Compressor control system and method

• US 6,082,971 A
• Filed: 10/30/1998
• Issued: 07/04/2000
• Est. Priority Date: 10/30/1998
• Status: Expired due to Term

• Current Assignee: Clark Equipment Company (Doosan Heavy Industries and Construction Company Limited)
• Original Assignee: Ingersoll-Rand Company (Trane Technologies plc)
• Inventors: Gerhardt, Don John, Harden, William H., Gunn, John T.
• Primary Examiner(s): ARGENBRIGHT, TONY MICHAEL
• Application Number:
  US09/183,250
• Time in Patent Office: 613 Days
• Field of Search: 417/32, 417/34, 417/53, 417/364
• US Class Current: 417/32
• CPC Class Codes: F04B 2201/0402 Lubricating oil temperature
• CPC Class Codes: F04B 2203/0605 Rotational speed
• CPC Class Codes: F04B 2203/0607 Fuel consumption
• CPC Class Codes: F04B 2205/05 Pressure after the pump outlet
• CPC Class Codes: F04B 2205/10 Inlet temperature
• CPC Class Codes: F04B 2205/11 Outlet temperature
• CPC Class Codes: F04B 2205/16 Opening or closing of a valve in a circuit
• CPC Class Codes: F04B 39/0207 with lubrication control systems
• CPC Class Codes: F04B 39/066 Cooling by ventilation
• CPC Class Codes: F04B 39/16 Filtration; Moisture separation
• CPC Class Codes: F04B 49/065 and making use of computers
• CPC Class Codes: F04C 2270/784 Light
• CPC Class Codes: F04C 2270/80 Diagnostics
• CPC Class Codes: F04C 28/08 characterised by varying the rotational speed
• CPC Class Codes: F04C 29/0014 with control systems for the injection of the fluid
• CPC Class Codes: F04C 29/04 Heating; Cooling of machines or engines in general F01P; Heat insulation heat insulation in general F16L59/00
• CPC Class Codes: F04D 25/068 Mechanical details of the pump control unit pump control details F04D27/00

Abstract

A method for optimizing the operating efficiency of a compressor having a compression module for compressing a fluid, the compression module including an inlet for receiving the fluid and an outlet for discharging compressed fluid, the compressor including a prime mover for driving the compression module and a rotatable fan for drawing ambient air into the compressor. The compressor includes a first temperature sensor for sensing the temperature of compressed fluid discharged from the compression module, a second temperature sensor for sensing the temperature of a coolant circulating through the prime mover, a third temperature sensor for sensing the temperature of the fluid entering the compression module, and a fourth temperature sensor for sensing the temperature of a lubricant mixed with the fluid as the fluid is compressed in the compression module. The compressor includes an electronic control module (ECM) electrically connected to the four temperature sensors for receiving signals therefrom. The ECM includes a non-volatile memory containing empirical data relating to optimal operating set points of the compressor and a logic routine for controlling the rotational speed of the fan and the volume of the lubricant mixed with the fluid so as to optimize the efficiency of the compressor. The method includes the steps of executing a temperature sensing subroutine whereby the first, second, third and fourth temperature sensors collect temperature data and relay the temperature data to the ECM, executing a fan speed subroutine whereby the ECM generates signals in response to the temperature data received by the ECM for controlling the rotational speed of the fan, and executing a lubricant volume control subroutine whereby the ECM generates signals in response to the temperature data received by the ECM for controlling the volume of the lubricant mixed with the fluid in the compression module.

