[001] The present invention relates to a connection bush for radiator elements and in particular to a bush of the lightweight type.

[002] Specifically, it is known of in the art to make connection bushes for radiators, called 'nipples' , which mechanically and fluidically connect two adjacent radiator elements. [003] In fact, the bushes are hollow, cylindrical bodies which define a through-aperture for the radiant liquid, for instance oil or water. Said bushes on the external lateral surface have a pair of threadings opposite each other, that is one right-handed and one left-handed, so as to be contemporaneously screwed onto the threadings of the connection holes of two radiator elements next to each other.

[004] The bushes also have on their external lateral surface a sealing element, typically an O-ring, to form a hydraulic seal with the inner walls of the radiator elements and channel all the water or oil through the through-section so as to enable the circulation of the radiant fluid between the radiator elements. [005] The known, state-of-the-art solutions have a number of drawbacks. [006] For example they are made in metallic material and are therefore heavy and expensive to make. The thickness, and therefore the weight and cost of the bushes, is high since the tightening torque of the bushes may reach as high as 20 Kgm.

[007] In addition, the metallic bushes tend to transmit the heat to the gasket sealing the bush body and the inner lateral walls of the radiator elements between which the bush is inserted. [008] The rubber gasket tends to become damaged as a result of overheating and no longer ensures tightness over time. This phenomenon may occur both during normal functioning of the radiator and also, above all, during the painting phase during which pre-assembled packs of radiators are placed in painting stoves at about 200 ⁰ C for approximately 10 minutes.

[009] In addition, in oil radiators using electric resistors inside the radiant elements, on account of thermal warping, accidental contact between the resistors and the inner lateral walls of the bushes may occur; as a result of such contacts the resistors transmit a large quantity of heat to the bushes and from these to the gaskets which thus easily deteriorate. In fact, the resistors reach temperatures of several hundred degrees centigrade. [0010] The excessive transmission of heat to the gaskets through the metal in the bushes may therefore irremediably compromise sealing performance and cause hazardous leakages of liquid from the radiator elements. [0011] In addition, the known, state-of-the-art bushes are heavy and expensive to transport.

[0012] The aim of the present invention is to produce a bush which resolves the drawbacks mentioned with reference to the known technique. [0013] Such drawbacks and limitations are resolved by a bush according to claim 1.

[0014] Other embodiments of the bush according to the invention are described in the subsequent claims. [0015] Further characteristics and advantages of the present invention will be evident from the description below, made by way of a non-limiting example, of its preferred embodiments, wherein:

- figure 1 shows a perspective view of a bush according to one embodiment of the present invention;

- figure 2 shows a front view of the bush in figure 1, from the side of the arrow II in figure 1;

- figure 3 shows a cross-section view of the bush in figure 1, along the cross-section plane III-III in figure 2; - figure 4 shows a perspective view of a component of the bush in figure 1.

[0016] The elements or parts of elements common to the embodiments described below will be indicated by the same reference numeral.

[0017] With reference to the aforesaid figures, reference numeral 4 globally relates to a connection bush for radiator elements, able to mechanically and fluidically connect two radiator elements adjacent to each other (not shown) .

[0018] The bush 4 comprises a bush body 8 which defines and delimits, in correspondence with an internal lateral wall 12, a through-section 16 of radiant liquid, such as water or oil for example. [0019] The bush body 8 presents, on an external lateral wall 20, opposite the internal lateral wall 12, a pair of threadings 24 for screwing the bush 4 onto the associable radiator elements, [0020] Preferably, the bush body 8 is a cylindrical body with an X-X axis.

[0021] The threadings 24 are preferably opposite each other, that is one right-handed and one left-handed, so as to enable contemporary screwing of the bush 4 onto the radiator elements next to each other. [0022] Advantageously, the bush body 8 is made in plastic material and comprises a core 28 in metallic material, mechanically separate from the bush body 8 and countersunk inside the body 8 itself.

[0023] Preferably, the plastic material comprises a thermoplastic and/or heat-hardening plastic.

[0024] According to one embodiment said plastic material comprises nylon loaded with glass fibre.

[0025] According to one embodiment, the core 28 comprises a cylindrical collar 32 fitted with a number of holes 36 able to form a bond between the bush body 8 and the core

28 countersunk inside it.

[0026] According to a further embodiment, said core 28 comprises a cylindrical collar 32 fitted with a number of protuberances or teeth (not shown) able to form a bond between the bush body 8 and the core 28 countersunk inside it.

[0027] Preferably, the core 28 presents, in correspondence with the axial rims 40, a regular profile comprising an alternation of ridges 44 and grooves 48. [0028] Axial rims are understood to be rims positioned in correspondence with opposite extremities of the bush body

8 along the X-X axis.

