EP0723111A1

EP0723111A1 - Lighting device for household appliances

Info

Publication number: EP0723111A1
Application number: EP96100974A
Authority: EP
Inventors: Stefano Belfiore; Daniele Cerruti; Costanzo Gadini; Diego Simonelli
Original assignee: Eltek SpA
Current assignee: Eltek SpA
Priority date: 1995-01-24
Filing date: 1996-01-24
Publication date: 1996-07-24
Anticipated expiration: 2016-01-24
Also published as: ITTO950040A0; ES2168398T3; IT1280798B1; DE69617062T2; ITTO950040A1; EP0723111B1; DE69617062D1

Abstract

A lighting device, specifically for household appliances, of the kind comprising a basic structure (2), provided with means for the screwing of a lamp (7,7A,8) and with contact and electric connection means (19,21A,21B); according to the invention additional means (3,4,5) are provided in the form of a seal to be inserted on said basic structure (2) and/or on said lamp (7,7A,8) to hermetically close for protection purposes against infiltrations one or more areas of the basic structure (2) and/or of the lamp (7,7A,8) assembled therein. In a preferred embodiment of the invention also the actuation means of the device are enclosed in an airtight housing.

The lighting device according to the present invention has particular advantages for application in the field of refrigerating appliances using gas of explosive nature.

Description

The present invention concerns a lampholder device for household appliances, specifically for application in refrigerating appliances as described in the preamble of the appended Claim 1.
It is known that the environmental harmfulness of the gases used so far in the refrigerating appliances has led the manufacturers of said household appliances to replace them with other equivalent less polluting gases.
However, some of these new gases being used are particularly explosive by nature, hence a likely saturation of the refrigerating cell in case of a casual gas leakage may cause a deflagration risk. Such a deflagration risk increases considerably in the presence of electric circuits, due to possible sparks essentially caused by defective contacts or by the normal opening-closing operation of electric push-buttons and contacts.
In the case of refrigerating appliances, the main spark source may be generated by the lighting circuit, particularly the lampholder usually located inside the cabinet of the refrigerating appliance.
In fact, should the refrigerator become actually saturated with explosive gas due to a fault, any likely sparks at lampholder level could cause a deflagration. Such a sparking could be due for instance to an uncorrect lamp screwing, a damaged lamp or defective electric contacts of the lampholder.
Moreover, mechanical tolerances between the lampholder seat and the lamp are usually such that they cannot warrant a correct resistance to unscrewing. As a result, the lamp may become loose due to the operating vibrations of the refrigerating appliance and generate an unsafe contact with the proper electric contact blades of the lampholder.
It should also be mentioned that even screwing manually the lamp in the lampholder may disconnect the electric contact between the glass bulb and the metal tang or bulb screw base; such an occurrence may cause an unsafe contact of the internal electric connections with a consequent sparking risk.
Finally, it is known that the lamps equipped with E14 standard thread available on the market may differ both for their power (10/15/20 W) and different dimensions and configurations of the glass bulb.
It is the object of the present invention to solve the above inconveniences. In this frame, it is a primary object of the present invention to provide a lighting device capable of removing the explosion risks related to possible sparks originated in a household appliance.
It is also an object of the present invention to provide a lampholder fitted with an airtight seal capable of fitting to the various types of available lamps and acting at the same time as a locking element against lamp unscrewing.
It is a further object of the present invention to allow the conversion of a common lampholder into an airtight sealed lampholder type, suitable for other likely applications as well.
These objects are obtained according to the present invention by providing a lighting device for household appliances incorporating the features of the appended claims.
The features and the advantages of the present invention will become apparent from the following description and appended drawings, which are supplied only by way of non limiting example, wherein:

Fig. 1 is a front view of a lampholder device according to the features of the present invention;
Fig. 2 shows the lampholder device according to section A-A of fig. 1;
Fig. 3 shows the lampholder device according to section B-B of fig. 1;
Fig. 4 is a sectional view of a first detail of the lampholder device according to figs. 1-3;
Fig. 5 shows the detail of fig. 4 according to section A-A of fig. 4;
Fig. 6 is a sectional view of a second detail of the lampholder device according to figs. 1-3;
Fig. 7 is a front view of the detail of fig. 6;
Fig. 8 is a sectional view of a third detail of the lampholder device shown in figs. 1-3;
Fig. 9 is a side view of a first lamp type with E14 thread showing max tolerance dimensions;
Fig. 10 is a side view of a second lamp type with E14 thread showing min tolerance dimensions.

