manufacturing thereof

FIELD OF THE INVENTION

The invention relates to high pressure and high temperature coolant line of a refrigerant circuit, particularly for carbon dioxide as a coolant. The coolant line is especially suitable for refrigerant circuit of automotive air conditioning systems . The invention relates also to a method for manufacturing a hose for coolant .

BACKGROUND OF THE INVENTION

For many years air conditioning systems for motor vehicles have been operated with chlorofluorocarbon. Recently, because of environmental constraints, carbon dioxide is becoming popular as a coolant. Since carbon dioxide must be used in the liquid state, the coolant is under high pressure. Thus the known resin or elastomer hoses can no longer be applied. There is a need to use rigid, resilient hoses.

From the international application WO2010145725 A1 is known a connection, a connecting part and an hybrid hose, in particular for r744 air conditioning applications. According to the invention a connection of a the first line element composed of a metallic material to at least one second line element composed of a metallic material and/or to an encapsulation for the second line element, in particular for R744 air conditioning hoses or for applications in the field of building services engineering. The connection is characterized in that the first line element and the second line element and/or the first line element and the encapsulation are connected to one another in a connecting region by means of magnetic forming.

The patent document US6354332 B1 discloses coolant line for air conditioning systems . A coolant line for air-conditioning systems that are operated with carbon dioxide as a coolant, particularly air-conditioning systems of motor vehicles, can be tightly connected at both ends to connecting parts . The line has an inside, metallic, corrugated hose that is coolant-tight, a radially pressure-resistant, flexible, metallic jacket that surrounds the hose with radial spacing and provides axial support, and a compression-proof, temperature-resistant intermediate plastic layer that fills the space between at least the radially- outside corrugation crests of the metal hose and the jacket so as to prevent play.

The patent document US7192063 discloses to metallic tubular hose having a rubber or resin hard material layer. According to the invention a metallic tubular hose which suppresses disintegration in which the metallic tubular hose comprises a hose body having a longitudinal edge at one end thereof and a bellows metallic tube inner layer with the inner layer composed of a corrugated bellows portion and a restricted portion, a jacket composed of a plurality of layers surrounding the inner layer. A rigid insert pipe extending into the hose body and a metallic sleeve engaging the hose body along said longitudinal edge for compressing said jacket against said rigid insert pipe wherein said plurality of layers in said jacket includes an inner layer adjacent to said restricted portion of said bellows metallic tube inner layer composed of a flexible and hard material possessing a tensile modulus of between 4 MPa and 8 MPa for a composition of rubber and about 300 MPa for a resin material composition and preferably between 1000 MPa and 6000 Mpa .

The objective of the present invention is to provide a coolant line of a refrigerant circuit for automotive air conditioning systems which will be suitable for coolant under high pressure and high temperature e.g. carbon dioxide.

SUMMARY OF THE INVENTION In accordance with the present invention, there is provided a coolant line of a refrigerant circuit consisting of at least one rigid pipe connected to an end of a flexible hose which comprises : an inner corrugated tube with outer surface coated with an elastomer, a cylindrical fitting at each end of the corrugated tube, an outer composite hose covering the corrugated tube and a major part of each fitting, a socket clamped around each fitting and end of the outer composite hose. The invention characterised in that the fittings are inseparably connected to the corrugated tube by a weld.

Preferably, the fitting contains an extension at the end which is inserted into the end of the corrugated tube and at the second end an enlargement of the inner diameter in which is inserted the rigid pipe. Preferably, the fitting at the outer surface contains three annular lugs, an annular flange and an annular groove.

Preferably, the least three ridges at each end of the corrugated tube are not coated with the elastomer, wherein the marginal ridge is flattened.

Preferably, the fitting is connected to the corrugated tube by a weld between the marginal ridge of the corrugated tube and the annular flange.

Preferably, the outer composite hose consists of three layers made of an elastomer material and a tubular metal mesh situated between layers .

Preferably, the socket is clamped in longitudinal direction around the fitting and end of the outer composite hose.

