EP2598351A1

EP2598351A1 - Device for attenuating the intensity of acoustical noise, and air-conditioning circuit including such a device

Info

Publication number: EP2598351A1
Application number: EP11752581.6A
Authority: EP
Inventors: Philippe Sene
Original assignee: Maflow France Automotive
Current assignee: Maflow France Automotive
Priority date: 2010-07-29
Filing date: 2011-07-27
Publication date: 2013-06-05
Also published as: FR2963280A1; FR2963280B1; WO2012013874A1

Abstract

The invention relates to a device for attenuating the intensity of acoustical noise in an air-conditioning circuit of a motor vehicle, and to a circuit including such a device. The circuit includes at least one flexible pipe (12), and the device includes an insert capable of being implanted inside the flexible pipe. The insert (15) consists of a flexible tube (15), which includes a bore (18) having a predetermined length for circulating the main flow of the unsettled fluid, which is capable of being implanted inside the flexible pipe and of being attached, on one side thereof, onto a flange (19) for connecting a rigid pipe (13) of the circuit to the flexible pipe (12), and which is freely inserted into said flexible pipe (12) on the other side thereof. The insert (15) is perforated with at least one set (21) of at least three holes (22) circularly distributed at a distance (d) from the stationary end of the flexible tube.

Description

DEVICE FOR ATTENUATING THE INTENSITY OF AN ACOUSTIC DISTURBANCE AND CONDITIONING CIRCUIT

The present invention relates to a device for attenuating the intensity of an acoustic disturbance in a motor vehicle air conditioning circuit.

It also relates to an air conditioning circuit comprising such a device.

It finds a particularly important, though not exclusive, application in the field of noise-limiting devices generated by an on-line device such as a compressor in the air-conditioning circuit of a motor vehicle.

It is known that the compressor of an air conditioning circuit generates noises and vibrations that can become troublesome for the occupants of the passenger compartment of the vehicle. Such noises must imperatively be removed in accordance with the manufacturers' specifications, which defines acceptable limits for them.

Systems are already known for filtering acoustic disturbances in the air conditioning circuits. These are essentially capacities placed in series on circuits to be soundproofed.

These capacities are usually composed of an aluminum receptacle with a diameter of about 50mm and a length of between 50mm and 80mm. Such devices are therefore particularly bulky. In addition, it requires cutting the pipework on a rigid portion of the pipe and imposes a brazed connection and waterproof which weakens the mechanical strength of the whole.

Noise attenuator devices formed by an insert using the Quincke principle in a rigid part of the pipework are also known. Such rigid devices allow excellent attenuation of a wave determined by addition with a wave in phase opposition, but they can not structurally treat all frequencies, and they create more significant pressure drops.

The present invention is based on a different idea making it possible to avoid the drawbacks of manufacturing costs and of large dimensions of the capacities of the prior art and / or known rigid inserts. It uses a montage that does not require the addition of a capacity and / or a complex insert by proposing a device, which is integrated in a simple and invisible way inside the pipe, at a location where there is already a connection, and this by inserting the device in a flexible pipe portion of the air conditioning circuit of the automobile.

Surprisingly, the damping or intensity attenuation results with the device of the invention are remarkable, much better than with the capabilities and / or insert of the prior art. The device is compatible with the dimensions of an air conditioning piping and generates acceptable pressure drops, lower than those of existing devices.

The present invention therefore aims to provide a device and a circuit that responds better than those previously known to the requirements of the practice, in particular in that it allows an optimized in-line filtration of noise for a reduced cost, all without additional bulk, with greater ease of manufacture and assembly, without weakening the circuit and with better results than those of the prior art.

For this purpose, the present invention proposes a device for attenuating the intensity of an acoustic disturbance in a motor vehicle air conditioning circuit, comprising at least one flexible hose, the device comprising an insert capable of being implanted in a motor vehicle. part of the circuit, characterized in that the insert is formed of a flexible tube comprising a flow bore of the main flow of the disturbed fluid of a given length 1 adapted to be implanted in the flexible pipe and to be fixed by a side on a connecting flange between a rigid pipe of the circuit and the flexible pipe and inserted freely on the other side into said flexible pipe,

said insert being pierced with at least one set of at least three holes distributed circumferentially at a distance d from the fixed end of the flexible tube.

In advantageous embodiments, one and / or the other of the following provisions is also used:

the distance d is between 1/2 and 3/4 of the length 1_;

- d = 1/2 1;

the set comprises four holes regularly distributed on the circumference of the tube; the flexible tube is grooved externally and internally;

the tube is smooth externally and internally;

the tube is alternately smooth and grooved externally and internally;

the device comprises fastening means comprising an aluminum sleeve adapted to be fixed on one side to the connection flange and fixed on the other side to the flexible tube, said sleeve being obtained by forming a fir tail.

