Device for optimizing the flow of refrigerant fluid fed to an evaporator of a refrigeration circuit and acting as an expansion noise level reducer

Abstract: A device for optimizing, within a refrigeration circuit, the flow of refrigerant fluid fed to an evaporator via an expansion member (1) and for reducing the expansion noise level comprises a body (10) constructed of porous material and positioned in correspondence with a free end (5) of said expansion member (1) along the refrigerant fluid path towards the evaporator within a containing tube (3) for said member (1) positioned at the entry to said evaporator, said body (10) containing at least a portion (7) of said free end (5) and being fixed within said tube (3).

Description: This invention relates to a device in accordance with the introduction to the main claim. A refrigeration circuit is known to comprise a compressor, a condenser, an expansion member and a evaporator. The expansion member is usually (but not necessarily) a tube of very small transverse dimensions or a so-called capillary tube (or simply a capillary). This latter is usually arranged with at least its end part positioned within a containing tube or conduit connected to the evaporator. A device for optimizing the flow of refrigerant is disclosed by US-A-3 815 379. The capillary tube type expansion member disclosed in such document is a relatively short tube supported in a housing and does not prevent vibration problems typical of capillary tubes. US-A-5 097 866 discloses a refrigerant meter device in which the capillary tube type expansion member is replaced by a porous body. It has been found that during the operation of the refrigeration circuit, the fluid expanding at the free end of the capillary generates noise which can be annoying to the user. This is caused by the turbulence in the refrigerant fluid leaving the capillary. Further noise can also be generated by vibration of the capillary within its containing conduit by the effect of fluid flow through the conduit and its outflow from the free end of the capillary, this noise being further amplified to a noticeable extent during the circuit operating transients or following the entry into operation or the deactivation of the compressor. This noise and vibration is mostly related to the effect of the variation in the physical characteristics of the refrigerant fluid on leaving the capillary. An object of this invention is to provide a device which enables the noise generated where the capillary opens into the containing tube or conduit to be reduced. A further object is to provide a device of the aforesaid type which enables the flow of fluid leaving the capillary and directed towards the evaporator to be improved. A further object is to provide a device of the aforesaid type which is of low constructional cost and is inexpensive to position within the refrigeration circuit. These and further objects which will be apparent to the expert of the art are attained by a device in accordance with the accompanying claims. The invention will be more apparent from the accompanying drawing, which is provided by way of example in which: Figure 1 is a longitudinal section through a device of the invention associated with a capillary positioned within a containing conduit; Figures 2 and 3 are two different embodiments of the invention; and Figure 4 is a section on the line 4-4 of Figure 2. With reference to said figures, a capillary tube (or capillary) 1 comprises a terminal portion 2 inserted in known manner in a containing tube or conduit 3 associated with an evaporator (not shown) of a refrigeration circuit. The conduit 3 comprises a funnel part 3A into which the capillary is inserted and which acts as the retaining element for this latter. The conduit can terminate with this part 3A or be joined to a further tube 3B, for example for returning the refrigerant fluid from the evaporator. The refrigeration circuit also comprises in known manner a known condenser and compressor, which are not shown. A refrigerant fluid directed towards the evaporator flows through the capillary 1 in the direction of the arrow F of Figure 1. This capillary has a free end 5, open at 6, through which the refrigerant fluid passes into the conduit 3 directed towards the evaporator. In reality the refrigerant fluid contains a portion of a lubricant fluid used in the compressor in known manner to lubricate the moving parts. According to the invention, at least a portion 7 of the free end 5 of the capillary 1 is inserted into a seat 9 of a body 10 mounted about the capillary. This body is constructed of porous material to enable the refrigerant fluid to correctly flow towards the evaporator. For example, the body 10 can be of sintered metal, such as copper and its alloys or steel. Alternatively, it can be of porous resin or a porous mixture of various materials such as silica gel together with calcium sulphate, aluminosilicate and alumina. Said body 10 cooperates with the inner wall 12 of the containing tube 3. It preferably engages said wall with a degree of clearance so as to create an interspace 13 therewith through which the refrigerant fluid can in any event flow to the evaporator should the pores in the body 10 become clogged during the course of time because of absorption of any impurities present in the refrigerant fluid (for example in the aforesaid small portion of lubricant fluid). This interspace (possibly formed by providing surface recesses in the body 10 in proximity to the wall 12 of the tube 3) allows flow towards the evaporator while at the same time allowing the capillary 1 to undergo small movements within the tube 3. The capillary is hence only limitedly stiffened, thus preventing its possible fracture. The body 10 is retained in the tube 3 by annular deformations or plastic points 15 on this latter, which define constrictions within the tube and delimit the seat for said body. As stated, the portion 7 of the capillary 1 is inserted into the seat 9 of the body 10. This seat is flared at least in proximity to its opening 18, to act as a lead-in for the insertion of the capillary into it. The seat is closed at its other end 19, the refrigerant fluid being able to pass beyond the body 10 only by passing through its pores. Said flared part can extend to different lengths within the seat 9 and have different diameters. In Figure 2 this seat has a part 17 of larger diameter than that in Figure 3. In this manner a safety conduit is formed for the refrigerant fluid which, if the pores of the body 10 become clogged, can flow through this conduit 17, through the interspace 13 and continue towards the evaporator. The conduit 17 can either be continuous about the capillary (ie the part 17 is always of greater diameter than the capillary) or can comprise a plurality of conduit parts providing the aforesaid safety. In all cases the body is fixed non-removably by interference at the end 5. By virtue of the invention, if during the operation of the refrigeration circuit noise should arise at the end 5 of the capillary, the body 10 acts as an absorber for this noise and hence as a silencer. The body also acts as a capillary vibration absorber. Moreover because of the type of material used for its construction, the body acts indirectly as an element for filtering any moisture present in the refrigerant fluid, if suitably dimensioned. In a modification of the invention, the body 10 is of differential density (lower at the capillary 1 and higher at its free end 22 in the direction of the refrigerant flow), this improving the passage of this refrigerant against any impurities present in it. This end can be shaped as a plurality of wires with arms extending in the direction of refrigerant flow, thus making this flow more laminar and optimizing it.

