COOLING DEVICE AND METHOD OF MAKING A COOLING DEVICE

Abstract: A cooling device of the kind used in transportation vehicles, designed to maintain the transportation space of such vehicles cool over prolonged periods. The device comprises an elongate housing (6) of gener­ ally rectangular cross-section, comprising side walls (8) and first and second end walls (10, 12). The cooling device com­ prises a cooling pipe (30) of elongate "U"-shape, comprising a curved portion (32) and parallel arms (34). The ends of the cooling pipe are secured within one end wall (10), and the central portion (32) of the pipe is supported in relation to the opposed wall (12) by a mounting device (14, 70) and a sup­ porting member (29, 28a). The device is produced by locating the cooling in a rotati­ onal moulding mould, whereby the various unions attached to the pipe are secured integrally with the end wall (10) of the housing, whilst, in one embodiment, the mounting device (14) is moulded into to opposed wall (12), whilst in a second emb­ odiment a threaded aperture is provided enabling the mount­ ing device (70) to be screwed into the opposed wall (12).

Description: Title: "Cooling device and method of making a cooling device" This invention is concerned with improvements relating to cooling devices, particularly of the kind (hereinafter referred to as "being of the kind specified") having a relatively high specificliatent heat, and which may be used to retain a space in which it is located cool for a relatively long period of time. For example, cooling devices of the kind specified are used in vehicles to retain the transportation compartment of the vehicle, and the goods transported, at low temperature. Conventionally a cooling device comprising an elongate housing is utilised, which may be mounted in the roof of the transparation compartment and which is filled with a eutectic liquid (conventionally comprising brine) and through which a cooling pipe extends. During charging of the cooling device a cooling liquid is fed through the cooling pipe from a refrigeration device to freeze the eutectic liquid, which then absorbs heat from the transparation compartment over a period of time to retain the transportotion compartment at a desired temperature. It will of course be appreciated that the nature of the eutectic liquid is selected so as to retain the transportation compartment at a desired temperature determined by the freezinglmelting point of the eutectic liquid. Whilst conventionally such cooling devices have been of metal, it has more recently been appreciated that plastics provides a highly desirable material for the elongate housing. A known method of manufacturing such cooling devices involves the use of an extrusion of generally rectangular cross-section, into which a cooling pipe is located and on to which end caps are secured. Desirably, however the cooling pipe enters and exits the housing at the same end, with the pipe extending as an elongate "U" within the housing. Thus the extrusion is of non-square rectangular cross-section. During the extrusion of the housing there is a tendancy for the side wails of larger width to collapse inwardly. Consequently it has become practice to utilise as a housing for a cooling device of the kind specified an extrusion having a web inter-connecting the opposite side walls approximately centrally thereof. However, the utilisation of such a web has the disadvantage, that it does not permit any significant increase in the volume confined by the housing under differential expansion, and It may be necessuryXorfhl°tge housing with eutectic liquid to an extent less than 100%, to provide space for such expansion. Difficulty is also encountered in cooling devices using extruded housings in the supporting of the cooling pipes, particularly during differential thermal expansion, and in practice It has been found necessary to utilise spacer elements on the pipe which engage with the walls on the housing compartments. This however restricts free-flow of the eutectic liquid within the housing, and localised areas of eutectic liquid may result which are surrounded by plugs of frozen material. This under certain circumstances con cause damage to the housing. Another difficulty which has been encountered is that, in cooling devices of the kind specified, it is on the one hand desirable to utilise steel as cooling pipework, but to utilise brass connections on the housing by which the device may be connected to a refrigeration unit. However, in use electrolytic action of the brine causes damages at the junction between the steel and brass. For this reason it is in general necessary to utilise copper for the cooling pipes. According to this invention there is provided a cooling device of the kind specified, comprising a cooling pipe located within a rotationally moulded housing. By rotationally moulding the housing, the need for and disadvantage of end caps is eliminated. In addition the need for a central web is also eliminated. Preferably the cooling pipe