Inlet silencer for positive displacement compressor and positive displacement compressor equipped therewith

Abstract

An inlet silencer for a positive displacement compressor, the inlet silencer (1) comprising a housing (2) having at least one inlet (3) and at least one outlet (4), and within the housing (2) there is provided at least one partition wall (6) that divides the housing (2) into at least a first chamber (7) and a second chamber (8), one chamber (7, 8) being connected to the inlet (3) and one chamber (7, 8) being connected to the outlet (4), and on the partition wall (6) there is arranged at least one opening (9) that connects both chambers (7, 8).

Description

Technical Field

[0001] The present invention relates to an inlet silencer.

[0002] More specifically, the present invention targets a positive displacement compressor.

Background Art

[0003] It is known that a positive displacement compressor not only generates pulsation at its outlet when the compressed gas exits the compressor discontinuously and non-uniformly, but also generates pulsation at its inlet when the gas to be compressed is sucked in discontinuously and non-uniformly. These pulsations cause undesirable unpleasant noises.

[0004] This phenomenon is known to exist in two-stage compressors, piston compressors, and to a lesser extent, screw compressors.

[0005] Therefore, in known compressors, an acoustic housing is arranged at the inlet and a baffle with acoustic foam is provided. Considering the space available within the compressor and the presence of the inlet filter and minimization of pressure loss as further restrictive constraints, such an acoustic housing is far from optimal.

[0006] In many cases, the above baffle is a structural part of the compressor and is not at all adapted to have acoustic attenuation characteristics.

[0007] In other words, in many cases, in anticipation of reducing undesirable pulsations, a plurality of structural elements are added to the compressor itself and optionally an acoustic foam is added to deflect or bend the flow path of the gas being sucked in.

Summary of the Invention

Problems to be Solved by the Invention

[0008] The present invention aims to provide a solution to at least one of the above-mentioned drawbacks and / or other drawbacks. [Means for solving the problem]

[0009] The present invention relates to an inlet silencer for a positive displacement compressor, the inlet silencer comprising a housing having at least one inlet and at least one outlet, the housing having at least one partition wall dividing the housing into at least a first chamber and a second chamber, one chamber connected to the inlet and the other chamber connected to the outlet, and the partition wall having at least one opening connecting both chambers.

[0010] The advantage is that the inlet silencer is a reactive silencer, which attenuates or reduces pulsations, thereby limiting unpleasant noise.

[0011] In addition, the inlet silencer generates very limited pressure loss for a maximum FAD (Free Air Discharge or Compressed Gas Output) of 140 liters / second.

[0012] In fact, the above-mentioned at least one opening may be substantially just one opening, but may also consist of two or three or more openings, which may or may not be grouped together in a partition wall.

[0013] For example, a partition wall may have perforations extending across a portion of its surface.

[0014] In its simplest embodiment, the inlet silencer comprises one inlet, one outlet, one partition wall, and a first chamber and a second chamber.

[0015] Furthermore, there may be, for example, three chambers created by placing two inlets and one outlet, as well as two partition walls within the housing. In this case, each of the two existing chambers would be connected to an inlet, and the third chamber would be connected to an outlet.

[0016] Preferably, at least one of the above openings is disposed near a corner of the partition wall, and the distance between the at least one opening and the corner is shorter than the distance between the at least one opening and the center of the partition wall.

[0017] In other words, at least one opening is not disposed at the center of the partition wall, but is disposed near the corner of the partition wall.

[0018] By disposing the opening near the corner, it is also possible to efficiently attenuate the higher-order acoustic modes of the pulsation.

[0019] According to a preferred feature of the present invention, a sound-absorbing material is disposed in the first chamber.

[0020] This sound-absorbing material can be disposed, for example, on the inner wall of the first chamber.

[0021] As a result, the muffler can be a dissipative muffler. The combination of the two chambers and the sound-absorbing material creates a hybrid dissipative-reactive muffler.

