FIELD OF THE INVENTION

The present invention relates to a heat exchange fluid line arrangement and a heat exchanger that employs a heat exchange fluid line arrangement and has been developed principally for use in the field of automotive air conditioning, for use in cars and trucks. However, the invention could have use in other areas where improved heat exchange performance is desirable, such as in commercial refrigeration systems.

BACKGROUND OF THE INVENTION

In automotive air conditioning, a capillary line or tube is employed for flow of liquid refrigerant while a suction line or tube is employed for flow of gas refrigerant. Invariably, the respective lines follow a convoluted path about the vehicle in order to extend about various other equipment, i.e. the engine, wheel arches etc. The lines are thus shaped or bent to the appropriate shape for the particular path which is required. The respective lines often follow a similar path, although at least at opposite ends of the lines, they are usually spaced apart. The heat exchange which occurs in an automotive air conditioning system normally occurs just at the heat exchangers which are connected at either end of the fluid lines. However, where this heat exchange can be assisted by heat exchange elsewhere in the system, efficiency gains can be made. European patent application 85108234.7, published under publication number 0 167 978, discloses an arrangement for connecting a suction tube and a capillary tube together. The suction tube is extruded with an integral groove into which the capillary tube is inserted and captured. The suction tube and the integral groove can be deformed to capture the capillary tube, or the capture can be by deformation of the integral groove only.

The disclosure of EP 0 167 978 is said to facilitate heat exchange between the suction tube and a capillary tube. However, a particular disadvantage with the arrangement of EP 0 167 978 is that it does not facilitate bending of the suction tube to route the tube about a convoluted path, because bending causes distortion of the groove. As indicated above, shaping or bending of the suction and capillary tubes is almost always required in automotive applications, in which the tubes must be routed about various equipment which is accommodated in an engine bay. Because of this, in EP 0 167 978, the teaching is to fit a short section of a suction tube with an integral groove to a major section of suction tube without an integral groove and to shape or bend only that section of tube that is formed without the groove. Thus, the arrangement of EP O 167 978 requires a section of a suction tube with the integral groove to be fitted to and soldered or brazed to a section of suction tube without an integral groove. In addition, the suction tube section which includes the integral groove must be a section which extends straight or linearly. The arrangement of EP 0 167 978 therefore is complex, thus adding cost to the tube arrangement, and is not particularly easy to adopt. The present applicant has recognised that a benefit can be provided by facilitating heat exchange between two lines or tubes of a heat exchange fluid line arrangement. However, the present applicant has also recognised the drawbacks associated with the arrangement of EP 0 167 978. SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a heat exchange fluid line arrangement, the arrangement including a suction or gas line and a liquid line, each of the gas and liquid lines having a generally circular outer surface and being connected by a connector which in a connected condition, connects to the outer surface of each of the gas and liquid lines, the connector being operable to facilitate a heat exchange between the gas and liquid lines, so that heat from the liquid line can be transferred to the gas line.

The connector provides for heat exchange between the gas and liquid lines by permitting conduction between the lines. Because the connector is not formed integrally as part of the gas and liquid lines, the lines can be shaped or bent to the required shape and thereafter joined or connected by the connector. The connector is of a material which is operable to facilitate a heat exchange between the gas and liquid lines, so that for example, heat from the liquid line can be transferred to the gas line.

In some forms of the invention, the connector has a pair of curved surfaces in facing connection with the respective gas and liquid lines, in which the curved surfaces are curved substantially complementary to the curve of the respective outer surfaces of the gas and liquid lines. This permits substantially flush connection of the connector to the outer surface of each of the gas and liquid lines. The pair of curved surfaces can have any relative orientation, although in some forms of the invention, the curved surfaces face in opposite directions.

The curved surfaces can have the same radius of curvature or a different radius of curvature depending on the radius of the outer surfaces of the gas and liquid lines. It is expected that the gas line will be of a greater diameter than the liquid line usually.

The connector can be connected to the outer surfaces of the gas and liquid lines in any suitable manner, although a connection of good thermal conduction is preferred. Thus the connection can be by a brazed or soldered connection to at least one of the gas and liquid lines, with the selection of braze or solder being made at least partly on the basis of compatibility with the material of the gas and liquid lines, as well as thermal conductivity and cost. Other considerations might also be made. In some arrangements, the connector is brazed or soldered to each of the gas and liquid lines. The brazing or soldering can be conducted in any suitable manner.

