WO2007017103A1

WO2007017103A1 - Refrigerant line

Info

Publication number: WO2007017103A1
Application number: PCT/EP2006/007346
Authority: WO
Inventors: Carlo Burkhardt; Carsten Ilg
Original assignee: Witzenmann Gmbh
Priority date: 2005-08-06
Filing date: 2006-07-26
Publication date: 2007-02-15
Also published as: DE102005037167A1; EP1910726A1

Abstract

The invention relates to a refrigerant line (1) for use in air-conditioning units in motor vehicles, with a corrugated metal tube (5) and an inner liner (8, 18) made from plastic. The inner liner (8, 18) is elastically flexible in the radial direction, is made from PTFE or a PTFE composite material and the wall thickness of the inner liner is in the range of 0.1 to 1.0 mm. Furthermore, the inner liner (8,18) lies in part regions on the radial inner side of the enclosing metal tube (5) and at a radial distance from the radially outer corrugation peaks (6) of the metal tube (5) such that a buffer region (9) is provided between the inner liner (8, 18) and the metal tube (5).

Description

Refrigerant line

The invention relates to a refrigerant line for use in air conditioning in particular of motor vehicles, consisting of a corrugated metal hose and an inner liner made of plastic, wherein the inner liner rests in partial areas on the radially inner side of the surrounding metal hose and radially opposite outer wave crests of the metal tube radially spaced is.

Meanwhile, air conditioners are increasingly being installed in automobiles, and accordingly, the refrigerant pipes required in large numbers are subject to ever-increasing demands. While elastomer lines have mostly been used for refrigerants such as R134 A, permeation-proof climate-control systems must now be used in R744 air-conditioning systems compared to CO ₂ , which requires the use of metallic lines. The essential component of known such metal refrigerant pipes consists of a flexible corrugated metal hose, which causes flow-induced whistling noises due to its corrugation under certain operating conditions, which are not accepted by the customer.

From DE-A 102 41 504 refrigerant pipes of the aforementioned type are known, which in addition to the metal hose still have an inner liner made of plastic, wherein the inner liner engages only slightly in the corrugation of the metal hose to reduce the flow resistance and in this case a nearly cylindric , the inner diameter of the corrugated hose corresponding flow space provides, whereby the whistling sounds described can be avoided.

The inner liner described in said document, which is referred to there as a support tube consists of polyamide, is heated after insertion into the corrugated tube and subjected to internal pressure to apply to the inner wall of the metal tube at least in the region of the radially inner troughs and to conserve the desired shape of the air conditioning line. After cooling, the support hose for the metal corrugated hose forms a skeleton, by means of which an axial stabilization of the corrugated hose is achieved and the corrugation of the corrugated hose is subject only to a slight bending cycle stress. However, the Applicant has set forth on this basis, further requirements for the refrigerant pipe, which are just not or only partially met by the described in DE-A 102 41 504 refrigerant pipe with integrated support hose: First, the refrigerant pipe - in contrast to the subject matter of DE 102 41 504 - be as mobile as possible to fulfill their intended function of recording larger movements; on the other hand, the refrigerant line should have a high pressure pulsation resistance for receiving pressure peaks of any pressure pulsations of the refrigerant so as to improve the life of the line. While you can get the increased pressure pulsation especially on a high wall thickness of the metal hose, a small wall thickness of the metal hose is required for the high mobility of the refrigerant pipe. It is accordingly an object of the present invention to provide a refrigerant pipe of the type mentioned above, which meets both actually contradictory requirements.

This object is achieved in a refrigerant line of the type mentioned above in that the inner liner is elastically yielding in relation to the radial direction in that it consists of PTFE or a PTFE composite material and that the wall thickness of the inner liner in the range between 0.1 to 1, 0 mm. This makes it possible to carry out the metal hose with a small wall thickness in the lower tenth-mm range and thus very flexible and on the other side to absorb the aforementioned pressure peaks through the additional inner liner. For this purpose, a buffer area is provided in each case between the inner liner and the wave crests of the metal hose spaced therefrom so that the inner liner can extend at least partially and for a short time radially outwardly into these buffer areas when the pressure peaks of any pressure pulsations of the refrigerant occur. When an approximate pressure equilibrium is established between the buffer area on the one hand and the interior of the inner liner on the other hand, the inner liner again elastically contracts into its starting position and can thus absorb any further pressure peaks in the same way.

