Intake muffler for a positive displacement compressor and positive displacement compressor

Abstract

The present application relates to an intake muffler for a positive displacement compressor and to a positive displacement compressor. An intake muffler for a positive displacement compressor, characterized in that the intake muffler (1) comprises a housing (2) having at least one inlet (3) and at least one outlet (4), wherein in the housing (2) at least one partition wall (6) is provided which divides the housing into at least a first chamber (7) and a second chamber (8), wherein one chamber is connected to the inlet (3) and the other chamber is connected to the outlet (4), wherein in the partition wall (6) at least one opening (9) is provided which connects the first chamber and the second chamber.

Description

TECHNICAL FIELD

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

[0002] More specifically, the present invention is intended for use in a positive displacement compressor. BACKGROUND

[0003] It is known that a positive displacement compressor generates pulses not only at the outlet of the compressor when the compressed gas leaves the compressor in a discontinuous and non-uniform manner, but also at the inlet of the compressor when the gas to be compressed is sucked in a discontinuous and non-uniform manner. These pulses can cause unwanted noise nuisance.

[0004] This phenomenon is known and occurs in toothed compressors, piston compressors and, to a lesser extent, also in screw compressors.

[0005] Therefore, in the known compressors, at the inlet there is arranged a silencing casing provided with baffles having silencing foam. Such a silencing casing is far from optimal since, due to the fact that the available space in the compressor must be taken into account, the presence of the intake filter and the minimization of the pressure drop are additional limiting constraints.

[0006] In many cases, the baffles are structural components of the compressor and are not suitable at all for having silencing properties.

[0007] In other words: in many cases, many structural elements are added to the compressor itself to deflect or twist the flow path of the sucked-in gas, optionally supplemented with silencing foam, with the hope of reducing the unwanted pulses in this way. SUMMARY

[0008] The present invention aims to provide a solution that solves at least one of the above and / or other drawbacks.

[0009] The object of the present invention is an intake silencer for a positive displacement compressor, wherein the intake silencer comprises a casing having at least one inlet and at least one outlet, wherein in the casing there is provided at least one partition wall dividing the casing into at least a first chamber and a second chamber, wherein one chamber is connected to the inlet and the other chamber is connected to the outlet, wherein in the partition wall there is provided at least one opening connecting the first chamber and the second chamber.

[0010] The advantage is that the intake silencer is a reactive silencer, which can suppress or attenuate the pulses, thus limiting the noise nuisance.

[0011] Furthermore, for FADs (free air delivered or compressed gas output) up to 140 liters per second, the intake silencer generates only a very limited pressure drop.

[0012] In practice, the at least one opening can effectively involve only one opening, but can also comprise two or more openings which can or can not be grouped in a partition wall.

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

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

[0015] According to a practical embodiment, the first chamber is connected to the inlet and the second chamber is connected to the outlet.

[0016] For example, it can also be the case of two inlets and one outlet and three chambers created by arranging two partition walls in the housing. In this case, two chambers will be connected to the inlet and the third chamber will be connected to the outlet.

[0017] Preferably, the at least one opening is arranged near a corner of the partition wall, so that the distance between the at least one opening and the corner is less than the distance between the at least one opening and the center of the partition wall.

[0018] Or, in other words, the at least one opening is not located in the center of the partition wall, but near a corner of the partition wall.

[0019] By arranging the opening near the corner, it is also possible to effectively suppress the high-order acoustic modes of the pulse.

[0020] According to a preferred feature of the invention, a sound-absorbing material is arranged in the first chamber.

[0021] Such a sound-absorbing material can be provided, for example, on the inner walls of the first chamber.

[0022] According to a practical embodiment, the sound-absorbing material is arranged at least in the first chamber or at least in the second chamber.

[0023] As a result, the muffler will also be a resistive muffler. The combination of the two chambers with the sound-absorbing material results in a resistive-reactive hybrid muffler.

[0024] As a result, high frequencies can be suppressed.

[0025] In a practical embodiment, the volume of the second chamber is at least 50% of the volume of the first chamber.

[0026] Thanks to the minimum volume of the second chamber, low frequencies will also be effectively suppressed.

