Compressor with a bypass port

Patent metadata

Field	Value
Publication number	US-9850902-B2
Application number	US-201013258494-A
Country	US
Kind code	B2
Filing date	Mar 26, 2010
Priority date	Mar 26, 2009
Publication date	Dec 26, 2017
Grant date	Dec 26, 2017

Abstract

A system is provided for adjusting the volume ratio of a screw compressor. The system can use a port in a rotor cylinder to bypass vapor from the compression chamber to the discharge passage of the compressor. A valve can be used to open or close the port to obtain different volume ratios in the compressor.

First claim

What is claimed is:

1. A compressor comprising:
a compression mechanism, the compression mechanism being configured and positioned to receive vapor from an intake passage and provide compressed vapor to a discharge passage;
a port positioned in the compression mechanism to bypass a portion of the vapor in the compression mechanism to the discharge passage;
a valve comprising a valve body positioned in a bore configured and positioned to control vapor flow through the port, the valve body having a first position to unobstructedly permit vapor flow from the compression mechanism to the discharge passage, a second position to prevent vapor flow from the compression mechanism to the discharge passage, and a third position between the first position and the second position to partially permit vapor flow from the compression mechanism to the discharge passage, the valve body in the second position preventing vapor flow by blocking the port without insertion of the valve body inside the port, and the valve body in the third position partially permitting vapor flow by partially blocking the port without insertion of the valve body inside the port;
the compressor having a first volume ratio in response to the valve body being in the second position, a second volume ratio in response to the valve body being in the first position, and a third volume ratio in response to the valve body being in the third position, the first volume ratio being greater than the second volume ratio and the third volume ratio being between the first volume ratio and the second volume ratio; and
the valve body being automatically positionable using the pressure of the vapor entering the intake passage and the pressure of the compressed vapor discharged from the discharge passage to operate the compressor at the first volume ratio, the second volume ratio or the third volume ratio;
wherein the valve body is movable in the bore between the first position and the second position in response to a difference in forces applied to opposite ends of the valve body.

2. The compressor of claim 1 wherein:
the compressed vapor discharged from the discharge passage at a first pressure is supplied to the bore to apply a first force on a first end of the valve body near the discharge passage; and
the vapor entering the intake passage at a second pressure is supplied to the bore to apply a second force on a second end of the valve body opposite the first end.

3. The compressor of claim 2 wherein:
the valve body is in the first position when positioned in the bore a distance from the port to unobstructedly permit flow of vapor through the port and into the bore;
the valve body is in the second position when positioned in the bore to close the port to prevent flow of vapor through the port and into the bore; and
the valve body is positioned in the first position in response to the first force being greater than the second force and the valve body is positioned in the second position in response to the second force being greater than the first force.

4. The compressor of claim 1 wherein the bore is positioned in the compression mechanism substantially parallel to a flow of vapor in the compression mechanism.

5. A screw compressor comprising:
a pair of intermeshing rotors, each rotor of the pair of intermeshing rotors being positioned in a corresponding cylinder, the pair of intermeshing rotors being configured to receive vapor from an intake passage and provide compressed vapor to a discharge passage;
a port positioned in at least one rotor cylinder to bypass a portion of the vapor from a compression pocket formed by the pair of intermeshing rotors to the discharge passage;
a valve comprising a valve body positioned in a bore configured and positioned to control vapor flow through the port, the valve body having a fully open position to unobstructedly permit vapor flow from the compression pocket to the discharge passage, a closed position to prevent vapor flow from the compression pocket to the discharge passage, and a partially open position to partially permit vapor flow from the compression pocket to the discharge passage, the valve body in the closed position preventing vapor flow by blocking the port without insertion of the valve body inside of the port, the valve body in the partially open position partially blocking the port without insertion of the valve body inside of the port;
the screw compressor having a first volume ratio in response to the valve body being in the closed position, a second volume ratio in response to the valve body being in the fully open position, and a third volume ratio in response to the valve body being in the partially open position between the closed position and the fully open position, the first volume ratio being greater than the second volume ratio and the third volume ratio being between the first volume ratio and the second volume ratio; and
the valve body being automatically positionable using the pressure of vapor entering the intake passage and the pressure of vapor discharged from the discharge passage to operate the compressor at the first volume ratio, the second volume ratio, or the third volume ratio.

6. The screw compressor of claim 5 wherein the bore is positioned between the cylinders or near one cylinder.

7. The screw compressor of claim 5 wherein:
the valve body comprises a first valve body portion positioned in a first bore portion of the bore and a second valve body portion positioned in a second bore portion of the bore;
the first bore portion and the second bore portion are positioned near a corresponding cylinder substantially parallel to a flow of vapor in the pair of intermeshing rotors; and
the valve body is in the fully open position in response to at least one of the first valve body portion or the second valve body portion being positioned in a corresponding bore portion a distance from the port to permit flow of vapor through the port.

8. The screw compressor of claim 5 wherein:
the vapor discharged from the discharge passage at a discharge pressure is supplied to the bore to apply a first force on a first end of the valve body near the discharge passage;
the vapor entering the intake passage at a second pressure is supplied to the bore to apply a second force on a second end of the valve body opposite the first end; and
the valve body is movable in the bore between the fully open position and the closed position in response to a difference in the first force and the second force applied to the valve body.

9. The screw compressor of claim 8 further comprising a control valve to control flow of the vapor entering the intake passage, the control valve being configured to provide the vapor discharged from the discharge passage at the discharge pressure or the vapor entering the intake passage at the second pressure, less than the discharge pressure.

10. The screw compressor of claim 8 wherein:
the valve body is in the fully open position when positioned in the bore a distance from the port to permit unobstructed flow of vapor through the port and into the bore;
the valve body is in the closed position when positioned in the bore to close the port to prevent flow of vapor through the port and into the bore; and
the valve body is positioned in the fully open position in response to the first force being greater than the second force and the valve body is positioned in the closed position in response to the second force being greater than the first force.

11. The compressor of claim 5 wherein the bore is positioned in the screw compressor substantially parallel to a flow of vapor in the screw compressor.

Assignees

• Nemit Jr Paul
• Comstock Angela Marie
• Kopko William L
• Johnson Controls Tech Co

Inventors

• Nemit Jr Paul
• Comstock Angela Marie
• Kopko William L

Classifications

• F04C18/16 Primary

  with helical teeth, e.g. chevron-shaped, screw type {(for non-parallel axes of movement F04C18/48)} · CPC title

• F04C28/06

  specially adapted for stopping, starting, idling or no-load operation · CPC title

• F04C28/12

  using sliding valves · CPC title

• F04C28/26 Primary

  using bypass channels · CPC title

• F04C28/125

  with sliding valves controlled by the use of fluid other than the working fluid · CPC title