DEVICE FOR DAMPING PRESSURE PULSATIONS FOR A COMPRESSOR OF A CASEOUS FLUID

Abstract

A process for manufacturing a device and the device for damping pressure pulsations for a compressor of a gaseous fluid, in particular a refrigerant, in a refrigerant circuit of a motor vehicle air-conditioning system. The device exhibits a housing that encompasses a chamber and features at least two outlet openings. Here, the housing is constructed between tubular connecting lines, whose ends are aligned with one another. An insert element for reducing the cross-sectional area of the pass-through opening is arranged inside at least one of the pass-through openings.

Claims

1-20. (canceled)

21. A device for damping pressure pulsations for a compressor of a gaseous fluid, the device comprising: a housing that encompasses a chamber and features at least two pass-through openings, wherein the housing is constructed between tubular connecting lines, whose ends are aligned with one another, and an insert element for reducing a cross-sectional area of at least one of the pass-through openings arranged inside the at least one of the pass-through openings.

22. The device according to claim 21, wherein each of the pass-through openings exhibits a diameter that corresponds to an inside diameter of the connecting lines.

23. The device according to claim 21, wherein the pass-through openings are arranged and aligned on a common axis.

24. The device according to claim 21, wherein the housing is produced around a longitudinal axis with rotational symmetry.

25. The device according to claim 21, wherein the housing exhibits two housing elements that are aligned with one another with first faces that are constructed as open ends and are connected to one another on the first faces.

26. The device according to claim 25, wherein each of the housing elements is constructed as a permanent component of one end of the connecting lines.

27. The device according to claim 25, wherein each of the housing elements exhibits a base on a second face that is aligned distally to each of the first faces in a longitudinal direction x.

28. The device according to claim 27, wherein one of the pass-through openings is constructed inside each of the bases.

29. The device according to claim 21, wherein a first one of the pass-through openings is constructed as an inlet opening and a second one of the pass-through openings is constructed as an outlet opening of the chamber.

30. The device according to claim 29, wherein the inlet opening and the outlet opening are arranged and aligned on a symmetry axis of the device.

31. The device according to claim 29, wherein a first insert element is arranged inside the inlet opening and a second insert element is arranged inside the outlet opening for reducing the cross-sectional area of the inlet opening and the outlet opening.

32. The device according to claim 31, wherein each of the first insert element and the second insert element essentially exhibit a shape of a hollow cylinder.

33. The device according to claim 32, wherein each of the first insert element and the second insert element exhibit an external diameter that essentially corresponds to an inside diameter of each of the connecting lines.

34. The device according to claim 31, wherein each of the first insert element and the second insert element is constructed with a total length L.sub.i wherein the first insert element and the second insert element are arranged with a length L.sub.0 projecting into the chamber, and wherein the length L.sub.0 is lower than the total length L.sub.i and is greater than or equal to zero.

35. The device according to claim 31, wherein the first insert element and the second insert element are constructed from a plastic.

36. The device according to claim 31, wherein the first insert element is constructed with an inlet section that exhibits a constant external diameter and a continuously reducing internal diameter in a flow direction of the fluid.

37. The device according to claim 31, wherein the second insert element is constructed with an outlet section that exhibits a constant external diameter and a continuously expanding internal diameter in a flow direction of the fluid.

38. The device according to claim 21, wherein a first one of the pass-through openings is connected to an intake area of the compressor.

39. A process for manufacturing the device for damping pressure pulsations for the compressor of the gaseous fluid according to claims 21, exhibiting the following steps: widening of one end of the connecting line up to an internal diameter of the chamber and forming the one end of the connecting line as housing elements with a base and one open end; widening of a first housing element in the area of the widened end and creating a flange for a flange connection of the housing elements in such a way that an internal diameter of the first housing element at the open end corresponds to an external diameter of a second housing element at the open end with enough play to connect the housing elements; insertion of prefabricated insert elements into pass-through openings produced in the housing elements; and insertion of the housing elements into one another at the flange connection, as well as fluid-tight connection of the housing elements.