[0027] In addition, this also makes the second chamber large enough to provide space for arranging an intake filter.

[0028] Preferably, the intake filter is arranged in the second chamber such that gas entering the second chamber has to pass the intake filter before it can leave the second chamber.

[0029] Integrating the intake filter into the intake muffler provides a space-saving integration, leaving more space to maximize the housing size, thus maximizing the volume of the first and second chambers.

[0030] According to a practical embodiment, the housing is provided with a closable access for removing or replacing the intake filter.

[0031] In a preferred embodiment, the total surface area of the at least one opening is larger than a certain value, such that the velocity of the gas through the at least one opening is at most 30 meters per second.

[0032] The exact dimensions are determined in relation to the (operational) parameters of the compressor, from which a certain minimum value for the surface area can be derived.

[0033] By limiting the velocity of the gas flowing through the at least one opening, the pressure drop can also be limited as much as possible.

[0034] In another preferred embodiment, at least one baffle or deflector plate is provided in the first chamber, which baffle or deflector plate is arranged to intersect the geometrical line between the inlet and the opening, wherein the baffle or deflector plate partially divides the first chamber into three sub-chambers, such that the gas flow from the inlet to one of the at least one openings has to flow around the baffle or deflector plate.

[0035] Or, in other words: the at least one opening, preferably all openings, are blocked or shielded from the gas flow entering the chamber through the inlet by the baffle or deflector plate.

[0036] This forces the gas to change direction to flow through the chamber, which will help to dampen the pulses.

[0037] It is also not excluded that multiple baffle or deflector plates are provided in the first chamber. The multiple baffle or deflector plates are then preferably arranged staggered, thus forming a structure in which the gas has to change or bend its flow direction multiple times to flow through the chamber.

[0038] The baffle or deflector plate can also divide the first chamber into only two sub-chambers or more than three sub-chambers.

[0039] In this case, the first chamber preferably has a tortuosity of at most 2.5.

[0040] The tortuosity of the first chamber is defined as the ratio of the length of the geometrical line from the inlet to the at least one opening and the shortest flow path of the gas flow through the first chamber around the at least one baffle or deflector plate.

[0041] In this case, the tortuosity is always equal to a value greater than 1.

[0042] By limiting the tortuosity of the first chamber to a value of maximum 2.5, the propagation of high frequency noise in the first chamber can be reduced by impeding the propagation of the high order acoustic modes in the gas, while the pressure drop over the first chamber remains surprisingly low.

[0043] This is because, according to the reflective acoustic mechanism, and not according to the resistive acoustic mechanism, which occurs if the tortuosity of the first chamber is higher than 2.5, the propagation of the high order acoustic modes is impeded.

[0044] According to a practical embodiment, the sound absorbing material is arranged on the baffle or the deflector.

[0045] According to a practical embodiment, the sound absorbing material is arranged on at least one side of the partition wall, wherein a channel is arranged in the sound absorbing material at the location of the opening to form a flow channel.

[0046] According to a practical embodiment, the sound absorbing material is a permeable material, preferably a polyurethane foam, melamine foam, viscoelastic foam, rock wool, glass wool or sound absorbing cloth.

[0047] According to a practical embodiment, the housing is beam-shaped.

[0048] According to a practical embodiment, the at least one opening in the partition wall is formed by, or is arranged with, at least one duct or conduit extending through the partition wall, wherein the two open ends of the duct or conduit are located in the first chamber and the second chamber, respectively.

[0049] The present invention also relates to a positive displacement compressor having a gas inlet, characterized in that the gas inlet muffler according to any one of the preceding embodiments is arranged on the gas inlet of the positive displacement compressor.

[0050] For example, the positive displacement compressor is a toothed compressor, a screw compressor, a scroll compressor, a Roots compressor, a vane compressor or a piston compressor.