[0022] As a result, high frequencies can be attenuated.

[0023] In a practical embodiment, the volume of the second chamber is at least 50% of the volume of the first chamber.

[0024] This minimum volume of the second chamber enables efficient attenuation of low frequencies as well.

[0025] Furthermore, this makes the second chamber large enough to provide space for an inlet filter.

[0026] Preferably, an inlet filter is disposed in the second chamber, and the gas entering the second chamber needs to pass through the inlet filter before exiting the second chamber.

[0027] Integrating the inlet filter into the inlet silencer enables space-saving integration and leaves space for maximizing the housing size, such that the first and second chambers have the maximum possible volume.

[0028] In a preferred embodiment, the total surface area of at least one opening is larger than a specific value, and the velocity of the gas passing through at least one opening is at most 30 meters per second.

[0029] The exact dimensions are determined based on the (operating) parameters of the compressor, which then results in a specific minimum value for the surface.

[0030] By limiting the velocity of the gas passing through the at least one opening, the pressure drop can also be limited as much as possible.

[0031] In another preferred embodiment, at least one reversing plate or baffle is arranged in the first chamber so as to cross the geometric line between the inlet and the at least one opening, and the reversing plate or baffle partially divides the first chamber into three partial chambers, and the air flow flowing from the inlet to one of the at least one opening needs to flow around the reversing plate or baffle.

[0032] In other words, at least one opening, preferably all openings, are, so to speak, blocked or shielded from the air flow entering the chamber through the inlet by the reversing plate or baffle.

[0033] Thereby, the direction of the gas flow is forced to change in order to pass through the chamber, which helps to attenuate the pulsation.

[0034] The arrangement of a plurality of reversing plates or baffles in the first chamber is not excluded. These are preferably arranged alternately, forming a structure such that the gas needs to reverse or bend its flow direction several times in order to pass through the chamber.

[0035] The inverting plate or baffle can also divide the first chamber into only two sub-chambers, or into four or more sub-chambers.

[0036] In this case, the first chamber preferably has a maximum tortuosity of 2.5.

[0037] The curvature of the first chamber is defined as the ratio (fraction) of the length of the geometric line from the inlet to at least one opening and the shortest path of the airflow around at least one inverting plate or baffle passing through the first chamber.

[0038] In this case, the degree of curvature will always be a value greater than 1.

[0039] By limiting the curvature of the first chamber to a maximum value of 2.5, the propagation of high-frequency noise within the first chamber can be reduced by hindering the propagation of higher-order acoustic modes of pulsations in the gas, while the pressure loss above the first chamber remains remarkably low.

[0040] This is because the propagation of higher-order acoustic modes is hindered according to a reflective acoustic mechanism, rather than a dissipative acoustic mechanism that occurs when the curvature of the first chamber exceeds 2.5.

[0041] Furthermore, the present invention relates to a positive displacement compressor, characterized in that an inlet silencer according to any one of the above embodiments is arranged at the gas inlet of the positive displacement compressor.

[0042] For example, positive displacement compressors include tooth compressors, screw compressors, scroll compressors, lobe compressors, vane compressors, or piston compressors.

[0043] The advantages of such positive displacement compressors are clearly similar to those of intake silencers.

[0044] In order to better illustrate the features of the present invention, several preferred embodiments of the inlet silencer for a positive displacement compressor and a positive displacement compressor equipped therewith according to the present invention are described below, non-limitingly and illustratively, with reference to the accompanying drawings. [Brief explanation of the drawing]

[0045] [Figure 1] The inlet silencer according to the present invention is shown schematically in a perspective view. [Figure 2] Figure 1 shows the inlet silencer with the housing partially cut away. [Figure 3] Another diagram of Figure 1 is shown. [Figure 4] Figure 3 shows a cross-section along line IV-IV. [Figure 5] Figure 3 shows a cross-section along line VV. [Modes for carrying out the invention]

[0046] The inlet silencer 1, schematically shown in Figures 1 and 2, mainly comprises a housing 2 having an inlet 3 and an outlet 4. The outlet 4 of the housing 1 can be connected to or attached to the gas inlet 5 of a positive displacement compressor.

