Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
  • F16L55/00—Devices or appurtenances for use in, or in connection with, pipes or pipe systems
  • F16L55/02—Energy absorbers; Noise absorbers
  • F16L55/027—Throttle passages
  • F16L55/02772—Throttle passages using spirally or helically shaped channels

Definitions

• the present invention relates to a device for attenuating the intensity of at least one wave generating an acoustic disturbance in a fluid circuit. It also relates to an air conditioning circuit comprising such a device. It finds a particularly important although not exclusive application in the field of devices limiting the noise generated by an on-line device such as a compressor in air conditioning circuits and / or power steering systems of a motor vehicle. Systems are already known for filtering acoustic disturbances in fluid circuits such as automobile air conditioning circuits. These are essentially capacities placed in series on the circuits to be soundproofed.
• the waves to be filtered arriving suddenly in a larger volume formed by the capacity there is creation of a wave in opposition of phase which by being added to the disturbing wave, generates a resulting wave of weaker amplitude, this which results in noise attenuation.
• Such devices have drawbacks due to their manufacturing cost and the large size they generate.
• the present invention starts from a different idea and uses the drift principle to do this.
• Angioedema The principle adopted this time is to divide the fluid into several parts and to make it travel different distances to obtain a phase shift of the waves with respect to each other and thereby create waves of lower amplitude by addition.
• the derivative flow is made to travel a distance different from that traversed by the main flow carrying the disturbing wave in the main section of the piping. If we know this Quincke drift principle to prevent a rigid tube from coming into resonance
• the present invention aims to provide a device which meets the requirements of practice better than those previously known, in particular in that it allows optimized online filtration of noise at a lower cost, all with less bulk and more great ease of manufacture and assembly.
• the present invention proposes in particular a device for attenuating the intensity of at least one frequency wave of between around 50 Hz and around 2000 Hz and more particularly between 200 Hz and 800 Hz, generating an acoustic disturbance in a circuit of fluid in compression, characterized in that the device comprises an insert suitable for being installed in a piping of the circuit, said insert comprising a tube pierced right through a bore for circulation of the main flow fluid disturbed by said wave, and at least one helical ramp for guiding a secondary spiral flow, the pitch of said ramp being arranged to generate a wave in opposition or substantially in phase opposition with the wave generating the disturbance, and in that the device is arranged to meet the following sections of reports: 0.6A 0 ⁇ A 2 ⁇ 1.4A 0 and 'A x> A 2, with A 0 : section of the bore i: difference in section between the internal section of the piping and the external section of the tube pierced with the bore A 2 : substantially rectangular section defined by the generatrices of
• the tube pierced with the bore comprises at least one connection orifice between the interior of the bore and the external volume delimited by the helical ramp.
• this or these orifices in fact further improve the attenuation, without annoyingly increasing the pressure drops;
• the section of the orifice is substantially equal to the section of the bore;
• the section of the orifice is substantially equal to the section of the piping.
• the attenuating device comprises two helical ramps for guiding secondary flows of different, or identical, pitch; the attenuating device comprises three helical ramps for guiding secondary flows of different, or identical, pitch;
• the tube is formed by a rigid central or substantially central duct, the helical ramp or ramps for guiding the secondary flows being wound around the peripheral surface of said central duct;
• the helical ramps open out at different locations inside the tube;
• the helical ramps open out substantially at the same location inside the tube;
• the bore is of diameter between 7 mm and 10 mm and the length of the insert is between 50 mm and 140 mm;
• the pitch of the helical ramps is between 5 mm and 15 mm.
• FIG. 1 is an exploded perspective view showing a first embodiment of a device according to the invention.
• Figure 2 is an exploded perspective view of another embodiment of Figure 1 with an orifice.
• FIG. 3 is a curve showing the attenuation obtained with the device in FIG. 1 at a disturbance frequency of 700 Hz as a function of a cross sectional area of the fluid passage.
• Figures 4 and 5 show respectively in lateral perspective and in front perspective of three quarters, another embodiment of the insert according to the invention.
• Figures 6 and 7 show in lateral perspective and in front perspective of three quarters, yet another embodiment of insert according to the invention.
• Figure 8 shows in exploded perspective, another embodiment of a device according to the invention inside a pipe.
• FIG. 9 shows three attenuation curves for acoustic disturbances as a function of frequencies on the one hand with a device according to an embodiment of the invention, and on the other hand with two damping devices of the prior art.