[0051] It is clear that the advantages of such a positive displacement compressor are similar to the advantages of the gas inlet muffler. BRIEF DESCRIPTION OF DRAWINGS

[0052] In order to better show the features of the present invention, some preferred embodiments of a gas inlet muffler for a positive displacement compressor and a positive displacement compressor equipped with such a gas inlet muffler according to the present invention are described below by way of non-limiting examples with reference to the accompanying drawings, in which:

[0053] Figure 1 a schematic perspective view of a gas inlet muffler according to the present invention is shown;

[0054] Figure 2 shows Figure 1 an intake muffler according to the application, the housing being partially cut away;

[0055] Figure 3 shows Figure 1 another view of the intake muffler according to the application;

[0056] Figure 4 shows a cross-sectional view according to the IV-IV line in Figure 3

[0057] Figure 5 shows a cross-sectional view according to the V-V line in Figure 3 DETAILED DESCRIPTION

[0058] As shown schematically in Figure 1 and Figure 2 , the intake muffler 1 mainly comprises a housing 2 having an inlet 3 and an outlet 4. The outlet 4 of the housing 2 can be connected or mounted to a gas inlet 5 of a positive displacement compressor.

[0059] As shown in Figure 1 , in the present example, the housing 2 is beam-shaped. Such a shape allows for an easy or better integration in a compressor head cover.

[0060] As shown in Figure 2 and Figure 3 , a partition wall 6 is provided in the housing 2.

[0061] The partition wall 6 is gas-impermeable and divides the housing 2 into a first chamber 7 and a second chamber 8.

[0062] The division will be such that one of the chambers 7, 8 is connected to the inlet 3 and the other of the chambers 7, 8 is connected to the outlet 4.

[0063] In the present example, the first chamber 7 will be connected to the inlet 3 and the second chamber 8 will be connected to the outlet 4.

[0064] In the present example, the volume of the second chamber 8 is equal or approximately equal to the volume of the first chamber 7. Of course, the application is not limited thereto. Preferably, the volume of the second chamber 8 is always at least equal to 50% of the volume of the first chamber 7.

[0065] At least one opening 9 connecting the two chambers 7, 8 is provided in the partition wall 6. In the present example, one opening 9 is provided. However, a plurality of openings 9 can be provided in the partition wall 6.

[0066] The above means that the gas will flow from the inlet 3 through the intake muffler 1, to the first chamber 7, through the opening 9, to the second chamber 8 and then to the outlet 4 to exit the intake muffler 1.​​

[0067] 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 will first flow through the second chamber 8 before entering the first chamber 7.

[0068] In the present example, the at least one opening 9 is arranged near a corner 10 of the partition wall 6. This is clearly visible in Figure 4 .

[0069] The distance A between the at least one opening 9 and the corner 10 is smaller than the distance B between the at least one opening 9 and the center 11 of the partition wall 6.

[0070] Or, in other words, the opening 9 is not located in the center of the partition wall 6.

[0071] The total surface area of the at least one opening 9 is larger than a certain value, such that the velocity of the gas through the at least one opening 9 is at most 30 meters per second.

[0072] The certain value is determined on the basis of the (operating) parameters of the compressor to which the gas inlet muffler 1 will be connected.

[0073] In both the first chamber 7 and the second chamber 8, additional means are provided.

[0074] In the first chamber 7, a deflection plate 12 or baffle is provided. In the present example, two deflection plates 12 or baffles are provided.

[0075] The deflection plates 12 intersect the geometric line 13 between the inlet 3 and the opening 9, wherein the deflection plates 12 or baffles divide the first chamber 7 partially into three sub-chambers 7a, 7b, 7c, such that the gas flow from the inlet 3 to the opening 9 has to flow around the deflection plates 12 or baffles.

[0076] A sound-absorbing material 14 is arranged in the first chamber 7. In the present example, the sound-absorbing material 14 is also arranged in the second chamber 8.

[0077] In the present example, the sound-absorbing material 14 is a permeable material, such as, for example, polyurethane foam, melamine foam, viscoelastic foam, rock wool, glass wool or sound-absorbing cloth.

[0078] As shown in Figure 5 , the sound-absorbing material 14 is arranged in the first chamber 7 and the second chamber 8 on all inner sides 15 of the housing 2. The sound-absorbing material 14 can also be provided only in the first chamber 7.