[0047] As can be seen from Figure 1, in this case, the housing 2 is beam-shaped. This shape allows for easy or better integration with the compressor canopy.

[0048] As can be seen from Figures 2 and 3, a partition wall 6 is located inside the housing 2.

[0049] This partition wall 6 is gas-impermeable and divides the housing 1 into a first chamber 7 and a second chamber 8.

[0050] This split will be carried out such that one chamber 7 and 8 are connected to the inlet 3, and the other chamber 7 and 8 are connected to the outlet 4.

[0051] In this case, the first chamber 7 is connected to the inlet 3, and the second chamber 8 is connected to the outlet 4.

[0052] In this case, the volume of the second chamber 8 is equal to or approximately equal to the volume of the first chamber 7. Of course, the present invention is not limited thereto. Preferably, the volume of the second chamber 8 is always equal to at least 50% of the volume of the first chamber 7.

[0053] The partition wall 6 has at least one opening 9 connecting both chambers 7 and 8. In this case, there is one opening 9. However, it is also possible to provide multiple openings 9 in the partition wall 6.

[0054] The above means that the gas flows from inlet 3 through inlet silencer 1 to the first chamber 7, through opening 9 to the second chamber 8, and then flows to outlet 4 and exits through inlet silencer 1.

[0055] It is also possible for the first chamber 7 to be connected to the outlet 4 and the second chamber 8 to be connected to the inlet 3. In this case, the gas first passes through the second chamber 8 before entering the first chamber 7.

[0056] In this case, at least one of the openings 9 is located near a corner 10 of the partition wall 6. This is clearly shown in Figure 4.

[0057] The distance A between at least one opening 9 and the corner portion 10 is shorter than the distance B between at least one opening 9 and the center 1 of the partition wall 6.

[0058] In other words, the opening 9 is not located in the center of the partition wall 6.

[0059] The total surface area of ​​at least one opening 9 is greater than a specific value such that the gas velocity passing through at least one opening 9 is at most 30 meters per second.

[0060] The specific values ​​mentioned above are determined based on the (operating) parameters of the compressor to which the inlet silencer 1 is connected.

[0061] Additional mechanisms are located in both the first chamber 7 and the second chamber 8.

[0062] The first chamber 8 is equipped with an inverting plate 12 or baffle. In this case, two inverting plates 12 or baffles are provided.

[0063] The inversion plate 12 crosses the geometric line 13 between the inlet 3 and the opening 9, and the inversion plate 12 or baffle partially divides the first chamber 7 into three sub-chambers 7a, 7b, and 7c, so the gas flowing from the inlet 3 to the opening 9 must flow around the inversion plate 12 or baffle.

[0064] This is schematically shown by arrows in Figure 3.

[0065] The sound-absorbing material 14 is placed inside the first chamber 7. In this case, the sound-absorbing material 14 is also placed inside the second chamber 8.

[0066] In this case, the sound-absorbing material 14 is preferably a permeable material such as polyurethane foam, melamine foam, viscoelastic foam, rock wool, glass wool, or acoustic cloth.

[0067] As shown in Figure 5, the sound-absorbing material 14 is placed on all inner surfaces 15 of the housing 2 in both the first chamber 7 and the second chamber 8. Alternatively, the sound-absorbing material 14 can be placed only in the first chamber 7.

[0068] Furthermore, the sound-absorbing material 14 is also placed on the two reversing plates 12 or baffles, which are located on both sides 16. It is also possible to place it on only one of the reversing plates 12 or baffles, or to place it on only one side 16 instead of both sides 16.

[0069] Furthermore, the sound-absorbing material 14 is placed on at least one side 17 of the partition wall 6, in this case on both side 17 of the partition wall 6.

