Field of the invention

The present invention refers to a construction for a discharge muffling chamber of the type formed in a single piece with the crankcase of a refrigeration reciprocating compressor disposed in the interior of a generally hermetic case. The invention further refers to a process for closing said discharge muffling chamber construction. Background of the invention

As illustrated in figures 1 and 2 of the appended drawings, the reciprocating hermetic compressors consist of a motor-compressor unit, which is mounted, usually through suspension springs, in the interior of a hermetically sealed case 1.. The motor-compressor unit comprises a crankcase 2 which defines a compression cylinder 3 and a shaft hub 4 for housing a non- illustrated crankshaft.

In general, the discharge of a compressor, of the type considered herein, presents a discharge muffling system comprising one or more discharge muffling chambers 10, 20, usually defined in a single piece in said crankcase 2 and through which the gas compressed in the compression cylinder 3 is passed, before being conducted outwardly from the compressor case 1, by means of a discharge tube 5 of the compressor, carried by the hermetic case 1.

In the illustrated construction, a first and a second muffling chamber 10, 20 are provided, interconnected by a duct 6, internal to the crankcase 2 and presenting a diameter sufficient to lodge, with a radial gap, an intermediary tube 7, having an inlet end (not illustrated)' connected to the head of the compressor, so as to receive the gas being compressed ^' by the latter, and an outlet end 7a open to the interior of the second muffling chamber 20. The radial gap ^" between the intermediary tube 7 and the duct 6 allows a portion of the compressed gas, fed to the second muffling chamber 20, to return to the first muffling chamber 10, tending to equalize the pressure between said chambers.

The discharge tube 5 presents an inlet end open to the interior of the second discharge muffling chamber 20, and an outlet end, affixed to a discharge inlet tube (not illustrated) , mounted through the hermetic shell 1, to connect the discharge of the compressor to the high pressure side of a refrigeration system to which the compressor is connected.

The discharge muffling system is designed to attenuate the pulsation of the gases pumped by the compressor to the refrigeration system or, generally, to the high pressure side of the circuit to which the compressor is associated, as well as to reduce the noise irradiated by the compressor to the external environment. The pulsation of the gases generates an excitation in the ducts and components to which the compressor discharge is coupled. Said excitation, on its turn, generates noise, which is always undesirable. Several constructions are used for said muffling chamber system, but, generally, the principle consists in making the gas flow to pass through a well defined sequence of tubes, volumes and localized restrictions, whose particular dimensions, arrangement and characteristics depend on the application, type and. size of the compressor, mass flow, working fluid, operational temperatures and conditions, on the noise bands intended to be attenuated, etc.

In a known construction, the discharge muffling chambers 10, 20, are provided in the crankcase 2 and each present, in the interior of a respective open end 11, 21, a -circumferential recess 12, 22, dimensioned to define an annular seat 12a, 22a, for the seating of a sealing gasket 30, of annular shape, and of a cover 40, to be seated on the sealing gasket ^' 30, in the annular seat 12a, 22a, in the circumferential recess 12, 22, in order to close each open end 11, 21 of the two discharge muffling chambers 10, 20. Each circumferential recess 12, 22 has the annular seat 12a, 22a surrounded by a peripheral lateral wall 12b, 22b.

Each discharge muffling chamber 10, 20 presents a generally cylindrical tubular shape, having a surrounding lateral wall 13, 23 and a closed bottom end wall 14, 24, presenting a blind axial hole (14a, 24a), internally threaded .

In this known construction, the closing of each discharge muffling chamber 10, 20 occurs by seating the sealing gasket 30 in the annular seat 12a, 22a, in the respective circumferential recess 11, 21, followed by the seating the respective cover 40 on the sealing gasket 30. Each cover 40 is affixed to the crankcase 2 by means of a respective fixation bolt 50, comprising a head 51 to be seated on the cover 40, a rod 52 disposed through a central hole 41 of the cover 40 and through the open median region of the sealing gasket 30, and a threaded end 53 to be affixed in the interior of the blind axial hole 14a, in the first muffling chamber 10 (figure 5) and in the blind axial hole 24a in the second muffling chamber 20 (see figures 2, 4 and 5) .

