Patent Description:
Portable combustion products, such as lighters, are commonly designed having a container to store a flammable material, that will be ignited to produce a flame. The flammable material is generally a liquefied petroleum gas (LPG), that is filled under pressure in the container of the lighter through a filling valve of the lighter. During release of the LPG from the container through a release device, in particular an exit valve arranged in the lighter, the gas expands and is mixed with the direct surrounding air. The mixture of gas with the oxygen contained in the surrounding air is ignited at the exit valve of the lighter to produce a flame. For example, <CIT> discloses a combustion device, which is provided with a combustion cylinder, in a lighter, such as a gas lighter for smoker's requisites or a pilot burner, <CIT> discloses a cigarette lighter having an ignition device and fuel storage container together with further chamber for the accommodation of mouthwash and <CIT> discloses a fuel control system for a gas fueled device.

The object of the present invention is to provide a lighter and a container for containing liquefied gas or a mixture of a liquid and gas with improved safety.

The present invention relates to a lighter as defined in claim <NUM>. The dependent claims depict advantageous embodiments of the present invention.

According to the present invention, a lighter comprises a container which is arranged within the lighter, and which is suitable for containing a liquefied gas or a mixture of a liquid and a gas, and a dividing element dividing the container volume into a first volume containing the liquefied gas or the mixture of liquid and gas and into a second separate volume. The dividing element are impermeable to gases and liquids.

In this document, a lighter can be defined as being a portable combustion product and/or a flame producing assembly. Such products and/or assemblies are generally designed to produce a flame out of the combustion of a flammable material, when ignited by an ignition device, that can be integrated to the lighter. The flammable material can be stored within the portable combustion product and/or flame producing assembly, for example in a container comprised within or at the housing of the lighter. The flammable material used in lighters can be liquefied gas, for example liquefied hydrocarbon of the n-butane, isobutane, propane type or a mixture of these gases commonly named liquefied petroleum gas (LPG). The portable combustion products and/or flame producing assemblies are widely used for igniting a variety of combustible materials and items such as cigarettes, candles, flammable gas (e.g., in gas stoves), fireplaces, and many others. Portable combustion products and/or flame producing assemblies can be commercially available in different forms and sizes.

Liquefied gas or a mixture of a liquid and a gas, in particular LPG, has the property to transform gas at least partially into liquid at certain pressure, which allows the gas to be stored in large quantities in a container, mainly in liquid phase, but also partially in gaseous phase (or gaseous sky), both in thermodynamic equilibrium. In filled condition, a typical pressure within the container at <NUM> is <NUM> kPa (above the ambient pressure surrounding the container). The liquid fraction of the liquefied gas can expand with temperature increase, this in proportions directly related to the cubic expansion coefficient of the liquefied gas. A risk situation can occur if an increase of the ambient temperature results in an increased pressure within the container (compared to the ambient pressure surrounding the container) associated without sufficient expansion space within the container. An increased pressure results in the risk that the container gets over pressurized and thus, may burst with possible rapid combustion of the gas into a fireball ("boiling liquid expanding vapor explosion"). This risk is particularly problematic in case of lighters having a refillable container. If the user overfills the container with liquefied gas, the volume for the gaseous phase is very small such that an increased temperature results in a higher internal pressure compared to the situation in which the container is initially filled with less liquefied gas. Non-refillable containers may also be subjected to this risk, but the problem is solved by the producer itself by controlling the filling level during factory filling.

According to the present invention, a dividing element dividing the container volume into a first volume containing the liquefied gas or the mixture of liquid and gas and into a second separate volume, in a gas- and fluid-tight manner, is used instead of or in addition to a compressible member. If the pressure within the first volume increases (in particular due to an increased ambient temperature), the dividing element may move or change its shape in order to increase the first volume and to decrease the second volume at the same time. The dividing element is a membrane. The total container volume comprising the first volume and the second volume is constant at a given ambient pressure and a given ambient temperature. The second separate volume can be reduced by expanding the first volume.

The compression state of the second separate volume may depend on the amount of the liquefied gas or the mixture of liquid and gas contained in the first volume.

The second separate volume may be compressed from an uncompressed state in which the pressure in the container is identical to the ambient pressure, to a first compressed state when the container is filled with a pre-set maximum amount of liquefied gas or of the mixture of liquid and gas.

The first compressed state of the second separate volume may be achieved when the container is filled with an amount of liquefied gas or of the mixture of liquid and gas at a pressure of <NUM> kPa above the ambient pressure.

The second separate volume could be further compressed from the first compressed state to at least a second compressed state when the pressure in the container is increased by an expansion of the liquefied gas or the mixture of liquid and gas caused in particular by an increased temperature, in particular <NUM>° or <NUM>, compared to the temperature, in particular <NUM>, which was present during the initial filling of the container with the pre-set maximum amount of liquefied gas or of the mixture of liquid and gas.