[0070] The sound-absorbing material 14 has a passage 18 at the location of the opening 9, forming what is known as a flow path 19.

[0071] As can be seen from Figure 5, the length C of this channel 19 corresponds to twice the thickness of the sound-absorbing material 14 and the thickness of the partition wall 9.

[0072] The channel 19 formed in this manner will result in further damping.

[0073] Such a flow path 19 between the first chamber 7 and the second chamber 8 can also be realized in another way.

[0074] The opening 9 in the partition wall 6 can be created, for example, by a pipe or conduit extending through the partition wall 6, or by a pipe or conduit placed within the opening 6, the open end of which extends into the first chamber 7 and the second chamber 8.

[0075] In this way, the length of the channel 19 can be freely selected.

[0076] Of course, the provision of multiple pipes or conduits is not ruled out. Preferably, at least one opening 9 in the partition wall 6 is formed by at least one pipe or conduit extending through the partition wall 6, or at least one pipe or conduit is located within this at least one opening 9, with the open end of the pipe or conduit located within the first chamber 7 and the second chamber 8.

[0077] Therefore, for example, if a partition wall 6 has multiple openings 9, a pipe or conduit can be placed in each of these openings 9.

[0078] In addition to the sound-absorbing material 14, the second chamber 8 also has an inlet filter 20 in this case, so the gas entering the second chamber 8 must pass through the inlet filter 20 before it exits the second chamber 8 through the outlet 4.

[0079] Since the second chamber 8 has a specific minimum size, there is room to place the inlet filter 20 within this second chamber 8. This integration allows for additional space on the compressor lid, enabling a larger inlet silencer 1 to be designed.

[0080] Finally, in this case, the housing 2 includes a closable access section 21 for removing or replacing the inlet filter 20.

[0081] In this case, the closable access section 21 is realized by providing a removable wall 22 in the housing 2, or in other words, a part of the wall 22 of the housing 1 is removable.

[0082] For example, a flap or door can be provided on housing 1.

[0083] The operation of the inlet silencer 1 is very simple and is as follows:

[0084] The outlet 4 of the inlet silencer 1 is connected to the gas inlet 5 of the positive displacement compressor.

[0085] When a positive displacement compressor is in operation, the gas being compressed, such as ambient air, is drawn in by the compressor.

[0086] This will occur in a discontinuous or non-uniform manner, meaning that the flow rate or velocity of the ambient air being drawn in is not constant.

[0087] The surrounding air will be drawn in through the inlet 3 of the inlet silencer 1.

[0088] The ambient air enters the first chamber 7, where the airflow is bent twice along the reversal plate 12. This is schematically shown by arrows in Figure 3.

[0089] As a result, the ambient air comes into contact with the sound-absorbing material 14 placed on all the inner walls 15 of the housing 2 and on both sides 16 of the inverting plate 12. This, in particular, attenuates undesirable pulsations at high frequencies and the sound produced by these pulsations.

[0090] When ambient air reaches the partition wall 6, it flows through the opening 9 into the second chamber 8. Due to the size of the opening 9, the ambient air will have a maximum velocity of about 30 meters per second. Due to the location of the opening 9 near the corner 10 of the partition wall 6, higher-order acoustic modes will be attenuated.

[0091] In the second chamber 8, low frequencies are attenuated, and the ambient air passes through the air filter 20 before flowing from the outlet 4 of the inlet silencer 1 to the gas inlet 5 of the compressor.

[0092] For completeness, it should also be noted that the inlet silencer 1 also has an attenuation effect on sound waves sent from the compressor's gas inlet 5 through the inlet silencer 1.

[0093] In the embodiments described above and illustrated, there is always one inlet and one outlet, a first chamber and a second chamber, but the existence of two or more inlets and outlets and / or three or more chambers is not excluded.

