Inlet silencer for a positive displacement compressor and a positive displacement compressor equipped with the same

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 generates pulsations not only at its outlet when the compressed gas exits the compressor discontinuously and non-uniformly, but also 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 also 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 the 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] It is an object of the present invention 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 is directed 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, and at least one partition wall is provided in the housing to divide the housing into at least a first chamber and a second chamber, one chamber is connected to the inlet, one chamber is connected to the outlet, and at least one opening connecting both chambers is arranged in the partition wall.

[0010] The advantage is that the inlet silencer is a reactive silencer, which attenuates or reduces pulsations and as a result limits unpleasant noise.

[0011] In addition, the inlet silencer generates very limited pressure loss even for an FAD (free air delivery or compressed gas output) of up to 140 liters per second.

[0012] In fact, the above at least one opening can be substantially only one opening, but can also be provided with two or more openings, and these openings may or may not be grouped on the partition wall.

[0013] For example, the partition wall can be provided with perforations over a part of its surface.

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

[0015] Also, for example, there may be two inlets and one outlet, and three chambers created by arranging two partition walls in the housing. In this case, each of the two chambers is connected to the inlet, and the third chamber is connected to the 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, higher-order acoustic modes of pulsation can also be efficiently attenuated.

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

[0034] The arrangement of multiple 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 reversing plate or baffle can also divide the first chamber into only two partial chambers or into four or more partial chambers.

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

[0037] The tortuosity of the first chamber is defined as the ratio of the length of the geometric line from the inlet to at least one opening on the one hand and the shortest flow path of the air flow around at least one reversing plate or baffle through the first chamber on the other hand.

[0038] In this case, the tortuosity is always a number greater than 1.

[0039] By limiting the tortuosity of the first chamber to a value of at most 2.5, the propagation of high-frequency noise in the first chamber can be reduced by preventing the propagation of higher-order acoustic modes of pulsations in the gas, while the pressure loss across the first chamber remains surprisingly low.

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

[0041] The present invention also 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, the positive displacement compressor is a two-stage compressor, a screw compressor, a scroll compressor, a lobe compressor, a vane compressor, or a piston compressor.

[0043] The advantages of such a positive displacement compressor are clearly the same as those of the inlet silencer.

[0044] For the purpose of better showing the features of the present invention, some preferred embodiments of an inlet silencer for a positive displacement compressor according to the present invention and a positive displacement compressor equipped with the same will be described below by way of non-limiting example with reference to the accompanying drawings.

Brief Description of the Drawings

[0045]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0046] The inlet silencer 1 schematically shown in FIGS. 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 or attached to the gas inlet 5 of the positive displacement compressor.

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

[0048] As can be seen from FIGS. 2 and 3, a partition wall 6 is arranged in 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 division is made such that one of the chambers 7, 8 is connected to the inlet 3 and one of the chambers 7, 8 is 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 to this. Preferably, the volume of the second chamber 8 is always at least 50% equal to the volume of the first chamber 7.

[0053] At least one opening 9 connecting both chambers 7 and 8 is arranged in the partition wall 6. In this case, there is one opening 9. However, it is also possible to provide a plurality of openings 9 in the partition wall 6.

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

[0055] It is also possible that the first chamber 7 is connected to the outlet 4 and the second chamber 8 is 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, the at least one opening 9 is arranged near the corner 10 of the partition wall 6. This is clearly shown in FIG. 4.

[0057] 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 1 of the partition wall 6.

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

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

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

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

[0062] In the first chamber 8, a reversing plate 12 or a baffle is arranged. In this case, two reversing plates 12 or baffles are arranged.

[0063] The reversing plate 12 crosses the geometric line 13 between the inlet 3 and the above opening 9, and the reversing plate 12 or the baffle partially divides the first chamber 7 into three partial chambers 7a, 7b, 7c. Therefore, the gas flowing from the inlet 3 to the opening 9 needs to flow around the reversing plate 12 or the baffle.

[0064] This is schematically shown by the arrow in FIG. 3.

[0065] The sound-absorbing material 14 is arranged in the first chamber 7. In this case, the sound-absorbing material 14 is also arranged in 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 FIG. 5, the sound-absorbing material 14 is arranged on all the inner surfaces 15 of the housing 2 in both the first chamber 7 and the second chamber 8. Also, the sound-absorbing material 14 can be arranged only in the first chamber 7.

[0068] Also, the sound-absorbing material 14 is arranged on the above two reversing plates 12 or baffles, which are arranged on both side surfaces 16. Also, this can be arranged on only one of the reversing plates 12 or baffles, or can be arranged on only one side surface 16 without arranging on both side surfaces 16.

[0069] Further, the sound-absorbing material 14 is disposed on at least one side surface 17 of the partition wall 6, and in this case, on both side surfaces 17 of the partition wall 6.

[0070] A passage 18 is provided in the sound-absorbing material 14 at the position of the opening 9, thus forming a so-called flow path 19.

