Patent Description:
Generally, the main purpose of the invention in question is related to functional optimization of the hermetic compressor minimizing the quantity of work fluid at high temperature sucked to the inside of the compression mechanism (piston-cylinder set).

As it is known by technicians on the art, hermetic compressor comprises electromechanical devices capable of compress a work fluid by successive alteration of the internal volume of a compression chamber. Hermetic compressors are mainly applied in cooling systems.

This successive alteration of volume is carried out, in reciprocating hermetic compressors, by means of a compression mechanism fundamentally integrated by a piston-cylinder set, in which said piston is capable of be reciprocating displaced, on axial direction, inside the cylinder, altering the volume of it. It should be noted that said compression mechanism is enclosed inside the hermetic housing of the compressor.

Due to piston reciprocating movement, it can be stated that a reciprocating hermetic compressor operates in suction and exhaust reciprocating cycles of the work fluid.

Among the multiple functional variables existing in hermetic compressors, and in view of the scope of the present application, there are discussed two of these functional variables. The first functional variable discussed refers to the temperature of the work fluid sucked by the compression mechanism, in which as higher the temperature of this fluid, lower will be the yield of the compressor. This functional variable is also broadly known by technicians on the art, besides being broadly described by technical specialized literature.

The current state of the art comprises multiple solutions especially for optimizing the first functional variable, this is, especially for cooling the work fluid temperature sucked by the compression mechanism. Document BRPI1 <NUM>, for example, describes the application of a pre evaporator inside the hermetic house of the compressor whose main objective is reducing the compression mechanism temperature, or still, the work fluid temperature sucked by the compression mechanism.

The second functional variable now approached refers to the noise level generated during hermetic compressor operation, noise that can come from different sources. The reciprocating between suction and exhaust cycles itself, during the compressor operation, is characterized by generating vibrations and pulsing noises extremely undesired.

The current state of the art comprises multiple solutions especially for optimizing the second functional variable, this is, especially for attenuation of the pulsing noise generated by the suction and exhaust cycles, and smog the solutions already known, it is highlighted the one known with suction acoustic filter. Suction acoustic filters are broadly known by technicians on the art, beyond being broadly described in specific technical literature. Generally, a suction acoustic filter comprises a chamber that, disposed in some part of the suction line, defines a broad volume (related to the volume of the suction line part) capable of minimizing the pulsing effects referred to the reciprocating between the suction cycles. Such functional principle is broadly known and applied in reciprocating hermetic compressors. Although the functional principle of a suction acoustic filter is invariable, the constructive possibilities and the assembling possibilities are wide. Embodiments are known of sealed suction acoustic filters (applied on hermetic or direct suction lines), and non-sealed suction acoustic filters (applied in equalized or indirect suction lines, and also applied on semi direct suction lines).

Different models of suction acoustic filters, with different purposes, are illustrated on <FIG> and <FIG>.

The suction acoustic filter schematically illustrated on <FIG> is about a usual embodiment pertaining to the current state of the art. Such acoustic filter is totally integrated by a pre chamber A and a main chamber B. Said pre chamber A comprises a fluid inlet area A1 and a fluid outlet area A2, while main chamber B comprises a fluid inlet tubing B1 and a fluid outlet tubing B2. As illustrated, the fluid outlet area A2 of pre chamber A and the beginning of the fluid inlet tubing B1 of main chamber B confuses between them, this is because both are fluidly connected. Generally, said pre chamber A has just the function of fluid confinement, while main chamber B has the function of pulsing attenuation. Thus, is possible to say that suction acoustic filter schematically illustrated on <FIG> do not comprises any feature, characteristic or implement for optimizing the functional variable related to the work fluid temperature sucked by the compression mechanism.

