ROTARY COMPRESSORS WITH VARIABLE SPEED AND VOLUME CONTROL

• US 20200132074A1
• Filed: 12/27/2019
• Published: 04/30/2020
• Est. Priority Date: 10/01/2013
• Status: Active Grant

• Current Assignee: Trane International Inc. (Trane Technologies plc)
• Original Assignee: Trane International Inc. (Trane Technologies plc)
• Inventors: Johnson, Jay H., Sauls, John R., Powell, JR., Gordon, Crum, Daniel R.
• Granted Patent: US 11,852,145 B2
• Time in Patent Office: Days
• CPC Class Codes: F04C 18/16 with helical teeth, e.g. chevron-shaped, screw type for non-parallel axes of movement F04C18/48
• CPC Class Codes: F04C 2240/403 with inverter for speed control
• CPC Class Codes: F04C 2240/81 Sensor, e.g. electronic sensor for control or monitoring
• CPC Class Codes: F04C 2270/025 Controlled or regulated
• CPC Class Codes: F04C 2270/585 Controlled or regulated
• CPC Class Codes: F04C 28/08 characterised by varying the rotational speed
• CPC Class Codes: F04C 28/12 using sliding valves
• CPC Class Codes: F04C 28/14 using rotating valves
• CPC Class Codes: F04C 28/24 characterised by using valves controlling pressure or flow rate, e.g. discharge valves or unloading valvesF04C28/10 takes precedence
• CPC Class Codes: F04C 28/28 Safety arrangements; Monitoring
• CPC Class Codes: F04C 29/124 with inlet and outlet valves specially adapted for rotary or oscillating piston pumps
• CPC Class Codes: F25B 1/047 of screw type
• CPC Class Codes: F25B 2600/0253 with variable speed
• CPC Class Codes: F25B 49/022 Compressor control arrangements

Abstract

Systems and methods are used to control operation of a rotary compressor of a refrigeration system to improve efficiency by varying the volume ratio and the speed of the compressor in response to current operating and load conditions. The volume of the axial and/or radial discharge ports of the compressor can be varied to provide a volume ratio corresponding to operating conditions. In addition, permanent magnet motors and/or control of rotor tip speed can be employed for further efficiency gains.

Claims

1. A refrigeration system, comprising:

a compressor comprising a compressor housing defining a suction port, a working chamber, and a discharge port, the compressor further comprising at least two rotors in the working chamber cooperatively arranged relative to one another to compress a fluid as the at least two rotors rotate relative to one another, the fluid being received into the working chamber through the suction port and being discharged from discharge ends of the rotors through the discharge port;

a motor assembly including a motor operable to drive at least one of the at least two rotors at a rotational speed;

a controller configured to receive operational parameters of the refrigeration system; and

a volume control assembly at the discharge port of the compressor that is configured to receive a command signal from the controller and displace at least one volume control member relative to the discharge ends of the at least two rotors to vary a volume ratio of the compressor from a first condition to a second condition in response to operational parameters of the refrigeration system;

wherein the volume control assembly includes a radial discharge port volume control assembly; and

wherein the volume control assembly further includes an axial discharge port volume control assembly.

2. The system of claim 1, wherein the rotational speed operates the at least one rotor at an optimum peripheral velocity that is independent of a peripheral velocity of the at least one rotor at a synchronous motor rotational speed for a rated capacity of the compressor.

3. The system of claim 1, wherein the fluid is a refrigerant.

4. The system of claim 1, wherein the motor comprises a permanent magnet motor.

11. The system of claim 1, wherein the volume control assembly further includes an axial discharge port volume control assembly.

12. The system of claim 11, wherein the axial discharge port volume control assembly includes a first end plate rotatably mounted at the discharge end of the first rotor and a second end plate rotatably mounted at the discharge end of the second rotor, each of the first and second end plates defining a notched region corresponding to an axial end outlet of respective ones of the first and second rotors.

13. The system of claim 12, wherein the first rotor includes a shaft extending through the first end plate and the second rotor includes a shaft extending through the second end plate.

14. The system of claim 12, wherein the first and second end plates each include an attachment member, and the axial port volume control assembly includes an elongated shaft with first and second engaging members engaged to respective ones of the attachment members, wherein rotation of the elongated shaft rotates the first and second end plates between first and second positions.

15. The system of claim 1, further comprising a variable speed drive connected to the motor, the variable speed drive being configured to receive a command signal from the controller and to generate a control signal that drives the motor at the rotational speed, wherein the variable speed drive is configured to vary the rotational speed of the motor in response to the command signal.