While in the prior art, the existing of metal hoses air conditioning lines only the wall thickness of the metal tubing was increased to achieve the required Druckpulsationsbeständigkeit and while in DE 102 41 504 a dimensionally stable support tube made of polyamide was provided, the existing metal corrugated hose in his Should support stability, Thus, the present invention refrains from making the air conditioning line stiffer in order to be able to absorb higher pressure peaks; instead, it builds up the refrigerant piping 3-ply, ie outer metal tube, inner inner liner and buffer area provided therebetween, the buffer area ensuring that the inner liner evades at pressure peaks in the direction of the wave peaks spaced apart from it and can thus absorb these pressure peaks. This makes it possible to form the extremely thin-walled metal hose supported by the innerliner and, together with the inner liner made of PTFE, to obtain a flexible refrigerant line as a whole.

Advantageously, the wall thickness of the inner liner is in the range between 0.25 mm to 0.6 mm and in particular between 0.4 mm to 0.6 mm, wherein the radial cross section of the inner liner is generally made round, but also formed polygonal can be.

In order not to impair the mobility of the metal hose, it is also important that the modulus of elasticity of the inner liner is less than that of the metal hose and in particular less than one-hundredth of its modulus of elasticity.

The inner liner expediently extends over the entire axial length of the metal tube; but it can also extend only over partial areas, if the required Druckpulsationsfestigkeit allows this. In addition, the innerliner is usually provided with a smooth flow surface so as not to unnecessarily increase the pressure loss; In addition, in certain cases, of course, a structured surface recommend, which must not necessarily have a negative effect on the pressure loss of the flow medium.

The inner liner abuts against the inside of the metal hose in the region of the radially inner wave troughs of the metal hose and expediently engages at least partially positively in the corrugations of the metal hose, wherein the inner liner and the metal hose either at least one terminal connection element or not at Axial direction are fixed to each other.

In order for the innerliner to have the required elastic compliance, it is necessary for it to have a memory function, so that after each of them it only has elastic properties. see area claiming stress case returns to its initial state.

Further features and advantages of the present invention will become apparent from the following description of an embodiment with reference to the drawings; show here

Figure 1 is a refrigerant line in a schematic side view;

Figure 2 shows the axial section through part of a refrigerant pipe according to the invention;

FIG. 3 shows the refrigerant line from FIG. 2 with additional components;

FIG. 4 shows an axial section through part of an alternative refrigerant line according to the invention; and

FIG. 5 shows the refrigerant line from FIG. 4 with additional components.

In Figure 1, a refrigerant pipe 1 is shown, which consists of two rigid connection elements 2, 3 in the form of smooth-walled tubes and arranged between the two pipes flexible conduit element 4. This flexible conduit element is explained in more detail in Figures 2 to 5, there by the here used main components are shown:

FIG. 2 shows a metal tube 5 with an annular corrugation, which has radially outer wave peaks 6 and radially inner wave troughs 7. At the radially inner wave troughs 7 is a cylindrical inner liner 8 over a substantial portion of the metal tube 5, wherein between the metal tube 5, in particular in the region of its wave peaks 6 and the inner liner 8 in the mutual Beabstan- ding area buffer areas 9 are left, the annular around the inner liner circulate.

If the inner space 10 of the inner liner 8, which is acted upon by the refrigerant, is exposed to high pressure loads, which often occur in a pulsed manner, the inner liner 8 can be prevented due to its PTFE material and its thin wall thickness. Preferably dodge between 0.4 and 0.6 mm radially outward in these buffer areas 9 and so intercept these pressure peaks and keep away from the wave crests. If, after some time, a pressure equilibrium is established between the buffer regions 9 and the flow interior 10, the inner liner can again move elastically back into its initial state.