The suction acoustic filter illustrated on <FIG> is about the suction acoustic filter described on document <CIT>, where it is described a suction acoustic filter defined by an inlet C1, an internal volume C2 and an outlet C3, being such acoustic filter specially cooperating with an extensor D coming from the suction passer. One of the main ideas foreseen on document <CIT> is that the suction acoustic filter gets (be fed) work fluid free from eventual turbulences existing on the environment defined inside the hermetic housing of the compressor. It is also not said any feature, aspect or implement to optimizing the functional variable related to the work fluid temperature sucked by the compression mechanism.

The suction acoustic filter illustrated on <FIG> is about the suction acoustic filter described on document <CIT>, where it is described a suction acoustic filter defined by a nozzle F1, an inlet pipe F4, an internal volume F2 and an outlet F3, being the nozzle F1 convergent, this is, with the inlet area greater than the outlet area. Beyond the examples listed above, and having in mind the current understandings, it is known that the current state of the art lacks of a unified solution that, implemented in suction acoustic filters, be the optimization of the two functional variables before explained. It is based on this scenario that arises the invention in question.

Additionally, document <CIT> discloses a hermetic compressor according the preamble of claim <NUM>.

Therefore, it is one of the objectives of the invention in question reveal a suction acoustic filter that, including a different nozzle, makes possible the suction and trapping of the work fluid on a temperature lower than the temperature of the work fluid existing on the internal environment of the hermetic housing, reaching the main majority of the observed benefits in systems capable of cooling the temperature of the work fluid sucked by compression mechanism. It is also one of the objectives of the invention in question that the suction acoustic filter including a nozzle reaches maximum optimization when related to pulsing noise attenuation generated by suction and exhaust cycles.

Additionally, it is one of the objectives of the invention in question reveal a suction line including a suction acoustic filter (including a nozzle) capable of optimizing the functioning of the hermetic compressor and, specially, capable of optimizing the efficiency of the hermetic compressor from the temperature reduction of the work fluid sucked by the compression mechanism and the reduction of the noise generated by the reciprocation between suction and exhaust cycles.

In this context, it is one of the main objectives of the invention in question that these optimizations are reached simply and non-costly, without the need to include further devices and/or systems.

All the objectives of the invention in question are reached by a hermetic compressor as defined in claim <NUM>.

Further advantageous aspects of the present invention are set out in the dependent claims.

The invention in question will be detailed based on the following listed figures, in which:.

As already mentioned, the current state of the art comprises some solutions dedicated to the cooling of the compression mechanism, or still, cooling means of the work fluid sucked by the compression mechanism. Such solutions of cooling, so ever are capable of maintaining said compression mechanism on a lower temperature, involve energetic costs, costs which can also damage the compressor efficiency.

Before the detailing of the embodiments of the inventions in question, it is important to define, punctually, the meaning of the expressions "main flow of outflow" and "pulsing reflux", following used as descriptive referential.

Main flow of outflow (FPE): Gas flow going from suction passer until the compression chamber.

Pulsing reflux (RP): Gas flow that return from the compression chamber to the internal of the suction acoustic filter and, eventually, outside the same due to the valves dynamic.

Thus, it is great the merit of the invention in question to keep the compression mechanism of the hermetic compressor to a lower temperature without being necessary to use the cooling means.

So, it is highlighted in the invention in question because it reveals a mean capable of guarantee that just (or at least mainly) the work fluid directly coming from the suction passer of the compressor, whose fluid comes from the evaporation line (which presents lower temperature that the work fluid enclosed on the internal environment defined by the hermetic housing of compressor) be sucked by the compression mechanism. Generally, such means are fundamentally composed by a nozzle that, preferentially (but not limitative) is disposed on the external portion of the suction acoustic filter and fluidly connected to the inlet path of said suction acoustic filter, is capable of act as a kind of work fluid concentrator directly coming from the suction passer of compressor and, simultaneously, with a kind of barrier to suction of the work fluid enclosed on the internal environment defined by the compressor hermetic housing. In other words, said nozzle ends acting as a "cold fluid trap", blocking (or making difficult) that said cold fluid (coming directly from the suction passer of the compressor) to be homogeneous, thermally, with the work fluid enclose on the internal environment defined by the hermetic housing of the compressor.