The second separate volume may occupy at least <NUM>% of the total volume of the container when the pressure in the container is identical to the ambient pressure surrounding the lighter, in particular at least <NUM>%, more particular at least <NUM>%.

The second separate volume may occupy not more than <NUM>% of the total volume of the container when the pressure in the container is <NUM> kPa higher than the ambient pressure surrounding the lighter, in particular not more than <NUM>%, more particular not more than <NUM>%.

The liquefied gas of the mixture of liquid and gas may have a vapour pressure at <NUM> that is equal or greater than <NUM> kPa.

The total container volume may be in the range of <NUM> to <NUM> cm3, in particular in the range of <NUM> to <NUM> cm3, more particular in the range of <NUM> to <NUM> cm3.

The container could be refilled with liquefied gas or a mixture of liquid and gas.

The lighter may comprise a first valve device for refilling the container.

The lighter further may comprise a second valve device for withdrawing gas from the container.

The lighter further may comprise an igniting device for igniting the gas exiting the container through the second valve.

The liquefied gas which may be used for the present invention can be for example liquefied hydrocarbon of the n-butane, isobutane, propane type or a mixture of these gases commonly named liquefied petroleum gas (LPG).

Additional details and features of the invention are described in reference to the following figures in which.

Embodiments of the lighter according to the invention will be described in reference to the figures as follows.

<FIG> present a container <NUM> of a lighter according to an example which is not in accordance with the present invention. The container <NUM> comprises a variable first volume <NUM> that can receive a liquefied gas, and a compressible member, that occupies and defines a variable second volume <NUM>. First volume <NUM> and second volume <NUM> constitute a total and constant volume of the container <NUM>. The compressible member is porous and consists of several closed and deformable/compressible cells. It can be made of a polymer, in particular polyurethane or butadiene-acrylonitrile copolymer. An important property of the member is its compressibility.

In <FIG>, the first volume <NUM> does not contain liquefied gas and the compressible member is only subjected to the ambient temperature and ambient pressure. In this configuration, the compressible member occupies an initial volume vi which represents at least <NUM> % (or at least <NUM>%, or at least <NUM>%), most preferably <NUM>% of the total volume V<NUM> of the container <NUM>. The compressible member is in an uncompressed state.

In <FIG>, liquefied gas has been filled in the first volume <NUM> through the filling valve <NUM>. The pressure in the first volume <NUM> typically corresponds to the pressure used for filling the liquefied gas. This pressure also compresses the compressible member. The liquid phase and gaseous phase (also called "gaseous sky") are contained within the first volume <NUM>. Both phases are present in the container in a thermodynamic equilibrium. In normal operation and at room temperature, when gas is withdrawn from the container, the liquid boils and the resulting vapour compensates the volume withdrawn to rebuild the equilibrium. At <NUM> filling temperature (equal to ambient temperature), the vapour pressure of the gaseous phase in the container <NUM> can be greater than <NUM> kPa. Due to the pressure of the first volume <NUM> on the second volume <NUM> (depicted with the arrows from the first volume to the second volume on <FIG>), the compressible member is compressed to a volume v<NUM>.

The size and material characteristics of the compressible member may be chosen in a way that, the compressible member occupies not less than <NUM>% (in some other examples not more than <NUM>%) of the total volume of the container <NUM> at <NUM> (v<NUM>/V<NUM> = <NUM>%) at a certain filling pressure, e.g. at 250KPa (above the ambient pressure). As consequence, the filling volume of the first volume <NUM> does not exceed <NUM>% under these conditions. Therefore, the compressible member limits the maximum amount of liquefied gas within the container during filling, wherein the first volume <NUM> can further expand after filing due to an increased temperature by further compressing the compressible member.

Any increase of temperature in the environment, for example to <NUM> or <NUM>, leads to a temperature increase of the liquefied gas in the container <NUM>, resulting in a pressure increase of the gaseous phase of the liquefied gas. In the case where the liquid occupies exactly the entire free volume of the reservoir, the compressible element will compress by a value proportional to the increase in volume of the liquid according to its coefficient of cubic expansion. Therefore, the pressure exerted on the compressible member also increases and can for example reach <NUM> kPa above the ambient pressure or more, which leads the second volume <NUM> of the compressible member to reduce even more (<FIG>). In this configuration, the compressible member occupies not more than <NUM>% of the total volume of the container <NUM>, or not more than <NUM>%, or not more than <NUM>%.

In the practical case of a lighter with an internal volume Vo = <NUM> cm3 filled with isobutane and where the liquid occupies exactly the entire free volume of the container, the rate of crushing vi / vf would be <NUM> at <NUM> kPa and <NUM>.

