Lamp holding fixture for a refrigeration apparatus

Abstract: Lamp-holding fixture for a refrigeration apparatus, in particular a household refrigerator or freezer, comprising one or more refrigerating circuits filled with inflammable refrigerant gases and including at least a compressor, a condenser, one or more evaporators associated to one or more food storage compartments, said food storage compartments being illuminated by at least an incandescent lamp supported by a respective lamp-holding fixture (1), wherein said lamp-holding fixture comprises an internal volume (25) that is hermetically sealed off the outside environment and is provided with at least a terminal (18, 35) adapted to establish a contact with or becoming separated from electrical lead wires connected with the power supply circuit of the lamp. Said lamp-holding fixture is provided with at least an opening (10), a shiftable element (12) being arranged inside said opening so as to be able to close said opening due to the action of a spring element (14), said shiftable element (12) being further adapted to slide so as to open said opening due to the action of a terminal (5) that pushes against said moving element, and with at least a contact element (18) that is arranged substantially in a line with said opening (10) being provided inside said lamp-holding fixture.

Description: The present invention refers to a lamp-holding fixture for a refrigeration apparatus. In particular, the present invention refers to a lamp-holding fixture which can be used with all types of refrigeration apparatuses, particularly of the household or residential type, which are provided with at least a food storage compartment, a lamp for the internal lighting of said food storage compartment and a refrigerating circuit, of which a portion, typically the evaporator, is at least partly housed inside said food storage compartment, said refrigerating circuit being filled with an inflammable gas, such as for instance methane or butane. For reasons of greater simplicity, the following description will refer to a refrigeration apparatus with a single food storage compartment, but it will be appreciated that the invention extends to also cover a lamp-holding fixture for refrigeration apparatuses that may be provided with several food storage compartments and related evaporators and internal lighting lamps. It is a largely known fact that the pressure exerted by the public opinion in favour of increasingly environment-friendly products, ie. products that must be environmentally sustainable even after they are discarded at the end of their life cycle, has had both directly and indirectly an impact on industry as a whole, inducing it to develop products that are capable of meeting such environment-oriented requirements to an ever greater extent. In this connection, a direct impact is unfolding through a clear trend which is discernible among consumers in general, who seem to increasingly favour so-called "ecological" or green products, putting environment-friendliness on top of their purchase criteria, as stimulated by press and advertising campaigns that are quite qften made on purpose, ie. for reasons of self-interest. On the other hand, an indirect impact is being produced by the setting up and the imposition of a whole set of regulatory, manufacturing and product design obligations aiming at gradually marginalizing products that are not considered or perceived as being adequately ecological. It is basically for this second reason that all types of refrigeration apparatuses making use of chlorofluorocarbons (CFCs) as blowing agents in their thermal insulation foams have been phased out, or are now being phased out, from production by the manufacturers in the most advanced countries of this world, while the public opinion is clearly showing a general sensitiveness for and interest in the purchase of refrigerators that do not contain chlorofluorocarbons at all, ie. not even as working fluids in the refrigeration circuit. As a consequence, refrigeration appliances have been developed in which the refrigerant or working fluid is made up by a gas or a mixture of gases that do not feature any significant ozone-depletion potential, but are in many cases inflammable. In order to avoid any risk of explosion in the case of such gases leaking into the closed compartment containing the stored food, particular configurations have been proposed for the internal lighting lamps, which, even if broken, do not trigger an ignition of a gas mixture that could possibly be around there. In this connection, reference should be made to the Italian application for a utility model no. PN93U000024. It has been however observed that, even if such lamps are effectively protected against the risk of their breakage turning them into a cause of ignition of a possible inflammable gas mixture, the same lamps must in any case be such as to be able of being replaced in the case of a malfunction or a breakage. If also the terminals that supply the power to said lamps are to be given such an explosion-proof quality, which is an obvious consideration since it would be perfectly useless to adopt explosion-proof lamps, if their power-supply terminals are anyway capable of triggering an explosion, then such terminals shall be unremovably locked or fixed to the lamp's own terminals or the screw attachment or cap thereof, so as to positively exclude the possibility of sparks being ever generated. Furthermore, the lead wire that branches off said terminals shall be in turn connected