• Figure 1 shows a noise attenuator device 1 inserted in a fluid circulation pipe 2 (arrow 3), for example refrigerant belonging to an automobile air conditioning circuit (not shown).
• the device comprises an insert 4 inscribed in a cylinder whose overall diameter is substantially equal to the internal diameter of the pipe 2 in which the insert is introduced with friction, and blocked for example by external clamping and / or by bonding or by any other means within the reach of the skilled person.
• the insert 4 comprises a central tube 5 pierced right through by the bore 6 and provided on its peripheral surface 7 with a helical ramp 8 of pitch p.
• the insert is for example obtained by plastic injection using a mold.
• the fluid which enters the inlet of the insert 4 is divided into two flows, namely a first flow 9 which passes directly and in a straight line through the bore 6 and which traverses a distance X and a second flow 10 which follows a helical course derived along the ramp 8 in the form of a propeller, over a length L.
• Figure 2 shows a device of the type of that described with reference to Figure 1, including the tube interior 5 is provided with an orifice 0 for example, in the embodiment more particularly described here, of dimensions substantially equal to those of section A 0 of the bore, for example of length equal to that of the pitch of the helix and width adapted accordingly, which gives it a rectangular or substantially rectangular shape.
• This orifice will allow a remixing of the first and second streams 9 and 10 which pass inside and outside the bore by improving the attenuation and this without generating too great a pressure drop.
• sections Ao, Ai and A 2 as defined above.
• Ai is for example greater than 1.2 A 2 , for example greater than 1.5 or 2 A 2 .
• a 2 is for example greater than 0.8 Ao, for example between 1 and 1.3 A o .
• Figures 4 and 5 show another embodiment of an insert 11 according to the invention provided with a central tube 12 and two helical ramps of different pitches 13 and 14, said ramps opening at different locations 15 and 16 on the length of the piping.
• a central tube 12 and two helical ramps of different pitches 13 and 14, said ramps opening at different locations 15 and 16 on the length of the piping.
• the main characteristics of an insert for piping with a diameter of 18 mm for an automobile air conditioning circuit have been given below.
• Tube diameter 18 mm
• Inner diameter of the spiral 8 mm (can vary between around 7 mm and around 10 mm)
• Ratio of the section of the drift from the main section ⁇ 40% (can vary between 30% and 100%).
• FIG. 6 and 7 show a third embodiment of an insert 16 according to the invention allowing this time to filter more particularly three determined or substantially determined acoustic frequencies by implementing three helical ramps 17, 18, 19 of pitch different and integral with the periphery of the central tube 20 for passage of the main flow over lengths L1, L2, L3 opening out at different locations.
• FIG. 8 shows a fourth embodiment of an insert 21 in a pipe 22 provided with two helical ramps 23 and 24 opening out at the same locations 25 inside the tube.
• the fluid for example a refrigeration fluid of the type known under the reference R134a for air conditioning circuit of a motor vehicle, is compressed by a noise generating compressor and circulates in the circuit generating noise at frequencies or over frequency ranges determined based on circuit configuration and traffic speeds.
• the fluid is divided into several parts or flow so as to cause the fluid flows to travel different distances which will, when leaving the insert, be out of phase with one another. Due to these phase shifts calculated to get as close as possible to the phase opposition, we obtain a resulting wave of amplitude as low as possible, which makes it possible to attenuate, or even suppress surprisingly, the noise generated. in the pipes.
• the curve 26 corresponds to the damper according to the invention more particularly described here, to a propeller and two regularly arranged holes, of the type described with reference to Figures 1 or 2, the curves 27 and 28 corresponding to conventional dampers with capacity prior art.
• the propeller damper allows in particular better results in the field of audible frequencies, that is to say between 0.2 and 1.0 KHz.
• the present invention is not limited to the embodiments more particularly described. On the contrary, it embraces all the variants thereof and in particular those in which it comprises four or more helical ramps and / or at least two orifices extend over the entire pitch, and / or the orifices are distributed not regularly over the tube.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Air-Conditioning For Vehicles (AREA)
• Soundproofing, Sound Blocking, And Sound Damping (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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Family Cites Families (5)

• 2003
  • 2003-10-10 FR FR0311871A patent/FR2860854B1/fr not_active Expired - Fee Related
• 2004
  • 2004-10-11 WO PCT/FR2004/002575 patent/WO2005035949A1/fr not_active Ceased
  • 2004-10-11 EP EP04817158A patent/EP1671015A1/de not_active Withdrawn

Non-Patent Citations (1)

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