This known type of construction uses the circumferential recess 12, 22 to allow the easy and correct positioning of both the sealing gasket 30 and the cover 40 in the open end 11, 21 of each discharge muffling chamber 10, 20, considering that the sealing gasket 30, presenting a medianly open annular shape, has its radial indexing guaranteed by the peripheral lateral wall 12b, 22b of each circumferential recess 12, 22.

Although the radial indexing of the cover 40, in relation to the open end 11, 21 of each discharge muffling chamber 10, 20, is also defined by the peripheral lateral wall 12b, 22b of each circumferential recess 12, 22, the indexed mounting thereof can be obtained by means of the fixation bolt 50. Thus, the provision of the circumferential recess 12, 22 results from the need to provide a radial indexing in the sealing gasket 30 with a medianly open annular shape.

As a function of the need to provide each circumferential recess 12, 22, the discharge muffling chambers 10, 20 of this known construction type have the total height of the peripheral lateral wall 12b, 22b higher than that required for defining the discharge muffling volume, since the upper portion of the peripheral lateral wall is defined by the depth of the circumferential recess 12, 22, more precisely by the height of its peripheral lateral wall 12b, 22b.

Such higher height for the discharge muffling chambers 10, 20 requires increasing the dimensions of the compressor case, in order to guarantee a minimum distance between the open end 11, 21 of said discharge muffling chambers 10, 20 and the adjacent portions of the case 1 of the compressor.

Moreover, the provision of the circumferential recess 12, 22 in the discharge muffling chambers 10, 20 weakens this cylinder block region, which is now defined by the peripheral lateral wall 12b, 22b of each circumferential recess 12, 22. Said fragile regions of the surrounding lateral wall 13, 23 of each discharge muffling chamber 10, 20, usually defined by the material of the crankcase 2, are vulnerable to breakage, damaging (scrapping) the crankcase 2 during machining or during handling and use. Other negative aspect of said prior construction refers to the mounting process of the compressor, which requires the sequential steps of : seating each sealing gasket 30 in the respective circumferential recess 12, 22; seating each cover 40 on a respective already mounted sealing gasket 30; and mounting the fixation bolt 50, through the central hole 41 of the cover 40, by affixing its threaded end 53 in the interior of the blind axial hole 14a, 24a in the bottom end wall 14, 24 of each discharge muffling chamber 10, 20, retaining the cover 40 in position and pressing the sealing gasket 30 against ^■ the circumferential recess 12, 22. Objects of the invention

Thus, it is a generic object of the present invention to provide a discharge muffling chamber of the type incorporated to the crankcase of a refrigeration compressor and which presents a total height corresponding to the height which forms the required volume so that it can actuate as a noise muffling chamber, allowing reducing the dimensions of the compressor case, by respecting the required minimum distances between the case and the adjacent portions of the compressor crankcase.

Other object of the present invention is to provide a chamber of the type cited above and which can reduce the fragility of the cylinder block during production, handling and operation thereof.

It is a further object of the present invention to provide a chamber of the type cited above and which can provide an easy indexing for the mounting of the cover and its sealing gasket, in the open end of the respective discharge muffling chamber.

It is still a further object to provide a new process for closing a discharge chamber as defined above, which is able to suppress the operations for forming an indexing means for the sealing gasket in the open end of each discharge muffling chamber.

Summary of the invention

These and other objectives are achieved through a discharge chamber for a refrigeration compressor of the type which comprises: a case, lodging a crankcase carrying at least one gas discharge chamber, with a tubular shape and having a closed bottom end wall presenting a threaded blind axial hole, a surrounding lateral wall and an open end, presenting an annular seat; an annular sealing gasket, seated on said annular seat; a cover provided with a median hole and seated on the sealing gasket; and a fixation bolt, having a head seated on the cover, a rod projecting from the head and ending in a threaded end which is affixed in the interior of said blind axial hole.

