A HEAT EXCHANGER AND A HEAT EXCHANGER/EXPANSION VALVE ASSEMBLY

Abstract: A heat exchanger for a heat exchanger/expansion valve assembly, said heat exchanger (11) being provided with at least one inlet (12) for refrigerant fluid and at least one outlet (13) for refrigerant vapour, said heat exchanger (11) being provided with a plurality of plates (14; 34a; 34b; 34c; 35) juxtaposed to one another to define a plurality of flow-trough chambers, said valve (10) comprising a first compartment (15) adapted to be in communication with a vapour equalization channel (18), and a second compartment (16), said compartments (15, 16) being separated by a diaphragm (17). The heat exchanger (11) is adapted for mounting of the expansion valve (10) directly thereon in the area of said inlet (12) and the equalization channel (18) is formed between two of said plates (34a; 34b; 34c; 35) and extends from said outlet (13) to said area of said inlet (12), the equalization channel in said area being adapted to communicate with said first compartment (15).

Description: λ A heat exchanger and a heat exchanger/expansion valve assembly". The present invention relates to a heat exchanger for a heat exchanger/expansion valve assembly for evaporation of a fluid, and a heat exchanger/expansion valve assembly. The basic structure of a known heat exchanger used as an evaporator comprises an inlet for a refrigerant fluid and an outlet for superheated refrigerant vapour, and is provided with a plurality of inner and outer plates, placed or juxtaposed to one another to define a stack of plates, between which flow-trough chambers for the refrigerant, are defined. An expansion valve, which has the function of regulating the inflow of the refrigerant fluid to maintain the system in a suitable equilibrium, is connected to the evaporator in the following way: the refrigerant exit of the valve is connected to the evaporator inlet, a temperature bulb communicating with the valve is clamped to the evaporator exit and a tube for refrigerant vapour forming an equalization channel is arranged between the valve and the evaporator exit. This particular known setup is now believed to be expensive, both in terms of cost of equipment and of cost of assembly. In fact, for connecting the valve to the evapora- tor, two connecting pipes have to be cut, bent and brazed, to the evaporator. The expansion valve then has to be fitted with two O-rings and mounted on the tubes . Moreover, the performance of the evaporator-valve assembly is influenced by such external factors as: i.e. valve position, connecting pipe length and diameter, pipe bends and so on. Also, the presence of the external tube forming the equalization channel results in a bulky and cumbersome design. A further problem of the known design is that, due to the presence of many external parts with respect to the body of the heat exchanger, the system can be damaged by a blow. An object of the invention is to provide a heat exchanger for a heat exchanger/expansion valve assembly with a simplified and cost effective design. A further object of the invention is to provide a heat exchanger for a heat exchanger/expansion valve assembly which allows for a compact overall design of the system. These and other objects of the invention are reached by a heat exchanger for a heat ex- changer/expansion valve assembly, according to Claim 1. The above and further features, objects and advantages of the present invention will more fully appear from the following detailed description of the preferred embodiments of the invention with reference to the accompanying drawings in which: figure 1 shows a schematic exploded view of a heat exchanger for a heat exchanger/expansion valve assembly according to a first embodiment of the present invention; figure 2 shows a schematic exploded view of a heat exchanger according to a second embodiment of the present invention; figure 3 shows a schematic exploded view of a heat exchanger according to a third embodiment of the present invention; and figure 4 shows a cross section view of a valve assembly according to the present invention. Referring now to figure 1, an expansion valve is globally indicated with the reference numeral 10, and is shown applied to a heat exchanger 11 for forming a heat exchanger/expansion valve assembly, according to a first embodiment of the invention. The heat exchanger 11 is provided with an inlet 12 for a refrigerant fluid and an outlet 13 for superheated refrigerant vapour and is composed of a plurality of plates 14 placed or juxtaposed to one another to define a plurality of flow-trough chambers. An expansion valve 10 used, as shown in the section of figure 4, comprises a first compartment 15 and a second compartment 16, where said compartments 15 and 16 are separated by a diaphragm 17. A valve element 23, which can open or close a valve passage 33 is connected to the diaphragm 17. A spring 22 may act on the valve element 23. The expansion valve 10 is mounted directly on the heat exchanger 11 in such a way that a vapour equalization channel 18 inside the heat exchanger 11 is in fluid communication with the first compartment 15. In figure 1, a valve inlet 