Preferably, the socket contains three annular lugs and one sharp ended annular lug at its inner surface, and annular tenon at the end of its inner surface, wherein the annular tenon is inserted into annular groove of the fitting. Preferably, the rigid pipe inserted into enlargement is connected with fitting by the weld.

Preferably, the rigid pipe, corrugated tube, fitting and socket are made of metal, favorably steel.

The present disclosure also provides a method of manufacturing a coolant line of a refrigerant circuit comprising the steps of: cutting a composite hose to the desired length, cutting a metal corrugated tube with outer surface coated with an elastomer to the desired length. The invention characterised in that the elastomer coating of the outer surface of the corrugated tube is removing from at least three ridges, an extension of each fitting is inserting into ends of the corrugated tube, the fitting is welding to each end of the corrugated tube, the corrugated tube and the fittings are inserting into an outer composite hose, the socket is clamping around each fitting and end of the outer composite hose rigid pipe is welding to the end of each fitting.

Preferably, the marginal ridge of the corrugated tube is flattening before welding. The sockets are clamping in longitudinal direction.

ADVANTAGES OF THE INVENTION

The coolant line of a refrigerant circuit according to the invention is resistant to high temperature and high pressure. Structure of the flexible hose provides reduction of the propagation of noise coming from refrigerant flow and noise coming from vibrations of vehicle's engine.

BRIEF DESCRIPTION OF DRAWING

The invention is presented in its embodiment in the drawing, where

Fig . 1 is a view of a coolant line of a refrigerant circuit in accordance with the preferred embodiment of the present invention .

Fig. 2 is a cross-sectional view of the coolant line of a refrigerant circuit assembly before clamping s socket.

Fig. 3 is a cross-sectional view of a portion of a corrugated tube .

Fig. 4 is a cross-sectional view of a portion of an outer composite hose.

Fig. 5 is a cross-sectional view of the corrugated tube and the outer composite hose assembly.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

As presented in the embodiment in Fig. 1, the coolant line of a refrigerant circuit consists of two rigid pipes 1 inseparably connected to each end of a flexible hose 2. The rigid pipes 1 are made of steel .

As shown in Fig. 2 the flexible hose 2 comprises the inner corrugated tube 3. The corrugated tube 2 is made of steel . The corrugated tube 2 contains rounded ridges 4. These ridges 4 allow bending the corrugated tube 3. Outer surface of the corrugated tube 3 is coated with the elastomer 5. The coating of the elastomer 5 prevents damages to the corrugated tube 3 due to operational load (pulsation of a refrigerant) and mechanical stress. As shown in Fig 3 the last three ridges 4 at each end of the corrugated tube 3 are not coated with the elastomer 5. Additionally, the marginal ridge 4 at each end of the corrugated tube 3 is flattened.

According to the invention, the cylindrical fitting 6 is inseparably connected to each end of the corrugated tube 3. The fittings 6 serve to connect the flexible hose 2 to the rigid pipes 1. Each fitting 6 contains at an end the extension 7 which is inserted into the end of the corrugated tube 3. At the second end of the fitting 6 is the enlargement 8 of the inner diameter. This enlargement 8 serves to insert the end of the rigid pipe 1.

At the outer surface of the fitting 6 are located three annular lugs 9, annular flange 10 and annular groove 11. The annular flange 10 is located at the end of the fitting 6 containing the extension 7. The annular flange 10 serves to connect fitting 6 to marginal ridge 4 of the corrugated tube 3. They are connected to each other by the weld 12. To connect these elements the TIG method and orbital welding is employed. The flattening of the marginal ridge 4 makes the contact surface between a side of the annular flange 10 and this ridge 4 bigger, and in consequence, the surface of the weld 12 is big. At the second end of the fitting 6 is situated annular groove 11. It has a rectangle shape. Three annular lugs 9 are situated between annular flange 10 and annular groove 11.