According to the present invention, said annular seat extends throughout the whole radial width of the surrounding lateral wall of the discharge muffling chamber, in the region of its open end, the sealing gasket comprising a peripheral annular portion seated on the annular seat, and a median hole, to be trespassed by the rod of the fixation bolt.

The construction proposed by the invention allows obtaining, simultaneously, a reduction in the height of the discharge muffling chamber, by eliminating the peripheral lateral wall of the recess of the previous constructions, with the consequent reduction of the dimensions of the compressor case and reduction of the fragility of the crankcase in the region of the open end of the discharge muffling chamber.

As a function of the elimination of the peripheral lateral wall of the recess, that is, of the recess itself, the surrounding lateral wall of the discharge muffling chamber can have its thickness reduced, allowing maintaining the necessary internal volume with a corresponding reduction in the height of the discharge muffling chamber and of the material required for the formation of the crankcase.

The construction proposed by the invention further allows the process for closing the muffling chamber to be carried out with the radial indexing of the cover and of the sealing gasket provided by the rod of the fixation bolt, upon mounting the threaded end of the latter in the blind axial hole provided in the bottom of the discharge muffling chamber.

Brief description of the drawings

The invention will be described below, with reference being made to the appended drawings, given by way of example and in which:

Figure 1 illustrates, in a perspective view, a crankcase defining the piston hub, the shaft hub to receive a crankshaft and two discharge muffling chambers, before the mounting of the respective sealing gaskets and covers and constructed according to the prior art;

Figure 2 represents a partial sectional view of the crankcase illustrated in figure 1 and mounted in the interior of a compressor case, said section being taken according to line II-II of the previous figure, illustrating one of the discharge muffling chambers, constructed according to the prior art and having the sealing gasket and the cover already mounted in its open end;

Figure 3 illustrates, in a perspective view, a crankcase defining the piston hub, the shaft hub for receiving a crankshaft and two discharge muffling chambers, before the mounting of the respective sealing gaskets and covers and constructed according to the present invention;

Figure 4 represents a partial sectional view of the crankcase illustrated in figure 3 and mounted in the interior of a compressor case, said section being taken according to line IV-IV of the previous figure, illustrating one of the discharge muffling chambers, constructed according to the prior art and having the sealing gasket and the cover already mounted in its open end; and

Figure 5 represents a sectional view of the crankcase illustrated in figure 3, said section being taken according to line V-V of said previous figure and illustrating the two discharge muffling chambers with the sealing gasket and the cover already mounted, according to the present invention.

Detailed description of the invention

The present invention will be described for a generally hermetic refrigeration compressor, of the type already described in the introduction of the present specification and represented in figures 1 and 2 and which comprises a case 1, which houses a crankcase 2 carrying at least one discharge muffling chamber 10, 20, with a tubular shape, having a closed bottom end wall 14, 24 presenting a threaded blind axial hole 14a, 24a, a surrounding lateral wall 13, 23 and an open end 11, 21, presenting an annular seat 12a, 22a.

The same reference numbers used in the figures of the appended drawings represent equal parts in the construction representative of the prior art and in the construction object of the present invention.

According to the illustrated embodiment, the crankcase 2 incorporates, generally in a single piece obtained by casting, two discharge muffling chambers 10, 20, with the bottom end wall 14, 24 being defined by the crankcase 2 itself.

According to the invention, the annular seat 12a, 22a extends throughout the whole radial width of the surrounding lateral wall 13, 23 of each discharge muffling chamber 10, 20, in the region of its open end 11, 21. This new construction for the annular seat 12a, 22a allows to completely eliminate the peripheral lateral wall 12b, 22b of the circumferential recess 12, 22 of the prior art constructions.

The elimination of said peripheral lateral wall 12b, 22b, existing in the state of the art, allows suppressing the height of said peripheral lateral wall 12b, 22b from the total height of the surrounding lateral wall 13, 23 of each discharge muffling chamber 10, 20. Thus, it can be obtained a corresponding reduction in the contour of the case 1 in the region adjacent to said discharge muffling chambers 10, 20.