extends in the housing from and to one end wall thereof (hereinafter referred to as the first end wall) in elongate "U" shape. Preferably a central portion of the pipe (the curved part of the U) is supported by a supporting means by which said central portion of the pipe may be supported relative to the other end wall (hereinafter referred to as the second end wall), and advantageously the supporting means is such as to permit relative movement between the cooling pipe and said second end wall, as occurs during expansion and contraction of the pipe. Thus, preferably a mounting device is inserted through an aperture provided in said second end wall with which a support member on the cooling pipe engages to provide the desired support. Advantageously the aperture is provided by the provision in the mould of an insert member which may be removed on completion of the moulding process, preferably the insert member providing on aperture which is interiorly threaded, allowing the mounting device to be screwed into the second end wall. Desirably the aperture so provided is utilised as an Inlet, by which fluid is introduced into the housing on completion of moulding thereof. Desirably the mounting device comprises a stem, and the support member is in the form of a sleeve slidable over the stem, or vice-versa. Alternatively a support member may be utilised which extends through a mounting device moulded into the second end wall of the housing, preferably being capable of limited relative axial movement therein during differential thermal expansion and contraction. Preferably the inlet and outlet end portions of the cooling pipe are secured to unions which are moulded into the first end wall of the housing. Since the unions during rotational moulding will become heated, plastics material will be adhered to the unions on the interior of the housing. In this manner by locating a junction between the cooling pipe and the union which is close to said first end wall, the junction will be covered with plastics material, enabling the cooling pipe to be provided in steel, and the union in brass, without corrosion of the junction under electrolytic action of the eutectic liquid taking place. According to this invention there is also provided a method of manufacturing a cooling device of the kind specified, involving (not necessarily in sequence) the steps: (a) providing a cooling pipe of elongate "U" shape; (b) securing an elongate support member to a central part of the cooling pipe, the suport member extending generally parallel to the arms of the "U"; (c) locating the cooling pipe in relation to one end wall of the mould; (d) utilising a mounting device with which the support member engages to provide support for the cooling pipe; and (e) rotationally moulding a housing around the cooling pipe. The mounting device may be located in the other end wall of the mould prior to commence of the moulding operation, the support member extending through and being in slidable engagement with the mounting device, or alternatively the mounting device may be located in an aperture In the end wall of the housing subsequent to completion of the moulding operation, the support member slideably engaging with the mounting device to provide the necessary support for the cooling pipe. Desirably fluid is introduced into the housing subsequent to the moulding thereof through said aperture prior to the location therein of the mounting device, the mounting device also serving to prevent escape of fluid from the housing through said aperture. Most conveniently the cooling pipe is located to in relation to said opposite end wall of the mould by the use of unions secured to the end portions of the cooling pipe, and by which a supply of coolant fluid may be connected to the cooling pipe. There will now be given a detailed description, to be read with reference to the accompanying drawing, of two cooling devices which are preferred embodiments of this invention, and which have been selected for the purposes of illustrating the invention by way of example. In the accompanying drawings: FIGURE I is a schematic section view of the cooling device which is the first embodiment of this invention; FIGURE 2 is a schematic section view of the cooling device which is the second embodiment of this invention; and FIGURE 3 is a sectional view showing a stage in the moulding of the second embodiment. The cooling devices which are the preferred embodiments of this invention are generally for use in transportation vehicles, and are designed to maintain the transportation space of such vehicles cool over prolonged periods. It will be appreciated however that the cooling device may also be used in relation to the maintenance of static places at a low temperature. The device which is the first embodiment comprises an elongate housing 6 of generally rectangular cross-section, comprising side walls 8 and first and second end walls 10, 12. Mounted generally centrally within the end wall 12 is a mounting device 14 comprising a boss 16, which