The invention also provides a circuit comprising a device as described above.

It also proposes a motor vehicle air conditioning circuit by circulating a gas or a two-phase air / liquid mixture in a given direction, comprising a portion of piping comprising a device for attenuating the intensity of the acoustic disturbances in the circuit, characterized in that the device comprises an insert fixed on one side to a connection flange between a rigid pipe and a flexible pipe of a determined length L belonging to said pipe portion, and inserted freely from the other side in said flexible pipe, said insert being formed of a flexible tube comprising a bore for circulating the disturbed fluid of the pipe to the flange of length 1 such that 1 / 2L <_1 <3 / 4L, pierced with at least one set of at least three holes distributed circularly at a distance d from the fixed end of the flexible tube. Advantageously, _1 is equal to or substantially equal to 2 / 3L.

Also advantageously, the distance d between 1/2 and 3/4 of the length 1..

In an advantageous embodiment d = 1/2 1.

Advantageously, the game comprises four holes distributed regularly over the circumference of the tube, the holes being of diameter between 1mm and 3mm.

Advantageously, the flexible tube is grooved externally.

In an advantageous embodiment, the number of flutes is between 50 and 100, for example 70.

Also advantageously the ratio of the sections between the internal diameter of the flexible tube and the internal diameter of the flexible hose is between 30% and 90% and in particular 80%.

The present invention will be better understood on reading the following description of embodiments given below by way of non-limiting examples. The description refers to the accompanying drawings in which:

Figure 1 is a perspective view of a conditioned air circuit portion with capacity, according to the prior art.

Figure 2 is a perspective view of a similar circuit portion with device according to the invention.

FIG. 3 shows in developed section a first embodiment of a device according to the invention, inside a flexible air conditioning circuit hose for vehicle air conditioning. Figure 3A is detail IIIA of Figure 3.

Figures 4 and 5 show in exploded perspective two embodiments of the fixing means of the device of Figure 3, inside the flexible pipe.

Figure 6 shows a second embodiment of the invention with fluted tube.

FIG. 6A is a sectional view of the end of the tube of FIG. 6.

Figure 7 shows in exploded perspective an embodiment of the fixing means of the splined tube of Figure 6 inside the flexible pipe.

Figures 8 and 9 show another embodiment of a corrugated tube according to the invention, respectively in front view and in section along IX IX.

FIG. 10 gives the attenuation curves obtained with the device of FIG. 8, without attenuator device, and with a more conventional attenuator of the prior art.

FIG. 1 shows a portion 1 of automobile air conditioning circuit provided according to the prior art with a device 2 formed by a cylindrical capacitance and disposed on a rigid portion 3 of the pipework. The pipework allows the circulation of a refrigerant gas or a biphasic gas / liquid mixture in the direction of arrow 4. The rest of the circuit (compressor, etc.) is not shown.

The portion 1 of the circuit comprises a flexible pipe 5 disposed between two rigid portions 6, 7 of the circuit piping. More specifically, the flexible pipe 5 is fixed to the rigid portions 6 and 7 in a manner known per se, by way of connection 8, 9 sealed between rigid metal tubes and the end of flexible pipe, for example by crimping a sleeve-shaped crimping element on the end of the flexible pipe itself inserted on the tubular end of the rigid pipe.

FIG. 2 shows a noise attenuator device 10 according to a first embodiment of the invention, the device is inserted in the conditioning circuit represented partially at 11, comprising a flexible hose 12 between two rigid tube portions 13 and 14 fixed. in a manner known per se, as described above with respect to FIG.

The device 10 comprises an insert shown in broken lines 15, implanted in the flexible hose 12, which will partly adopt the curvature of the flexible hose 12.

It is initially in the axis of the rigid tube 13 and then just pressed by its end 16, on the inside 17 of the flexible hose 12.

FIG. 3 shows, in section and in developed view, the flexible hose 12 of FIG. 2 and its flexible tube-shaped insert 15.

In the remainder of the description, the same reference numbers will be used to designate similar or identical elements.

The flexible tube 15 comprises a bore 18 for circulating the main flow in the direction of the arrow S, from one evaporator to the compressor.

More precisely and according to the invention, it has a determined length _1 and is fixed on one side to the connection flange 19 between the rigid pipe 13 and the flexible pipe 12, and is free on the other side 20. The flexible tube 15, behaves as a beam embedded on the side of the rigid pipe.

More precisely and according to one embodiment of the invention, the insert formed by the flexible tube 15 is pierced with a set 21 of four holes 22 distributed circularly and at a distance d from the fixed end of the tube.

In this particular embodiment, the holes are at 90 ° and have, for example, a diameter of 1.7 mm. The distance d is equal to 1/2 1 which can for example and when to be equal to 8cm.

The connector 19 is located on the compressor side, the connector 23, on the other end between the rigid pipe 14 and the flexible pipe 12 is on the contrary located on the evaporator side.

