Lighter with a container for liquid gas and a compressible element to prevent overfilling of the container

Description

Technical Field

[0001] The present invention concerns the field of lighters for usage with liquefied gas or a mixture of liquid and gas.Technical Background

[0002] 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, US5716204 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, DE10009361 discloses a cigarette lighter having an ignition device and fuel storage container together with further chamber for the accommodation of mouthwash and US3406000 discloses a fuel control system for a gas fueled device.

[0003] 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.Summary

[0004] The present invention relates to a lighter as defined in claim 1. The dependent claims depict advantageous embodiments of the present invention.

[0005] 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.

[0006] 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.

[0007] 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 23°C is 250 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.

[0008] 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.

[0009] 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.

[0010] 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.

[0011] 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 250 kPa above the ambient pressure.

[0012] 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 60° or 90°C, compared to the temperature, in particular 23°C, 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.

[0013] The second separate volume may occupy at least 10% 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 20%, more particular at least 30%.

[0014] The second separate volume may occupy not more than 20% of the total volume of the container when the pressure in the container is 250 kPa higher than the ambient pressure surrounding the lighter, in particular not more than 15%, more particular not more than 10%.

[0015] The second separate volume may occupy not more than 10% of the total volume of the container when the pressure in the container is 1700 kPa higher than the ambient pressure surrounding the lighter, in particular not more than 8%, more particular not more than 5%.

[0016] The liquefied gas of the mixture of liquid and gas may have a vapour pressure at 23°C that is equal or greater than 104 kPa.

[0017] The total container volume may be in the range of 2 to 200 cm3, in particular in the range of 3 to 100 cm3, more particular in the range of 3 to 20 cm3.

[0018] The container could be refilled with liquefied gas or a mixture of liquid and gas.

[0019] The lighter may comprise a first valve device for refilling the container.

[0020] The lighter further may comprise a second valve device for withdrawing gas from the container.

[0021] The lighter further may comprise an igniting device for igniting the gas exiting the container through the second valve.

[0022] 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).Brief description of the drawings

[0023] Additional details and features of the invention are described in reference to the following figures in which Figures 1a to 1care schematic views of a container of a lighter which is not in accordance with the present invention, in empty state (1a), filled state (1b) and pressurized state (1c); Figure 2 isa schematic view of a lighter; Figures 3a to 3care schematic views of a container of a lighter according to the invention, in empty state (3a), filled state (3b) and pressurized state (3c); and Figure 4 isa schematic view of a container for a lighter according to an embodiment that is not in accordance with the present invention; and Figure 5a to 5care schematic views of a container of a lighter according to another aspect of the invention, in empty state (5a), filled state (5b) and pressurized state (5c). Detailed Description

[0024] Embodiments of the lighter according to the invention will be described in reference to the figures as follows.

[0025] Fig. 1a to 1c present a container 1 of a lighter according to an example which is not in accordance with the present invention. The container 1 comprises a variable first volume 2 that can receive a liquefied gas, and a compressible member, that occupies and defines a variable second volume 3. First volume 2 and second volume 3 constitute a total and constant volume of the container 1. 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.

[0026] In Fig. 1a, the first volume 2 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 v i which represents at least 10 % (or at least 20%, or at least 30%), most preferably 15% of the total volume V 0 of the container 1. The compressible member is in an uncompressed state.

[0027] In Fig. 1b, liquefied gas has been filled in the first volume 2 through the filling valve 4. The pressure in the first volume 2 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 2. 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 23°C filling temperature (equal to ambient temperature), the vapour pressure of the gaseous phase in the container 1 can be greater than 104 kPa. Due to the pressure of the first volume 2 on the second volume 3 (depicted with the arrows from the first volume to the second volume on Fig. 1b), the compressible member is compressed to a volume v 0 .

[0028] The size and material characteristics of the compressible member may be chosen in a way that, the compressible member occupies not less than 15% (in some other examples not more than 10%) of the total volume of the container 1 at 23°C (v 0 / V 0 = 15%) at a certain filling pressure, e.g. at 250KPa (above the ambient pressure). As consequence, the filling volume of the first volume 2 does not exceed 85% under these conditions. Therefore, the compressible member limits the maximum amount of liquefied gas within the container during filling, wherein the first volume 2 can further expand after filing due to an increased temperature by further compressing the compressible member.

[0029] Any increase of temperature in the environment, for example to 60°C or 90°C, leads to a temperature increase of the liquefied gas in the container 1, 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 1700 kPa above the ambient pressure or more, which leads the second volume 3 of the compressible member to reduce even more (Fig. 1c). In this configuration, the compressible member occupies not more than 10% of the total volume of the container 1, or not more than 8%, or not more than 5%.

[0030] In the practical case of a lighter with an internal volume Vo = 10 cm3 filled with isobutane and where the liquid occupies exactly the entire free volume of the container, the rate of crushing v i / v f would be 7 at 1700 kPa and 90°C.