40. A use of the device for damping pressure pulsations for the compressor of the gaseous fluid according to claim 21 in a refrigerant circuit, in particular of a motor vehicle air-conditioning system.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0042] Further details, features and benefits of embodiments of the invention result from the following description of embodiment examples with reference to the accompanying drawings. These display the following:

[0043] FIG. 1: A device for damping pressure pulsations for a compressor inside a chamber enclosed by a housing, shown as an axial longitudinal section from the state of the art

[0044] FIGS. 2A and 2B: A comparison between a conventional device and a device according to the invention for damping pressure pulsations for a compressor, each shown as an axial longitudinal section with calculation parameters

[0045] FIG. 3A: A device according to the invention for damping pressure pulsations for a compressor with insert elements inside the chamber enclosed by the housing, shown as an axial longitudinal section

[0046] FIG. 3B: Various conditions of a housing element of the device housing as per FIG. 3A during manufacture

[0047] FIG. 4: A comparison between transmission losses or damping behavior of conventional silencers and a device according to the invention for damping pressure pulsations based on frequency

[0048] FIGS. 5A and 5B: Detailed depictions of the device for damping pressure pulsations for a compressor under variation of the total length of the insert element with constant internal diameter, as well as comparison of transmission losses or damping behaviour of the devices based on frequency, as well as

[0049] FIGS. 6A and 6B: Detailed depictions of the device for damping pressure pulsations for a compressor under variation of the internal diameter of the insert element with constant total length and length that reaches both into the volume of the device and into the connecting line of the insert element, as well as comparison of transmission losses or damping behaviour of the devices based on frequency.

DETAILED DESCRIPTION OF AN EMBODIMENT

[0050] FIG. 1 shows a device 1′ for damping pressure pulsations for a compressor inside a chamber 3 enclosed by a housing 2′, provided as an axial longitudinal section from the state of the art.

[0051] The produced housing 2′ that encloses the chamber 3 exhibits a first housing element 2a′ and a second housing element 2b′, which are attached to one another by brazing or welding at open ends that are facing and in contact with one another. The open ends are each provided on a first face of the housing elements 2a′, 2b′. On a first face arranged distally relative to the second face, the housing elements 2a′, 2b′ each exhibit a base 4a, 4b. A pass-through opening 6a′, 6b′ is provided in the bases 4a, 4b of the housing elements 2a′, 2b′, each of which represents a permanent component of a connecting line 5 of a refrigerant circuit. The diameters of the pass-through openings 6a′, 6b′ are preferably identical and smaller than the internal diameter of the connecting line 5.

[0052] The connection of the connecting line 5 to the base 4a, 4b is produced with a transition area 7′ in each case. Within the transition area 7′, the connecting line 5 exhibits a constant external diameter, which also corresponds to the external diameter of the connecting line 5 in sections of the refrigerant circuit located away from the device 1′ and expands in the area of the base 4a, 4b.

[0053] The internal diameter of the connecting line 5 is constant in the direction of the device 1′ up to the transition area 7′ and then continuously decreases within the transition area 7′. The internal diameter of the connecting line 5 is minimal in the area of the base 4a, 4b and corresponds to the diameter of the respective pass-through opening 6a′, 6b′. The wall thickness of the connecting line 5 continuously increases in the transition area in the direction of the device 1′.

[0054] FIGS. 2A and 2B provide a comparison between a conventional device 1′ and a device according to the invention 1 for damping pressure pulsations for a compressor, each shown as an axial longitudinal section with calculation parameters.

[0055] The damping behaviour D.sub.TL of a reflective silencer, also known as the transmission loss coefficient D.sub.TL, can be calculated on the basis of the frequency or wavelength to be damped and the installation space available using the following formula (source: Wallin, H.-P., Carlsson, U., Abom, M., Boden, H., & Glab, R. (2012). Sound and vibration [Book]. Stockholm, Sweden: The Marcus Wallenberg Laboratory.):

[00001]$D_{\mathrm{TL}}=10\log \left(1+{\left(\frac{S_1}{2.Math.S_2}-\frac{S_2}{2.Math.S_1}\right)}^2{\sin }^2\left(\mathrm{kL}\right)\right)\left[\mathrm{dB}\right]$

[0056] The installation space is dictated by the internal diameter of the chamber 3. The inner volume of the chamber 3 or the volume enclosed by the housing 2′ is defined on the basis of the length L in the longitudinal direction x, as well as the cross-sectional area S.sub.2. S.sub.1 corresponds to the cross-sectional area of the pass-through openings 6a′, 6b′ for fluid entry into the chamber 3, as well as for fluid exit from the chamber 3, while k corresponds to the wave number as k=2π/λ. As a result, the damping behaviour D.sub.TL of the device 1′ produced as a reflective silencer is also dependent on the flow cross-section S.sub.1 of the inlet opening 6a′ and the outlet opening 6b′, as well as the inner flow cross-section S.sub.2 of the chamber 3.