FIG. 3 shows a possible use of the main components from FIG. 2, namely by providing a silicone casing 11 on the radial outside of the metal hose 6, which is preferably incompressible and thus protects the metal hose 6 against further deformations. On the radial outer side of the silicone sheath 1 1, a conventional braid 12 of intersecting metal wires for axial support of the metal tube or the elastic element 4 of the refrigerant line 1 is finally provided. For this purpose, the braided hose 12 is fixed to the two axial terminal connection elements 2a, 3a.

FIG. 4 now shows a construction which essentially corresponds to the variant from FIGS. 2 and 3 (for which reason identical parts are provided with the same reference numerals), whereby only one inner liner 18 is provided which, in contrast to the inner liner 8 from FIGS. 2 and 3 - Is not executed exactly smooth cylindrical, but slightly wavy. Here, the inner liner 18 extends in itself with the wave crests 6 of the

Metal hose 5 overlapping areas slightly radially outwardly into the buffer areas 9 and slightly reduces these buffer areas. Due to the corrugated shape of the inner liner 18, this is connected in a form-fitting manner to the metal hose 5 and is thus prevented from shifting in the axial direction relative to the metal hose 5.

FIG. 5 shows - in accordance with FIG. 3 - a silicone sheath 11 and a braided hose 12, also in the second embodiment according to FIG. 4 with corrugated inner liner 18.

In summary, the present invention enables two contradictory requirements, namely mobility on the one hand, and stability or compressive strength, on the other hand, to be met by the new refrigerant line by adding an additional element to the corrugated metal hoses, namely a PTFE innerliner on the one hand does not affect the mobility of the metal tube and on the other hand but intercepts the pressure peaks of the flow medium.

Claims

claims

1 . Refrigerant line for use in air conditioning systems, in particular of motor vehicles, with a corrugated metal hose (5) and an inner liner (8, 18) made of plastic, wherein the inner liner (8, 18) rests in partial areas on the radially inner side of the surrounding metal hose (5) and is radially spaced relative to radially outer lying wave crests (6) of the metal tube, characterized in that the inner liner (8, 18) is elastically yielding in relation to the radial direction in that it consists of PTFE or a PTFE composite material and that the wall thickness of the inner liner is in the range between 0, 1 to 1, 0 mm.

2. Refrigerant pipe according to at least claim 1, characterized in that the wall thickness of the inner liner (8, 18) in the range between 0.25 to 0.6 mm and in particular between 0.4 to 0.6 mm.

3. Refrigerant pipe according to at least one of the preceding claims, characterized in that between inner liner (8, 18) and spaced from him Wellenberg gene (6) of the metal hose (5) buffer areas (9) for the pressure peaks at any pressure of the refrigerant is provided radially outwardly expanding inner liner.

4. refrigerant line according to at least claim 3, characterized in that the inner liner (8, 18) at pressure peaks of any pressure pulsations of the refrigerant at least partially and for a short time in the buffer areas (9).

5. Refrigerant pipe according to at least one of the preceding claims, characterized in that the radial cross section of the inner liner (8, 18) is round or polygonal.

6. Refrigerant pipe according to at least one of the preceding claims, characterized in that the modulus of elasticity of the inner liner (8, 18) is less than that of the metal hose (5), in particular less than 1/100 thereof.

7. Refrigerant pipe according to at least one of the preceding claims, characterized in that the inner liner extends over the entire axial length of the metal tube.

8. Refrigerant pipe according to at least one of the preceding claims, characterized in that the inner liner (8, 18) has a smooth surface.

9. Refrigerant pipe according to at least one of the preceding claims, characterized in that the inner liner (8, 18) on the inside of the metal hose (5) in the region of the radially inner troughs (7) of the metal hose rests.

10. Refrigerant pipe according to at least one of the preceding claims, characterized in that the inner liner (8, 18) engages at least partially positively in the corrugation of the metal hose (5).

1 1. Refrigerant pipe according to at least one of the preceding claims, characterized in that the inner liner and the metal hose are fixed at least at one axial end to terminal connection elements.

12. Refrigerant pipe according to at least one of the preceding claims 1 to 10, characterized in that the inner liner (8, 18) and the metal hose (5) abut each other in the radial direction and / or are not fixed to each other.

3. Refrigerant pipe according to at least one of the preceding claims, characterized in that the inner liner (8, 18) has a memory function.