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

[0072] The flow path 19 formed in this way will bring about further attenuation.

[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 of 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 disposed within this opening 6, and the open ends of the above pipe or conduit extend into the first chamber 7 and the second chamber 8.

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

[0076] Of course, the provision of a plurality of pipes or conduits is not excluded. Preferably, at least one opening 9 of 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 disposed within this at least one opening 9, and the open ends of the above pipe or conduit are located within the first chamber 7 and the second chamber 8.

[0077] Therefore, for example, when a plurality of openings 9 are arranged in the partition wall 6, pipes or conduits can be arranged in each of these openings 9.

[0078] In the second chamber 8, in addition to the sound-absorbing material 14, in this case, the inlet filter 20 is also arranged. Therefore, the gas entering the second chamber 8 needs to pass through the inlet filter 20 before exiting the second chamber 8 through the outlet 4.

[0079] Since the second chamber 8 has a specific minimum size, there is room to arrange the inlet filter 20 within this second chamber 8. This integration can create additional space in the compressor canopy, so that the inlet silencer 1 can be designed larger.

[0080] Finally, in this case, the housing 2 is provided with a closable access part 21 for removing or replacing the inlet filter 20.

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

[0082] For example, it is also possible to provide a flap or a door on the 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] During the operation of the positive displacement compressor, the gas to be compressed, for example, ambient air, will be sucked in by the compressor.

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

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

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

[0089] As a result, the ambient air will come into contact with the sound-absorbing material 14 arranged on all the inner walls 15 of the housing 2 and both side surfaces 16 of the reversing plate 12. This will attenuate the undesirable pulsations at high frequencies in particular and the sounds caused by these pulsations.

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

[0091] In the second chamber 8, the low frequencies will be attenuated, and the ambient air will pass 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 the sake of completeness, it is also mentioned here that the inlet silencer 1 will also have an attenuation effect on the sound waves sent from the gas inlet 5 of the compressor through the inlet silencer 1.

[0093] In the above-described and illustrated embodiments, there is always one inlet and one outlet, and the first chamber and the 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 embodiments described and illustrated by way of example, and the inlet silencer for a positive displacement compressor according to the present invention and the positive displacement compressor provided with the same can be realized in any kind of shape and size without departing from the scope of the present invention.

Description of Reference Numerals

[0095] 1 Inlet silencer 2 Housing 3 Inlets 4 Outlets 6 Partition Walls 7 First Chamber 8 Second Chamber 9 Opening

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), at least one partition wall (6) is provided in the housing (2) for dividing 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 one chamber (7, 8) is connected to the outlet (4), and at least one opening (9) connecting both of the chambers (7, 8) is arranged in the partition wall (6). Inlet silencer.

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. An inlet filter (20) is arranged in the second chamber (8), and the gas entering the second chamber (8) needs to pass through the inlet filter (20) before leaving the second chamber (8). The inlet silencer according to claim 2.

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

5. At least one reversing plate (12) or baffle is arranged (7) in the first chamber (7) so as to cross the geometric line (13) between the inlet (3) and the opening (9). The reversing plate (12) or the baffle partially divides the first chamber (7) into a plurality of sub-chambers (7a, 7b, 7c), and the air flow flowing from the inlet (3) to one of the at least one opening (9) needs to flow around the reversing plate (12) or the baffle. The inlet silencer according to any one of claims 1 to 4.

6. The inlet muffler according to claim 5, wherein the first chamber (7) has a bending degree of at most 2.

5.

7. The inlet muffler according to any one of claims 1 to 6, wherein the sound-absorbing material (14) is disposed at least in the first chamber (7) or at least in the second chamber (8).

8. The inlet muffler according to claim 5 or 6, wherein the sound-absorbing material (14) is disposed on the reversing plate (12) or on the plate.

9. The inlet muffler according to claim 7 or 8, wherein the sound-absorbing material (14) is disposed 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).

10. The inlet muffler according to any one of claims 7 to 9, wherein the sound-absorbing material (14) is a permeable material, preferably polyurethane foam, melamine foam, viscoelastic foam, rock wool, glass wool or acoustic cloth.

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

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

13. The inlet muffler according to any one of claims 1 to 12, wherein a total surface area of the at least one opening (9) is larger than a specific value, and a speed of gas passing through the at least one opening (9) is at most 30 meters per second.

14. The inlet muffler according to any one of claims 1 to 13, wherein the housing (2) is in the shape of a beam.

15. 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 disposed within the at least one opening (9), and the open ends of the pipe or conduit are located within the first chamber (7) and the second chamber (8). The inlet muffler according to any one of claims 1 to 14.

16. A positive displacement compressor provided with a gas inlet, the positive displacement compressor further comprising the inlet muffler (1) according to any one of claims 1 to 15 disposed at the gas inlet.

17. The positive displacement compressor according to claim 16, which is a two-stage compressor, a screw compressor, or a piston compressor.

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