Another advantage of the new construction for the annular seat 12a, 22 results from the fact that its radial width is defined by the radial thickness of the surrounding lateral wall 13, 23 in the region of the annular seat 12a, 22a, allowing the radial thickness of the surrounding lateral wall 13, 23 ^' to be dimensioned to define, simultaneously, the required structure of the discharge muffling chamber 10, 20 and the minimum radial width required for the definition of the annular seat 12a, 22a.

As previously described, the construction of the discharge muffling chamber 10, 20 further comprises a sealing gasket 30, constructed in any adequate material well known in the prior art, presenting a peripheral annular portion 31 to be seated on the annular seat 12a, 22a, upon the closing of the discharge muffling chamber 10, 20, and having a median hole 32.

In the preferred illustrated embodiment, the median hole 32 of the sealing gasket 30 is defined in a median annular portion 33, radially spaced from the peripheral annular portion 31 and incorporated to the latter by means of a plurality of radial bridges 34.

Still according to the illustrated construction, the sealing gasket 30 has its peripheral annular portion 31 and median annular portion 33 and its radial bridges 34 coplanar to one another and obtained in a single piece. The discharge muffling chamber 10, 20 further comprises a cover 40 provided with a preferably central median hole 41, to be seated on the sealing gasket 30, more particularly on the peripheral annular portion 31 thereof .

The closing of each discharge muffling chamber 10, 20 further includes the provision of a fixation bolt 50 having a head 51, to be seated on the cover 40, a rod 52 projecting from the head 51 and to be fitted through the 41 of the cover 40, and which ends in a threaded end 53 to be affixed in the interior of the blind axial hole 14a, 24a of the bottom end wall 14, 24 of each discharge muffling chamber 10, 20.

The above-described construction, object of the present invention, allows the process for _e closing each discharge muffling chamber 10, 20 to be carried out through the steps defined below, after the formation of the discharge muffling chamber (s) 10, 20, with its annular seat 12a, 22a extending through the whole radial width of the surrounding lateral wall 13, 23 of the discharge muffling chamber 10, 20 in the region of its open end 11, 21, thus eliminating the provision of the peripheral lateral wall 12b, 22b, necessary in the prior art constructions, in which the open end 11, 21 of each discharge muffling chamber 10, 20 is provided with the circumferential recess 12, 22.

The closing process comprises the consecutive steps of: fitting the cover 40, through its median hole 41 around the rod 52 of the fixation bolt 50, maintaining the head 51 of the latter positioned in the outer side of the cover 40; providing the sealing gasket 30 as defined above and fitting it, through its median hole 32, around the rod 52 of the fixation bolt 50, already carrying the cover 40; and mounting the assembly consisting of the fixation bolt 50, cover 40 and sealing gasket 30 in the discharge muffling chamber 10, 20, seating the peripheral annular portion 31 of the sealing gasket 30 against the annular seat 12a, 22a and affixing the end 53 of the fixation bolt 50 in the blind axial hole 14a, 24a, in order to press the cover 40 against the sealing gasket 30, closing the open end 11, 21 of the discharge muffling chamber 10, 20.

The elimination of the circumferential recess 12, 22, further allows the production of sealing gaskets 30 and covers 40 with higher dimensional tolerances and higher concentricity deviations between the region of the blind axial hole 14a, 24a and the center of the open end 11, 21 of the discharge muffling chambers 10, 20, since it is no more necessary to fit said component in the interior of the circumferential recess 12, 22, said components being only seated on the annular seat 12a, 22a and radially indexed by the rod 52 of the fixation bolt 50. The elimination of the circumferential recess 12, 22 further allows optimizing the design of the case 1 of the compressor, by using larger radiuses of curvature in the region of the case 1, adjacent to said discharge muffling chambers 10, 20, with a significant noise reduction, by maintaining the thickness of the case, or reducing said thickness, without impairing its acoustic characteristics, nor its recommended minimum distance in relation to the motor-compressor unit.