With reference to the above figures, 1 indicates a lampholder device as a whole, which is part of the lighting device according to the present invention, specifically suitable for application in refrigerating appliances.
Said device 1 comprises a basic structure 2 consisting of a standardized lampholder type, known as such, where said structure 2 has a kind of nut-screw to lock a lamp and the related contact and electric connection elements; according to the present invention, some additional components are related to this basic structure 2 as indicated by 3, 4 and 5 in the various figures, each one of them capable of warranting a different protection degree to the device according to the present invention.
Specifically, 3 indicates a first seal made of flexible material, such as rubber, forming the main element of a protection system for the device according to the present invention. Said first seal 3 is suitable to hermetically enclose the area where a likely loosening of the glass bulb 7 from the screw base 8 of a lamp assembled on the structure 2 may occur.
As best shown in Fig. 5, the first seal 3 has a breakthrough area or section for the lamp screw base 8 with teeth 9 made of the same material as seal 3. Said teeth 9 are so configurated in their dimensions and orientation to allow an easy screwing of the lamp and oppose on the other hand an unscrewing of the lamp 7-8 inserted in the structure 2.
As said above, the seal 3 is manufactured from flexible material and comprises a first upper lip termination 10, which fits flexibly to the various dimensions and configurations of the lamp bulb screwed in the lampholder to obtain a gastight sealing right on the bulb side.
To this purpose, the device 1 according to the present invention is shown schematically in figs. 2 and 3 as if it were housing two lamps of different type, corresponding to those illustrated in figs. 9 and 10. The larger bulb shown in fig. 9 is indicated with 7, whereas the smaller bulb for the lamp of fig. 10 is indicated with 7A. In the same figures, 6 and 6A indicate the joining area between the lamp bulb and the screw base.
As shown in figs. 2 and 3, said termination 10 is fit to take different positions according to the bulb geometry of the lamp in use.
The seal 3 also comprises a second lower termination 11 as clearly shown in the enlarged detail of Fig. 4. Said second termination 11 fits flexibly to the screw base 8 upon screwing and is suitable to ensure gastightness right on the screw base 8 side facing the lampholder.
Therefore, said terminations 10 and 11 are delimiting an intermediate chamber 12 shown in figs. 2 and 3, to protect the joining area 6 or 6A between the bulb 7 or 7A and the lamp screw base 8 against a possible explosive gas infiltrations. As previously explained, said area is particularly at risk due to a possible loosening of the bulb from the screw base with a consequent sparking within the live electric wires.
Said terminations 10 and 11 pressing the external profile also aid to avoid any unwanted loosening of the lamp.
As best seen from Fig. 4, the seal 3 comprises a throat 13 towards the outside to insert the seal 3 with interference on the structure 2. In particular, both surfaces 14 and 15 opposite the throat 13 are fit to perfectly adhere to the structure 2, thus obtaining a subsequent seal against withdrawal. Said seal can eventually be improved by bonding the parts together or adding an outside band, which is not shown.
The seal 3 also has a peripheral seat 16 to fasten a second element 5 of the device according to the present invention, as it will be further described.
20A and 20B indicate two flat surfaces obtained on the external and internal surface of the seal 3, respectively. Said flat surfaces 20A and 20B represent the supporting points of a special assembly tool - not shown in the figures - which provides an axial thrust for the seal 3 to be inserted on the structure 2 without the risk of damaging the parts.
In the above figures 4 indicates a second seal made of flexible material, which is fit for insertion in the lower side of the basic structure 2. As best seen in Figs. 6 and 7, to this purpose said second seal has two slots 17 and 18, whose dimensions are slightly smaller than the ones of the electric connection terminals of the structure 2, indicated with 19.
Then the seal 4 can be inserted on the lampholder lower side with the terminals 19 forced in the slots 17 and 18. As a result, the seal 4 is gastight by adhering to the terminals 19 and to the structure 2, isolating the area where the electric contact elements 21A and 21B of the lamp are shown, assuring a second degree of protection in agreement with the device according to the invention.
Finally, 5 indicates a third seal or outside housing made of transparent flexible material, such as silicone, which allows a third degree of protection against the risk of cracking for the lamp glass bulb 7 or 7A. In the practice said outside housing 5 configurated as a cap is inserted over the bulb 7 or 7A and on the first seal 3. In particular, the outside housing 5 has a termination 5A configurated as an O-ring type seal, fit to engage the peripheral seat 16 of the first seal 3. Therefore the housing 5 can be inserted over the lamp bulb and enclose it completely to warrant the required airtightness. Also the housing 5 based on the type of lamp inserted in the structure 2 can aid to avoid any unwanted lamp loosening.
Finally, actuation means of the device 1 are provided according to the invention, located on a doorpost of the cabinet containing the refrigerating appliance. The purpose of said actuation means, which may consist eg. of a push-button switch - not shown in the figure for simplicity's sake - is to detect the opening and closing of the door and consequently control the switching on and off of the lamp screwed in the lampholder.
Assembly and operation of the device according to the present invention is as follows.
The seals 3 and 4 are inserted over the basic structure 2 consisting practically of a substantially standardized lampholder type as mentioned above. In particular, the seal 4 is forced on the electric connection terminals 19 of the lampholder through the slots 17 and 18 to warrant gastigthness on that side and specifically in the electric contacting area 21, whereas the seal 3 is inserted over the part where the lamp will be fastened through the throat 13, using the above mentioned assembly tool.
Then the lamp is screwed as usual in the lampholder. Due to the existing seal 3, at least a part of the lamp screw-base 8 is located within the teeth 9 suitable to hinder a loosening of the lamp. Independently from the lamp dimensions, lip termination 10 of the seal 3 warps flexibly against the lamp bulb 7 or 7A to warrant the sealing on that side. The second termination 11 of that same seal 3 warrants on the other hand a gastightness in the lower side of the joining area 6 between the lamp bulb and the screw base. Thus, a gastight chamber 12 is practically formed between lip termination 10 and termination 11 to protect against a likely loosening of the bulb from the screw base.
Finally, the outside housing 5 made of transparent flexible material is inserted over the lamp and fits to the bulb 7 or lamp 7A geometry. Said housing 5 is fastened through its end section 5A having the form of an O-ring seal, which mates with the relevant peripheral seat 16 of the seal 3; as a result a further protection related to the possibility of a lamp bulb cracking is warranted.
In case of a lamp replacement, it will be enough to remove the housing 5A, unscrew the lamp to be replaced, screw on the new lamp and assemble the housing 5A back again.
It should be noticed that teeth 9 are provided to hinder any unwanted lamp unscrewing; to this purpose both the seal 3 and teeth 9 are designed to require at least 0.3 N.m unscrewing torque. Obviously, this does not hinder a manual unscrewing of the lamp.
According to the above description the characteristics of the present invention appear quite obvious and also its advantages are clear.
One of the main advantages according to the present invention is the possibility of converting a conventional lampholder (2) in an airtight lampholder (1) in a rather simple and low-cost manner, whose application is especially beneficial in the field of the refrigerating appliances, and which is suitable to warrant three different airtightness degrees:

for the electric contacts between lampholder and lamp,
for the joining area between lamp bulb and screw base,
for the lamp bulb.

At the same time, the special design of this same device according to the present invention avoids the risk of casual lamp unscrewing; on the other hand its gastightness and resistance to undesired loosening does not hinder a replacement of the lamp.
Also the advantages of the present invention appear clear in terms of design simplification and manufacturing standardization, since the manufacturer can use the same lampholder basic structure 2 both for the applications that do not require airtight sealing and for those where such a sealing is required. To this purpose it should also be mentioned how the device can flexibly fit the various geometrical configurations of the lamps available, i.e. using the same components all time.
Finally, it is obvious that many changes and modifications are possible to the lampholder device described only by way of example, without departing from the novelty spirit of the innovative idea.
As said above, in the case of refrigeration appliances the main sparks source can be represented by the lighting circuit, which besides the lampholder also has a push-button switch located on the doorpost of the refrigerator cabinet. Therefore, if the refrigerator is saturated with explosive gas, also the likely sparks due to the closing of said push-button may cause a deflagration when opening the door. Therefore, a special advantageous embodiment of the present invention is provided with an airtight push-button whose electric contacts are isolated from the sorrounding environment by an adequate airtight housing enclosing them.
It is also clear that the device described above by way of example can find application in other fields other than refrigeration, i.e. wherever an airtight protection on one or more lampholder areas is required; for instance, the device described herein can be used on washing-machines, such as laundry-washers, eg. for lighting inside the washing tank , i.e. with the purpose of isolating the electric parts of the lighting system inside the washing tank and avoid humidity and water infiltrations.