[0057] When fluid flows through the device 1′ with the chamber 3 and the pass-through openings 6a′, 6b′, the pressure pulsations are reduced by the level of transmission loss coefficient D.sub.TL.

[0058] Consequently, the damping behaviour D.sub.TL of a reflective silencer is determined by the length of the chamber 3, in particular the inner volume of the chamber 3, and an expansion ratio. The expansion ratio is understood to mean the ratio between the internal diameter of the chamber 3 and the diameter of the pass-through openings 6a′, 6b′.

[0059] In order to improve the damping behaviour D.sub.TL of the reflective silencer with constant inner volume of the chamber 3, in particular with consistent length L and consistent cross-sectional area S.sub.2 (in other words essentially the same housing 2 with constant installation space), the cross-sectional area S.sub.1 of the pass-through openings 6a, 6b, in particular inlet opening 6a or outlet opening 6b, can be reduced to a cross-sectional area S.sub.1*. In particular, this changes the expansion ratio.

[0060] The expansion ratio, and thereby the damping behaviour D.sub.TL, of the reflective silencers can also be kept constant with a smaller installation space.

[0061] As can in particular be seen in FIG. 2B, the cross-sectional areas of the pass-through openings 6a, 6b of the device 1 are each reduced by the arrangement of an insert element 8a, 8b. Firstly, a length L.sub.i of the area that changes the cross-section of the insert elements 8a, 8b has an effect on the damping behaviour D.sub.TL. Secondly, the damping behaviour D.sub.TL is also influenced by the insert elements 8a, 8b reaching into the chamber 3. Here, the insert elements 8a, 8b are arranged with a section of length L.sub.0 inside the chamber 3.

[0062] FIG. 3A shows an embodiment of a device according to the invention 1 for damping pressure pulsations for a compressor with insert elements 8a, 8b inside a chamber 3 that is enclosed by the housing 2, depicted as an axial longitudinal section.

[0063] The housing 2 is produced with a first housing element 2a and a second housing element 2b. The housing elements 2a, 2b are aligned with one another, with the open ends arranged in contact, and then connected to one another in particular by brazing or welding. Here, the housing elements 2a, 2b are each arranged with a first face facing each other. On a first face that is aligned distally in the longitudinal direction x to the second face, the housing elements 2a, 2b each exhibit a base 4a, 4b. The housing elements 2a, 2b are produced with the bases 4a, 4b each as a permanent component of a connecting line 5 of a refrigerant circuit. One pass-through opening 6a, 6b is provided within each of the bases 4a, 4b. The diameters of the pass-through openings 6a, 6b and the internal diameters of the connecting lines 5 are preferably identical.

[0064] The connecting lines 5 are produced with both a constant external diameter and a constant internal diameter, in other words with a constant wall thickness.

[0065] With the pass-through openings 6a, 6b, the housing 2 that encloses the chamber 3 exhibits an inlet opening 6a, as well as an outlet opening 6b, each of which are produced in the base 4a, 4b of the housing elements 2a, 2b. The fluid that is to be compressed when flowing through the compressor flows through the connecting line 5 and the inlet opening 6a in the longitudinal direction x into the chamber 3 of the device 1 and then back out the chamber 3 and into the connecting line 5 through the outlet opening 6b. Here, the inlet opening 6a is produced as a connection to a low-pressure side of the refrigerant circuit, while the outlet opening 6b is connected to an intake area of the compressor via the connecting line 5. The inlet opening 6a and the outlet opening 6b are aligned with one another coaxially, i.e. on a common axis, which also corresponds to the symmetry axis or the longitudinal axis of the device 1.

[0066] When manufacturing the device 1, a pressing tool is used to widen one end of a connecting line 5 up to a final diameter in a cold forming process, wherein the end of the connecting line 5 then represents a housing element 2a, 2b with the base 4a, 4b. FIG. 3B shows the first housing element 2a of the housing 2 of the device 1 as per FIG. 3A in four different conditions and the second housing element 2b in three different conditions, each during manufacture.

