WO2010116239A1

WO2010116239A1 - Double pipe system for an air conditioning system of a vehicle

Info

Publication number: WO2010116239A1
Application number: PCT/IB2010/000772
Authority: WO
Inventors: Mariofelice Zanardi
Original assignee: Dytech - Dynamic Fluid Technologies S.P.A.
Priority date: 2009-04-09
Filing date: 2010-04-08
Publication date: 2010-10-14
Also published as: IT1394141B1; EP2416976A1; ITTO20090276A1

Abstract

An air conditioning system for motor vehicles provided with a fluidic unit (1), wherein a first line (9) for a low temperature heat exchanger fluid and a second line (6) for the high temperature heat exchanger fluid are coupled to a heat exchanger (12) provided with at least one connector (14) for the connection to the two lines (6, 9); and wherein the heat exchanger (12) has an inner tubular wall (15) forming part of one of the two lines (6; 9), and a plurality of peripheral pipes (18') arranged outside the inner tubular wall (15) and forming part of the other of the two lines (9; 6); and the connector (14) has a through pipe (20) coaxial to the longitudinal axis (B) and crossed by the inner tubular wall (15); a radial channel (27); and an annular chamber (30) defined by the inner tubular wall (15) along a part of the through pipe (20), surrounding the inner tubular wall (15) and communicating both with the peripheral pipes (18') / and with the radial channel (27).

Description

DOUBLE PIPE SYSTEM FOR AN AIR CONDITIONING SYSTEM OF A VEHICLE

TECHNICAL FIELD The present invention relates to a fluidic unit for an air conditioning system of a motor vehicle, such a unit being provided with a heat exchanger which is connected to a plurality of inlet and outlet pipes of the system by means of at least one connector. BACKGROUND ART

An air conditioning system for a motor vehicle is known to comprise a compressor, a condenser, an expansion system, an evaporator and a fluidic unit to connect the previously cited components to one another. In particular, an air flow passes through the evaporator, the air current being fed by appropriate pipes within the passenger compartment and the compressor may be arranged in the engine compartment either at the front or at the back. The compressor provides work to bring a heat exchanger fluid from a relatively low temperature and pressure, to e.g. respectively 2⁰C and 2 bars to a higher pressure and temperature, e.g. 80⁰C and 15 bars.

The fluid transfers heat to the environment in the condenser and flows towards the evaporator through an expansion valve that, causing a pressure drop, determines the evaporation of the fluid in the evaporator with the subsequent heat subtraction from the air flow passing through the evaporator and which is conveyed within the passenger compartment.

Downstream of the evaporator, the compressor must provide the fluid with a work equivalent to the enthalpy change between the suction and the delivery. In order to make the refrigeration cycle more efficient and reduce polluting emissions, it is known to provide a heat exchanger in which the fluid exiting the evaporator is heated by the fluid exiting the condenser. Thereby, the fluid sucked by the compressor has a higher pressure and a higher temperature and both the enthalpy change and therefore the work of the compressor are decreased.

In the case of a conditioning system having the compressor arranged in a front position within the engine compartment, the pipes of the fluidic unit run along most of the path within the engine compartment and the exchanger has an elongated profile that follows the path of the pipes .

Heat exchangers are known comprising a main body to deliver both the exchanger fluid to be heated and the heating fluid; and a pair of connectors mounted to respective ends of the main body to connect the exchanger to the pipes of the air conditioning system.

The main body defines a central pipe and a plurality of peripheral pipes that surround the central pipe. The central pipe is defined by a tubular wall. The peripheral pipes are defined in a radial direction by the tubular wall of the central pipe and by an outer tubular wall concentrical to the tubular wall of the central pipe and, in a circumferential direction, by a plurality of rectilinear partitions angularly equally spaced from one another. The central pipe delivers the exchanger fluid exiting the evaporator and directed towards the suction of the compressor and the peripheral pipes deliver the exchanger fluid exiting the condenser countercurrent .

In particular, the main body is made by extrusion and subsequently may be folded in order to adapt to the available space in the engine compartment.

Currently, a connector for such a main body made by extrusion comprises a metal block defining a connection opening for an end of the main body, an opening for the low temperature exchanger fluid and an opening for the high temperature fluid exchanger.