The compression property of the member permits to balance the pressure increase between the first volume <NUM> and the second volume <NUM> at constant total volume of the container <NUM> instead of having the container <NUM> itself expand and possibly even burst. For portable products such as torches, lighters or utility lighters, the liquefied gas used can be for example liquefied hydrocarbon of the n-butane, isobutane, propane type or a mixture of these gases commonly named liquefied petroleum gas (LPG).

One risk using LPG is that if the initial liquid level is too high (above <NUM>% of the volume fraction at <NUM>), thermal expansion can cause the gas phase to disappear (the container is then in "full hydraulic state"), and the internal pressure can increase very quickly at the slightest increase in environment temperature. This can cause the container to burst as a result of excessive pressurization of the inner walls of the container. An explosion, also called a "boiling liquid expanding vapor explosion" (BLEVE) could even occur in the worst case. This situation is caused by the complete destruction of the pressurized container containing a liquid, whose temperature is much higher than its boiling point at atmospheric pressure with dramatic consequences following the expansion of the gas sky, the sudden vaporization of the liquid, the possible rapid combustion into a fireball and the dispersion of the container fragments.

<FIG> shows a standard lighter, comprising a container <NUM> with a first valve device <NUM> for refilling the container <NUM>, a second valve device <NUM> for withdrawing the gas from the container, and an igniting device <NUM> for igniting the gas exiting the container through the second valve <NUM>.

<FIG> present a container <NUM> of a lighter according to the invention. Here, the total container volume is divided by a dividing element <NUM> such as a membrane or a flexible element into a variable first volume <NUM> and a variable second volume <NUM>. The first volume <NUM> is configured to be filled with the liquefied gas and the second volume <NUM> is filled with air, and the dividing element <NUM> has the function to balance the pressure differences between the first volume <NUM> and the second volume <NUM>. The addition of the first volume <NUM> and the second volume <NUM> is always constant and represents the total volume of the container <NUM>. To not mix the content of the first volume <NUM> with the content of the second volume <NUM>, the dividing element <NUM> is fixed to the inner surface of the container <NUM> and defines a gas and fluid tight separation. The location of the attachment point of the dividing element <NUM> to the inner surface of the container <NUM> is determined in combination with the material characteristics of the dividing element <NUM> such as to obtain an optimum volume repartition between the first volume <NUM> and the second volume <NUM>, especially once the liquefied gas is filled within the first volume <NUM>.

In <FIG>, the first volume <NUM> is empty from liquefied gas and the dividing element <NUM> is only subjected to the ambient temperature and ambient pressure. At this state, the second volume <NUM> may occupy at least <NUM>% of the total volume of the container <NUM>, or at least <NUM>%, or at least <NUM>%.

In <FIG>, liquefied gas is filled in the first volume <NUM> through a filling valve <NUM>. The liquefied gas exerts a pressure on the dividing element <NUM> of, for example, <NUM> kPa higher than the ambient pressure at <NUM>, which leads the dividing element <NUM> to bend in direction of the second volume <NUM>. Pressure is thus applied on both sides of the dividing element <NUM>, which brings it to an equilibrium position within the container <NUM>. Ideally, at this state, the second volume <NUM> occupies approximately <NUM>% of the total volume of the container <NUM> to assure enough volume for the liquefied gas to expand. Alternatively, the second volume can occupy not more than <NUM>% of the total volume of the container <NUM>, or not more than <NUM>%, or not more than <NUM>%.

In <FIG>, the dividing element <NUM> is further pushed in direction to the second volume <NUM> by the vapour pressure of the liquefied gas with increased temperature. The balance between the pressure differences within the first volume <NUM> and the second volume <NUM> is guaranteed by the flexion property of the dividing element <NUM>. The risk of over pressurization of the container <NUM> is maintained to a minimum, therefore the risk of bursting is limited.

<FIG> presents an alternative embodiment that is not in accordance with the present invention: a compressible element <NUM> is placed within a container <NUM> of a lighter, wherein the compressible element <NUM> is not connected to the side walls of the container, and has, for example, the shape of a ball. The element <NUM> divides the total volume of the container <NUM> in a first volume <NUM> configured to contain a liquefied gas or a mixture of a liquid and a gas, and a second volume <NUM> delimited by the external shape of the element <NUM>. As for the previous aspects of the invention, the second volume <NUM> is subjected to pressure variations of the first volume <NUM> and can compress according to the expansion of the first volume <NUM>. Element <NUM> may have the shape of a hollow ball, or may have the shape of a ball with multiple enclosed pores or cells.

