Method for controlling the outlet temperature of an oil injected compressor or vacuum pump and oil injected compressor or vacuum pump implementing such method

Patent metadata

Field	Value
Publication number	US-11073148-B2
Application number	US-201716318172-A
Country	US
Kind code	B2
Filing date	Aug 8, 2017
Priority date	Aug 18, 2016
Publication date	Jul 27, 2021
Grant date	Jul 27, 2021

Abstract

The present invention is directed to a method for controlling the outlet temperature of an oil injected compressor or vacuum pump comprising a compressor or vacuum element provided with a gas inlet, an element outlet, and an oil inlet, said method comprising the steps of: measuring the outlet temperature at the element outlet; and controlling the position of a regulating valve in order to regulate the flow of oil flowing through a cooling unit connected to said oil inlet; whereby the step of controlling the position of the regulating valve involves applying a fuzzy logic algorithm on the measured outlet temperature; and in that the method further comprises the step of controlling the speed of a fan cooling the oil flowing through the cooling unit by applying the fuzzy logic algorithm and further based on the position of the regulating valve.

First claim

The invention claimed is:

1. A method for controlling an outlet temperature of an oil injected compressor or vacuum pump comprising a compressor or vacuum element provided with a gas inlet, an element outlet, and an oil inlet, said method comprising the steps of:
measuring an outlet temperature at the element outlet; and
controlling a position of a regulating valve in order to regulate a flow of oil flowing through a cooling unit connected to said oil inlet;
wherein the step of controlling the position of the regulating valve comprises applying a fuzzy logic algorithm on the measured outlet temperature; and
controlling a speed of a fan cooling the oil flowing through the cooling unit by applying the fuzzy logic algorithm, wherein the speed of the fan is controlled based on the position of the regulating valve and the measured outlet temperature.

2. The method according to claim 1 , further comprising the step of measuring an inlet temperature, the inlet pressure at the gas inlet and the outlet pressure at the element outlet.

3. The method according to claim 2 , wherein the controlling of the position of the regulating valve involves applying said fuzzy logic algorithm further on the measured inlet temperature, inlet pressure and the outlet pressure.

4. The method according to claim 1 , wherein the step of controlling the position of said regulating valve involves regulating the flow of oil flowing through said cooling unit and through a bypass pipe fluidly connected said oil inlet, for bypassing the cooling unit.

5. The method according to 2 , wherein the method further comprises the step of maintaining the outlet temperature at approximately a predetermined target value, said predetermined target value being calculated by determining an atmospheric dew point based on the measured inlet temperature, inlet pressure and outlet pressure and an estimated or measured relative humidity of the gas flowing through the gas inlet.

6. A method for controlling an outlet temperature of an oil injected compressor or vacuum pump comprising a compressor or vacuum element provided with a gas inlet, an element outlet, and an oil inlet, said method comprising the steps of:
measuring an outlet temperature at the element outlet; and
controlling a position of a regulating valve in order to regulate a flow of oil flowing through a cooling unit connected to said oil inlet;
wherein the step of controlling the position of the regulating valve comprises applying a fuzzy logic algorithm on the measured outlet temperature; and
the method further comprises the step of controlling a speed of a fan cooling the oil flowing through the cooling unit by applying the fuzzy logic algorithm based on the position of the regulating valve,
wherein the method further comprises the step of measuring an inlet temperature, an inlet pressure at the gas inlet and an outlet pressure at the element outlet,
wherein the method further comprises the step of maintaining the outlet temperature at approximately a predetermined target value, said predetermined target value being calculated by determining an atmospheric dew point based on the measured inlet temperature, inlet pressure and outlet pressure and an estimated or measured relative humidity of the gas flowing through the gas inlet, and
wherein the fuzzy logic algorithm comprises the step of determining a first error by subtracting the predetermined target value from a first measured outlet temperature and determining a second error by subtracting the predetermined target value from a subsequent measured outlet temperature.

7. The method according to claim 6 , wherein the fuzzy logic algorithm further comprises the step of calculating an evolution of the error, by calculating the derivative of the error over time, by subtracting the second error from the first error, and dividing it over a time interval, calculated between the moment when the first outlet temperature is measured, and the moment when the subsequent outlet temperature is measured.

8. The method according to claim 7 , wherein the fuzzy logic algorithm further comprises the step of determining the direction towards which the position of the regulating valve should be changed based on the first error or the second error, and the evolution of the error.

9. The method according to claim 7 , wherein the fuzzy logic algorithm further comprises the step of determining the speed rate with which the position of the regulating valve should be changed based on the first error or the second error, and the evolution of the error.

10. The method according to claim 7 , wherein the fuzzy logic algorithm determines the direction in which the regulating valve is to be changed by applying:
if the second error is negative or if the second error is approximately equal to zero, and the evolution of the error is negative, the direction in which the position of the regulating valve is to be changed is such that more oil is flowing through the bypass pipe; or
if the second error is positive or if the second error is approximately equal to zero, and the evolution of the error is positive, the direction in which the position of the regulating valve is to be changed is such that more oil is flowing through the cooling unit.

11. The method according to claim 9 , wherein the fuzzy logic algorithm determines the speed rate with which the position of the regulating valve is to be changed according to one or more of the following steps:
if the second error is negative and the evolution of the error is negative, the position of the regulating valve is to be changed at a first predetermined speed rate;
if the second error is negative and the evolution of the error is positive, the position of the regulating valve is to be changed at a second predetermined speed rate;
if the second error is approximately equal to zero and the evolution of the error is negative, the position of the regulating valve is to be changed at a third predetermined speed rate;
if the second error is approximately equal to zero and the evolution of the error is positive, the position of the regulating valve is to be changed at a fourth predetermined speed rate;
if the second error is positive and the evolution of the error is negative, the position of the regulating valve is to be changed at a fifth predetermined speed rate;
if the second error is positive and the evolution of the error is positive, the position of the regulating valve is to be changed at a sixth predetermined speed rate.

12. The method according to claim 11 , wherein the first predetermined speed rate is lower than the sixth predetermined speed rate; and/or the second predetermined speed rate is lower than the fifth predetermined speed rate; and/or the third predetermined speed rate is lower than the fourth predetermined speed rate.

13. The method according to claim 7 , wherein the regulating valve comprises a central rotating element, the fuzzy logic algorithm determines the angle with which the position of the regulating valve is to be changed by applying a first control function, and determining the minimum between one and the result of adding a fuzzy value associated with the second error, multiplied by a first coefficient to a fuzzy value associated with the evolution of the error multiplied by a second coefficient.

14. The method according to claim 13 , wherein the fuzzy logic algorithm further comprises the step of determining the position of the regulating valve by applying the calculated angle to a current position of the regulating valve.

15. The method according to claim 14 , wherein the fuzzy logic algorithm is determining

Assignees

• Atlas Copco Airpower Nv

Inventors

• COECKELBERGS Joeri
• Shi Yun

Classifications

• F04B2205/01

  Pressure before the pump inlet · CPC title

• F05B2210/12

  gaseous, i.e. compressible · CPC title

• F04D29/00

  Details, component parts, or accessories (machine elements in general F16) · CPC title

• F05B2270/303

  Temperature · CPC title

• F05B2270/3013

  Outlet · CPC title