Silencer for a vacuum pump and vacuum pump provided with such a silencer

Abstract

The present invention relates to a silencer (S) for a vacuum pump (P) - having a first port (1) for a gas flow, - having a second port (2) for the gas flow and - having a pipe arrangement (3) between the first port (1) and the second port (2), wherein the silencer (S) is tuned for damping sound waves with a selected wavelength of (λ), wherein the pipe arrangement (3) comprises - a first pipe (31) which is connected to the first port (1), - a second pipe (32) which is connected to the second port (2), and - two central pipes (33, 34), wherein the central pipes (33, 34) are connected at a first end to the pipe (31) on the side of the first port (1) and at a second end to the pipe (32) on the side of the second port (2), and wherein a first central pipe (33) of the two central pipes (33, 34) has a first length (l1) and the second central pipe (34) of the two central pipes (33, 34) has a second length (l2) which is longer or shorter than the first length (l1) by half (λ / 2) of the selected wavelength (λ).

Description

[0001] The invention relates to a silencer for a vacuum pump having the features of the preamble of claim 1. It thus relates to a silencer. with an inlet for a gas flow, with an outlet for the gas flow and with a conduit arrangement between the inlet and the outlet, the silencer is tuned to dampen sound waves with a selected wavelength.

[0002] Silencers are known, for example, from documents DE 40 11 658 A1, DE 43 33 374 C1, JP 2003-184767 A, CN 110259545 A, DE 692 13 709 T2, and WO 03 / 056223 A2. The silencers known from these documents utilize interference effects to dampen sound in a fluid line.

[0003] The silencer described in document DE 43 33 374 C1 comprises a first reflection silencer and a second reflection silencer, the latter having two branch lines extending from a main line and connected to the main line at their first ends. The second reflection silencer operates on the interference principle. The branch lines have lengths of λ / 2 and λ / 4, where λ is the length of the sound waves to be attenuated. The branch lines are closed at one end. Waves entering the branch lines are reflected at these closed ends. The reflections travel back into the main line, causing attenuation. The silencer described in document DE 43 33 374 C1 has a complex structure and is composed of several pipes with different cross-sections and other components. At least the assembly of the silencer is complex.

[0004] A silencer known from document WO 03 / 056223 A2 has a straight main channel around which helical bypass channels are wound, through which sound attenuation can be achieved by utilizing the interference effect. The design of the silencer known from document WO 03 / 056223 A2 is also complex and its assembly is labor-intensive.

[0005] Document DE 692 13 709 T2 discloses a silencer of the type commonly used in the exhaust systems of motor vehicles. The silencer known from document DE 692 13 709 T2 comprises monolithic parts in which linear recesses are provided, forming the silencer's ducts when these two parts are assembled together. The silencer known from document DE 692 13 709 T2 has the features of the preamble of claim 1.

[0006] The inventors faced the task of designing a silencer for a vacuum pump. This silencer should take up as little space as possible and have a simple design.

[0007] This is where the present invention comes in.

[0008] This problem is solved according to the invention with a silencer having the features of claim 1. Further developments of this invention are specified in the dependent claims. The invention also utilizes the principle of destructive interference to dampen or cancel out the sound waves. However, the construction of the silencer according to the invention is significantly simpler than the construction of silencers known from the prior art. The silencer according to the invention is multi-part and has at least a first part and a second part that are connected to each other to form an assembly, wherein the first and / or the second part are monoliths. Linear recesses are provided in the first part and / or the second part, which form the first central channel and the second central channel of the channel arrangement, the channels being provided in the assembly.The first part of a silencer according to the invention is a ring or ring-shaped, and the second part is also a ring or ring-shaped. The assembly consisting of the first and second parts can then enclose another assembly or something else, such as a vacuum pump. It is possible that the first line runs in a circular arc and / or the second line runs in a circular arc.

[0009] The silencer may have a connecting stub or nipple that is connected to the second port of the silencer, or forms the second port or part of the second port.

[0010] The first part and / or the second part can be castings. In these castings, the channels or other linear depressions forming the first or second conduit can be manufactured particularly easily. The castings can be made of aluminum, aluminum alloys, zinc, zinc alloys, or plastic.

[0011] The first part and the second part of a silencer according to the invention can form a housing.

[0012] The silencer according to the invention can be used in vacuum pumps.

[0013] Vacuum pumps according to the invention are specified in claims 5 and 6.

[0014] The invention is explained in more detail below with reference to the accompanying drawings. These show: Fig. 1 a side view of a vacuum pump according to the invention, partially in exploded view, Fig. 2 the vacuum pump according to the invention, partially in exploded view, Fig. 3 a top view of a first part of a silencer of the vacuum pump according to Fig. 1 , Fig. 4 the vacuum pump according to the invention partly in a sectional view.