[0067] After widening two connecting lines 5 up to an internal diameter of the chamber 3 to be produced later in two shown steps, the first housing element 2a is widened further at the open end in a further step, in particular a third step shown, in order to produce a flange for the flange connection of the housing elements 2a, 2b. The first housing element 2a is widened on the open face in such a way that the internal diameter then corresponds to the external diameter of the second housing element 2b in the widened section plus enough play to connect the housing elements 2a, 2b to one another.

[0068] After inserting the prefabricated insert elements 8a, 8b into the housing elements 2a, 2b and connecting the housing elements 2a, 2b with one another, in particular inserting the second housing element 2b into the first housing element 2a, the housing elements 2a, 2b are, for example, brazed or welded to one another in order to guarantee a fluid-tight connection of the housing 2.

[0069] The essentially hollow cylinder-shaped, specifically circular hollow cylinder-shaped, insert elements 8a, 8b, in particular to reduce the cross-sectional areas S.sub.1 of the pass-through openings 6a, 6b, are preferably manufactured from a plastic and exhibit an external diameter that corresponds to the internal diameter of the connecting line 5. This secures fluid-tight insertion of the insert element 8a, 8b into the respective housing element 2a, 2b, in particular via an interference fit. Here, fluid-tight insertion is understood to mean that the outer shell surface area of the insert element 8a, 8b is in fluid-tight contact with the internal surface of the connecting line 5 and thereby that the entire mass flow of the fluid is guided through the respective insert element 8a, 8b. Any occurrence of a bypass flow of the fluid on the outside of the insert element 8a, 8b is prevented. The insert elements 8a, 8b, preferably produced from a plastic, are to be formed very flexibly, wherein the use of other easily formable materials can be provided for the insert elements 8a, 8b.

[0070] The insert elements 8a, 8b are matched to the necessary areas of application, in particular the specific frequency ranges in which targeted damping is to be achieved, in terms of their shape, in particular with regard to their total length L1 and cross-sectional area S.sub.1*. Alongside the total length L.sub.0 and an internal diameter of the insert element 8a, 8b, the length L.sub.0 of the insert element 8a, 8b can also be varied inside the chamber 3.

[0071] When the housing elements 2a, 2b have been assembled and connected, the device 1 preferably exhibits a length of around 50 mm and external diameter of around 37 mm with a wall thickness of around 1.5 mm. In the area where they are connected to one another, the housing elements 2a, 2b are arranged with an overlap of around 5 mm to one another.

[0072] Construction of a conventional device 1′ with an internal diameter of the chamber 3 of 48 mm and an internal diameter of the connecting lines 5 of 16 mm results in an expansion ratio of 3. In the case of a space-saving embodiment of the device 1 with an internal diameter of the chamber 3 of 36 mm and the same length L, the diameter of the pass-through openings 6a, 6b is reduced to 12 mm in order to keep the expansion ratio, and thereby also the damping behaviour D.sub.TL, constant. Alongside the same length L and expansion ratio, the device according to the invention 1 also delivers the same performance as the conventional device 1′.

[0073] FIG. 4 compares transmission losses or damping behaviour based on the frequency of a reflective silencer known from the state of the art, a conventional device 1′ as per FIG. 1 and a device according to the invention 1 as per FIG. 3A for damping pressure pulsations within a refrigerant circuit that employs R134a as the refrigerant.

[0074] It becomes clear here that the device according to the invention 1 in the space-saving embodiment can close a gap that occurs in the damping behaviour, in particular in the low frequency range, for example in the range up to around 800 Hz, between a reflective silencer known from the state of the art and the conventional device 1′ as per FIG. 1. Particularly in the stated frequency range, the pressure pulsation damping performance of the device 1 is greater than that of the conventional device 1′.

[0075] FIGS. 5A and 5B show and compare detailed depictions of the device 1 for damping pressure pulsations for a compressor, in particular the housing elements 2a, 2b with the insert elements 8a, 8b, under variation of the total length L.sub.i , of the insert elements 8a, 8b with a constant internal diameter of 12 mm, as well as the transmission losses or damping behaviour of the device 1 with the various insert elements 8a, 8b based on the frequency inside a refrigerant circuit. The insert elements 8a, 8b are each arranged in such a way that they do not reach into the chamber 3 of the device 1. The length L.sub.0 of the insert elements 8a, 8b inside chamber 3 is therefore zero in each case.

