RESONATOR ELEMENT IN A SUCTION FILTER FOR HERMETIC COMPRESSOR AND METHOD OF MANUFACTURE OF A RESONATOR ELEMENT

Abstract

This invention refers to a suction filter (B) for hermetic compressor of type variable speed comprised, preferably of an arrangement of a volume (5), two tubes (1, 2), an inlet nozzle (3) and an outlet nozzle (4), having an internal resonant system, in which is positioned a set (10) of ducts (9), these having variable length. Different lengths represent different tunings for each frequency band of interest, and the fixed diametrical dimension having an perimeter extension at the base of the suction filter (B), the perimeter extension having an extension greater than or equal to the resonant tube (9), but smaller than or equal to the length of the tube. In the suction filter of the present invention the resonators (9) and the position of them are determined by the need for attenuation of the filter without introducing losses to the pulsating flow in the filter. The suction filter (B) is determined by the fact that the main tubes have a geometric correlation with the resonating tubes (9) producing the desired attenuation effect without affecting the other performance characteristics of the compressor.

Claims

1. RESONATOR ELEMENT (9) in a suction filter (B, C) for a hermetic compressor, the said filter comprising at least one volume (5), two tubes (1, 2), an inlet nozzle (3) and an outlet nozzle (4), the said resonator element (9) characterized by the fact that it is located internally the filter (B) at its upper part (6) and it is formed by at least two ducts (9) with varying lengths determined by the values and by the amount of frequencies to be attenuated.

2. ELEMENT, according to the claim 1, characterized by the fact that the ducts (9) are adjacently arranged aligned with each other and have a symmetrical format between them.

3. ELEMENT, according to the claim 1, characterized by the fact that three or more ducts (9) have harmonically increasing or decreasing lengths between each other.

4. ELEMENT, according to the claim 1, characterized by the fact that the set (10) of resonant ducts (9) comprises at least two ducts (9) with lengths L determined by the equation $f=i.Math.\frac{v}{4.Math.L}$ in which f=frequency, v=density, L=tube length and i=a harmonic number.

5. ELEMENT, according to the claim 1, characterized by the fact that physical characteristics of the resonator duct (9) are defined in function of the dimensions and geometry of the volume (5) of the suction filter (B), as well as the density of the refrigerant gas to be used.

6. ELEMENT, according to the claim 5, characterized by the fact that the dimensions and geometry of the suction filter volume comprise the length of the first tube (1) and the distance (7) formed between the lid (6) of the filter and the lower wall of the volume (5).

7. ELEMENT, according to the claim 1, characterized by the fact that the number of resonant ducts (9) is directly related to the bandwidth of the frequency and to the amount of frequencies, which are desired to be attenuated, in function of the available internal space of the filter (B).

8. ELEMENT, according to the claim 1, characterized by the fact that the positioning of the ducts (9) in the volume (5) of the filter is defined by the wave pressure variation of the resonance frequency that will be attenuated.

9. ELEMENT, according to the claim 1, characterized by the fact that the material of its constitution and suction filter is plastic with special characteristics in function of the temperature or any material with low thermal conductivity.

10. ELEMENT, according to the claim 1, characterized by the fact that the suction filter (C) can present more than one volume (5).

11. ELEMENT, according to the claim 1, characterized by the fact that the ducts (9) are originally molded into the lid (6) of the filter (B, C).

12. ELEMENT, according to the claim 1, characterized by the fact that the ducts are mounted as an independent component, fixed to the upper part (6) of the filter (B, C).

13. METHOD FOR THE MANUFACTURE OF A RESONATOR ELEMENT, characterized by the fact that it comprises: performing an acoustic simulation in a software to determine the geometric position of the resonators within the filter in function of the location of the frequencies that are desired to mitigate; providing an excitation in the filter inlet representing the pressure variation in the suction valve; determining the response function in frequency of the filter; and locating in which frequency band and at which filter location such frequency band presents its maximum and minimal acoustic pressure fluctuation.

14. METHOD, according to the claim 13, characterized by comprising the step of determining the length of the resonator element L by the equation $f=i.Math.\frac{v}{4.Math.L}$ in which f=frequency, v=density, L=tube length and i=a harmonic number.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0057] FIG. 1 illustrates a representation of a mass-spring system that behaves in a manner equivalent to the acoustic resonator.

[0058] FIG. 2 illustrates a suction filter from the Brazilian prior art.

[0059] FIG. 3 illustrates the opaque representation of a suction filter considering the main external constructive aspects of the filter.

[0060] FIG. 4 shows a cutting representation of a filter of the state of the art.

[0061] FIG. 5 is another cutting view in which the resonators are positioned on the lid relative to the internal volume of the filter.

[0062] FIG. 6 shows a superior view illustrating the geometric symmetry between the resonant tubes.

[0063] FIG. 7 is an isometric view showing the positioning of the resonating tubes detached from the filter body and positioned on the upper lid.

[0064] FIG. 8 illustrates a lower perspective view of the resonators.

[0065] FIG. 9 shows a side view of the resonators.