[0094] The present invention is not limited to the exemplary embodiments described and illustrated, and an inlet silencer for a positive displacement compressor and a positive displacement compressor equipped therewith according to the present invention can be realized in any shape and size without departing from the scope of the present invention. [Explanation of symbols]

[0095] 1 Inlet silencer 2 Housing 3 entrance 4 exit 6 Partition walls 7. First Chamber 8. Second Chamber 9 aperture

Claims

1. An inlet silencer for a positive displacement compressor, wherein the inlet silencer (1) comprises a housing (2) having at least one inlet (3) and at least one outlet (4), The housing (2) is provided with at least one partition wall (6) that divides the housing (2) into at least a first chamber (7) and a second chamber (8). One chamber (7, 8) is connected to the inlet (3), and another chamber (7, 8) is connected to the outlet (4). The partition wall (6) has at least one opening (9) that connects both of the chambers (7, 8). Within the first chamber (7), at least one inverting plate (12) or baffle is positioned (7) across a geometric line (13) between the inlet (3) and the opening (9), the inverting plate (12) or baffle partially divides the first chamber (7) into a plurality of sub-chambers (7a, 7b, 7c), and the airflow from the inlet (3) to one of the at least one opening (9) must flow around the inverting plate (12) or baffle. The first chamber (7) has a maximum curvature of 2.5, The curvature of the first chamber (7) is defined, on the one hand, as the ratio of the length of the geometric line from the inlet (3) to the at least one opening (9) to the other hand, as the shortest path of the airflow through the first chamber (7) to the at least one inverting plate (12) or baffle. An inlet silencer characterized by the following features.

2. The inlet silencer according to claim 1, wherein the first chamber (7) is connected to the inlet (3) and the second chamber (8) is connected to the outlet (4).

3. The inlet silencer according to claim 2, wherein an inlet filter (20) is located inside a second chamber (8), and gas entering the second chamber (8) must pass through the inlet filter (20) before exiting the second chamber (8).

4. The inlet silencer according to claim 3, wherein the housing (2) is provided with a closable access section (21) for removing or replacing the inlet filter (20).

5. The inlet silencer according to any one of claims 1 to 4, wherein the sound-absorbing material (14) is disposed in at least the first chamber (7) or at least the second chamber (8).

6. The inlet silencer according to any one of claims 1 to 4, wherein the sound-absorbing material (14) is arranged on the reversing plate (12) or the baffle.

7. The inlet silencer according to claim 5, wherein the sound-absorbing material (14) is arranged on at least one side surface (17) of the partition wall (6), and a passage (18) is provided in the sound-absorbing material (14) at the position of the opening (9) to form a flow path (19).

8. The inlet silencer according to claim 5, wherein the sound-absorbing material (14) is a permeable material.

9. The inlet silencer according to claim 5, wherein the sound-absorbing material (14) is polyurethane foam, melamine foam, viscoelastic foam, rock wool, glass wool, or acoustic cloth.

10. The inlet silencer according to any one of claims 1 to 4, wherein the at least one opening (9) is located near a corner (10) of the partition wall (6), and the distance (A) between the at least one opening (9) and the corner (10) is shorter than the distance (B) between the at least one opening (9) and the center (11) of the partition wall (6).

11. The inlet silencer according to any one of claims 1 to 4, wherein the volume of the second chamber (8) is at least 50% of the volume of the first chamber (7).

12. The inlet silencer according to any one of claims 1 to 4, wherein the housing (2) is beam-shaped.

13. The inlet silencer according to any one of claims 1 to 4, wherein the at least one opening (9) of the partition wall (6) is created by at least one pipe or conduit extending through the partition wall (6) or by at least one pipe or conduit positioned within the at least one opening (9), and the open end of the pipe or conduit is located within the first chamber (7) and the second chamber (8).

14. A positive displacement compressor having a gas inlet, wherein the positive displacement compressor further comprises an inlet silencer (1) according to any one of claims 1 to 4, which is disposed at the gas inlet.

15. The positive displacement compressor according to claim 14, which is a tooth compressor, a screw compressor, or a piston compressor.

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