Claims

1. A method for optimizing the operating efficiency of a compressor having a compression module for compressing a fluid, the compression module including an inlet for receiving the fluid and an outlet for discharging compressed fluid, the compressor including a prime mover for driving the compression module and a rotatable fan for drawing ambient air into the compressor, the compressor including a first temperature sensor for sensing the temperature of compressed fluid discharged from the compression module, a second temperature sensor for sensing the temperature of a coolant circulating through the prime mover, a third temperature sensor for sensing the temperature of the fluid entering the compression module, and a fourth temperature sensor for sensing the temperature of a lubricant mixed with the fluid as the fluid is compressed in said compression module, the compressor including an electronic control module (ECM) electrically connected to the temperature sensors for receiving signals therefrom, the ECM including a non-volatile memory containing empirical data relating to optimal operating set points of the compressor and a logic routine for controlling the rotational speed of the fan and the volume of the lubricant mixed with the fluid so as to optimize the efficiency of the compressor, the method comprising the steps of:

A) executing a temperature sensing subroutine whereby the first, second, third and fourth temperature sensors collect temperature data during operation of the compressor and relay the temperature data to the ECM;

B) executing a fan speed subroutine whereby the ECM generates signals in response to the temperature data received for controlling the rotational speed of the fan; and

C) executing a lubricant volume control subroutine whereby the ECM generates signals in response to the temperature data received for controlling the volume of the lubricant mixed with the fluid during compression of the fluid in the compression module.

2. The method as claimed in claim 1, wherein the compressor module has an outlet for discharging the compressed fluid and the first temperature sensor is in communication with the compressed fluid at the outlet of the compressor module.

3. The method as claimed in claim 1, wherein the compression module has an inlet for introducing the fluid into the compression module and the third temperature sensor is in communication with the fluid at the inlet of the compression module.

4. The method as claimed in claim 1, wherein the ECM logic routine for controlling the fan speed and the lubricant volume is continuously repeated during operation of the compressor for maintaining the prime mover and the compression module within an optimum temperature range.

5. The method as claimed in claim 4, wherein the ECM logic routine is repeated at least approximately every 20-30 milliseconds.

6. The method as claimed in claim 5, wherein the ECM logic routine is repeated at least approximately every 8-12 milliseconds.

7. The method as claimed in claim 1, wherein the step of executing a temperature sensing subroutine includes the steps of:

(i) sensing the actual temperature of the compressed fluid discharged from the outlet of the compression module;

(ii) sensing the actual temperature of the coolant circulating through the prime mover;

(iii) sensing the actual temperature of the fluid entering the inlet of the compression module;

(iv) sensing the actual temperature of the lubricant mixed with the fluid in the compression module; and

(v) sending the temperature data compiled in subroutine steps (i)-(iv) to the ECM.

8. The method as claimed in claim 1, wherein the step of executing a fan speed subroutine includes the steps of:

(i) comparing the actual temperature of the compressed fluid discharged from the compression module with a set point compressed fluid discharge temperature stored in the ECM memory;

(ii) increasing the speed of the fan if the actual temperature of the compressed fluid discharged from the compression module is greater than the set point fluid discharge temperature stored in the ECM memory;

(iii) comparing the actual prime mover coolant temperature with a set point prime mover coolant temperature stored in the ECM memory;

(iv) decreasing the speed of the fan if the actual prime mover coolant temperature is less than the set point prime mover coolant temperature; and

(v) proceeding to the lubricant volume control subroutine if the actual prime mover coolant temperature is greater than the set point temperature stored in the ECM memory.

9. The method as claimed in claim 8, wherein the compressor includes a fan clutch in communication with the ECM and the fan for adjusting the speed of rotation of the fan.

10. The method as claimed in claim 8, further comprising the step of determining the magnitude of the increase or decrease of the speed of the fan, wherein the magnitude of the increase or decrease of the speed of the fan is based upon the empirical data stored in the ECM memory.

11. The method as claimed in claim 1, further comprising the step of storing the empirical data relating to the optimal set points of the compressor in the ECM memory.

12. The method as claimed in claim 8, wherein the step of increasing the speed of the fan increases the volume of the ambient air drawn into the compressor for decreasing the actual temperatures of the compression module and the prime mover.

13. The method as claimed in claim 8, wherein the step of decreasing the speed of the fan decreases the volume of the ambient air drawn into the compressor for increasing the actual temperature of the compression module and the prime mover.