The above disclosed known connector has the drawback of being made in a single block with significantly thicker walls than the walls of the exchanger to which it must be applied, thus making the operation of connection of the connector with the main body especially complicated, in particular in the case in which such a connection operation is made by welding and/or brazing. The above said known connector also has the drawback of comprising within its main body a first channel in communication with the central pipe of the exchanger and for the passage of the low temperature exchanger fluid, and a second channel communicating with the plurality of peripheral pipes adapted to allow the passage of the high temperature exchanger fluid. In particular, the cited first and ⁼ second channel are separated from one another by a wall, which has an opening crossed by the main body of the exchanger; therefore sealing elements or inner brazing couplings must be provided interposed between this wall and the main pipe, to prevent possible leakages of the exchanger fluid from one pipe to another; however, the risk remains of a possible leakage of the exchanger fluid from one channel to another in case of damage or wrong assembly of the sealing elements. These elements are also not visible when the coupling is finished. Document DE102004004027 discloses an exchanger comprising a pair of concentrical pipes and a pair of connectors to determine two fluidic lines through which the exchanger fluid of the air conditioning system flows . The concentrical pipes have a series of seals which may be damaged by wear and cause leakages of the exchanger fluid. Furthermore, the number of components is high and the assembly is difficult to automate along a production line and requires many elements to be anchored to adjacent structures. Therefore, it is difficult to assemble the shown exchanger directly to flexible pipes.

Document EP-A- 1101638 discloses an exchanger comprising a connector, an inner pipe and an outer pipe defining respective passages for an exchanger fluid. The document does not mention production features required to obtain an exchanger having a high mechanical resistance and how to obtain the fluidic seals required in all of the components of an air conditioning system. DISCLOSURE OF INVENTION

It is an object of the present invention to provide a fluidic unit for an air conditioning system of a motor vehicle, which does not have the above disclosed drawbacks and at the same time has a high mechanical resistance and a structure such as to optimise the production process.

According to the present invention there is provided a fluidic unit for an air conditioning system of a motor vehicle according to claim 1 and, preferably, in any of the following claims whether directly dependent or indirectly dependent on claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described with reference to the accompanying drawings, which illustrate non- limitative embodiments thereof, in which: figure 1 is a partial perspective view of a preferred embodiment of the air conditioning system of the present invention;

- figure 2 shows a detail of figure 1 in partial axial section and on an enlarged scale;

- figure 3 is a section taken along line III-III of figure 2 ; and

- figure 4 is similar to figure 3 and relates to a variant of the detail of figure 2.

BEST 'MODE FOR CARRYING OUT THE INVENTION In figure 1, A indicates as a whole an air conditioning system of a motor vehicle, system A comprising a compressor (not shown) , an expansion valve (not shown) , a condenser (not shown) , an evaporator (not shown) and a fluidic unit, indicated as a whole by numeral 1, for connecting these member to one another.

Unit 1 comprises a high pressure line 2 to convey a high temperature exchanger fluid from the delivery of the compressor to the expansion valve (not shown) , and a low pressure line 3 to convey the low temperature exchanger fluid from the expansion valve to the suction of the compressor (not shown) .

In particular high pressure line 2 comprises metal and rubber pipes assembled in series, a joint 4 connected, in a known manner (not shown) , to the delivery of the compressor (not shown) , a joint 5 connected, in a known manner (not shown) , to the inlet of the condenser (not shown) and a pipe 6' between joints 4 and 5. Furthermore, high pressure line 2 comprises a line 6 to connect the condenser (not shown) to the expansion valve (not shown) . Line 6 comprises a joint 7 connected, in a known manner (not shown) , to the outlet of the condenser (not shown) and a joint 8 connected, in a known manner (not shown) , to the expansion valve (not shown) .

Low pressure line 3 comprises a line 9 having a joint 10 connected, in a known manner (not shown) , to the outlet of the evaporator (not shown) and a joint 11 connected, in a known manner (not shown) , to an inlet of the compressor (not shown) .

The pipes of lines 2, 3 comprise at least one layer of a barrier material to prevent the outflow of the exchanger fluid, normally very volatile. For example, this barrier material may be made of aluminium or polyamide 6,10. In the case of a carbon dioxide system, the piping is made of steel.

