The invention also relates to a lamp system comprising a lamp with a valve device in the fuel reservoir and a filling device therefor.

A lamp as described above is known from SU-A1-1 749 611 that teaches a transparent lamp with a fuel reservoir between an external tubular member and an internal tubular member, wherein the two tubular members are connected at the bottom by an annular wick of a porous, ceramic material that can be soaked by the fuel (paraffin), but does not allow the fuel to flow freely out of the fuel reservoir. In order to ensure that the paraffin can be drawn out through the porous wick, as it is combusted, the fuel reservoir is upwardly open such that a sub-atmospheric pressure is not generated within the fuel reservoir. Such sub-atmospheric pressure would have an inhibiting effect on the paraffin supply to the flame.

When the ceramic wick is lit, the heat from the flame will cause the paraffin in the fuel reservoir to melt, and a lens is formed between the internal and external

tubular members of the lamp. A reflector can be provided to orient the light of the flame in a given direction.

The lamp shown and described in the above-mentioned disclosure is a so-called top/bottom-hole lamp as it is provided with an opening below as well as above the burning area. Hereby it is ensured that there will always be a large amount of oxygen available for the combustion, but simultaneously a very unsteady flame is obtained, since the movement of the ambient air heavily influences the flame and, likewise, movement of the lamp will influence the flame considerably.

Another lamp wherein the fuel reservoir is situated above the burning area as such is known from eg German patent No 8804 that teaches a lamp with a fuel reservoir that is in communication with two open burning areas. Prior to use, the fuel reservoir is charged with oil through a supply opening that is subsequently sealingly closed.

When a tap at the bottom of the reservoir is opened, some of the oil leaves the reservoir and is distributed in the two burning areas, while simultaneously air penetrates and takes the place of the oil thus left, within the reservoir through a tubular member that extends upwards to the upper end of the reservoir. When the oil level reaches the lower end of the tubular member, no more air is able to penetrate into the reservoir, and it follows that no more oil is able to leave either. Upon combustion of the oil in the two burning areas, the oil level will slowly decrease and when it has dropped to a point below the end of the air pipe, air will again enter the reservoir whereby a certain amount of oil leaves until the oil level reaches the lower end of the pipe again. In this manner the level is automatically adjusted.

That lamp comprises a central fuel reservoir and two burners with open burning areas and pipes that convey the oil from the central fuel reservoir to the two burners.

The two burners being arranged at a long distance from the fuel reservoir, it is not possible with that lamp to make use of the fuel for achieving special optical effects.

It is the object of the present invention to provide a lamp of the kind described above that will, in addition to the option of accomplishing the special optical effects by use of a transparent fuel, enable that a very steady flame is also obtained in a very simple manner.

This is obtained by configuring the lamp described above in such a manner that, in the in-use situation, the fuel reservoir is upwardly sealingly closed, whereas at the lower end it is in open connection with the burning area; said lamp being configured such that, during operation, a substantially uniform fluid level is maintained in the burning area, and wherein the burning area is exclusively in contact with the surroundings via the opening provided at the upper end of the lamp.

Hereby a lamp is obtained that is of a very simple design, but still ensures a very steady flame. The lamp according to the invention can be designated a top-hole lamp; the lamp obtaining oxygen exclusively from the air that is drawn down through the opening in the upper end of the lamp or the top hole, as opposed to the lamps according to the prior art wherein the oxygen is primarily supplied from below or laterally of the flame.

In this manner it is obtained that it is primarily the

heat from the flame itself that is determining for the pressure conditions that prevail in the burning area; and that the flame is influenced only to an insignificant degree by the movements of the ambient air.

The lamp is made essentially of transparent glass, such as borosilicate glass that exhibits very suitable properties with regard to deformability and heat resistance.

Preferably the fuel reservoir extends 360° around the open burning area such that optical effects can be generated at all sides.

According to a preferred embodiment an external tubular member that is sealingly connected to a bottom and a top, and an internal tubular member that is sealingly connected only to the top delimit the fuel reservoir. At the same time the wick device is provided at the bottom and extends upwards within the internal tubular member, while the opening is arranged at the top within the inner wall of the interior pipe. This embodiment forms a simple and very harmonious lamp.

In the simplest embodiment the external tubular member as well as the internal tubular member is configured with circular cross sections, but in order to obtain special optical effects the lamp can be provided with a non- circular, internal tubular member.

Preferably the wick device comprises a tubular wick holder with an opening at the lower end and a wick tube with a wick, said wick tube being arranged inside the

wick holder. Thus, the wick tube can be removed for adjustment of the wick's position within the wick tube.