[0029] According to possible embodiments, the profile is a triangular, sinusoidal or staggered (figure 4) profile. [0030] The bush body 8 comprises, in correspondence with the inner lateral wall 12, a number of teeth 52 able to permit the grasping and rotation of the bush 4 from the inside, for clamping of the same between the radiator elements .

[0031] Preferably, the teeth 52 extend along the entire axial extension of the bush body 8.

[0032] The bush body 8 comprises at least two teeth, positioned diametrically opposite each other ; according to possible embodiment variations, the bush body comprises three or four teeth positioned angularly at set intervals, that is the teeth 52 are equally angularly distanced at angles of 120 and 90 degrees respectively. [0033] Preferably, the teeth 52 are made in one piece with the bush body 8, that is in the same injection moulding. [0034] The bush body 8, in correspondence with the external lateral wall 20 comprises a central ring or seat 56, delimited axially by the pair of threadings 24. [0035] The central ring 56 is axial-symmetric in relation to the axis X-X so as to form a constant support wall for an associable gasket (not shown) . [0036] In other words, the central ring 56 is a smooth, cylindrical, lateral wall, free of grooves, hollows or protuberances. Such central ring 56 forms a seat for the gasket and provides constant support of the gasket as well as an improved hydraulic seal between the gasket and the walls of the radiator elements between which the bush is placed.

[0037] Preferably, the central ring or seat 56 is radially included between the ridges 44 and the grooves 48 of the external threadings 24 of the bush I: this way the ridges 44 of the threadings 24 form an axial bond with the gasket which remains positioned in the centre line of the bush body 8.

[0038] The method of producing a bush according to the invention will now be described. [0039] Specifically, the method of realisation comprises the phase of predisposing a cylindrical core 28 in metallic material, positioning it in a mould for the production of the bush body 8 and then injecting plastic material so as to form the bush body 8 englobing the core 28 in the plastic.

[0040] The phase of predisposing the metallic core 28 preferably comprises cutting a band having an axial width equal to the core 28 from a sheet, and a rolling phase of the cut band into a cylindrical shape. Preferably, the sheet rolled into a cylindrical shape may be directly positioned in the mould before the injection without sealing the rolled band, for example by welding. [0041] In fact, the rolled band is in itself sealed by the injection of plastic material. [0042] Following extraction of the bush from the mould, the superficial finishing of the external lateral wall 20 of the bush 4 both in correspondence with the external threadings 24 and with the central ring or seat 56 of the gasket, may be performed. [0043] As may be appreciated from the description, the bush according to the invention makes it possible to overcome the drawbacks mentioned in relation to the known technique. [0044] Specifically, the bushes made according to the present invention have a mass of approximately one-third of the bushes of the known art, but with the same through-section diameter of the radiant liquid. [0045] In addition such bushes are less expensive to produce given that they require a significantly smaller quantity of metallic material than those of the known art, despite ensuring a hermetic seal and mechanical resistance of the same level.

[0046] In addition, the bushes are extremely cheap to transport given that they are decidedly lighter than the bushes of the known art.

[0047] Moreover, the bushes of the present invention are coated in a polymer material which does not transmit heat and therefore preserves the gaskets from heat damage both during painting in the stove and during functioning of the radiators. [0048] In addition, in the case of electric radiators working on oil, any accidental contact of the internal resistors with the inner lateral wall of the bushes will not transmit great heat to the gaskets. [0049] Moreover, thanks to the fact that the bush body is made by moulding, the realisation of the teeth for screwing on the bush does not entail the creation of hollows or recesses on the external wall of the bush body. This way the external lateral wall acts as a constant and regular support to the associable gasket which is evenly compressed and deformed against the seats of the radiator elements, ensuring a safe hermetic seal. [0050] Advantageously, the inner metallic core enables the bush to withstand the high axial traction loads generated following tightening of the bush between the radiator elements .

[0051] The use of holes or protuberances in the core makes it possible to create bonds or undercuts between the core and the plastic die of the bush body which the core is countersunk in by moulding: such bonds ensure the cohesion of the core and the bush body even when the latter is subjected to high axial loads.

[0052] In addition, the core in metallic material ensures resistance of the bush to axial loads over time; specifically, it prevents any sudden tensile breaking of the bush body even in the event that the plastic of the bush body should weaken on account of ageing. [0053] Advantageously, teeth can be made all along the axial length of the bush body by moulding without having to thereby modify the geometry of the seat or central ring for the gasket: such teeth are therefore very resistant and can withstand high tightening torques of the bush without requiring reinforcements of said teeth. [0054] A person skilled in the art may make numerous modifications and variations to the bushes described above so as to satisfy contingent and specific requirements while remaining within the sphere of protection of the invention as defined by the following claims .