Also in this embodiment, the free length of the hose being L, the length 1 is chosen equal to 2/3 of L.

The tube is made of a chemically neutral material, for example a material known under the trade mark TEFLON, but can also be made for example by molding, in other materials such as polypropylene.

The specific characteristics of the type described above make it possible curiously to obtain a particularly strong attenuation, and this for reasons that are not explained.

Insofar as the pressurized fluid arrives from the opposite side to its recess (evaporator to compressor), it will naturally pass through the bore 18, accelerating due to the slight shrinkage. The cul de sac existing between the inner wall of the flexible pipe and the outer wall of the pipe flexible should therefore have no influence. In fact, the behavior of the gas in this cul de sac is itself disturbed by the flows from the holes 22, which is probably the cause of this incomprehensible attenuation effect.

FIGS. 4 and 5 show two embodiments of the attachment of the flexible tube 15 of FIG. 3 at the connection 19.

A first embodiment consists in providing crimping of an element of crimping 24 of the known sleeve type itself, one end of which is clamped between two lips 26 of rigid pipe 13.

The rigid pipe 13 further comprises a pipe end 27 comprising, for example, splines 28 to promote the fixing by the friction by fitting of the end 29 of the flexible hose 12 made of elastomer resistant to refrigerating fluids.

The flexible tube is inserted into the end 27 of the tube 13 via a portion 31.

It engages with friction over a distance e in the bore 32 of said end or tip 27, itself abutting on a ring 33 of the tube 15.

The portion 31 is further deformed by inserting into the forming of the tip, the fixing being finalized by the crimping of the element 24, in a manner known per se.

FIG. 5 shows another embodiment of the means for fastening the flexible tube to the end 27 of the tube 13. Here the tube is housed in an insert or sleeve 34, for example made of aluminum itself inserted in the bore 32 of the end 27. The holding of the insert is for example through a forming said tail fir.

More precisely, the insert 34 is in the form of a cylindrical sleeve and comprises a first cylindrical part of larger internal diameter, into which the end of the flexible tube is inserted by friction and up to an annular stop, the first portion being connected to a second portion of smaller diameter, corresponding to the internal diameter of the flexible tube and outer diameter corresponding to the internal diameter of the tip 27 of the tube 13.

The assembly is then crimped as indicated above for FIG. 4.

There is shown in the following figures 6 to 9 embodiments of device comprising a fluted flexible tube.

FIG. 6 shows a first cylindrical flexible tube 40 which has on its side 41 an end part fitting into the end 45 of the tube 13 (see FIG. 7) and in the rest of the annular parts formed by successions of cylinders or repetitive grooves, not determined, showing differences between external diameters of the grooves (dl, d2 and d3) and corresponding roll heights el, e2, e3.

The corrugated or corrugated flexible tube is for example polypropylene, the pitch and the number of grooves may be regular or variable as just indicated.

FIG. 6A shows in FIG. 6A the free end 42 of the simple tube 40 with grooves of different thicknesses and external diameters (dl, d2, d3), for example between 1 and 3 mm difference.

FIG. 7 shows a method of fixing the corrugated flexible tube 40, of the type of that described with reference to FIG. 4.

The annular ring 44 allows blocking in abutment on the end 45 of the tube 13, the tip 46 of the corrugated tube 40 penetrating into the bore 32 of the rigid tube. Holes 47 are also present according to the invention, for example 4 holes at 90 ° at mid-length.

FIGS. 8 and 9 show, in side view and in section IX-IX, another embodiment of a splined tube 50 of the device according to the invention.

The tube 50 here comprises a fixing end having an elongate portion 51 adapted to be inserted into the bore of the tube 13, provided with 1 to 3 annular protuberances 52 adapted to allow good frictional fixing inside the end 45 of the tube 13, and a locking ring 53 on the end 45 of the tube once the flexible tube 50 has been inserted therein.

The flexible tube 50 is for the remainder consists of a succession of splines 54 of thickness eo, the tubes being also provided, according to this embodiment of the invention, holes 55 distributed circularly at 90 ° for example of diameter 1 , 7 mm for an internal diameter of 2.8 mm, and an outer diameter of the entire flexible tube 12.8 mm.

The length of the end 51 is for example 28 mm and an outer diameter equal to the internal diameter of the bore 32 of the end 45 of the tube 13, by example of 12.5mm. The corrugated tube comprises, for example, 25 to 100 splines for example 70 splines and ends on the other side with a free end portion 56 in the form of a smooth cylinder a few millimeters in height, for example between 1 / 10 and 1/2 of the height of the portion 51.

FIG. 10 shows four curves showing the acoustic pressure observed in Pa / Pa as a function of the noise frequencies generated by the compressor in Hz.