42 is in communication with the inlet 12 for the refrigerant fluid and a valve outlet 43 is in communication with the outlet 13 for the superheated refrigerant vapour. To achieve said fluid communication with the equalization channel, the valve 10 is connected to a connection pipe, or any similar means, in a front plate 34a of the heat exchanger 11. In this embodiment, liquid refrigerant enters the valve inlet 42, expands in the valve and leaves the valve 10 as a fluid containing liquid and va- porized refrigerant. The fluid then passes through heat exchanger inlet 12 and enters the plate package of the heat exchanger 11. The vapourized refrigerant passes through an em- bossed channel 19 in the front plate 34a and the heat exchanger outlet 13, then enters a first compartment of the valve 10, which works as an equalization compartment, and immediately leaves the valve 10 via valve outlet 43, having relayed the pressure to one side of a diaphragm. In this case, the refrigerant vapour pressure controls the valve 10, although, as it will be explained later on, the valve 10 may be provided with a thermostatic bulb. Also, the diaphragm and a second compartment may form a thermostatic bulb inside the valve 10, which bulb is sensitive to the temperature of the refrigerant vapour. Besides forming a passage for vapourized refrig- erant, the embossed channel 19 also forms an equalization channel communicating with the first compartment of the valve 10. In figure 2 a second embodiment of the invention is shown in which the equalization channel is provided for by means of an embossed channel 29, in a front plate 34b, which allows only the passage of a sufficient quantity of vapour to relay the exit pressure of the refrigerant vapour to a first compartment of the valve 10. In this embodiment, the refrigerant enters the valve 10 through inlet 42 and the heat exchanger through inlet 12, then the refrigerant vapour leaves the heat exchanger 11 through an outlet 13 for the superheated refrigerant vapour. In this case there is no net refrigerant flow in the embossed channel 29, the flow is caused only by changing pressure, and the first compartment of the valve 10 is closed in the sense that it has no exit port, like the first compartment 15 of the valve 10 shown in figure 4. In fact, a valve assembly similar to the valve assembly of this embodiment is shown in a cross section in figure 4, in which the second compartment 16 of the valve 10 is shown in fluid commu- nication with an optional temperature sensing bulb 25 through a connecting tube 24. The diaphragm 17, which separates the first compartment 15 from the second compartment 16, is in a substantially vertical position when the valve 10 is mounted on the heat exchanger 11. In this arrangement the valve 10 opens if the pressure inside the second compartment 16 increases due to an increased temperature in the bulb 25, forcing the valve element 23 to open the valve passage 33, while the valve 10 closes if the pressure inside the first compartment 15 increases because of an increased pressure relayed trough the equalization channel 18. The bulb 25 may, for instance, abut against a conduit connected to an outlet for superheated refrigerant vapour of the heat exchanger 11. In figure 3 a third embodiment of the present invention is shown in which an embossed channel 30 is pressed in one of the internal plates 35 and a plate 34c is provided on the front of the heat exchanger 11. The fluid flow is basically the same as in the embodiment of figure 2. In a possible embodiment of the heat exchanger of the invention a pipe arranged between two plates may, at least partly, form the equalization channel 18, as shown in figure 4. In all the above embodiments the valve 10 may be fitted and sealed with O-rings and fixed on the heat exchanger 11 with two bolts. Preferably, the inlet 12 for refrigerant fluid is arranged at the bottom of the heat exchanger. It is advantageous for the flow and evaporation of the refrigerant when the refrigerant flows upwards in the chambers of the heat exchanger. From the above description the characteristics of the expansion valve assembly for a heat exchanger of the present invention should be evident, and also evident are the advantages thereof. More particularly, the main advantages of the present invention can be summarized as follows: reduced production and assembly costs, due to the fact that there is no need for an external copper tube for forming the equalization chan- nel, no need for a special attaching plate with threaded holes for the valve and no need for a number of brazed connections; the heat exchanger and the valve are adapted to each other resulting in a compact and ra- tional design, which also allows for a more reliable functioning of the valve; - the invention offers the possibility of mounting a valve on the heat exchanger with no need for special external parts. It will be understood that, although there have been described some preferred embodiments of the invention, the expansion valve assembly described may be embodied in other specific forms without departing from the essential characteristics thereof as claimed in the appended claims.

