Acoustics – Sound-modifying means – Muffler – fluid conducting type
Reexamination Certificate
2002-05-22
2004-07-20
Lockett, Kimberly (Department: 2837)
Acoustics
Sound-modifying means
Muffler, fluid conducting type
C181S211000
Reexamination Certificate
active
06763909
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is entitled to the benefit of and incorporates by reference essential subject matter disclosed in German Patent Application No. 101 28 225.7 filed on Jun. 11, 2001.
FIELD OF THE INVENTION
The invention concerns a suction muffler for a hermetically enclosed compressor with a housing that has at least a first and a second chamber, separated from each other by means of a dividing wall and connected with each other by means of a throttling channel, which is designed to allow flow from the first to the second chamber.
BACKGROUND OF THE INVENTION
A suction muffler of this kind is known from DE 199 23 734. This muffler has a housing that consists of an upper part, a bottom part and an insert. The insert divides the housing into two chambers, which are connected with each other by means of a tubular throttling channel. The throttling channel is made as part of the insert. Together with the housing bottom part, a wall section of the insert forms a capillary slot, in which oil can accumulate. This improves the noise damping of the muffler. The channel extends substantially into the first chamber, whereas in the second chamber merely a short channel section projects over the bottom surface of the insert.
Among other things, such suction mufflers serve the purpose of damping sound waves resulting from the opening and closing movements of a suction valve arrangement, which is arranged in a cylinder head of a compressor. The noise caused by this can be undesirably transferred to the environment via the volume enclosed by the compressor shell.
An additional suction muffler is known from U.S. Pat. No. 3,750,840 A. In this case, the throttling channel connecting the two chambers of the housing is formed by a channel structure pressed into an insert plate. The insert plate is fixedly connected with a division plate. Openings formed in the insert plate and in the division plate provide the connection between the two chambers. This design is relatively expensive to manufacture.
SUMMARY OF THE INVENTION
The invention is based on the task of improving noise suppression.
With a suction muffler as mentioned in the background, this task is solved in that the throttling channel comprises a lateral opening, which opens into a chamber via a branch channel.
Thus, the lateral opening is not directly connected with the chamber, into which it opens. On the contrary, an additional branch channel is arranged between the opening in the wall of the throttling channel and the actual exit into the corresponding chamber, which branch channel can further contribute to noise suppression. Basically, this provides in a simple manner an extension of the distance which must be travelled by the sound waves. As both the throttling channel and the branch channel have limited cross-sectional surfaces, a muffling of the sound waves takes place in both channels.
Preferably, the branch channel opens into the second chamber. The second chamber is the chamber which is closest to the outlet of the muffler and thus to the inlet of the compressor. Here, the sound waves still have their largest intensity so that a damping in the branch channel is preferred to take place here, before the sound waves reach the inside of the compressor housing through the inlet of the suction muffler.
Preferably, the throttling channel has a tubular section in the second chamber, in which the opening is arranged. Thus, the throttling channel can be extended into the second chamber by the tubular section. An extension of this kind is very advantageous for noise suppression. However, it has the disadvantage that oil, which is entrained by the gaseous refrigerant flowing through the throttling channel, can no longer flow off from the second chamber. The oil thus collecting up in the second chamber would cause a deterioration of the effective volume of the second chamber, which would again deteriorate noise suppression.
The opening now remedies the above-described problem. As the opening is arranged laterally, the oil in the second chamber can flow off when it reaches the level of the opening. This means that the oil can no longer collect up to the level of the tubular section, as the opening and the branch channel permit the oil to flow off, before it reaches the level of the tubular section. Thus, it is achieved that a relatively large volume of the second chamber is still available for noise suppression. Additionally, it is avoided that too much oil is drained off from the lubricating circuit of the compressor, which would, among other things, deteriorate the cooling of some components and have a negative influence on the life of the compressor.
It is particularly preferred that the opening is in the shape of a slot and that in the longitudinal direction the branch channel has a slot-like cross-section. This design has turned out to be particularly advantageous for noise suppression. The term “slot-like” suggests that in the cross-section the channel has a substantially larger dimension in one direction than in the other direction. Preferably, the larger dimension is parallel to the flow direction through the throttling channel. In principle, the channel thus has the shape of a flat plate, the plate having, of course, a certain, but small thickness.
Preferably, the opening ends at the bottom of the chamber. Due to gravity, oil that has been taken into the second chamber by the gas flow accumulates at the bottom of the chamber and can, as the opening goes right down to the bottom, flow back to the first chamber through this opening.
Preferably, the branch channel is limited by the bottom of the chamber. Thus, the oil is free to reach the opening of the branch channel, so that oil is prevented from accumulating in the second chamber.
Preferably, the opening is arranged at the lowest point of the chamber. Or, more precisely, the opening in the wall of the tubular section is extended down to the lowest point of the chamber. Oil that usually accumulates at the lowest point due to gravity is then free to flow off. In this case, an escape path is always available for any oil that starts accumulating.
Preferably, the length of the branch channel substantially corresponds to the height of the branch channel. The “length” of the branch channel means the distance from the opening to the oppositely arranged exit of the branch channel into the second chamber. The height is the extension perpendicularly to this, that is, the extension in parallel to the flow direction through the throttling channel. The adaptation to each other of length and height has turned out to be advantageous for the muffling qualities.
Preferably, the branch channel extends in an arch shape. The arch-shaped extension serves the purpose of improving the noise suppression.
It is particularly preferred that the branch channel runs substantially parallel to the circumferential wall of the throttling channel. In this case, the branch channel also provides an additional thermal isolation for the refrigerant flowing through the throttling channel, which means that the efficiency of the compressor on a whole is improved.
Preferably, the circumferential wall of the throttling channel forms a limiting wall of the branch channel. This results in a particularly simple design. Only one additional wall is required for the branch channel.
Preferably, the branch channel is open on the face side. This means that the branch channel has a second outlet opening, which may, for example, be arranged in the same level as the outlet opening of the throttling channel. Under certain circumstances, it can also be arranged in a different level. Thus, the flow resistance of the arrangement is reduced. The gas that passes through the throttling channel has a movement component in the direction of the longitudinal axis of the throttling channel. The face side opening of the branch channel now permits the gas to flow on with this movement component.
REFERENCES:
patent: 3750840 (1973-08-01), Holme
patent: 5173034 (1992-12-01), Riffe
patent: 5330329 (1994-07-01), Clark
Danfoss Compressors GmbH
Lockett Kimberly
McCormick, Paulding & Hauber LLP
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