compressor, and spring means disposed to counter said interstage pressure on said adjusting means, c. pressure sensing means for sensing the outlet medium pressure and providing a control pressure to the adjusting means when said outlet medium pressure exceeds said predetermined value, d. said adjusting means being responsive to said control pressure to aid said spring means in countering the interstage pressure whereby the input power to said motor is reduced in response to an increase in the output medium pressure from said compressor.

Claim 7

A control assembly as defined in claim 4 wherein said pressure sensing means includes a converter means for amplifying an increase in the outlet medium pressure above the predetermined value whereby the control pressure is a multiple of said pressure increase.

Claim 8

A control assembly as defined in claim 4 which includes an unloading mechanism adapted to be connected to the delivery side of said compressor for relieving the outlet medium pressure, and a control valve operatively connected to said unloading mechanism and responsive to said control pressure whereby said unloading mechanism is actuated to relieve the outlet medium pressure from said delivery side of said compressor when the control pressure reaches a certain value.

Claim 9

A control assembly as defined in claim 4 wherein said control pressure is proportional to the change in the outlet medium pressure above the predetermined value of the outlet medium pressure at the delivery side of the compressor, and said pressure sensing means includes a spring biasing means which is adapted to define the predetermined value of the outlet medium pressure and a tension adjusting means for said spring biasing means whereby the predetermined value may be adjusted.

Claim 10

A control assembly as defined in claim 4 wherein said adjusting means includes a pressure fluid cylinder, a piston and piston rod slidably mounted in said cylinder, connecting means adapted for connecting said piston rod to the motor whereby the input power to said motor may be varied by movement of said piston rod, said pressure fluid cylinder including a first chamber at one side of the piston subjected to said control pressure and a second chamber in the cylinder at the opposite side of the piston subjected to an interstage pressure of the compressor whereby said interstage pressure moves said piston in a direction so as to increase the power input to said motor.

Claim 11

A control assembly as defined in claim 4 wherein said adjusting means includes a pressure cylinder, a piston and piston rod slidably mounted in said pressure cylinder, and connecting means adapted for connecting said piston rod to the motor whereby the motor input power may be varied by movement of said piston rod, and said pressure sensing means includes a pressure converter and a conduit connecting said pressure converter with said pressure cylinder whereby the control pressure causes the piston and piston rod to reduce the input power to said motor in response to an increase in the control pressure, and said pressure converter including two chambers separated by a pressure diaphragm, a valve member connected to said diaphragm and arranged so that when one one of said diaphragm chambers is connected to the output medium pressure at the delivery side of the compressor, the valve member is moved in an opening direction and when control pressure is applied to the opposite diaphragm chamber, said valve member is actuated in a closing direction.