The wick tube can be mounted in the wick holder in various ways. For instance, at the upper end the wick tube can be provided with an outwardly oriented collar such that it can be suspended on the upper edge of the wick holder, or there can be provided an internal thread in the wick holder, which thread is able to cooperate with a thread provided on the outside of the wick tube.

This latter solution using a thread means that the wick tube cannot drop out, if for instance the lamp overturns.

Thus the risk of a fire breaking out is minimised.

Besides this solution presents certain advantages from a cleaning point of view, as it can be emptied of oil and optionally arranged upside down in a dishwasher without the wick tube falling out.

In order to facilitate filling of the lamp it can be provided with a device that will, during charging with fuels, allow air to exit at the top of the fuel reservoir, but that will, during operation, prevent air from entering at the top of the fuel reservoir.

Preferably this device consists of an oil lock that comprises an internal tubular member that is open at both ends and that is in open communication with a ventilation opening at the top of the fuel reservoir, and an external tubular member that surrounds the internal tubular member in a non-sealing manner and that is closed at the bottom and is in open communication with the upper, internal area of the fuel reservoir. Such device effectively prevents, during operation, air from entering the reservoir for fuel, while simultaneously it allows air to

leave the fuel reservoir during renewed charging with oil.

For use in the filling operation for a lamp that is configured in this manner, a filling device has been developed that comprises a plug that is able to shut off an area above the open burning area, and a filling pipe that will, during charging with fuel, extend through the plug from a level above the top of the fuel reservoir to a point below the level of liquid in the open burning area. Preferably the filling pipe is provided with a funnel at its upper end. In this lamp system the charging of oil can be accomplished in a simple and auto- regulating manner.

The invention will now be described in further detail with reference to the drawing, wherein Figure 1 shows a lamp according to the invention in its most simple, fundamental configuration; Figures 2a-2f show lamps featuring a number of alternative embodiments of the internal tubular member; and Figure 3 shows a detail of an embodiment wherein the wick tube and wick holder of the lamp are threaded; Figure 4 shows a lamp provided with an'oil lock'whereby charging of oil is facilitated.

Figure 1 shows a lamp according to the invention in its most simple fundamental configuration. Preferably the lamp is made of transparent glass, and in a preferred

embodiment of so-called borosilicate glass that has, on the one hand, a very high melting point and is hence refractive and, on the other hand, it is comparatively easy to mould to a desired shape.

The lamp comprises an external tubular member 1, an internal tubular member 2, a bottom 3, a top 4, a wick holder 5 and a wick tube 6 with a wick 7. In the embodiment shown, the external tubular member 1 as well as the internal tubular member 2 is configured with circular cross sections. The external tubular member is configured integrally with the bottom 3 that is configured as a circular disc, and with the top 4 that is also configured as a circular disc, albeit provided with a circular, centrally situated opening 8. The internal tubular member 2 is sealingly connected to the top 4 around the central opening 8, but is freely suspended a distance above the bottom 3.

Centrally on the bottom 3 a wick holder 5 is mounted that extends upwards within the internal tubular member 2. The wick holder 5 is not sealingly connected to the bottom 3, but it is provided with an opening that allows oil to flow into the wick holder 5.

Inside the wick holder 5 a wick tube 6 is arranged that is, at the upper end, provided with an outwardly protruding collar such that the wick tube 6 is able to hang on the upper end of the wick holder 5 without sealingly connecting to the bottom 3. A wick of a woven material is arranged in a manner known per se within the wick tube 6.

Figure 1 shows the lamp in its in-use position, ie the space between the external tubular member 1 and the internal tubular member 2-the fuel reservoir-are partially filled with a burnable liquid, such as lamp oil.

In the starting position, the fuel reservoir is preferably filled completely with oil, and since it is impossible for air to enter at the top of the fuel reservoir, it is possible to establish an oil level in level with the lower end of the internal tubular member 2. When the wick 7 is lit, it draws oil from the fuel reservoir below the internal tubular member 2, whereby the oil level at the lower end of the internal tubular member 2 is slowly decreased. At a given time the oil level has sunk so far that an air bubble will find its way around the lower edge of the internal tubular member 2 and disappear upwards into the fuel reservoir whereby a corresponding amount of oil will flow from the fuel reservoir to the burning area. This process repeats itself for as long as the wick 7 is lit, and in this manner a constant oil level is maintained in the burning area in level with the lower end of the internal tubular member 2.