to the power delivering points within the refrigeration apparatus in such a manner as to ensure full safety as far as said explosion hazards are concerned. It is of course fully possible to implement all such precautionary measures, but this anyway involves an intervention of adequately skilled personnel to perform the related operations, as well as to possibly replace not only the lamp, which, as already noted, is not separable from its holding fixture, but also the lamp-holding fixture and the related lead wires. In practice, it would be impossible for an average user, ie. a person with an average degree of skill and ability, to replace the lamp, while the compulsory intervention of an external serviceman would bring about unreasonably high costs if related to the value of the apparatus and the actual cost of the lamp itself. Furthermore, even in the case that a defective lamp has to be removed, without being able or wishing to immediately replace it with a new one, the refrigeration apparatus should of course be capable of keeping operating. In such a case, the presence of live terminals which become exposed through the removal of the lamp would undoubtedly constitute a hazardous situation. It would therefore be desirable, and it actually is a main purpose of the present invention, to provide a lamp-holding fixture for a refrigeration apparatus, such as in particular a household refrigerator or freezer, which is equipped with a lamp, said lamp and said lamp-holding fixture having an explosion-proof construction, wherein the lamp is readily removable from its holding fixture even by relatively unskilled persons, whereas the lamp-holding fixture itself cannot represent a hazard situation even when the lamp is removed therefrom, without this involving a more complicated construction or the use of new, not readily available techniques, while keeping production costs at a quite low level. These aims are reached by a lamp-holding fixture as defined in the appended claims. To provide a better insight into the present invention, this will be described more in detail below by way of non-limiting examples with reference to the accompanying drawings, in which: Figure 1 is a cross-sectional view illustrating schematically the structure of a lamp-holding fixture according to the present invention, as shown without the lamp; Figure 2 is the same cross-sectional view as described in connection with Figure 1, however with the lamp mounted in place; Figure 3 is an enlarged view of a portion of the cross-section shown in Figure 2; Figure 4 is a view of a second embodiment of a lamp-holding fixture according to the present invention; Figure 5 is a view of the lamp-holding fixture shown in Figure 4, however without the lamp mounted in place; Figure 6 is a second cross-sectional view of the lamp-holding fixture appearing in Figure 4. The following description will be referred, by mere way of example and for reasons of greater simplicity, to a refrigeration apparatus with single refrigerated storage compartment lighted by a single lamp. It will be however appreciated that what is here described and claimed similarly applies to any type of refrigeration apparatus, regardless of the number of food storage compartments and internal lighting lamps used. The devised solution to the afore cited problems substantially consists in providing a lamp-holding fixture 1 having a box-like, sealed construction, with a single recess 2 provided for the insertion of the cap 3 of the lamp 4. Said cap is provided with at least an electric power-supply terminal for the lamp, and the contact between said terminal and the corresponding power-supply member occurs in a sealed chamber which is impervious to the gas around it and is a part of said lamp-holding fixture, said electric contacts between the lamp terminals and the corresponding power supply terminals taking therefore place in the inner volume of said chamber. According to a first embodiment of the present invention, as illustrated in the accompanying Figures 1, 2 and 3, said cap is provided with two prominent, parallel terminals 5, 6 connected to the lighting element (not shown) inside the lamp. On a closed wall 7 arranged in front of said recess 2, said lamp-holding fixture is provided with two guiding provisions 8, 9, having preferably a conical shape and arranged at an equal distance with respect to said respective terminals 5, 6. Each one of said two guiding provisions 8, 9 terminates with a small opening 10, 11, respectively, which is just sized to allow for the passage therethrough of the respective terminal of the lamp, whereas beyond said opening there is arranged a shiftable element 12, 13, respectively, adapted to close the respective opening 10, 11 by displacing transversally with respect to the respective opening owing to the action of a respective spring element 14, 15. By moving further on into the inner side of said lamp-holding fixture, it is possible to find, beyond said shiftable element provided to close said respective opening, two respective housings 16, 17 having a elongated shape and provided there in an aligned arrangement with respect to the respective openings, said housings being such as to be capable of accomodating said respective terminals. Along said respective housings there are arranged two respective contact elements 18, 19 having preferably the form of an elastic blade, in such a position as to be able to come into contact with said respective terminals when inserted full-depth in the respective openings. In view of