The objectives of the invention in question are more explored based on the illustrative <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>.

In this sense, according to the present invention (<FIG>) has a suction acoustic filter <NUM> fundamentally formed by an inlet path <NUM>, a main chamber <NUM> with functions of attenuating fluid flow pulsing (and, consequently, noise attenuation), and an outlet path <NUM>, which is functionally liked with the compression mechanism head (not illustrated).

It worth to say that said suction acoustic filter <NUM> comprises, roughly, a suction acoustic filter conventional and also the generic. This means that the core of the invention in question (detailed as follows) can be applied in several models and constructions of suction acoustic filters, since such filter comprises at least one inlet path <NUM>, at least one main chamber <NUM> and at least one outlet path <NUM>. Preferably, and as illustrated on <FIG>, the inlet path <NUM> and the outlet <NUM> are spaced apart, said inlet path <NUM> being disposed laterally on the suction acoustic filter <NUM>.

Said suction acoustic filter <NUM> comprises a nozzle <NUM> fluidly connected to at least one inlet path <NUM> and having a fluid inlet area <NUM> and a fluid directing area <NUM> for the inlet path <NUM> of the suction acoustic filter <NUM>.

Moreover, and according to the invention in question, the nozzle <NUM> of said suction acoustic filter <NUM> comprises a part of divergent section <NUM> related to the main flow of outflow (FPE). As illustrated on <FIG>, <FIG>, the part of divergent section <NUM> - related to the main flow of outflow (FPE) - comprises the own fluid inlet <NUM>, which has a smaller area than the fluid directing area <NUM>. Particularly according to the preferential embodiment of the invention, the inlet area of the nozzle <NUM> is, at maximum, <NUM>% lower than the fluid directing area <NUM>.

In <FIG>, which is not part of the presently claimed invention, the part of divergent section <NUM>, related to the main flow of outflow (FPE), comprises kind of a narrow or choke related to the pulsing reflux direction (RP), where the fluid inlet area <NUM> is larger than the fluid directing area <NUM>.

The existence of the divergent section part <NUM> - related to the main flow of the outflow (FPE) - is on the own fluid inlet area <NUM> of nozzle <NUM> or between the fluid inlet area <NUM> and the fluid directing area <NUM> - it is about one of the most preponderant features of the invention in question, after all, this is the part where the area suffers a reduction - related to the pulsing reflux (RP) - that is responsible by the work fluid trapping directly coming from the compressor suction passer and that defines the barrier to the suction of the work fluid enclosed on the internal environment defined by the hermetic housing of the compressor.

As illustrated on <FIG>, it can be stated that nozzle <NUM> defines a volume with at least one divergent part considering the direction of the main flow outflow (FPE). This way, the fluid coming from the suction passer is directed and stored inside the nozzle <NUM>, for, then, be converted in "suction fluid" FS, which enters on the suction acoustic filter <NUM> by the inlet path <NUM><NUM> whose fluid directing area <NUM> of the nozzle <NUM> communicates. At the most, it is further verified that the "housing fluid" FC is mainly blocked from entering on the nozzle <NUM>.

As illustrated on <FIG>, it can be said that the nozzle <NUM> defines a volume with at least one convergent part, now considering the direction of the pulsing reflux (RP). This ends blocking or making difficult fluid outlet at low temperature of said pulsing reflux (RP) for the environment out of the nozzle <NUM>.

As the suction dynamic of reciprocating hermetic compressors is fundamentally constant (pulsed in high frequency), there is no sufficient time so the temperature of the "suction fluid" FS increase related to the temperature of the main flow fluid of outflow (FPE). This way, said volume of nozzle <NUM> ends acting as work fluid accumulator at "low" temperature.