The connection can alternatively be a weld connection or a conductive braze paste could be employed to make the connection. The braze paste is heated to melt the paste to form the connection. In an alternative arrangement, the connector can be in clip connection or snap fit connection with at least one of the gas and liquid lines. In some arrangements, the connector is in clip connection or snap fit connection with each of the gas and liquid lines. The connector can be arranged to engage the surface of the or each of the gas and liquid lines closely to ensure good thermal conduction between the gas and liquid lines. A conductive paste or other conductive material can be employed between the connector and the facing surface of the or each of the gas and liquid lines to improve thermal conduction

In still an alternative arrangement, the connector can be in brazed or soldered connection to one of the gas and liquid lines and in clip connection or snap fit connection with the other of the gas and liquid lines. In another arrangement, a clip or snap fit connection can be employed which is also brazed, soldered, welded or adhered to one or each of the gas and liquid lines.

Where a clip or snap fit connection is employed, the clip or snap fit connection can be deformed to connect to the or each of the gas and liquid lines. For example, the clip or snap fit connection can be crimped to connect to the or each of the gas and liquid lines. Other forms of deformation could also be appropriate. Alternatively, the connector can be resiliently flexible to flex to receive the or each of the gas and liquid lines and to return to the pre-flexed condition to hold the or each of the gas and liquid lines.

Typically the gas and liquid lines are made of aluminium, copper or brass, although stainless steel can also be employed. The connector can be of any suitable material compatible with the material of the gas and liquid lines for thermal conduction and for brazing or soldering or other adhesion where that is the manner of connection between the connector and the gas and liquid lines. The connector can for example, be predominantly of aluminium material. Other metals can be employed for the connector, as can other materials such as thermal plastics or carbon composites.

The connection between the gas and liquid lines can be about 20% to 50% of the total length of the gas and liquid lines, although a greater or lesser percentage can be adopted depending on the shape of the lines and the required heat exchange. Clearly, the heat exchange between the gas and liquid lines can be greater as the above percentage increases, although the integrity of the connection between the connector and the gas and liquid lines and the selection of the material of the connector and the gas and liquid lines can also have an influence on this.

The present invention also extends to a heat exchanger which includes a heat exchange fluid line arrangement of the above described kind.

The present invention also extends to a method of assembling gas and liquid lines of a heat exchange fluid line arrangement in which each of the gas and liquid lines is of a circular cross-section, the method involving shaping or bending each of the gas and liquid lines to the lengthwise shape required, thereafter connecting the gas and liquid lines with a connector at sections of the gas and liquid lines that are adjacent and parallel, the connector being of a material which is operable to facilitate a heat exchange between the gas and liquid lines, so that heat from the liquid line can be transferred to the gas line.

Benefits provided by the present invention include a greater heat exchange efficiency or performance of a heat exchanger which employs the heat exchange fluid line arrangement of the invention. This is because heat exchange not only occurs in the heat exchanger, but also in the fluid lines ahead of the exchanger, so that the temperature exchange required of the heat exchanger can be reduced or improved.

An additional benefit that the invention can provide is a noise reduction through a reduction in the amount of vibration of the gas and liquid lines, by the connection between them. This is thought to be maximised where the connector is brazed or soldered to the gas and liquid lines, but where the connector is of a clip or snap fit form, the benefit can still be provided. The connection employed in the invention is such as to provide increased rigidity compared to some arrangements in which the lines have little or no connection between them. A still further benefit that can be provided is that the lines can be assembled together remotely and prior to installation into a vehicle. This has the benefit that a single part (comprising the two lines) is installed in a vehicle as a composite component, rather than two separate lines, so that installation requires less handling and is therefore less complex and time consuming, while the packaging and delivery of a single part is also more convenient than two separate parts.

For a better understanding of the invention and to show how the same may be carried into effect, an embodiment thereof will now be described, by way of non-limiting example only, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is an isometric view of a pair of fluid lines for use in a heat exchange fluid line arrangement of the invention.

Figure 2 is a cross-sectional view taken through A-A of Figure 1.

Figure 3 is an alternative view of the fluid line arrangement of Figure 1. Figure 4 is a cross-sectional view of an alternative arrangement of heat exchange fluid line according to the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Figure 1 is a perspective view of a section of a heat exchange fluid line arrangement 10. The arrangement includes a gas line 1 1 and a liquid line 12. The liquid line 12 is of reduced diameter compared to the gas line 1 1. Once installed, the ends of the gas line 11 would be connected to an evaporator and a compressor while the ends of the liquid line 12 would be connected to a condenser and an evaporator. Each of the gas and liquid lines 11 and 12 are of generally circular cross-section as shown in Figure 2.

With reference to the gas line 1 1 , as shown in Figure 1 , four linear sections 13i _, 13 ₂ , 13 ₃ and 13 ₄ are illustrated. A joint 14 extends between each of these linear sections. The path of the gas line 11 is convoluted and three dimensional. That is, the path does not extend in a single plane.

