ES2829828T3 - Screw Compressor with Economizer Orifice - Google Patents

Abstract

A screw compressor (12) comprising: a screw compressor rotor (32), the rotor including a helical spline extending outwardly from a rotor shaft; a compressor casing (34) surrounding the rotor and including a suction port (40) and a discharge port (42), the casing having an inner casing wall abutting the rotor and an outer casing wall forming an outer part of the compressor, such that a housing socket (44) is disposed between the outer housing wall (48) and the inner housing wall (46); and an economizer orifice (30) is present extending from the casing socket through the inner casing wall to direct a flow of gaseous refrigerant into the compressor, wherein the economizer orifice (30) comprises an aperture outer wall (50) in the outer casing wall (48), the socket (44), and an inner wall opening (52) in the inner casing wall (46), characterized in that the inner wall opening ( 52) of the economizer hole (30) has a width between 1/32 inch (0.79 millimeters) and 1/4 inch (6.35 millimeters).

Description

DESCRIPTION

Thyme Compressor with Economizer Orifice

Background

The subject matter disclosed herein refers to refrigeration systems. More specifically, the subject matter disclosed herein relates to screw compressors for refrigeration systems.

Refrigeration systems typically include a compressor that supplies compressed refrigerant to a condenser. From the condenser, the refrigerant travels to an expansion valve and then to an evaporator. From the evaporator, the refrigerant returns to the compressor to be compressed. To increase the efficiency of the system, an economizer is often included between the condenser and the evaporator, more specifically between the condenser and the expansion valve. The economizer is a heat exchanger that returns a portion of the refrigerant that flows through the system as a gas to the compressor, where it is injected into the compressor at a selected location through an economizer orifice.

In some compressors, the economizer hole is a slot milled into the rotor housing from an outside of the housing, or formed into a rotor housing by casting. The typical slot, however, allows inadvertent and unwanted leakage between adjacent lobes of the screw rotor as the lobe passes through the slot. This leakage adversely affects compressor performance and limits the slot width and slot placement in the compressor. For example, typically only grooves are located in the female rotor of a two-rotor screw compressor, because a thicker seal line is present in the female rotor, thereby reducing the possibility of leakage.

Document WO2006 / 041494 discloses a compressor comprising a housing assembly, a male and female rotor, and an end seal having a first surface that engages the first end of a female body portion and exhibits asymmetry around a second axis. An economizer hole may be present in the housing. Document WO2006 / 062741 discloses a compressor comprising an economizer orifice, the compressor being adapted to limit external sound radiated by the housing.

Brief summary

The present invention provides a screw compressor according to claim 1.

The present invention also provides a refrigerant system according to claim 7.

These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.

Brief description of the drawings

The subject matter, which is considered as the invention, is particularly pointed out and clearly claimed in the claims at the end of the specification. The foregoing and other features and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

Figure 1 is a schematic view of one embodiment of a refrigerant system;

Figure 2 is a cross-sectional view of one embodiment of a screw compressor;

Figure 3 is a cross-sectional view of one embodiment of a screw compressor;

Figure 4 is a plan view of an economizer orifice in one embodiment of a screw compressor; and Figure 5 is a cross-sectional view of another embodiment of a screw compressor.

The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawing.

Detailed description

A schematic of one embodiment of a refrigerant system 10 is shown in Figure 1. The refrigerant system 10 includes a screw compressor 12. An evaporator 14, in some embodiments a flooded style evaporator 14, supplies a flow of refrigerant to the compressor 12 through a passage 16. From compressor 12, the Refrigerant flows through line 18 to condenser 20. Compressed gaseous refrigerant is cooled in condenser 20, transferred to a liquid phase, and passed through expansion valve 24 on its way to evaporator 14. through conduit 22.

An economizer 26 is located between evaporator 14 and condenser 20, in some embodiments between condenser 20 and expansion valve 24 along conduit 22. Economizer 26 may be, for example, an exchange-type economizer 26. heat or separator type. Gaseous refrigerant is directed from economizer 26 to compressor 12 through economizer conduit 28, where the gaseous refrigerant is injected into compressor 12 at economizer port 30.

Referring to Figure 2, an embodiment of screw compressor 12 is shown. Compressor 12 includes two compressor rotors 32 arranged in a compressor housing 34. Each of compressor rotors 32 includes a plurality of helical rotor splines. 36. Compressor rotors 32 are arranged in parallel such that rotor shafts 38 are parallel and rotor splines 36 mesh. In the embodiment shown, compressor 12 includes two compressor rotors 32, known in the art as male rotor 32 and female rotor 32. In other embodiments, compressor 12 includes other numbers of rotors 32, for example, three rotors 32. Compressor rotors 32 are located within housing 34, which also includes a suction port 40 through which refrigerant flows from evaporator 14, and a discharge port 42 through which compressed refrigerant is discharged to condenser 20. In some embodiments, suction port 40 and discharge port 42 are located at opposite axial ends of housing 34.