Claims: . A device for optimizing, within a refrigeration circuit, the flow of refrigerant fluid fed to an evaporator via a capillary tube type expansion member (1) and for reducing the expansion noise level, comprising a body (10) constructed of porous material and positioned in correspondence with a free end (5) of said expansion member (1) along the refrigerant fluid path towards the evaporator, and a containing tube (3) in which said member (1) is positioned and in which the body (10) is fixed, whereby said expansion member is a capillary tube (1) and in that at least a portion (7) of said free end (5) of said capillary tube (1) is inserted into a seat (9) of the body (10). A device as claimed in claim 1, characterised in that its porous material body (10) is of sintered metal. A device as claimed in claim 1, characterised in that its body (10) is of porous resin. A device as claimed in claim 2 or 3, characterised in that the density of its body (10) varies in passing from one (18) of its ends to the other (22) in the direction of the refrigerant fluid flow. A device as claimed in claim 1, characterised in that its body (10) comprises a seat (9) containing the portion (7) of the end (5) of the capillary tube (1), said seat being at least partly conical (at 17). A device as claimed in claim 5, characterised in that the seat (9) of its body (10) is closed at one (19) of its ends. A device as claimed in claim 1, characterised in that the seat (9) of the body (10) comprises at least one channel (17) about the portion (7) of the capillary tube (1), an interspace (13) being provided between the body (10) and a wall (12) of the containing tube (3). A device as claimed in claim 7, characterised in that the interspace is in the form of surface channels provided on the body (10) in correspondence with the wall (12). A device as claimed in claim 1, characterised in that the containing tube (3) comprises deformed parts (15) defining constrictions within said tube, these latter being spaced apart along the tube (3) so as to receive the porous material body (10) between them. A device as claimed in claim 1, characterised in that the porous material body comprises, distant from the end (18), an end (22) by way of which the capillary tube (1) is inserted into the seat (9) of the body, and is shaped such as to generate laminar flow of the refrigerant fluid beyond the body in the direction of said flow, so optimizing said fluid flow directed to the evaporator.

Inventors: GENONI CARLO, MARITAN MARCO, GENONI,CARLO, Genoni,Carlo, Whirlpool Europe s.r.l., Maritan Marco, Whirlpool Europe s.r.l.
Applicants: WHIRLPOOL CO, WHIRLPOOL CORPORATION
Application year: 1999
Main classification: F25B41
IPC codes: F25B41