facilitating such contact, said element are provided, on their end portion facing the lamp, with two respective guiding provisions 20, 21, which are preferably made by bending the corresponding contact elements accordingly, the latter being firmly connected to the power-supply lead wires. Finally, said shiftable elements 12, 13 are provided, in correspondence of their portion closing said corresponding openings, with respective oblique sides 22, 23 facing said respective openings. The box-shaped lamp-holding fixture 1 has therefore a fully sealed construction and, when applied on to the inner wall of the food storage compartment that must be lighted, it further seals up in an air-tight manner its inner volume, with particular reference to its inner volume 25 that houses the contact surfaces of said terminals and said corresponding contact elements 18, 19. In order to ensure a most reliable air-tight sealing of said inner volume 25, it is advantageous to provide a flexible inner sealing ring 26, arranged to face the oblique sides of said shiftable elements 12, 13. Such a ring is elastic and preferably made of an elastomeric material, so that, when the lamp is removed, the two shiftable elements 12 and 13, by moving forward due to the action of their respective spring elements, go pushing against said sealing ring 26, thereby ensuring a perfectly air-tight sealing of said inner volume 25. The operation of the above described arrangements is as follows: if it is assumed that the lamp-holding fixture is installed correctly and the lamp is not inserted therein, but is on the contrary removed from its seat (Figure 1), in such a case the two shiftable elements 12 and 13, due to the biasing action of their respective spring elements 14, 15 are shifted in such a manner as to obstruct the respective openings 10, 11 and, as a result, the gas surrounding the lamp-holding fixture is positively prevented from leaking into the inner volume thereof and this practically eliminates any explosion hazard in case of sparks being generated between the contact elements 18, 19. Such an air-tight sealing action is ensured in a particularly effective manner by the elastic ring 26 or similar means which, being arranged in front of said shiftable elements 12, 13, are adapted to back up the pushing action thereof and determine an effective air-tight sealing of said respective openings 10, 11. When the lamp is then introduced in its seat, with its cap entering the recess 2, the terminals 5 and 6, as guided by the respective guiding provisions 8 and 9, go striking and then pushing against the oblique sides 22, 23 of said shiftable elements, thereby causing them to slide transversally in opposition to the biasing action of the spring elements, and setting then the respective passages free for the entry of the respective terminals which, by continuing their sliding motion along said housings 16, 17 to complete their insertion, come into contact with the corresponding contact elements 18, 19, as facilitated in doing this by their respective guiding provisions 20, 21 which practically guide them into slidingly position themselves in a side-by-side arrangement between said terminals 5, 6 and said corresponding contact elements (Figure 2). When the lamp needs to be replaced, it will be sufficient to pull it out using just the force that is required to overcome the force of friction existing between said terminals and the respective contacts, as well as between the same terminals and the shiftable elements 12, 13 that push transversally against these terminals. When said terminals are pulled out, said shiftable elements 12, 13, being no longer stopped by the terminals, will regain their position in which they obstruct their respective openings, owing to the biasing action of their respective spring elements. A second embodiment of the present invention is illustrated in the Figures 4 to 6. With particular reference to Figure 4, the inner air-tight volume 25 of the lamp-holding fixture can be seen to contain a first moving electric terminal 31 which is substantially cylindrical in its shape and passes slidingly through an appropriate air-tightly sealable opening of said inner volume, said terminal being further adapted to come into contact with the lower contact point 32 of a traditional screw-attachment type lamp which is screwed on a corresponding threaded attachment 33 in a traditional manner. In a frontal position with respect to the inner portion 34 of said moving electric contact there is arranged a conductive terminal 35, which is adapted to rotate about an appropriate pin 36, which is also arranged within said air-tight inner volume, owing to a pushing effect applied at the opposite end 37 by said conductor 35. Said opposite end is adapted to be shifted by an elastic relief 38 which is a part of the elements provided to ensure air-tight sealing of the inner volume 25, said elastic relief 38 being in turn shiftable by a moving element 39 actuated by the door-actuated switch. The second electric contact is supplied by a side terminal 31B, which protrudes from the threaded wall of the lamp-holder and comes into contact with the threaded attachment or conductive cap 33 of the lamp. Said second electric contact 31B enters said inner volume 25 through an elastic air-tight sealing gasket 50, while, inside said inner volume 25, the other end portion of said electric contact 31B is capable of coming into releasable contact with a conductor 45B connected to the other polarity of the power supply. Said elastic air-tight