Claims

A lighting device, in particular for household appliances, of the type comprising a basic structure (2), provided with means for the screwing of a lamp (7,7A,8) and with contact and electric connection means (19,21A,21B), characterized in that additional means (3,4,5) are provided in the form of a seal to be inserted on said basic structure (2) and/or on said lamp (7,7A,8) to hermetically close for protection purposes against infiltrations one or more areas of the basic structure (2) and/or of the lamp (7,7A,8) assembled therein.
A device according to the previous Claim, characterized in that said additional means (3,4,5) are also provided for avoiding undesired unscrewing of the lamp (7,7A,8) assembled in the basic structure (2).
A device according to Claim 1 or 2, characterized in that a plurality of said additional means (3,4,5) is provided, each one being apt at providing the device with different protection degrees, through airtight protection of a precise area of the basic structure (2) and/or of the lamp (7,A,8) assembled therein.
A device, according to at least one of the previous Claims, characterized in that said additional means (3,4,5) comprise a first seal (3), in particular made of flexible material, which hermetically encloses the joining area (6,6A) between the glass bulb (7,7A) and the screw base (8) of the lamp assembled in the basic structure (2).
A device, according to at least one of the previous Claims, characterized in that said additional means (3,4,5) comprise a first seal (3), in particular made of flexible material, having a passage zone or section for the screw base (8) of lamp (7,A,8), said passage zone comprising teeth (9) whose dimensions and orientation are so configurated to allow an easy screwing of the lamp and oppose resistance on the other hand to an unscrewing of the lamp (7,7A,8).
A device, according to Claim 4, characterized in that said first seal (3) comprises a first termination (10) to flexibly fit to the various dimensions and/or shapes of the bulb (7,7A) of the lamp assembled in the basic structure (2), in particular to obtain an airtight seal on the bulb side.
A device, according to Claim 4, characterized in that said first seal (3) comprises a second termination (11) to flexibly fit to the screw base (8) of the lamp assembled in the basic structure (2), in particular to obtain an airtight seal on the screw base side.
A device, according to Claim 4, characterized in that said first and second terminations (10,11) delimit an intermediate airtight protection chamber (12) of the joining area (6,6A) between the glass bulb (7,7A) and the screw base (8) of the lamp assembled in the basic structure (2).
A device, according to Claim 4, characterized in that said first seal (3) has a throat (13) for the fastening on the basic structure (2), the fastening of the two elements being in particular improved through bonding and/or by the addition of an external band.
A device, according to at least one of the previous Claims, characterized in that said additional means (3,4,5) comprise a second seal (4), in particular made of flexible material, fit to hermetically close the zone of the electric contacts (21A,21B) between the lamp and the basic structure (2).
A device, according to the previous Claim, characterized in that said second seal (4) has at least a slot (17,18) for its forced insertion on at least an electric connection terminal (19) of the basic structure (2), said second seal (4) adhering onto said terminal (19) and to the basic structure (2) to obtain the required airtight seal.
A device, according to at least one of the previous Claims, characterized in that said additional means (3,4,5) comprise an external housing (5), in particular made of transparent flexible material, such as silicone, for hermetically enclosing the bulb (7,7A) of the lamp assembled in the basic structure (2).
A device, according to the previous Claim, characterized in that said outside housing (5) is inserted over the lamp bulb (7,7A) to fully enclose it, and partially on said first seal (3), said esternal housing (5) having in particular a termination (5A) apt at engaging a peripheral seat (16) available on said first seal (3).
A device, according to Claim 12, characterized in that said outside housing (5) aids to avoid any unwanted lamp unscrewing.
A device, according to one or more of the previous Claims, characterized in that a lamp actuating switch is provided, in particular to detect the opening and closing of a door and consequently to control the switching on and off of said lamp, whose electric contacts are isolated from the sorrounding environment through a proper airtight housing enclosing them.
A device, according to one or more of the previous Claims, characterized in that it is used for illuminating the inside of refrigerating appliances or washing machines, respectively for hermetically enclosing possible spark generating areas, to protect them against deflagration caused by casual gas leakage, and for protecting electric parts against humidity and water infiltrations.
A refrigerating appliance, having a cabinet and a refrigeration circuit, with live operating electric means provided inside the cabinet, characterized in that the refrigeration circuit uses a gas capable of explosion under determined failure conditions of the appliance and wherein the electric means are enclosed in airtight housings and hinder the gas eventually seeped from the refrigeration circuit to reach any live electric parts of said electric means, said electric means being in particular a lighting lamp located inside the cabinet and/or its lampholder and/or the lamp actuating switch.