[0079] The sound-absorbing material 14 is also provided on the two deflection plates 12 or baffles and on the two side faces 16. It is also possible to arrange the sound-absorbing material only on one of the deflection plates 12 or baffles or not on both side faces 16 but only on one side face 16.

[0080] The sound absorbing material 14 is also provided on at least one side face 17 of the partition wall 6, and in the present case on both side faces 17 of the partition wall 6.

[0081] A passage 18 is provided in the sound absorbing material 14 at the location of the opening 9, to form a flow channel 19.

[0082] As Figure 5 indicated, the length C of the flow channel 19 corresponds to twice the thickness of the sound absorbing material 14 and the thickness of the partition wall 6.

[0083] The flow channel 19 thus formed will provide additional sound damping.

[0084] This flow channel 19 between the first chamber 7 and the second chamber 8 can also be realized in a different way.

[0085] For example, the opening 9 in the partition wall 6 can be formed by a pipe or conduit extending through the partition wall 6, or by a pipe or conduit arranged in the opening 9, with both open ends of the pipe or conduit extending into the first chamber 7 and the second chamber 8, respectively.

[0086] In this way, the length of the flow channel 19 can be freely chosen.

[0087] Of course, it is not excluded that more than one pipe or conduit is provided. Preferably, the 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 arranged in the at least one opening 9, with both open ends of the pipe or conduit being located in the first chamber 7 and the second chamber 8, respectively.

[0088] Thus, for example, if a plurality of openings 9 is provided in the partition wall 6, a pipe or conduit can be provided for each of these openings 9.

[0089] In the second chamber 8, in addition to the sound absorbing material 14, in the present case also an intake filter 20 is provided, so that the gas entering the second chamber 8 has to pass through the intake filter 20 before leaving the second chamber 8 via the outlet 4.

[0090] Because the second chamber 8 has a certain minimum size, there is space in the second chamber 8 to arrange the intake filter 20. This integration allows to create additional space in the compressor head, so that the intake silencer 1 can be designed larger.

[0091] Finally, in the present case, the housing 2 is provided with a closable inlet 21 for removing or replacing the intake filter 20.

[0092] In the present case, the closable inlet 21 is achieved by providing a removable wall 22 in the housing 2, or in other words, a part of the wall 22 of the housing 2 is removable.

[0093] For example, a lid or door can also be provided in the housing 2.

[0094] The operation of the intake muffler 1 is very simple, as described below.

[0095] The outlet 4 of the intake muffler 1 is connected to the gas inlet 5 of the positive displacement compressor.

[0096] During operation of the positive displacement compressor, the gas to be compressed, for example ambient air, will be sucked in by the compressor.

[0097] This will happen in a non-continuous or non-uniform manner, i.e. the flow or flow rate of the ambient air sucked in is not constant.

[0098] The ambient air will be sucked in through the inlet 3 of the intake muffler 1.

[0099] The ambient air enters the first chamber 7, in which the gas flow along the reversing plate 12 is bent twice.

[0100] The ambient air will then come into contact with the sound-absorbing material 14 arranged on all the inner sides 15 of the housing 2 and on the two side faces 16 of the reversing plate 12. This will dampen unnecessary pulses, in particular at higher frequencies, and the sound caused by these pulses.

[0101] When the ambient air reaches the dividing wall 6, it will flow to the second chamber 8 through the opening 9. Due to the size of the opening 9, the ambient air will only have a speed of at most 30 meters per second. Due to the position of the opening 9 close to the corner 10 of the dividing wall 6, higher-order acoustic modes will be dampened.

[0102] In the second chamber 8, lower frequencies will be dampened, and the ambient air will flow through the intake filter 20 before flowing to the gas inlet 5 of the compressor via the outlet 4 of the intake muffler 1.

[0103] For the sake of completeness, it is also mentioned here that the intake muffler 1 will also have a dampening effect on sound waves sent from the gas inlet 5 of the compressor through the intake muffler 1.

[0104] Although in the above-described and illustrated embodiment there is always one inlet and one outlet, a first and a second chamber, it is not excluded that there are more than one inlet and outlet and / or more than two chambers.