is threaded both interiorly and exteriorly, and a stem 18 provided with a through-bore 20 which opens into the central aperture 22 defined by the boss 16. A lock-nut 24 screwed on to the exterior of the boss 16 clamps the end wall 12 against a flange 26 of the mounting device. The cooling device also comprises a cooling pipe 30 of elongate "U"shape, comprising a curved portion 32 and parallel arms 34. The cooling pipe is of steel, and comprises an elongate support member 28 welded to the centre of the curved portion 32, so as to extend generally parallel to, but in opposite directions from, the parallel arms 34. The support member extends Into the bore 20 of the stem 18, a sleeve 21 beIng provided to assist such relative movement. At the left hand end, the member 28 extends into a bore of a cap 28. Each of the arms 34 is welded to a brass union 36, each union 36 being somewhat similar to the mounting device 14, comprising an exteriorly threaded boss 38 located in an aperture 40 of the end wall 10, a lock-nut 44 on the boss clamping the wall 10 against a flange 46. On the exterior of the housing, an exterior pipe may be connected to the boss 38 by a clamping nut (not shown). Also provided in the end wail 10 is an inlet fitting 56, through which the housing 6 may be filled with a eutectic liquid, the fitting 56 subsequent to such filling being closed by a sealing cap 58. In use the cooling device which is the first embodiment of this invention is mounted adjacent to the roof of a transportation vehicle, conveniently utilising as mounting means the boss 16, and if desired the bosses 38 and the exterior pipes are connected to a refrigeration unit, conventionally mounted behind the vehicle cab. At a convenient time (usuolly overnight, or when the vehicle is not otherwise being used) the refrigeration unit is powered, and cooling liquid flows into the cooling pipe 30 via the exterior pipes, reducing the temperature of the eutectic liquid within the housing 6 until such liquid freezes. During such reduction in temperature, differential thermal contraction, particularly of the pipe 30 relative to the housing 8, involves an extension of the support member 28 within the bore 20 (that is, movement to the left, as shown in the drawings). In the method of manufacture of the cooling device which is the first embodiment of the invention, said method also being illustrative of certain aspects of this invention, the mounting device 14 is first located in one end wall of a rotational moulding mould, and the pipe 30, with unions 36 and supporting device 26 secured thereto, is located within the mould cavity, the support member 28 being inserted into the bore 20 of the stem 18 of the mounting device, and the unions 36 being located in bores in the opposite end walls of the mould. Plastics material is introduced into the mould cavity and the mould heated in conventional manner, and rotated about a number of axes, to deposit plastics material on the walls of the mould to provide the housing. Since the pipe 30 is not heated to any signifIcant extent, plastics material wlll not be deposited thereon. However mounting device 14 and the unions 36, being supported in the walls of the mould, wIll be heated to some extent, causing plastics material to be deposited thereon. Thus a skin of plastics material extends from the wall over the mounting device 14 and over both unions 36. This skin of plastics material has two advantages: in relation to the mounting device 14 and unions 36, it may wholly prevent eutectic liquid leaking from the housing 6 during use of the cooling device, and in relation to the unions 36, covers the junction (indicated by the letter "J" in the drawing) between the steel pipe 30 and the brass unions 36, protecting the junction against damage to due to electrolytic action of the eutectic liquid. The cooling device which is the second embodiment of this is similar to that which is the first embodiment, and will be described hereinafter only in as much as it differs from said first embodiment, similar numerals being utilised in Figure 2 in relation to the second embodiment, with a suffix a where appropriate. In the second embodiment, the end wall 12 is provided, during the moulding thereof, with a threaded aperture 27, within which a mounting device 70 is screwed, the mounting device comprising a plug 72, and a stem 74. The support member secured to the cooling pipe 32 is in the form of a hollow sleeve 28a, in which the stem 62 extends, providing support for the cooling pipe 32 whilst allowing a small degree of relative movement to take place longitudinally of the stem 74, due to expansion and contraction of the cooling pipe. The aperture 27 is provided in the end wall 12 by the use of an insert member 60, located in an aperture in the end wall mould portion 4 prior to commencement of the rotational moulding operation (see Figure 3). The insert member 60 is positioned within an aperture 5 of the mould portion, with a shoulder 61 engaging an inner wall of the mould. A hollow tube 