It is to be noted at this point that the oil level may rise slightly within the internal tubular member 2, immediately after the wick 7 has been lit, since the oil in the fuel reservoir is heated by flame and therefore expands.

The lamp shown in Figure 1 has a very simple construction and due to the configuration of the fuel reservoir around the wick 7 and the flame, it presents some interesting

optical properties. Of course, they are particularly pronounced when the fuel reservoir is filled completely, but interesting optical effects are also obtained when the fuel reservoir is filled to a smaller extent.

In order to obtain further optical properties, the external tubular member 1 as well as the internal tubular member 2 may have other configurations than that of a circular tube. Figures 2a-2f show a number of examples of different embodiments of the internal tubular member 2a- 2f that each imparts to the lamp some interesting optical properties.

In Figure 2a the internal tubular member 2a is configured as a square tube with rounded corners.

In figure 2b the internal tubular member 2b is configured as a triangular tube with rounded corners.

In figure 2c the internal tubular member 2c is configured as a tube with a hexagonal cross section.

In Figure 2d the internal tubular member 2d is configured as an approximately square tube with inwardly curved sides.

In Figure 2e the internal tubular member 2e is configured as an approximately triangular tube with inwardly curved sides.

In Figure 2f the internal tubular member 2f is configured as an approximately triangular tube with dent formations on the sides.

Many other configurations of the internal tubular member are possible, albeit practice has shown that the smallest distance from the wick to the inside of the internal tubular member should not be less than about 20 mm if a controlled heat formation without turbulence is to be achieved in the tube in order for the flame to remain steady.

Of course, the external tubular member 1 can be modified in a similar manner for obtaining special optical effects.

Figure 3 shows a detail from an alternative embodiment of a lamp according to the invention. In this lamp the wick holder 15 and the wick tube 16 is provided with cooperating threads such that the wick tube 16 does not fall out of the wick holder 15 in case the lamp accidentally overturns or in case it is positioned in its inversed position in a dish washer for cleaning purposes.

When the lamp shown in Figure 1 is to be charged with oil it is necessary to pour the oil down through the internal tubular member 2 and then turn and rotate the lamp in order in order to make the oil enter the fuel reservoir.

This is not particularly convenient and there is a high risk that oil is spilled during handling of the lamp.

A solution to this filling problem could be to provide the top 4 of the fuel reservoir with an opening that is, in the in-use situation, closed by means of e. g. a plug.

When the lamp is to be charged with oil, the plug is removed following which the oil can be poured directly down into the fuel reservoir. In order to avoid that the oil rises within the internal tubular member 2, the

central opening 8 in the top 4 is to be closed such that the trapped air keeps the oil level within the internal tubular member 2 down. This can be accomplished by means of a plug.

Instead of a plug at the top 4 of the fuel reservoir, the opening can be provided with a one-way valve that allows air to flow out of the fuel reservoir, but not into same.

The filling could be accomplished through a filling pipe that extends through the plug in the central opening 8 and debouches in the burning area around the wick holder.

When the oil is poured through the filling pipe it will rise in the fuel reservoir and press the repressed air out through the one-way valve.

An opening at the bottom of the fuel reservoir is a third solution for charging oil. However, this solution requires that the lamp is turned upside down when oil is to be charged with an ensuing risk that oil runs out through the central opening 8 at the top 4 of the lamp.

Figure 4 shows a lamp with a device that facilitates the charging of oil. The device comprises an'oil lock'20 that is integral with the lamp and a filling device that is, in the preferred embodiment, a separate element that is used only during charging of oil.

The lamp is constructed in the same manner as the lamp shown in Figure 1, ie with an external tubular member 1, an internal tubular member 2, a bottom 3, a top 4, a wick holder 5 and a wick tube 6 with a wick 7. As described above the external tubular member 1 and the internal tubular member 2 delimit the fuel reservoir.

In the fuel reservoir an'oil lock'20 is configured that is constituted by two tubes, an internal tube 21 and an external tube 22, wherein the internal tube 21 is arranged within the external tube 22. The internal tube 21 is sealingly connected to a ventilation opening 23 at the top 4 and is thus in open communication with the ambient air. The external tube 22 that is downwardly closed encloses the internal tube 21, albeit it opens towards the fuel reservoir at the top. In practice the external tube 22 will be connected to the top and merely be provided with an opening towards the fuel reservoir, but for the sake of overview it is shown as being completely open at the upper end.

A filling device comprising a plug 24, a funnel 25 and a filling pipe 26 is shown in its almost mounted position and its functioning will be described in the following.