[0105] The present application is not limited to the embodiments described by way of example and illustrated in the drawings, but the intake muffler according to the present application for a positive displacement compressor and the positive displacement compressor equipped with the intake muffler can be realized in various shapes and sizes without departing from the scope of the present application.

Claims

1. An intake muffler for a positive displacement compressor, characterized in that, An intake muffler (1) includes a housing (2) having at least one inlet (3) and at least one outlet (4), wherein at least one partition wall (6) is provided in the housing (2) to divide the housing (2) into at least a first chamber (7) and a second chamber (8), wherein one chamber is connected to the inlet (3) and the other chamber is connected to the outlet (4), wherein at least one opening (9) is provided in the partition wall (6) to connect the first chamber (7) and the second chamber. At least one diverter plate (12) or baffle is provided in the first chamber (7), which is arranged to intersect the geometric line (13) between the inlet (3) and the opening (9), wherein the diverter plate (12) or baffle partially divides the first chamber (7) into a plurality of sub-chambers (7a, 7b, 7c), such that the airflow from the inlet (3) to one of the at least one opening (9) must flow around the diverter plate (12) or baffle, wherein the first chamber (7) has a tortuosity of up to 2.

5.

2. The intake muffler for a positive displacement compressor according to claim 1, characterized in that, The first chamber (7) is connected to the inlet (3), and the second chamber (8) is connected to the outlet (4).

3. The intake muffler for a positive displacement compressor according to claim 2, characterized in that, An intake filter (20) is provided in the second chamber (8) such that gas entering the second chamber (8) must pass through the intake filter (20) before it can leave the second chamber (8).

4. The intake muffler for a positive displacement compressor according to claim 3, characterized in that, The housing (2) is provided with a shut-off inlet (21) for removing or replacing the air intake filter (20).

5. The intake muffler for a positive displacement compressor according to claim 1 or 2, characterized in that, The sound-absorbing material (14) is arranged in at least the first chamber (7) or at least in the second chamber (8).

6. The intake muffler for a positive displacement compressor according to claim 1, characterized in that, The sound-absorbing material (14) is placed on the commutator plate (12) or the baffle plate.

7. The intake muffler for a positive displacement compressor according to claim 5, characterized in that, The sound-absorbing material (14) is disposed on at least one side (17) of the partition wall (6), wherein a channel (18) is provided in the sound-absorbing material (14) at the location of the opening (9) to form a flow channel (19).

8. The intake muffler for a positive displacement compressor according to claim 5, characterized in that, The sound-absorbing material (14) is a permeable material.

9. The intake muffler for a positive displacement compressor according to claim 1 or 2, characterized in that, The at least one opening (9) is arranged near the corner (10) of the partition wall (6) such that the distance (A) between the at least one opening (9) and the corner (10) is less than the distance (B) between the at least one opening (9) and the center (11) of the partition wall (6).

10. The intake muffler for a positive displacement compressor according to claim 1 or 2, characterized in that, The volume of the second chamber (8) is at least 50% of the volume of the first chamber (7).

11. The intake muffler for a positive displacement compressor according to claim 1 or 2, characterized in that, The total surface area of ​​the at least one opening (9) is greater than a certain value, such that the velocity of the gas through the at least one opening (9) is at most 30 meters per second.

12. The intake muffler for a positive displacement compressor according to claim 1 or 2, characterized in that, The shell (2) is beam-shaped.

13. The intake muffler for a positive displacement compressor according to claim 1 or 2, characterized in that, The 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 arranged in the at least one opening (9), wherein the two open ends of the pipe or conduit are located in the first chamber (7) and the second chamber (8), respectively.

14. The intake muffler for a positive displacement compressor according to claim 8, characterized in that, The sound-absorbing material (14) is polyurethane foam, melamine foam, viscoelastic foam, rock wool, glass wool or sound-absorbing cloth.

15. A positive displacement compressor having a gas inlet, characterized in that, The positive displacement compressor further includes an intake muffler (1) for the positive displacement compressor according to any one of claims 1-14, the intake muffler being disposed on the gas inlet.

16. The positive displacement compressor according to claim 15, characterized in that, Positive displacement compressors are gear compressors, screw compressors, or reciprocating compressors.

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