<FIG> present a container <NUM> of a lighter according to the invention. Here, the total container volume is divided by a dividing element <NUM> into a variable first volume <NUM> and a variable second volume <NUM>. The dividing element is a membrane. The first volume <NUM> is configured to be filled with the liquefied gas and the second volume <NUM> comprises a compressible member <NUM>. In <FIG>, the second volume is partially filled with the compressible member <NUM>. Alternatively, the second volume may be fully filled with the compressible member. The dividing element <NUM> has the function to balance the pressure differences between the first volume <NUM> and the second volume <NUM>. The addition of the first volume <NUM> and the second volume <NUM> is always constant and represents the total volume of the container <NUM>. To not mix the content of the first volume <NUM> with the content of the second volume <NUM>, the dividing element <NUM> defines a gas and fluid tight separation. In this embodiment, the dividing element <NUM> is fixed to the inner surface of the container <NUM>. The location of the attachment points of the dividing element <NUM> to the inner surface of the container <NUM> is determined in combination with the material characteristics of the dividing element <NUM> such as to obtain an optimum volume repartition between the first volume <NUM> and the second volume <NUM>, especially once the liquefied gas is filled within the first volume <NUM>.

This embodiment presents a combination of the previously disclosed embodiments, comprising simultaneously a dividing element <NUM> and a compressible member <NUM>. <FIG> shows the container <NUM> in an empty state. The first volume <NUM> does not contain any liquified gas nor any mixture of liquid and gas. The dividing element <NUM> and the compressible member <NUM> are subjected to ambient temperature and pressure. In <FIG>, the first volume <NUM> is filled with liquefied gas (or a mixture of liquid and gas). The dividing element <NUM> contacts the compressible member <NUM> as a result of the pressure of filling exerted by the first volume <NUM> on the dividing element <NUM>. In <FIG>, the dividing element <NUM> is further pushed in direction to the second volume <NUM> (and compressible member <NUM>) by the vapour pressure of the liquefied gas with increased temperature. The balance between the pressure differences within the first volume <NUM> and the second volume <NUM> is guaranteed by the flexion property of the dividing element <NUM> and the compression property of the compressible member <NUM>. The risk of over pressurization of the container <NUM> is maintained to a minimum, therefore the risk of bursting is limited.

The volume proportions disclosed above also apply for the embodiment of <FIG>. In the empty state (uncompressed state), the second volume <NUM> defined by the dividing element <NUM> and/or the compressible member <NUM> may occupy at least <NUM>% of the total volume of the container <NUM>, or at least <NUM>%, or at least <NUM>%. In the filled state (first compressed state), the liquefied gas exerts a pressure on the dividing element <NUM> of, for example, <NUM> kPa higher than the ambient pressure at <NUM>, which leads the dividing element <NUM> to bend in direction of the second volume <NUM>, i.e. the compressible member <NUM>, and the compressible member to be compressed (by the pressure exerted by the first volume on the dividing element and/or the compressible member via the dividing element). Pressure is thus applied on both sides of the dividing element <NUM>, which brings it to an equilibrium position within the container <NUM>. Ideally, at this state, the second volume <NUM> occupies approximately <NUM>% of the total volume of the container <NUM> to assure enough volume for the liquefied gas to expand.

Alternatively, the second volume can occupy not more than <NUM>% of the total volume of the container, or not more than <NUM>%, or not more than <NUM>%. Finally, in the pressurized state (second compressed state), the pressure exerted on the compressible member <NUM> further increases and can for example reach <NUM> kPa above the ambient pressure or more, which leads the second volume <NUM> to reduce even more; the compressible member <NUM> occupies not more than <NUM>% of the total volume of the container <NUM>, or not more than <NUM>%, or not more than <NUM>%.

Claim 1:
A lighter comprising a container (<NUM>, <NUM>) which is arranged within the lighter and which is suitable for containing a liquefied gas or a mixture of a liquid and a gas, and a dividing element (<NUM>, <NUM>) dividing the container volume in fluid-tight and gas-tight manner into a first volume (<NUM>, <NUM>) containing the liquefied gas or the mixture of liquid and gas and into a second separate volume (<NUM>, <NUM>), wherein the pressure differences between the first volume (<NUM>, <NUM>) and the second volume (<NUM>, <NUM>) are balanced within the container by deformation of the dividing element (<NUM>, <NUM>),
wherein the total container volume comprising the first volume (<NUM>, <NUM>) and the second volume (<NUM>, <NUM>) is constant at a given ambient pressure and a given ambient temperature, wherein the second separate volume (<NUM>, <NUM>) can be reduced by expanding the first volume (<NUM>, <NUM>),
characterized in that the dividing element (<NUM>, <NUM>) is fixed to the inner surface of the container (<NUM>, <NUM>), and the dividing element (<NUM>, <NUM>) is a membrane.