As discussed above, the compressor 12 includes an economizer orifice 30 through which gaseous refrigerant is pushed from the economizer 26. Referring to Figures 3 and 4, the housing 34 is formed by casting. A monolithic economizer socket 44 is formed or tapped into the casing 34 during the casting of the casing 34. The economizer socket 44 is a space located radially between an inner casing wall 46 abutting the rotors 32, and an outer shell wall 48 that forms the outer portion of the shell 34. The formation of the socket 44 leaves a relatively thin inner shell wall 46, 10-15 millimeters thick in some embodiments. The economizer orifice 30 comprises an outer wall opening 50 in the outer wall 48, the socket 44, and an inner wall opening 52 in the inner wall 46. In alternative embodiments, a metal housing 34 can be formed from other processes. , such as machining, while housing 34 can also be formed of other non-metallic materials, such as composites or plastics.

Referring to Figure 4, the inner wall opening 52 is slot-shaped, with a lateral side 54 of the opening 52 extending substantially parallel to the rotor splines 36.

In accordance with the invention, the inner wall opening 52 has a width between 1/32 inch and% inch (0.79 to 6.35 millimeters). In some embodiments, the inner wall opening 52 has a length between about 1.9 inches and 3.5 inches (about 50 to 90 millimeters). In other embodiments, the inner wall opening 52 may have other shapes, such as circular or triangular. The inner wall 46 is sufficiently thin, due to the inclusion of the socket 44 in the housing 34, to allow the inner wall opening 52 to be formed by a secondary process, such as plasma cutting or water jet cutting. These processes allow an inner wall opening 52 of economizer hole 30 to be significantly narrower than a typical economizer hole formed monolithically by casting or through profile milling; narrower inner wall opening 52 resulting in reduced leakage in compressor 12.

In another embodiment, as shown in Figure 5, multiple economizer ports 30 may be included in compressor 12, at different locations in compressor 12. For example, economizer ports 30 may be located in either one or both. of male or female rotors 32, the thinner profile of economizer hole 30 allowing location on male rotor 32, even though there is typically a thinner seal line on male rotor 32. Multiple economizer holes 30 they improve compressor performance by allowing refrigeration system 10 to direct gas from economizer 26 to selected economizer orifice (s) 30, depending on operating conditions.

Although the invention has been described in detail in relation to only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention may be modified to incorporate any number of variations, alterations, substitutions, or equivalent arrangements not described heretofore, but which are consistent with the scope of the invention. Additionally, although various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be viewed as limited by the foregoing description, but is only limited by the scope of the appended claims.

Claims (8)

1. A thyme compressor (12) comprising: a thyme compressor rotor (32), the rotor including a helical spline extending outwardly from a rotor shaft; a compressor casing (34) surrounding the rotor and including a suction port (40) and a discharge port (42), the casing having an inner casing wall abutting the rotor and an outer casing wall forming an outer part of the compressor, so that a housing socket (44) is disposed between the outer housing wall (48) and the inner housing wall (46); Y An economizer orifice (30) is present extending from the casing socket through the inner casing wall to direct a flow of gaseous refrigerant into the compressor, wherein the economizer orifice (30) comprises an opening of outer wall (50) in the outer casing wall (48), the socket (44), and an inner wall opening (52) in the inner casing wall (46), characterized in that the inner wall opening (52) of the economizer hole (30) has a width between 1/32 inch (0.79 millimeters) and 1/4 inch (6.35 millimeters). The screw compressor of claim 1, wherein the economizer hole is slot-shaped and extends circumferentially parallel to the helical spline. The screw compressor of claim 1, comprising at least two rotors arranged in the housing. 4. The screw compressor of claim 3, wherein the helical splines of the at least two rotors mesh. The screw compressor of claim 1, comprising two or more economizer holes extending through the inner casing wall. The screw compressor of claim 1, wherein the economizer orifice is formed by a plasma or water jet cutting one. 7. A refrigerant system comprising: an evaporator (14); Y a compressor (12) operatively connected to the evaporator, a compressor housing surrounding the rotor and including a suction port to receive refrigerant from the evaporator and a discharge port to transport refrigerant to a condenser, wherein said compressor is a screw compressor according to any of claims 1 to 6. 8. The refrigerant system of claim 7, wherein the economizer is disposed between the condenser and the evaporator.