Before the lamp is used for the first time it must be charged with oil. This is accomplished by positioning the filling device as shown in Figure 4 in the central opening 8 of the lamp, the plug 24 being pressed downwards and sealingly closing the central opening 8.

When the oil is subsequently charged to the funnel 25, it will run downwards to the bottom of the lamp and start to rise in both the internal tubular member 2 and the fuel reservoir, whereas the repressed air will disappear through the oil lock 20.

When the oil level reaches the lower edge of the internal tubular member 2, a closed space is formed therein, which is delimited by the oil level at the bottom and by the sealing plug 24 in the central opening 8. Thus air will no longer be repressed from this space and the oil will

rise only in the fuel reservoir. This continues until the oil reaches the opening at the upper end of the external tube 22 in the oil lock 20. Now the oil starts to fill the oil lock 20 as it continues from the external tube 22 into the internal tube 21 via the opening at the bottom thereof. The charge of oil can be stopped when the oil lock 20 is approximately half filled since, already at this point, it acts as an'oil plug'for the ventilation opening 23 and it does not allow air to be drawn into the oil reservoir this way. The filling device is removed following which equilibrium will be established in the oil-charged portions and the lamp is ready for use.

The functioning of the oil lock 20 will be described in the following. When lit, the wick 7 draws oil from the burning area below the internal tubular member 2. As described above with reference to Figure 1 the oil level in the burning area will be at an approximately constant level at the lower end of the internal tubular member 2, the consumed amount of oil being replaced by a corresponding amount of oil from the fuel reservoir while simultaneously air enters the fuel reservoir at the lower end of the internal tubular member 2 and replaces the oil thus discharged.

Despite the fact that a minor subatmospheric pressure prevails in the air-containing portion of the fuel reservoir (above the oil in both the fuel reservoir as well as within the oil lock 20), the force of gravity will prevent that the oil in the oil lock 20 will be drawn into the fuel reservoir. Thus, the oil in the oil lock 20 forms an oil plug that effectively prevents that air can be drawn into the fuel reservoir along this way for equalising the pressure difference.

When the lamp is to be replenished with oil, the filling device is once again used. The plug 24 is sealingly positioned in the central opening 8 of the lamp, and the filling pipe 26 is positioned as shown in Figure 4. The oil lock 20 will continue to contain oil that forms an oil plug that prevents air from entering the lamp.

However, the funnel 25 of the filling device being located at a higher point than the oil plug in the oil lock 20, the oil plug will, however, be pressed out of the oil lock when oil is charged thereto. This will happen until the"rear"end of the oil plug reaches the bottom of the oil plug 20 since the air that pushes the oil plug will subsequently start to rise up through the oil plug due to the difference in densities of oil and air.

When the lamp is filled to a sufficient degree the filling device is again removed and renewed equilibrium will prevail.

In case the oil lock 20 is completely filled with oil, a certain amount of oil flows out of the ventilation opening 23 when new oil is supplied through the filling device. If, however, there is only a small amount of oil in the oil lock 20, it is possible that the oil plug is merely pressed into the internal tube 21 of the oil lock 20 following which the repressed air will move upwards through the oil plug and escape through the ventilation opening 23. It can thus be avoided that oil flows out of the ventilation opening 23 during replenishing with oil.

In the embodiment shown the oil lock 20 consists of an internal tube 21 and an external tube 22. However, it may

also consist of a single U-shaped tube wherein the one end of the tube is in open communication with the ventilation opening 23 whereas the other end of the tube is in open communication with the upper area of the fuel reservoir.

The oil lock 20 can thus be positioned such that the optical effects are enhanced, or it can be arranged such that it disturbs the optical effects as little as possible.

Preferably the entire lamp is made of glass, in particular borosilicate glass exhibiting, as mentioned above, adequate material properties, but parts of the lamp could also be made of some other material, eg in case the lamp is provided with a ventilation valve of metal, rubber, plastics or the like.

Typically the oil used is colourless, but in order to provide further optical and aesthetic effects the oil can be coloured.

In the embodiments shown, the fuel reservoir of the lamp is formed of two concentric tubes. However, nothing hinders that the fuel reservoir does not extend 360° around the burning area and thus around the flame, but merely extends partially around the burning area. The lamp could for instance be configured with a plane rear and a fuel reservoir that extends in front of the flame only with a cross section as a semi-disc. Such lamp could be positioned against a wall.

Other modifications are also perceivable without thereby departing from the idea of the invention.