[0076] The total length L.sub.i, of the insert elements 8a, 8b varies between 5 mm (a), 10 mm (b), 25 mm (c) and 50 mm (d), while the internal diameter exhibits the value of 12 mm.

[0077] FIG. 5B clearly shows that the damping behaviour of the device 1 is improved with increasing total length L.sub.i, of the insert elements 8a, 8b.

[0078] FIGS. 6A and 6B provide a comparison that includes detailed depictions of the device 1 for damping pressure pulsations for a compressor, in particular the housing elements 2a, 2b with the insert elements 8a, 8b, under variation of the internal diameter of the insert elements 8a, 8b, each with constant total length L.sub.i, and constant length L.sub.0 penetrating into both the volume of the device 1 and the connecting line 5, as well as the transmission losses or damping behaviour of the devices 1 with the various insert elements 8a, 8b based on the frequency inside a refrigerant circuit. The total length L.sub.i, of the insert elements 8a, 8b is 65 mm in each case, while the insert elements 8a, 8b are each arranged in such a way that they reach into the chamber 3 of the device 1 with a length L.sub.0 of 15 mm.

[0079] The internal diameter of the insert elements 8a, 8b varies between 11 mm (d), 12 mm (e) and 13 mm (f).

[0080] FIG. 6B clearly shows that the damping behaviour, in particular the high-frequency damping behaviour of the device 1, is improved over a known reflective silencer above a certain frequency. In addition to this, the damping behaviour of the device 1 is in particular improved as the internal diameter of the insert elements 8a, 8b is reduced.

[0081] With the production and arrangement of the insert elements 8a, 8b inside the housing elements 2a, 2b, a desired internal geometry of the device 1 is created which in particular increases the low-frequency pressure pulsation damping effect and, at the same time, reduces the drop in pressure when the fluid flows through the device 1.

[0082] Consequently, the improved pressure pulsation damping effect primarily occurs in operating states with a low mass flow to be transported, and thereby a low compressor load, which should be considered highly critical in the context of pressure pulsations in vehicles.

[0083] As shown in particular by FIGS. 5A and 6A, the first insert elements 8a are each produced with an inlet section. Inside the inlet section, the insert element 8a exhibits an internal diameter that reduces in the flow direction of the fluid and then remains constant from the end of the inlet section, while maintaining a constant external diameter. The wall thickness of the first insert element 8a inside the inlet section is therefore continuously reduced in the direction of the chamber 3.

[0084] The internal diameter of the second insert element (not shown) in the flow direction of the fluid is also constant up to an outlet section and then increases continuously inside the outlet section, meaning that the wall thickness of the second insert element inside the outlet section continuously decreases in the direction away from the chamber 3.

[0085] The internal diameter of each of the insert elements 8a, 8b is minimal in the area of the end open to the chamber 3.

LIST OF REFERENCE NUMBERS

[0086] 1, 1′ Device

[0087] 2, 2′ Housing

[0088] 2a, 2a.′ First housing element

[0089] 2b, 2b′ Second housing element

[0090] 3 Chamber

[0091] 4a Base of the first housing element 3a

[0092] 4b Base of the second housing element 3b

[0093] 5 Connecting line

[0094] 6a, 6a.′ Pass-through opening, inlet opening, fluid flow path

[0095] 6b, 6b′ Pass-through opening, outlet opening, fluid flow path

[0096] 7′ Transition area

[0097] 8a First insert element

[0098] 8b Second insert element

[0099] D.sub.TL Damping behaviour, transmission loss coefficient

[0100] S.sub.1 Cross-sectional area of pass-through openings 6a, 6b, 6a.′, 6b′

[0101] S.sub.1* Reduced cross-sectional area

[0102] S.sub.2 Cross-sectional area with inner volume of chamber 3 in the longitudinal direction x

[0103] L Length of inner volume of chamber 3

[0104] L.sub.i Length of altered cross-section area, length of insert element 8a, 8b

[0105] L.sub.0 Length of insert element 8a, 8b inside chamber 3

[0106] k Wave number

[0107] λ Wavelength

[0108] x Longitudinal direction