14. The method as claimed in claim 1, wherein the empirical data relating to the optimal operating set points is compiled through evaluating the compressor for determining optimum operating characteristics.

15. The method as claimed in claim 7, wherein the executing the lubricant volume control subroutine includes the steps of:

(i) subtracting the actual temperature of the lubricant mixed with the fluid in the compression module from the actual temperature of the fluid entering the inlet of the compression module for calculating an actual temperature differential;

(ii) comparing the actual temperature differential calculated in step (i) with a predetermined set point temperature differential stored in the ECM memory;

(iii) increasing the volume of the lubricant mixed with the fluid in the compression module if the actual temperature differential is greater than the predetermined set point temperature differential;

(iv) decreasing the volume of the lubricant mixed with the fluid in the compression module if the actual temperature differential is less than the predetermined set point temperature differential.

16. The method as claimed in claim 1, wherein said lubricant includes oil.

17. The method as claimed in claim 1, wherein said fluid includes air.

18. The method as claimed in claim 1, wherein said compression module includes one or more rotors.

19. A method for optimizing the operating efficiency of a compressor having a compression module for compressing a fluid, the compression module including an inlet for receiving the fluid and an outlet for discharging compressed fluid, the compressor including a prime mover for driving the compression module and a rotatable fan for drawing ambient air into the compressor, the compressor including a first temperature sensor for sensing the temperature of compressed fluid discharged from the compression module, a second temperature sensor for sensing the temperature of a coolant circulating through the prime mover, a third temperature sensor for sensing the temperature of the fluid entering the compression module, and a fourth temperature sensor for sensing the temperature of a lubricant mixed with the fluid as the fluid is compressed in said compression module, the compressor including an electronic control module (ECM) electrically connected to the temperature sensors for receiving signals therefrom, the ECM including a non-volatile memory containing empirical data relating to optimal operating set points of the compressor and a logic routine for controlling the rotational speed of the fan and the volume of the lubricant mixed with the fluid so as to optimize the efficiency of the compressor, the method comprising the steps of:

A) executing a temperature sensing subroutine routine comprising the steps of;

(i) sensing the actual temperature of the compressed fluid discharged from the outlet of the compression module;

(ii) sensing the actual temperature of the coolant circulating through the prime mover;

(iii) sensing the actual temperature of the fluid entering the inlet of the compression module;

(iv) sensing the actual temperature of the lubricant mixed with the fluid in the compression module; and

(v) sending the temperature data compiled in subroutine steps (i)-(iv) to the ECM; and

then

B) executing a fan speed subroutine for modulating the rotational speed of the fan comprising the steps of;

(i) comparing the actual temperature of the compressed fluid discharged from the compression module with a set point compressed fluid discharge temperature stored in the ECM memory;

(ii) increasing the speed of the fan if the actual temperature of the compressed fluid discharged from the compression module is greater than the set point fluid discharge temperature stored in the ECM memory;

(iii) comparing the actual prime mover coolant temperature with a set point prime mover coolant temperature stored in the ECM memory;

(iv) decreasing the speed of the fan if the actual prime mover coolant temperature is less than the set point prime mover coolant temperature; and

(v) proceeding to the lubricant volume control subroutine if the actual prime mover coolant temperature is greater than the set point temperature stored in the ECM memory; and

then

C) executing the lubricant volume control subroutine comprising the steps of;

(i) subtracting the actual temperature of the lubricant mixed with the fluid in the compression module from the actual temperature of the fluid entering the inlet of the compression module for calculating an actual temperature differential;

(ii) comparing the actual temperature differential calculated in step (i) with a predetermined set point temperature differential stored in the ECM memory;

(iii) increasing the volume of the lubricant mixed with the fluid in the compression module if the actual temperature differential is greater than the predetermined set point temperature differential;

(iv) decreasing the volume of the lubricant mixed with the fluid in the compression module if the actual temperature differential is less than the predetermined set point temperature differential.