[0066] FIG. 10 illustrates a new disposition of resonators.

[0067] FIG. 11 shows a two-volume filter.

DESCRIPTION OF THE DRAWINGS

[0068] In FIG. 1 it is observed a representation of a mass-spring system that behaves in a manner equivalent to the acoustic resonator. In which the pressure p0 on the neck of the tube behaves like the mass m, and volume v0 as a spring k of the system. With the tuning of resonators (refrigerant columns), it is possible to tune to a broadband frequency band and, thus, avoid possible low and high frequency problems in the noise spectrum, which will depend on the size and position of the resonators.

[0069] In FIG. 2, a representation of the Brazilian prior art is shown, in which the positioning of an arrangement of resonators in the filter body is observed, wherein these resonators of circular format, spaced from each other and with varying and non-symmetrical lengths. One of the problems that such filter face, with such resonant ducts, due to its location and non-symmetrical sizes, is the turbulence and the fact that the used refrigerant clogs the ducts and prevent an adequate attenuation from being proportionate.

[0070] In FIG. 3, it can be seen the suction filter representation considering the main constructive aspects of the filter with the arrangements of tubes and volumes in the form of external representation. For simplicity, the setting of a volume and two tubes is illustrated, wherein the first tube 1 is located at the suction inlet and the second tube 2 is in the filter outlet, so as to represent the concept of passive filter. Elements 3 and 4 are, respectively, the inlet and outlet holes of the filter under the noise point of view. The numbers 5 and 6 refer to the body and filter lid, respectively.

[0071] In FIG. 4, a cut representation of the filter can be seen, showing the volume arrangement and proportions 7 (indicated by a line) that define the length of the first tube 1. In this figure, the elements 3 and 4 and the body 5 and the filter lid 6 are illustrated.

[0072] When the filter is in operation, the noise generated at the filter inlet 3, due to the pressure fluctuation in function of the suction valve opening and the density of the refrigerant used, propagates through the first tube 1 reaching the volume 5 by pressure waves. These pressure waves, which propagate the noise, are attenuated in the ducts 9 (see FIG. 5) due to the impedance modification between the volume 5 and the resonant tubes/ducts 9. For each length of the first tube 1 and the distance 7 formed between the lid 6 and the lower wall of volume 5, internal resonances are created that will require attenuation.

[0073] In FIG. 5, another cut view can be seen, in which the resonators 9 are positioned relative to the internal volume 5 creating a relative distance between them. That is, the height L of the resonators 9 varies, as well as the distance 8 between its opened ends and the bottom of the filter. The height L of the resonators 9 and its diameter define the frequency of the resonator (shown in FIG. 9) that will be attenuated.

[0074] FIGS. 6, 7 and 8 illustrate the set 10 of resonators 9 positioned in the filter and also highlighted. The top view in FIG. 6 shows the geometric symmetry between the tubes. FIG. 7 is an isometric view showing the positioning of the resonant tubes detached from the filter body and positioned on the upper lid 6 of it. In the lower perspective view in FIG. 8, it is also defined therein the various lengths of the resonators in function of the equivalent resonance. The idea of the amount of tubes forming the set of resonators 10 is also shown in FIG. 8. It is noted that the quantity of tubes depends on the available space and the frequency band that it is desired to attenuate.

[0075] The height L of the resonators 9 defines the frequency of the resonator shown in FIG. 9. In general a set 10 of resonators 9 will have between 10 and 15 tubes to cover a 500 Hz region in the frequency band. The greater the number of resonators 9, the greater the coverage of the frequency band and, hence, the greater the attenuation.

[0076] In FIG. 10, a new arrangement of a set 10 of resonators is shown in order to represent the various possibilities of arrangement of tubes 9, which can be used to seek the desired attenuation. A set 10 of resonators 9 in square format exemplifies this possibility, this format can be extended to any format that allows for its production and the arrangement of the resonant tubes 9 side by side. That is, the format is important for it will define the attenuation that will be necessary and, consequently, the region where the set 10 of resonants 9 will act as already described and identified by simulation. It is understood by region the set of frequencies that is sought to attenuate, i.e., the attenuation frequency band, which in the typical compressor is located between 2500 and 4000 Hz.

[0077] Finally, FIG. 11 shows that the filter is not restricted to the use of only one volume 5, but which can be formed by several volumes 5. An example with one volume 5 was described and presented in several figures from 3 to 10. In FIG. 11 a filter (C) is illustrated with first 1 and second 2 tubes and an outlet hole 4, wherein the said filter has two volumes 5 and is presented with the introduction of a barrier 11 and a third tube 12, which in this way, create other volumes that would form other resonances and would define another set 10 of resonators 9 to attenuate them. With the introduction of the barrier 11 to create other volumes, the filter's internal resonances will be altered and a new set 10 of resonators 9 will be required to attenuate this new frequency and/or frequency band. This new determination is made by simulation using the software already described and the new geometric format of the filter.

[0078] Having described examples of preferred embodiments, it is to be understood that the scope of the present invention encompasses other possible variations, being limited only by the content of the attached claims, including possible equivalents thereto.