sealing gasket and said electric contacts 31B and 45B are arranged and shaped in such a manner as to ensure that, when the lamp is fully screwed in, its threaded portion 33 establishes a contact with said electric contact 31B and pushes it so that the latter, by moving inwards, ultimately establishes a contact, with its opposite end portion, with the conductor 45B. When the lamp is removed, as it is shown in Figure 5, said contact 31B, which is no longer pushed by the threaded portion of the lamp, moves forward owing to the effect of the elastic sealing gasket 50, thereby separating its opposite end portion from said conductor 45B and, as a result, isolating itself from its power supply source. With reference to Figure 5, where the same lamp-holding fixture is illustrated without a lamp mounted, it should be noticed that the outer portion 40 of the recess provided to accomodate the lamp is made of an elastic material and is in the shape of an inwardly oriented frustum of a cone. Additionally, the inside diameter of said outer portion 40 for the passage of the lamp is so sized as to be able to elastically interfere with the bulb of the lamp when the latter is being screwed on into its seat, so that an inflammable atmosphere being possibly present in the compartment is positively prevented from reaching the attachment edge 41 between the bulb of the lamp and the cap 42 thereof. In this way, even considering the possibility of a breakage occurring in correspondence of said attachment edge, the air-tight sealing effect ensured by said outer portion 40 of the recess acting against the bulb of the lamp, makes it possible to use any type of lamp, and not special explosion-proof lamps only. With reference to Figure 6, which illustrates a cross-sectional view taken orthogonally with respect to the cross-section illustrated in Figure 4, it should be noticed that an elastic element 43 is applied between the body of the lamp-holder and said passing-through electric terminal 31. When in a resting state, ie. when no lamp is mounted, the elastic action exerted by said element 43 on the passing-through electric terminal 31 causes the latter to take a position in which it is situated out of said inner volume 25. The operation of such a lamp-holding fixture is as follows: when the lamp is removed (Figure 5), the elastic element 43 causes the inner portion 34 of the passing-through moving terminal 31 to move away from the conductive terminal 35, while the air-tight construction of the conduit in which said passing-through terminal 31 is sliding ensures that there are no infiltrations of gas into said inner volume 25, so that there is no possibility for situations capable of triggering an explosion to occur inside said volume. A similar condition occurs, as described above, for the other contact 31B, so that said passing-through moving terminal 31 and said contact 31B are both isolated from their power supply source and, as a result, are not able to give rise to explosion triggering hazards when the lamp is removed. When the lamp is on the contrary mounted, the point of contact 32 of the lamp goes pushing against the head portion of the passing-through terminal 31, thereby causing it to move inwardly up to the point in which its inner end portion comes into contact with the conductive terminal 35 that is permanently connected to the power supply through a further elastic contact 45. A similar condition occurs for the contact 31B with respect to the screw cap of the lamp, as described previously, so that the lamp can now be supplied correctly. Furthermore, the points of mutual contact between live conductors are between the contact 31B and the conductor 45B, as well as between the passing-through terminal 31 and the terminal 35, ie. both of them occur within the inner volume 25 so as to ensure a complete isolation from the outside atmosphere, excluding all related hazards even in the case of sparks being generated between said electric contacts. When the door of the refrigeration apparatus is closed, the related lever 39 is caused to act against the elastic sealing element 38, which, yielding to said force, moves forward until it abuts against the end portion 37 of the conductive terminal 35 which, by acting as a lever about the pin 36, moves said terminal away from the inner end portion 34 of said passing-through electric terminal 31, thereby cutting the power supply to the lamp. However, the spark that can possibly be generated between said terminals when they separate, would occur within the inner volume 25 which, being sealed off the outer atmosphere in an air-tight manner, would not give rise to any explosion triggering hazard. As a result, following advantages are reached with the present invention: a) possibility to mount and remove the lamp by the user, without the need arising for calling a serviceman; b) rapidity in establishing the connection between the lamp and the related power-supply circuit; c) use of regular, commercially available lamps; d) possibility of using the refrigeration apparatus even without a lamp being mounted in the lamp-holding fixture of the food storage compartment; e) overall cost-effectiveness of the proposed construction, and possibility of using simple, reliable and readily available techniques. It will of course be appreciated that lamp-holding fixtures according to the present invention may also be provided in forms and shapes that differ from the ones described above, without departing from the scope of the present invention as defined in the claims.