The path of the gas line 1 1 is substantially mirrored by the path of the liquid line 12, so that the liquid line 12 also includes four linear sections 15i, 15 ₂ , 15 ₃ and 15 ₄ and three joints 16. However, the paths differ most noticeably between the linear sections 13 ₃ and 15 _3, where those sections are spaced apart. A connection is made between each of the sections 13i, and 15i, 13 ₂ and 15 ₂ , and 13 ₄ and15 ₄ . There is no connection between the linear sections 13 ₃ , 15 ₃ . This arrangement is more clearly illustrated in Figure 3, in which the connectors 17 are more readily evident.

With reference to Figure 2, the connector 17 is seen to have a generally frustoconical cross-section, with oppositely facing curved surfaces 18 and 19. The curved surfaces 18 and 19 are curved complementary to the curve of respective outer surfaces of the gas and liquid lines 1 1 and 12 to form a generally flush connection between the connector 17 and the curved surfaces 18 and 19 of the lines 1 1 and 12. Heat conduction occurs through the connector 17 between the gas and liquid lines 11 and 12. The connector 17 is of an aluminium material, and is brazed to each of the outer surfaces of the gas and liquid lines 1 1 and 12. The braze is selected to facilitate conduction between the gas and liquid lines 11 and 12 and the connector 17. As illustrated in Figure 3, the connector extends for a significant portion of the length of the respective linear sections of the gas and liquid lines 1 1 and 12, but the connectors 17 do not extend through the joints 14 and 16. It can be seen that in the section of the fluid line 10 in Figure 3, approximately one third to one half of the length of the respective lines 1 1 and 12 is connected together by the connectors 17.

In an alternative arrangement shown in Figure 4, a clip can be employed, rather than a brazed or soldered or other similar connection. In Figure 4, the gas line 1 1 and the liquid line 12 are connected by a clip 20, which is deformable to accept each of the gas and liquid lines 1 1 and 12, by outward splaying of the respective legs 21 and 22.

Once the gas and liquid lines 1 1 and 12 have been accepted by the clip 20, the respective legs 21 and 22 can be returned to the position shown in Figure 4, to capture the lines 1 1 and 12, either by deformation or by resilience, depending on the material of the clip 20. The material of the clip 20 can be any suitable material, such as a suitable metal or polymer. As indicated earlier, in some arrangements, the gas line 11 and the fluid line 12 can be connected by a combination of the clip 20 and a brazing arrangement of a kind employed with the connector 17. Thus, a braze connection could be made between the clip 20 and the outer surface of each of the gas and liquid lines 11 and 12.

The clip 20 could be formed with each of the legs 21 and 22 formed to accept the gas and fluid lines 1 1 and 12 without any resilient flexing, and thereafter the legs could be deformed, such as by crimping, into the curved arrangement shown in Figure 4, in which each of the lines 1 1 and 12 are captured. Alternatively, a resiliently flexible material can be employed which allows the legs 21 and 22 to splay outwardly to accept the lines 11 and 12 and to resiliently return to the position shown in Figure 4, in which the lines 1 1 and 12 are captured.

In relation to the clip 20, heat conduction occurs through the legs 21 and 22, although if appropriate, the lines 1 1 and 12 can be in contact, rather than being spaced apart as shown in Figure 4, or further, an appropriate material could be disposed within the gap G to promote conduction between the lines 11 and 12. The material could be a conductive paste or a braze or solder or the like. Other materials might be employed.

Alternatively, the clip 20 could be solid at this location, potentially enhancing the conduction of heat through the clip 20.

A benefit of the arrangement illustrated in Figures 1 to 3, is that the connector 17 can be produced in standard lengths and cut to size as required. In addition, brazing or soldering facilities are commonplace in manufacturing or assembly facilities and therefore little or no additional equipment would be required for the arrangement of Figures 1 to 3 to be employed. In fact, it is commonplace for gas and fluid lines to be soldered to various components of an automotive air conditioning arrangement, inlets and outlets of heat exchangers for example, so additional skilled personnel would also not be required if the arrangement of Figures 1 to 3 is adopted.

The clip arrangement of Figure 4 is advantageous for ease of assembly, as it does not necessarily require brazing or soldering. It is to be appreciated that in adopting the invention into an air conditioning system, a combination of both a connector 17 and a clip 20 might be employed. It might be possible for example, to employ a clip arrangement between the linear sections 13 ₃ and 15 ₃ where, in the illustrated embodiment, no such connection exists, given the space in between those linear sections.

It will be evident from Figure 3, that the brazed connection between the lines 1 1 and 12 extends for a significant percentage of the overall line length, and this has additional benefits in providing rigidity to the lines. Increased rigidity has the clear benefit of reducing vibration in the lines and thus reducing noise that might otherwise be created by vibration. It also facilitates a reduction or even elimination of the requirement for a hard rigid mount of the lines to the vehicle structure.

The invention described herein is susceptible to variations, modifications and/or additions other than those specifically described and it is to be understood that the invention includes all such variations, modifications and/or additions which fall within the spirit and scope of the above description.