Curve 60 represents the specification of automobile manufacturers, also referred to as "customer template". This is the goal to achieve in terms of attenuation and frequency.

Curve 61 gives the results obtained with a pipe without damper. These results are measured with a white noise measurement device characterized according to the method of the French car manufacturers, meeting the requirements of the specifications.

The curve 62 corresponds to the results obtained with a more conventional damper, here a sophisticated rigid insert. It is found that the damping between 0.2 and 1.0 KH _Z (audible frequencies) is better, but that it nonetheless has significant peaks around 0.3KH _Z and above 0.7KH _Z.

The curve 63 is that obtained with a damping device according to the invention, much more satisfactory and which is very close to the client template.

We will now describe the operation of the noise attenuator device according to the invention. The fluid, for example a refrigeration fluid of the type known under the reference Rl34a for motor vehicle circuit, is compressed by a noise generating compressor and circulates in the circuit generating noise at frequencies and frequency ranges determined depending on the configuration of the circuit and the speed of circulation.

In order to limit the noise of the acoustic disturbance, a flexible tube according to the invention is inserted into the tube at the level of the flexible pipe so that the free edge is attacked by the circulating fluid, on the opposite side to the recess. flexible tube on one end of the rigid pipe.

Due to the dimensional arrangements of the flexible tube, the holes drilled in the middle of this flexible tube and the compression / decompression phenomena which do not fail to occur at the level of the attenuator device, a surprising attenuation is then observed with a strong attenuation of the noise generated in the pipes.

As is obvious and as also follows from the above, the present invention is not limited to the embodiments more particularly described. On the contrary, it embraces all the variants and in particular those in which additional holes are provided and / or the grooves are different.

Claims

Device (10) for attenuating the intensity of an acoustic disturbance in a motor vehicle air conditioning circuit (11), comprising at least one flexible hose (12), the device comprising an insert adapted to be implanted in a part of the circuit, characterized in that the insert (15, 40, 50) is formed of a flexible tube (15, 40, 50) comprising a bore (18) for circulating the main flow of the disturbed fluid of a specific length 1. adapted to be implanted in the flexible pipe and to be fixed on one side to a flange (19) for connection between a rigid pipe (13) of the circuit and the flexible pipe (12) and inserted freely from the pipe; other side in said flexible pipe (12),

said insert (15, 40, 50) being pierced with at least one set (21) of at least three holes (22, 47, 55) distributed circumferentially at a distance d from the fixed end of the flexible tube.

2. Attenuator device according to claim

1, characterized in that the distance d is between 1/2 and 3/4 of the length 1.

3. Attenuator device according to claim

2, characterized in that d = 1/2 _1.

4. Device according to any one of the preceding claims, characterized in that the play (21) comprises four holes (22, 47, 55) regularly distributed on the circumference of the tube.

5. Device according to any one of the preceding claims, characterized in that the flexible tube (40, 50) is grooved externally.

6. Device according to any one of claims 1 to 4, characterized in that the tube (15) is smooth externally.

7. Device according to any one of the preceding claims, characterized in that it comprises fastening means comprising a sleeve (34) of aluminum adapted to be fixed on one side to the connection flange (19) and fixed to the other side on the flexible tube, said sleeve (34) being obtained by forming.

8. Motor vehicle air conditioning circuit by circulating a gas or a biphasic air / liquid mixture in a determined direction S, comprising a portion (11) of piping comprising a device (10) attenuator of the intensity of the acoustic disturbances in the circuit, characterized in that the device comprises an insert (15, 40, 50) fixed on one side to a connection flange between a rigid pipe (13) and a flexible pipe (12). a length L determined belonging to said pipe portion, and inserted freely on the other side into said flexible pipe, said insert being formed of a flexible tube (15,40,50) comprising a bore (18) for circulating the fluid disturbed from the pipe to the flange of length 1. such that 1 / 2L <1 <3 / 4L, pierced with at least one set (21) of at least three holes (22, 47, 55) distributed circularly at a distance distance d from the fixed end of the flexible tube.

9. Circuit according to claim 8, characterized in that 1 is equal to or substantially equal to 2 / 3L.

10. Circuit according to any one of claims 8 and 9, characterized in that the distance d is between 1/2 and 3/4 of the length 1.

11. Circuit according to claim 10, characterized in that d = 1/2 _1.

12. Circuit according to any one of claims 8 to 11, characterized in that the set comprises four holes (22, 47, 55) regularly distributed on the circumference of the tube, the holes being of diameter between 1mm and 3mm.

13. Device according to any one of claims 8 to 12, characterized in that the flexible tube (40, 50) is grooved externally.

14. Circuit according to any one of claims 8 to 13, characterized in that the ratio of the sections between the internal diameter of the flexible tube and internal diameter of the flexible pipe is between 30% and 90%.

15. Circuit according to claim 14, characterized in that the ratio is of the order of 80%.