In accordance with the invention, the outer composite hose 13 covers the corrugated tube 3 and a major part of each fitting 6. The fitting 6 is covered by the outer composite hose 13 up to the edge of the annular groove 11. As shown in Fig. 4 the outer composite hose 13 consists of three layers 14a, 14b, 15 made of an elastomer material and the tubular metal mesh 16 situated between layers 14a and 14b. Layer 14a constitutes the outer layer of whole outer composite hose 13. Layer 15 constitutes the inner layer of whole outer composite hose 13. Layers 14a and 14b are made of the same material and have the same thickness. Layer 15 is thinner. The outer composite hose 13 thanks to its inner enforcement in the form of tubular metal mesh 16 helps to keep corrugated tube 3 resistant to internal pressure.

As shown in Figs. 1 in accordance with the embodiment of the present invention around each fitting 6 and end of the outer composite hose 13 is clamped the socket 17. They are made of steel. The sockets 17 are clamped in longitudinal direction. As of the invention the socket 17 contains three annular lugs 18 and one sharp ended annular lug 19 and annular tenon 20 at its inner surface. The annular tenon 20 has a rectangle shape. After clamping socket 17 this annular tenon 20 is inserted into annular groove 11 of the fitting 6. The annular tenon 20 and annular groove 11 constitute connection preventing the movement of the socket 16 in longitudinal direction. Also the lugs 18 and 19 serve to keep socket 17 fixedly around the end of the outer composite hose 13. These lugs are situated is such manner to overlap three annular lugs 9. When the socket 17 is clamped the lugs at the composite hose 13 and the fitting 6 bend the outer composite hose 13 and block its move. To additionally increase fixing the flange 19 next to the end of the socket 17 has a sharp end.

In accordance with the embodiment of the present invention to each end of a flexible hose 2 is mounted rigid pipe 1. This rigid pipe 1 is inserted into enlargement 8 in the fitting 6. This rigid pipe 1 is inseparably connected to the end of the fitting 6 by the weld 21.

The invention relates also to the method of manufacturing a coolant line of a refrigerant circuit. In accordance with the invention, the first step of manufacturing the coolant line is cutting the outer composite hose 13 to the desired length. The length tolerance depends on the length of the hose. It varies from +/- 1 mm to +/- 0.5% of total length. The next step is cutting the corrugated tube 3 to the desired length. The cutting is done at the bottom of ridge 4 with total length tolerance +/- 0.8 mm. Next, the elastomer 5 coating of the outer surface of the corrugated tube 3 is removing from last three ridges 4 at each end. Further, the marginal ridges 4 on both ends of the corrugated tube 3 are flattening keeping squareness tolerance 0.05. After completing these actions the extension 7 of each fitting 6 is inserting into ends of the corrugated tube 3. Next, the annular flange 10 of each extension 7 is welding to flattened marginal ridge 4. In the preferred embodiment the elements are welding with the use of TIG method. Moreover the orbital welding is employed. After inseparably coupling corrugated tube 3 with fittings 6 they are assembled with the outer composite hose 13. The corrugated tube 3 with fittings 6 is inserted into the outer composite hose 13. The outer composite hose 13 is positioned to cover each fitting 6 up to the edge of the annular groove 11. In the next step the socket 17 is putted on each fitting 6 and end of the outer composite hose 13. Then these sockets are clamped in longitudinal direction with the use of clamping jaws. In the preferred embodiment the clamping jaws form eight folds. Circularity tolerance is 0.1. After this step the flexible hose 2 is completed.

The final step to manufacture the coolant line of a refrigerant circuit as of the invention is to mount rigid pipe 1 to each end of the flexible hose 2. To do so the rigid pipe 1 is inserted into enlargement 8 in fitting 6. Next, the rigid pipe 1 and the edge of the fitting 6 are welding to each other. In the preferred embodiment the elements are welding with the use of TIG method. Moreover the orbital welding is employed.

Although the invention has been explained in relation to its preferred embodiment as mentioned above, it is to be understood that many other possible modifications and variations can be made without departing from the scope of the present invention. Hence, the indicated embodiment of the invention relating to the coolant line of a refrigerant circuit and method of doing thereof cannot limit the scope of protection which is defined in the claims.