Claims: Lamp-holding fixture for a refrigeration apparatus, in particular a household refrigerator or freezer, comprising one or more refrigerating circuits filled with inflammable refrigerant gases and including at least a compressor, a condenser, one or more evaporators associated to one or more food storage compartments, said food storage compartments being illuminated by at least an incandescent lamp supported by a respective lamp-holding fixture (1), characterized in that said lamp-holding fixture comprises an inner volume (25) which is sealed off the outside environment in an air-tight manner, and that inside said inner volume there is provided at least a terminal (18, 35) adapted to establish a contact with or become separated from electrical lead wires connected with the power supply circuit of the lamp. Lamp-holding fixture according to claim 1, characterized in that said inner volume (25) is provided with at least an opening (10), a shiftable element (12) being arranged inside said opening so as to be able to close said opening due to the action of a spring element (14), said shiftable element being further adapted to slide so as to open said opening due to the action of a lamp terminal (5) that pushes against said shiftable element, at least a contact element (18) being further arranged inside said lamp-holding fixture substantially in a line with said opening (10). Lamp-holding fixture according to claim 2, characterized in that said at least a shiftable element (12) is provided, in correspondence of its portion obstructing said opening (10), with an oblique side (22) facing said opening. Lamp-holding fixture according to claim 2 or 3, characterized in that said opening (10) is provided with guiding means (8), which may have a conical shape, adapted to facilitate the introduction of said lamp terminal (5) in said opening. Lamp-holding fixture according to any of the preceding claims from 2 to 4, characterized in that it is provided internally with a housing (16) having an elongated shape and provided there in an aligned arrangement with respect to said opening, and that along said housing there is arranged a contact element (18) having preferably the form of an elastic blade and provided, at its end portion facing said opening, with a guiding means (20) formed preferably by bending. Lamp-holding fixture according to any of the preceding claims from 2 to 5, characterized in that said shiftable element (12) is adapted to slide in an orthogonal direction with respect to the axis of said opening. Lamp-holding fixture according to any of the preceding claims from 2 to 6, characterized in that there are provided elastic means (26) that are adapted to elastically and sealingly stop the movement of said shiftable elements (12) by sustaining the force exerted by said oblique side (22) when said lamp is removed. Lamp-holding fixture according to any of the preceding claims from 2 to 7, characterized in that in correspondence of the side containing said opening there is provided a recess (2) adapted to accomodate the cap (3) of a lamp (4) in such a manner that said lamp terminal (5) is able to get inserted in said opening (10). Lamp-holding fixture according to claim 1, characterized in that said inner volume (25) contains a first electric moving terminal (31) passing slidingly through an appropriate air-tightly sealing opening in said inner volume and adapted to come into contact with the lower point of contact (32) of a lamp that is screwed on a corresponding threaded portion (33), a conductive terminal (35) being provided in a frontal position with respect to the inner portion (34) of said moving electric terminal, said conductive terminal being adapted to be displaced from a position of contact with to a position of separation from said inner portion depending on the position of a shiftable element (39) actuated by the door-actuated switch button. Lamp-holding fixture according to claim 9, characterized in that said shiftable element (39) is arranged to act upon an elastic relief (38), which impresses a corresponding pushing action on to the opposite end portion (37) of said conductive terminal (35). Lamp-holding fixture according to claim 10, characterized in that said conductive terminal (35) is adapted to rotate about a pin (36) arranged inside said inner volume. Lamp-holding fixture according to any of the preceding claims from 9 to 11, characterized in that a second electric contact is provided by a side terminal (31B) protruding from the threaded wall of the lamp-holding fixture and coming into contact with the conductive threaded portion (33) of the lamp, said second electric contact (31B) entering said inner volume (25) through an elastic air-tightly sealing gasket (50), the other end portion of said electric contact (31B) being capable of establishing a releasable contact with a conductor (45B) connected to the other polarity of the power supply, said elastic air-tightly sealing gasket and said electric contacts (31B, 45B) being arranged so that, when the lamp is screwed in, its threaded portion (33) pushes said electric contact (31B) inwardly, thereby causing the opposite end portion thereof to come into contact with the conductor (45B), whereas, when the lamp is removed, said contact (31B) moves backwards, thereby separating its opposite end from said conductor (45B). Lamp-holding fixture according to any of the preceding claims from 9 to 12, characterized in that the outer portion (40) of the recess provided to accomodate the lamp is made of an elastic material and is in the shape of an inwardly oriented frustum of a cone, the inside diameter of said outer portion being such as to elastically interfere with the bulb of the lamp when the latter is mounted in place.

Inventors: PARONI LUIGI, PARONI, LUIGI
Applicants: ELECTROLUX ZANUSSI ELETTRODOME, ELECTROLUX ZANUSSI S.P.A.
Application year: 1995
Main classification: F25D27
IPC codes: F21V25, H01R33, H01R13, F25D27