[0015] The in the Figures 1 to 4 The vacuum pump P shown has a pump housing in which a pump chamber is provided. The pump chamber is not shown. One or more working elements are provided in the pump chamber by which the vacuum is generated. These working elements are driven by a motor.

[0016] Pump P has a silencer that dampens the noise transmitted through a medium line. The medium extracted from the container to be evacuated is transported via this medium line. The pump chamber has a second connection that serves as an outlet. A first connection, which in this example forms an inlet, is connected to the container to be evacuated.

[0017] A first connection 1 of the silencer, provided in a first part 4 of the silencer, is connected to the second connection of the pump chamber. A second connection 2 and a nipple 7, to which the medium line can be connected, are also connected to this first part 4. The first part 4 is essentially ring-shaped and arranged around the pump chamber.

[0018] In the first part 4, channels are provided. These are parts of a piping arrangement 3 and comprise a very short first piping 31, which is connected to a first port 1 of the silencer, and a very short second piping 32, which is connected to the second port 2 of the silencer. The second piping is also provided in the nipple 7. Between the channels provided in the first part 4, which form parts of the first piping 31 and the second piping 32, linear recesses are provided, which provide parts of a first middle piping 33 and a second middle piping 34, which are arranged partly on circular paths around a center point of the ring forming the first part 4.

[0019] A second part 5 of the silencer is also essentially ring-shaped. On one side facing the first part 4, it has a channel structure corresponding to the channel structure of the first part 4. The channel structures together form the duct arrangement 3 of the silencer.

[0020] Both middle lines 33, 34 have a first common end that connects to the first line 31, and a second common end that connects to the second line 32.

[0021] The length of the first middle line 33 has a length that corresponds to the wavelength λ to be attenuated or quenched, or a multiple of this wavelength λ.

[0022] The length of the second middle line 34 is half a wavelength λ or an odd multiple longer than the first middle line 33. As a result, a wave crest and a wave trough of the sound waves transmitted via the middle lines meet at the second end, leading to destructive interference and consequently to cancellation or at least attenuation of the sound waves at the second ends of the middle lines. Reference symbol list

[0023] 1. First connection 2. Second connection 3. Pipe arrangement 31. First pipe 32. Second pipe 33. First middle pipe 34. Second middle pipe 4. First part of the silencer 5. Second part of the silencer 7. Nipple PV vacuum pump

Claims

1. Silencer for a vacuum pump (P) • with a first connection (1) for a gas stream, • with a second connection (2) for the gas stream and • with a pipework arrangement (3) between the first connection (1) and the second connection (2), said silencer being tuned to attenuate sound waves with a selected wavelength (λ), the pipework arrangement (3) • having a first line (31) that is connected to the first connection (1), • a second line (32) that is connected to the second connection (2), and • two intermediate lines (33, 34), said silencer consisting of multiple parts and having at least a first part (4) and a second part (5) that are connected together to form an assembly, with the lines being arranged in the assembly, in which the first and / or second part are monoliths, with linear recesses being provided in the first part (4) and / or the second part (5), which form the first intermediate line (33) and the second intermediate line (34) of the pipework arrangement (3), characterised in that the first part (4) is a ring or ring-like and the second part (5) is a ring or ring-like, the intermediate lines (33, 34) are connected on one side of the first connection (1) with a first end to the first line (31) and on one side of the second connection (2) with a second end to the second line (32), and a first intermediate line (33) of the two intermediate lines (33, 34) has a first length (11) and the second intermediate line (34) of the two intermediate lines (33, 34) has a second length (12) that is longer or shorter than the first length (11) by half ( λ 2 ) of the selected wavelength (λ).

2. Silencer according to claim 1, characterised in that the silencer has a connection fitting or nipple (7) that is connected to the second connection (2) of the silencer or forms the second connection (2) or part of the second connection (2).

3. Silencer according to claim 1 or 2, characterised in that the first part (4) and / or the second part (5) are castings, in particular made of aluminium, aluminium alloys, zinc, zinc alloys or plastic.

4. Silencer according to one of claims 1 to 3, characterised in that the first part (4) and the second part (5) form a housing.

5. Vacuum pump (P) with a pump housing and a pump chamber arranged therein that has a first connection for a gas flow and a second connection for the gas flow, characterised in that the vacuum pump has a silencer according to one of claims 1 to 4.

6. Vacuum pump (P) according to claim 5, characterised in that the first connection of the silencer is connected to the second connection of the pump chamber of the vacuum pump, and the first part (4) and the second part (5) of the silencer are parts of the pump housing or are arranged in the pump housing or are attached to the pump housing.

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