The exchanger fluid that flows in line 9 is at a low temperature and is heated by the exchanger fluid that flows along line 6 to the outlet of the condenser

(not shown) . For this purpose, unit 1 comprises a heat exchanger 12 comprising a main body 13 and a pair of connectors 14 to hydraulically and mechanically connect main body 13 to lines 6 and 9. According to the present invention, exchanger 12 results especially resistant and light. Therefore it may be fixed to a structure of the vehicle by means of a single bracket S if connected to at least one flexible pipe of line 9. In figure 2 only one end portion of exchanger 12 is shown for the sake of conciseness, being understood that the other end portion is identical to that shown.

Main body 13 of exchanger 12 comprises an inner tubular wall 15 having an axis B, an outer tubular wall 17 coaxial to inner tubular wall 15 and a plurality of radial partitions 18, which make tubular walls 15 and 17 integral according to an embodiment of the present invention not claimed in claim 1.

Inner tubular wall 15 defines a pipe 16 forming line 9 to convey the exchanger fluid from the outlet of the evaporator (not shown) to the suction of the compressor (not shown) . Inner tubular wall 15, outer tubular wall 17 and partitions 18, respectively define radially and circumferentially, a plurality of pipes 18' arranged in parallel to one another and forming part of line 6 to convey the high temperature exchanger fluid from the outlet of the condenser (not shown) to the expansion valve (not shown) . Preferably, main body 13 is made by extrusion in a single body.

According to figure 2, connector 14 comprises a tubular body 19 having a longitudinal axis coaxial to axis B and delimiting a through pipe 20 having a circular section coaxial to axis B; the diameter of the section of through pipe 20 is variable along axis B so as to define, within body 19, a plurality of sections having different size from one another.

In particular, through pipe 20 comprises a positioning section 21, which faces outside connector 14 through an axial end surface 22 of body 19 and has a diameter approximating by excess the diameter of outer tubular wall 17, an intermediate section 23 having a diameter smaller than that of end section 22 and joined to end section 22 by an annular shoulder 26, and a centring section 24, that faces outside connector 14 through an axial end surface 25 opposite to end surface 22 and has a smaller diameter than that of intermediate section 23 approximating by excess the outer diameter of inner tubular wall 15.

A channel 27, which extends radially with respect to axis B between an outer side surface 28 of connector 14 and intermediate section 23 of through pipe 20 is obtained through connector 14.

Main body 13 of exchanger 12 is inserted within connector 14 in a position coaxial to axis B and so that its inner tubular wall 15 passes completely through connector 14 and couples with centring section 24.

An end portion of outer tubular wall 17 of exchanger 12 is inserted within connector 14, engages positioning section 21 and is arranged in abutment against annular shoulder 26, which defines the relative axial position of connector 14 with respect to main body 13 of exchanger 12.

Outer tubular wall 17 is integrally connected to connector 14 by means of a continuous annular brazing line 29a arranged at end surface 22 of connector 14; similarly, inner tubular wall 15 is integrally connected to connector 14 by means of a continuous annular brazing line 29b arranged at end surface 25 of connector 14.

Lines 29a and 29b are adapted to form a fluid- sealing connection between connector 14 and outer tubular wall 17 and, respectively, between connector 14 and inner tubular wall 15.

According to figure 2, intermediate section 23 and outer surface of inner tubular wall 15 define an annular chamber 30, which radially communicates with channel 27 and axially with pipes 18' surrounding central pipe 16 of main body 13 of exchanger 12.

Line 6 for feeding high temperature exchanger fluid is connected by means of elements of the known type (not shown) to channel 27; while line 9 for feeding low temperature exchanger fluid is connected with pipe 16 by means of a connection made by known modes (not shown) , to a portion of inner tubular wall 15 that projects externally from connector 14 through end surface 25.

Connector 14 may also have a geometrical shape other than that shown in figure 2; in this connection figure 4 shows by way of example a connector 14 having a side surface 28 having a hexagonal section. From the above there follows that connector 14 has an extremely simple geometrical shape, with walls having size substantially equivalent to that of exchanger 12, allowing:

- to easily connect by welding and/or brazing or other (maGNWEETO) between connector 14 and exchanger 12;

- to connect two lines 6 and 9 with pipes 18' and, respectively, with pipe 16 separately, eliminating the risk of leakage of the fluid from a duct to another at connector 14 ; to significantly reduce the production time and costs as connector 14 may be entirely made by moulding; - to reduce the assembly time and the weight of air conditioning system A at exchanger 12.

It is finally apparent that exchanger 12 disclosed and shown herein may be modified or varied without departing from the scope of protection as specified in the appended claims.