16. The system of claim 1, wherein the volume control member is displaced transversely to a rotational axis of at least one of the at least two rotors.

5. (canceled)

6. The system of claim 5, wherein the radial discharge port volume control assembly includes a slide valve movable axially along a periphery of the first and second rotors adjacent the discharge port to vary a radial discharge volume of the rotors at the discharge port.

7. The system of claim 5, wherein the radial discharge port volume control assembly includes a valve movable radially toward and away from the first and second rotors adjacent the discharge port to vary a radial discharge volume of the rotors at the discharge port.

8. The system of claim 7, wherein the valve is connected to an actuator assembly, the actuator assembly including a piston movably positioned in a chamber defined by the compressor housing, wherein the chamber is selectively in fluid communication with the discharge port and the suction port to vary a pressure on the piston to adjust a radial position of the valve relative to the rotors.

9. The system of claim 8, further comprising a biasing member in the chamber engaged to the piston to bias the valve toward the working chamber.

10. (canceled)

17. A refrigeration system, comprising:

a compressor comprising a compressor housing defining a suction port, a working chamber, and a discharge port, the compressor further comprising at least two rotors in the working chamber cooperatively arranged relative to one another to compress a fluid as the at least two rotors rotate relative to one another, the fluid being received into the working chamber through the suction port and being discharged from discharge ends of the rotors through the discharge port;

a motor assembly including a motor operable to drive at least one of the at least two rotors at a rotational speed;

a controller configured to receive operational parameters of the refrigeration system; and

a radial discharge port volume control assembly at the discharge port of the compressor that is configured to receive a command signal from the controller and displace at least one volume control member relative to the discharge ends of the at least two rotors to vary a volume ratio of the compressor from a first condition to a second condition in response to operational parameters of the refrigeration system,

wherein the radial discharge port volume control assembly includes a slide valve movable axially along a periphery of the first and second rotors adjacent the discharge port to vary a radial discharge volume of the rotors at the discharge port.

18. The system of claim 17, further comprising a variable speed drive connected to the motor, the variable speed drive being configured to receive a command signal from the controller and to generate a control signal that drives the motor at the rotational speed, wherein the variable speed drive is configured to vary the rotational speed of the motor in response to the command signal.

20. The system of claim 17, wherein the radial discharge port volume control assembly includes a valve movable radially toward and away from the first and second rotors adjacent the discharge port to vary a radial discharge volume of the rotors at the discharge port.

21. The system of claim 20, wherein the valve is connected to an actuator assembly, the actuator assembly including a piston movably positioned in a chamber defined by the compressor housing, wherein the chamber is selectively in fluid communication with the discharge port and the suction port to vary a pressure on the piston to adjust a radial position of the valve relative to the rotors.

22. The system of claim 21, further comprising a biasing member in the chamber engaged to the piston to bias the valve toward the working chamber.

19. (canceled)

23. A refrigeration system, comprising:

a compressor comprising a compressor housing defining a suction port, a working chamber, and a discharge port, the compressor further comprising at least two rotors in the working chamber cooperatively arranged relative to one another to compress a fluid as the at least two rotors rotate relative to one another, the fluid being received into the working chamber through the suction port and being discharged from discharge ends of the rotors through the discharge port;

a motor assembly including a motor operable to drive at least one of the at least two rotors at a rotational speed;

a controller configured to receive operational parameters of the refrigeration system;

an axial discharge port volume control assembly at the discharge port of the compressor that is configured to receive a command signal from the controller and displace at least one volume control member relative to the discharge ends of the at least two rotors to vary a volume ratio of the compressor from a first condition to a second condition in response to operational parameters of the refrigeration system; and

a radial discharge port volume control assembly at the discharge port of the compressor that is configured to receive the command signal from the controller and displace at least one volume control member relative to the discharge ends of the at least two rotors to vary the volume ratio of the compressor from the first condition to the second condition in response to operational parameters of the refrigeration system.

24. The system of claim 23, further comprising a variable speed drive connected to the motor, the variable speed drive being configured to receive a command signal from the controller and to generate a control signal that drives the motor at the rotational speed, wherein the variable speed drive is configured to vary the rotational speed of the motor in response to the command signal.

25. (canceled)

26. The system of claim 25, wherein the radial discharge port volume control assembly includes a slide valve movable axially along a periphery of the first and second rotors adjacent the discharge port to vary a radial discharge volume of the rotors at the discharge port.

27. The system of claim 25, wherein the radial discharge port volume control assembly includes a valve movable radially toward and away from the first and second rotors adjacent the discharge port to vary a radial discharge volume of the rotors at the discharge port.

28-33. -33. (canceled)