Patent Application
20130136626
The application generally relates to a compressor muffle structure. The application relates more specifically to a rotor seat for a screw compressor with a muffle structure.
The working principle of compressors commonly used in cooling systems is to increase the pressure of a refrigerant gas from an evaporator to the pressure of the refrigerant gas in a condenser, so that under the increased pressure, the utilization of the refrigerant can be maximized to cool a medium to be cooled. In such compressor systems, a screw compressor can be a commonly used type of compressor. The screw compressor can be provided with a female rotor and a male rotor (also called a concave rotor and a convex rotor), which rotate in a compression cavity. When the rotors rotate, the suction port corresponding to the compression chamber is closed, and as the volume of the chamber decreases, a gas compression effect is achieved.
A pair of female and male rotors in the screw compressor can incur strong fluid dynamic noise during high-speed rotation. The noise mainly includes periodic gas suction and exhaust noise, expansion and backflow noise of the over-compressed and under-compressed gas, and vortex noise in the tooth slot primitive volume. The fluid dynamic noise is always the main noise source of a screw compressor and a corresponding cooling system. Noise control targeting the fluid dynamic noise can be the most effective type but also has long been a technical problem to be solved in the art.
In order to solve the problem of the exhaust noise, U.S. Pat. No. 5,051,077 entitled “SCREW COMPRESSOR” proposes to form different steps at a radial exhaust port under female and male rotor holes on a rotor seat body, so as to attenuate the exhaust noise. A drawback of this patent is that only when the volume ratio of the slots formed at the exhaust port reaches a certain value can noise attenuation be accomplished. However, the formation of the slots reduces the design VI (volume ratio or volume index) of the compressor, thereby deteriorating the performance of the compressor at designed working conditions.
Therefore, what is needed is a solution which can effectively reduce the exhaust noise and suppress the exhaust noise energy at the source without deteriorating compressor performance.
The present invention is directed to a rotor seat for a screw compressor with a muffle structure. The rotor seat includes a seat body, a radial exhaust port arranged at the seat body, a female rotor hole and a male rotor hole and a plurality of axial blind holes arranged on an arc surface where the radial exhaust port is located.
The present invention is also directed to a screw compressor with a muffle structure. The screw compressor includes a suction port, an exhaust port, and an operation cavity in communication with the suction port and the exhaust port. The screw compressor also includes female and male rotors arranged inside the operation cavity and a rotor seat to receive the female and male rotors. The rotor seat includes a seat body, a radial exhaust port arranged at the seat body, a female rotor hole and a male rotor hole and a plurality of axial blind holes arranged on a surface where the radial exhaust port is located.
The present application provides a rotor seat for a screw compressor with a muffle structure. The rotor seat includes a seat body, a radial exhaust port arranged at the seat, and a female rotor hole and a male rotor hole. The rotor seat further includes a plurality of axial blind holes arranged on a surface where the radial exhaust port is located. In one embodiment, the axis of the blind hole is the normal line, at the hole, of the arc surface where the radial exhaust port is located. In another embodiment, the depths of the blind holes are in the range of ¼λ±15% of an interested sound frequency or an odd multiple of ¼λ±15% of the interested sound frequency, where λ is the wavelength of the interested sound frequency. In yet another embodiment, the diameters D of the blind holes are D≦0.586×c/f, where f is the interested sound frequency, and c is the sound speed in a medium. In still another embodiment, the blind holes are distributed in a uniform or non-uniform manner on the surface where the radial exhaust port is located. In a further embodiment, the quantity of the blind holes is at least two.
The present application further provides a screw compressor with a muffle structure. The screw compressor includes a suction port, an exhaust port, an operation cavity in communication with the suction port and the exhaust port, and female and male rotors arranged inside the operation cavity. The screw compressor further includes a rotor seat as described above for receiving the female and male rotors.
The muffle structure formed by the blind holes according to the present application can attenuate the acoustic energy in an outlet stream upon the discharging of a gas flow from a screw tooth slot primitive volume, thereby forming the muffle structure of the rotor seat for the screw compressor. When the unit operates with different loads, the muffle structure can attenuate the exhaust acoustic pulsation. Furthermore, since the blind holes are side branch holes and the gas flow can flow by the side of the opening of the blind holes rather than flow into the blind holes, a measurable pressure drop may not be caused. Thus, the additional loss of the outlet pressure can be ignored.
One advantage of the present application is a muffle structure with a structure which is simple, compact and very reliable.
Another advantage of the present application is that no additional structure is needed for noise control, which provides for a reduced cost.
Other features and advantages of the present invention will be apparent from the following, more detailed description of the preferred embodiments, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.