For example, main body 13 of exchanger 12 may be made with two elements, i.e. an inner cylindrical pipe and an outer pipe having partitions 18. The outer pipe is fitted on the inner pipe and is preferably made by extrusion.

Outer tubular wall 17 is integrally connected to connector 14 even by methods other than brazing. For example a welding or a magnetic welding may be provided. In particular, in this latter case, the shape of connector 14 is modified and there is a number of collars equivalent to the number of magnetic weldings to be made. In particular, magnetic welding is a method for rigidly connecting in a non removable manner, which is performed in this case between two metal elements and which implies the exposure to an electromagnetic radiation pulse that does not imply the fusion of metal but instead a cold welding at a liquid state.

Furthermore, other technologies that may be used are TIG, MIG and laser welding. Welding has the advantage of not requiring a cleaning step which is instead required when a brazing is carried out. Furthermore, the previous welding techniques are easily automatable to make the production line more efficient. Therefore the production time is reduced.

Furthermore, when main body 13 is made in two pieces, lines 29a and 29b serve the dual function of fluid-tightly sealing exchanger 12 and fixing inner tubular wall 15, outer tubular wall provided with partitions 18 and connectors 14. There results a great advantage connected to the assembly time. The quality and the long working life of exchanger 12 are ensured by the use of welded connections. Furthermore, a welded connection between the tubular walls and connector 14 allows to make exchanger 12 as a structurally rigid unit that requires the lowest possible number of anchorings to the structure of the vehicle. Thereby, exchanger 12 provides the possibility of being fixed to the structure of the vehicle in a simple and cost-effective manner. Indeed, tubular body 15 may be connected to one or two flexible pipes comprising a rubber layer and a barrier layer to avoid the permeation of exchanger fluid. The barrier layer, as already mentioned, may comprise an aluminium layer or a polyamide 6,10.

Preferably, each connection between tubular walls and connectors is also performed by the same welding technique. Thereby, during assembly, exchanger 12 passes through a single welding station where all of the connections are carried out. Advantageously, when channel 27 is connected to a metal tube, also this welding is performed with the same technique used for lines 29a and 29b. Thereby the flow of the production steps is rationalised in order to decrease the required time .

Claims

1. A fluidic unit (1) for an air conditioning system of a motor vehicle comprising a first line (9) for a low temperature heat exchanger fluid; a second line (6) for the high temperature heat exchanger fluid; and a heat exchanger (12) provided with at least one connector (14) for the connection to the two lines, having a longitudinal axis (B) and comprising, in turn, an inner tubular wall (15) forming part of one of the two lines (6; 9), and an outer tubular wall separated from the inner tubular wall (15) and defining therewith a plurality of peripheral pipes (18') arranged outside the inner tubular wall (15) and forming part of the other one of the two lines (9; 6) ; wherein the connector (14) has a through pipe (20) coaxial to the longitudinal axis (B) and crossed by the inner tubular wall (15) ; a radial channel (27) ; and an annular chamber (30) defined by the inner tubular wall (15) along a part of the through pipe (20) , surrounding the inner tubular wall (15) and communicating both with the peripheral pipes (18'), and with the radial channel (27); said unit being characterised in that the connector (14) connects the inner and outer tubular walls to one another by means of weld lines (29a, 29b) configured so as to define both fluid- sealing elements and the connection elements to rigidly connect to one another the inner and outer tubular walls by means of the connector (14) .

2. The fluidic unit according to claim 1, characterised in that the weld lines (29a, 29b) are made by the same welding technique .

3. The fluidic unit according to one of claims 1 or 2, 'wherein the tubular wall (15) is directly connected to at least one flexible tube.

4. The fluidic unit according to claim 3, comprising a single bracket (S) to fix the exchanger (12) to a structure of the vehicle.

5. The fluidic unit according to any of the preceding claims, wherein the weld lines (29a, 29b) are opposite with respect to the connector (14) .

6. The fluidic unit according to any of the preceding claims, wherein the weld lines (29a, 29b) are made by magnetic welding.

7. The fluidic unit according to any of claims 1 to 5, wherein the weld lines (29a,- 29b) are made by means of one of laser welding, TIG welding, MIG welding.

8. The fluidic unit according to any of the preceding claims, wherein the tubular walls are drawn and made of aluminium like the connector (14) .