Claims: CLAIMS 1. A heat exchanger for a heat exchanger/expansion valve assembly, said heat exchanger (11) being provided with at least one in- let (12) for refrigerant fluid and at least one outlet (13) for refrigerant vapour, said heat exchanger (11) being provided with a plurality of plates (14; 34a; 34b; 34c; 35) juxtaposed to one another to define a plurality of flow-trough chambers, said valve (10) comprising a first compartment (15) adapted to be in communication with a vapour equalization channel (18), and a second compartment (16), said compartments (15, 16) being separated by a diaphragm (17) , characterized in that the heat exchanger (11) is adapted for mounting of said expansion valve (10) directly thereon in the area of said inlet (12) and in that said equalization channel (18) is formed between two of said plates (34a; 34b; 34c; 35) and extends from said outlet (13) to said area of said inlet (12) , the equalization channel in said area being adapted to communicate with said first compartment (15) . 2. A heat exchanger, according to Claim 1, char- acterized in that said inlet (12) is arranged at the bottom of said heat exchanger (11) . 3. A heat exchanger, according to Claim 1, characterized in that an embossed channel (19) , which is provided on a plate (34a) , is in fluid commu- nication with said first compartment (15) of said valve (10) , in order to provide for said vapour equalization channel. 4. A heat exchanger, according to Claim 1, characterized in that said equalization channel is provided for by an embossed channel (29) in a front plate (34b) , which allows only the passage of a sufficient quantity of vapour to relay the exit pressure of the refrigerant vapour, and in that the refrigerant vapour leaves said heat ex- changer/expansion valve assembly through said outlet (13) for refrigerant vapour of the heat exchanger . 5. A heat exchanger, according to Claim 1, characterized in that said equalization channel is provided for by an embossed channel (30) , which is formed in one of the internal plates (35) . 6. A heat exchanger/expansion valve assembly, said heat exchanger (11) being provided with at least one inlet (12) for refrigerant fluid and at least one outlet (13) for refrigerant vapour, said heat exchanger (11) being provided with a plurality of plates (14; 34a; 34b; 34c; 35) juxtaposed to one another to define a plurality of flow-trough chambers, and comprising a valve (10) coupled to said heat exchanger (11) , said valve (10) comprising a first compartment (15) adapted to be in communication with a vapour equalization channel (18), and a second compartment (16), said compartments (15, 16) being separated by a dia- phragm (17), characterized in that the valve (10) is mounted on said heat exchanger (11) directly thereon in the area of said inlet (12) and in that said equalization channel (18) of said heat exchanger (11) is formed between two of said plates (34a; 34b; 34c; 35) and extends from said outlet (13) to said area of said inlet (12), the equalization channel in said area being adapted to communicate with a first compartment (15) of said valve (10) . 7. A heat exchanger/expansion valve assembly, according to Claim 6, characterized in that said inlet (12) , which is in communication with said valve (10) , is arranged at the bottom of said heat exchanger (11) . 8. A heat exchanger/expansion valve assembly, ac- cording to Claim 6, characterized in that an embossed channel (19) which is provided in a plate (34a) of said heat exchanger (11) is in fluid communication with said first compartment (15) of said valve (10), in order to provide for said vapour equalization channel. 9. A heat exchanger/expansion valve assembly, according to Claim 6, characterized in that said equalization channel is provided for by an em- bossed channel (29) in a front plate (34b) of said heat exchanger (11), which allows only the passage of a sufficient quantity of vapour to relay the exit pressure of the vapour, and in that the refrigerant vapour leaves the heat ex- changer/expansion valve assembly through said outlet (13) for refrigerant vapour of said heat exchanger (11) . 10. A heat exchanger/expansion valve assembly, according to Claim 6, characterized in that said equalization channel is provided for by an embossed channel (30), which is pressed inside a channel in one of the internal plates (35) of said heat exchanger (11) . 11. A heat exchanger/expansion valve assembly, according to one or more of the Claims from 6 to 10, characterized in that said second compartment (16) of said valve (10) is in fluid communication with a temperature sensing bulb (25) . 12. A heat exchanger/expansion valve assembly, according to one or more of the Claims from 6 to 11, characterized in that said diaphragm (17) of said valve (10), separating said first compartment (15) from said second compartment (16), is in a substantially vertical position when the valve (10) is mounted on said heat exchanger (11) .

Inventors: STENHEDE CLAES, STENHEDE, CLAES
Applicants: ALFA LAVAL AB, STENHEDE CLAES, STENHEDE, CLAES
Application year: 2000
Main classification: F25B39
IPC codes: F25B39, F25B41, F28D1, F28F27