Motor 50 used with compressor 32 can be powered by a variable speed drive (VSD) 52 or can be powered directly from an alternating current (AC) or direct current (DC) power source. VSD 52, if used, receives AC power having a particular fixed line voltage and fixed line frequency from the AC power source and provides power having a variable voltage and frequency to motor 50. Motor 50 can include any type of electric motor that can be powered by a VSD or directly from an AC or DC power source. Motor 50 can be any other suitable motor type, for example, a switched reluctance motor, an induction motor, or an electronically commutated permanent magnet motor. In an alternate exemplary embodiment, other drive mechanisms such as steam or gas turbines or engines and associated components can be used to drive compressor 32.
Compressor 32 compresses a refrigerant vapor and delivers the vapor to condenser 34 through a discharge passage. Compressor 32 can be a screw compressor in one exemplary embodiment. The refrigerant vapor delivered by compressor 32 to condenser 34 transfers heat to a fluid, for example, water or air. The refrigerant vapor condenses to a refrigerant liquid in condenser 34 as a result of the heat transfer with the fluid. The liquid refrigerant from condenser 34 flows through expansion device 36 to evaporator 38. In the exemplary embodiment shown in
The liquid refrigerant delivered to evaporator 38 absorbs heat from another fluid, which may or may not be the same type of fluid used for condenser 34, and undergoes a phase change to a refrigerant vapor. In the exemplary embodiment shown in
In an exemplary embodiment, compressor 32 can include a compressor housing that contains the working parts of compressor 32. Vapor from evaporator 38 can be directed to an intake passage of compressor 32. Compressor 32 compresses the vapor with a compression mechanism and delivers the compressed vapor to condenser 34 through a discharge passage. Motor 50 may be connected to the compression mechanism of compressor 32 by a drive shaft.
Vapor flows from the intake passage of compressor 32 and enters a compression pocket of the compression mechanism. The compression pocket is reduced in size by the operation of the compression mechanism to compress the vapor. The compressed vapor can be discharged into the discharge passage. For example, for a screw compressor, the compression pocket is defined between the surfaces of the rotors of the compressor. As the rotors of the compressor engage one another, the compression pockets between the rotors of the compressor, also referred to as lobes, are reduced in size and are axially displaced to a discharge side of the compressor.
An exemplary embodiment of a rotor seat for a screw compressor is shown in
In another exemplary embodiment, the depths of the blind holes 103 can be in the range of ¼λ±15% of an interested sound frequency, e.g., a sound frequency to be attenuated, or an odd multiple of ¼λ±15% of the interested sound frequency, where λ is the wavelength of the interested sound frequency. For example, if the interested sound frequency is 750 Hz, and the sound speed is 150 m/s, the values of the depths of the blind holes 103 can be in the range of 50 mm±15% or an odd multiple of ¼λ±15% (for example, 150 mm±15%).
In a further exemplary embodiment, the diameters D of the blind holes 103 can be defined by D≦0.586×c/f (where f is the interested sound frequency, and c is the sound speed in a medium).
The blind holes 103 may be distributed in a uniform or non-uniform manner on the surface where the radial exhaust port 101 is located, and the quantity of the blind holes 103 can be at least two.
One exemplary embodiment provides a screw compressor with the muffle structure or muffler. The screw compressor can include a suction port, an exhaust port, an operation cavity in communication with the suction port and the exhaust port, and female and male rotors arranged, located or positioned inside the operation cavity. The screw compressor can further include the rotor seat 100 as shown in
The muffle structure formed by the blind holes 103 can attenuate the acoustic energy in an outlet stream upon the discharging of a gas flow from a screw tooth slot primitive volume, thereby forming the muffle structure of the rotor seat 101 for the screw compressor. When the unit operates with different loads, the muffle structure can always attenuate the exhaust acoustic pulsation. Furthermore, since the blind holes 103 are side branch holes and the gas flow can flow by the side of the opening of the blind holes 103 rather than flow into the blind holes 103, a measurable pressure fall or pressure drop may not be caused. Thus, the additional loss of the outlet pressure can be ignored. In addition, the muffle structure has a structure which is simple, compact and very reliable, and no additional structure is needed, which will not bring additional costs.
It is important to note that the construction and arrangement of the present application as shown in the various exemplary embodiments is illustrative only. Although only a few embodiments have been described in detail in this application, those who review this application will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters (e.g., temperatures, pressures, etc.), mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter described in the application. For example, elements shown as integrally formed may be constructed of multiple parts or elements, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. Accordingly, all such modifications are intended to be included within the scope of the present application. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. In the claims, any means-plus-function clause is intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments without departing from the scope of the present application. Accordingly, the present application is not limited to a particular embodiment, but extends to various modifications that nevertheless fall within the scope of the appended claims.
Furthermore, in an effort to provide a concise description of the exemplary embodiments, all features of an actual implementation may not have been described (i.e., those unrelated to the presently contemplated best mode of carrying out the invention, or those unrelated to enabling the invention). It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure, without undue experimentation.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201120472818.5 | Nov 2011 | CN | national |