The potentiation of this thermal dynamic, by the suction line including a suction acoustic filter here revealed, is other great merit of the invention in question.

According to the suction line including suction acoustic filter here revealed, the suction passer <NUM> of the hermetic compressor <NUM>, shown on <FIG>, have its adjacent outlet to the fluid inlet area <NUM> of nozzle <NUM> of the suction acoustic filter <NUM>. Evidently, when closer and aligned the suction passer <NUM> of the hermetic compressor and the fluid inlet area <NUM> of the nozzle of the suction acoustic filter <NUM>, greater will be the work fluid concentration effects directly coming from the evaporation line, and better will be the barrier to the work fluid suction enclosed on the internal environment defined by the hermetic housing of the compressor.

Related to the constructive features more predominant of the preferred embodiment of the suction acoustic filter <NUM>, it remains to emphasizes that - preferentially, but not limitative - said nozzle <NUM> comprises a modular body to the suction acoustic filter <NUM>, this is, comprises an independent body related to the suction acoustic filter <NUM>. On this embodiment, the nozzle <NUM> is fixed to the suction acoustic filter <NUM> by a hermetic fixing means, as for example, a sealing and glutinous resin.

Alternatively, it is observed that the nozzle <NUM> could comprise also a body integrated with the suction acoustic filter <NUM>, this is, both bodies are part of the same monoblock. In this alternative embodiment, such monoblock could be made by thermoforming processes, for example.

Additionally, and considering that the preferred embodiment of the suction acoustic filter <NUM> foresee inlet paths <NUM> and outlet <NUM>, where the inlet path <NUM> is disposed laterally on the suction acoustic filter <NUM>, it is worth to say that - preferably, but not limitative - the fluid inlet <NUM> of the nozzle <NUM> is laterally disposed related to said suction acoustic filter <NUM>.

Now related to the suction line itself, it remains to emphasize that the suction passer outlet <NUM> can be directly or indirectly aligned to the fluid inlet area <NUM> of the nozzle <NUM> of the suction acoustic filter <NUM>, in a way that on the indirect option, it is foreseen the use of an extensor pipe (not illustrated).

Preferentially, said nozzle <NUM> should have a maximum volume approximate the same as half the volume displaced from the compressor, because this would be the maximum fluid volume accumulated during a cycle.

<FIG>, that refers to the specific areas illustrated on <FIG> shows a graphic where is demonstrated that the suction acoustic filter <NUM> with nozzle <NUM> including a divergent section part <NUM> is more effective thermodynamically than the acoustic filter belonging to the current state of the art illustrated on <FIG>, because the temperature of the fluid on the outlet of the acoustic filter is lowered.

Claim 1:
Hermetic compressor comprising a suction line, said suction line comprising an acoustic filter, with:
at least one acoustic chamber (<NUM>), and at least one outlet path (<NUM>);
a nozzle (<NUM>), said nozzle (<NUM>) having a fluid inlet area (<NUM>) at its first end and a fluid directing area (<NUM>) at its second end, the fluid directing area (<NUM>) of the nozzle (<NUM>) being situated on a portion of a side of the corresponding acoustic chamber (<NUM>);
said nozzle (<NUM>) comprising at least one part of divergent section (<NUM>) related to the main flow of the outflow (FPE);
said part of divergent section (<NUM>) being situated between the at least one fluid inlet area (<NUM>) and the at least one fluid directing area (<NUM>); and
wherein the part of divergent section (<NUM>), related to the main flow of outflow (FPE), comprises the own fluid inlet (<NUM>), which has a smaller area than the fluid directing area (<NUM>);
characterized in that
the acoustic filter comprises at least one inlet path (<NUM>);
said nozzle (<NUM>) is fluidly connected to the at least one inlet path (<NUM>) via its fluid directing area (<NUM>);
said fluid inlet area (<NUM>) is in fluid communication with a housing of the hermetic compressor.