64 of PTFE Is inserted through a longitudinal bore of the insert member, the tube 64 entering the hollow sleeve 28a secured to the cooling pipe 32, to support the cooling pipe during moulding, as has previously been described. A plug 66 is then screwed onto the exterior of the insert member 60, to hold the assembly In position during use. During rotational moulding, the Insert member 60 becomes hot and moulding material adheres to the exterIor thereto, as is shown at 13. As will be seen from Figure 3, the part of the insert member 60 which projects interiorly of the mould cavity is threaded, as at 62. Thus on completion of moulding the plug 66 may be withdrawn, and on separation of the mould members, the insert member 60 may be screwed away from the thickened portion 13 leaving the threaded aperture 27 extending through the end wall 12. It will be appreciate that whilst moulding material may temporarily adhere to the tube 64, particularly in the region thereof immediately adjacent to the insert member 60, it may nonetheless readily be withdrawn by virtue of its construction of PTFE. The aperture 27 may be utilised for the introduction of eutectic liquid into the interior of the housing, and on completion of filling, the aperture 27 may be closed by the use of the mounting device 72, an "0" ring being utilised to prevent leakage of fluid between the bore 27 and the mounting device. During the insertion of the mounting device into the bore 27, the stem 66 enters the hollow sleeve 28a, conveniently being guided therein by a flaring of the outer end of the sleeve 28a. As will be appreciated, by virtue of the fact fact that eutectic liquid may be introduced into the housing through the aperture 27, the aperture and plug system 56/58 required in the first embodiment is no longer necessary. The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method of process for attaining the disclosed result, or a class or group of substances or compositions, as appropriate, may, separately or any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims: CLAIMS: I. A cooling device comprising a housing (6), a cooling liquid in the housing, and a cooling pipe (30) located within the housing, whereIn the housing Is rotationally moulded around the cooling pipe. 2. A cooling device according to Claim I wherein the cooling pipe (30) extends in the housing (6) from and to one end wall (10) thereof. 3. A cooling device according to one of Claims I and 2 wherein a central portion (32) of the cooling pipe (30) is supported by a supporting means (28, 14; 28a, 72) by which said portion (32) of the pipe is supported relative to the other end wall (12) of the housing. 4. A cooling device according to Claim 3 wherein the supporting means comprises a mounting device (7cm) inserted through an aperture (27) provided in said second end wall (12) with which a support member (28a) on the cooling pipe engages. 5. A cooling device according to Claim 4 wherein the aperture (27) is provided by the provision in the mould of an insert member (60) which is removed on completion of the moulding process, preferably the insert member providing an aperture which is interiorly threaded (62) and the mounting device (70) is screwed into the second end wall (12). 6. A cooling device according to any one of Claims 4 and 5 wherein the aperture (27) is utilised as an inlet, by which fluid is introduced into the housing (6) on completion of moulding thereof. 7. A cooling device according to any one of Claims 4, 5 and 6 wherein the mounting device comprises a stem (74), and the support member (28at is in the form of a sleeve slidable over the stem, or vice-versa. 8. A method of manufacturing a cooling device, involving (not necessarily in sequence) the steps: (a) providing a cooling pipe (30) of elongate "un shope; (b) securing an elongate support member (28, 28a) to a central pert (32) of the cooling pipe, the suport member extending generally parallel to the arms of the "U"; (c) locating the cooling pipe in relation to one end wall (10) of the mould; (d) utilising a mounting device (14, 70) with which the support member (28, 28a) engages to provide support for the cooling pipe (30); and (e) rotationally moulding a housing (6) around the cooling pipe(30). 9. A method according to Claim 8 wherein the mounting device (14) is located in the other end wall (12) of the mould prior to commencement of the moulding operation, the support member (28) extending through and being in slidable engagement with the mounting device (14). 10. A method according to Claim 8 wherein the mounting device (70) is located in an aperture (27) in the end wall (12) of the housing subsequent to completion of the moulding operation, the support member (28a) slidably engaging with the mounting device (70) to provide the necessary support for the cooling pipe (30).

Inventors: FOX, IAN FREDERICK, GATLEY, RICHARD, NEALE, GREVILLE THEODORE
Applicants: POLARPAC SYSTEMS LIMITED
Application year: 1986
Main classification: F25D3
IPC codes: B29C41, B29C70, F25D3