[0031] The compression property of the member permits to balance the pressure increase between the first volume 2 and the second volume 3 at constant total volume of the container 1 instead of having the container 1 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).

[0032] One risk using LPG is that if the initial liquid level is too high (above 85% of the volume fraction at 23°C), 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.

[0033] Fig. 2 shows a standard lighter, comprising a container 20 with a first valve device 21 for refilling the container 20, a second valve device 22 for withdrawing the gas from the container, and an igniting device 23 for igniting the gas exiting the container through the second valve 22.

[0034] Fig. 3a to 3c present a container 30 of a lighter according to the invention. Here, the total container volume is divided by a dividing element 31 such as a membrane or a flexible element into a variable first volume 32 and a variable second volume 33. The first volume 32 is configured to be filled with the liquefied gas and the second volume 33 is filled with air, and the dividing element 31 has the function to balance the pressure differences between the first volume 32 and the second volume 33. The addition of the first volume 32 and the second volume 33 is always constant and represents the total volume of the container 30. To not mix the content of the first volume 32 with the content of the second volume 33, the dividing element 31 is fixed to the inner surface of the container 30 and defines a gas and fluid tight separation. The location of the attachment point of the dividing element 31 to the inner surface of the container 30 is determined in combination with the material characteristics of the dividing element 31 such as to obtain an optimum volume repartition between the first volume 32 and the second volume 33, especially once the liquefied gas is filled within the first volume 32.

[0035] In Fig. 3a, the first volume 32 is empty from liquefied gas and the dividing element 31 is only subjected to the ambient temperature and ambient pressure. At this state, the second volume 33 may occupy at least 10% of the total volume of the container 30, or at least 20%, or at least 30%.

[0036] In Fig. 3b, liquefied gas is filled in the first volume 32 through a filling valve 34. The liquefied gas exerts a pressure on the dividing element 31 of, for example, 250 kPa higher than the ambient pressure at 23°C, which leads the dividing element 31 to bend in direction of the second volume 33. Pressure is thus applied on both sides of the dividing element 31, which brings it to an equilibrium position within the container 30. Ideally, at this state, the second volume 33 occupies approximately 15% of the total volume of the container 30 to assure enough volume for the liquefied gas to expand. Alternatively, the second volume can occupy not more than 20% of the total volume of the container 30, or not more than 15%, or not more than 10%.

[0037] In Fig. 3c, the dividing element 31 is further pushed in direction to the second volume 33 by the vapour pressure of the liquefied gas with increased temperature. The balance between the pressure differences within the first volume 32 and the second volume 33 is guaranteed by the flexion property of the dividing element 31. The risk of over pressurization of the container 30 is maintained to a minimum, therefore the risk of bursting is limited.

[0038] Fig. 4 presents an alternative embodiment that is not in accordance with the present invention: a compressible element 41 is placed within a container 40 of a lighter, wherein the compressible element 41 is not connected to the side walls of the container, and has, for example, the shape of a ball. The element 41 divides the total volume of the container 40 in a first volume 42 configured to contain a liquefied gas or a mixture of a liquid and a gas, and a second volume 43 delimited by the external shape of the element 41. As for the previous aspects of the invention, the second volume 43 is subjected to pressure variations of the first volume 42 and can compress according to the expansion of the first volume 42. Element 41 may have the shape of a hollow ball, or may have the shape of a ball with multiple enclosed pores or cells.

[0039] Figs. 5a to 5c present a container 50 of a lighter according to the invention. Here, the total container volume is divided by a dividing element 51 into a variable first volume 52 and a variable second volume 53. The dividing element is a membrane. The first volume 52 is configured to be filled with the liquefied gas and the second volume 53 comprises a compressible member 54. In Fig. 5a, the second volume is partially filled with the compressible member 54. Alternatively, the second volume may be fully filled with the compressible member. The dividing element 51 has the function to balance the pressure differences between the first volume 52 and the second volume 53. The addition of the first volume 52 and the second volume 53 is always constant and represents the total volume of the container 50. To not mix the content of the first volume 52 with the content of the second volume 53, the dividing element 51 defines a gas and fluid tight separation. In this embodiment, the dividing element 51 is fixed to the inner surface of the container 50. The location of the attachment points of the dividing element 51 to the inner surface of the container 50 is determined in combination with the material characteristics of the dividing element 51 such as to obtain an optimum volume repartition between the first volume 52 and the second volume 53, especially once the liquefied gas is filled within the first volume 52.

[0040] This embodiment presents a combination of the previously disclosed embodiments, comprising simultaneously a dividing element 51 and a compressible member 54. Fig. 5a shows the container 50 in an empty state. The first volume 52 does not contain any liquified gas nor any mixture of liquid and gas. The dividing element 51 and the compressible member 54 are subjected to ambient temperature and pressure. In Fig. 5b, the first volume 52 is filled with liquefied gas (or a mixture of liquid and gas). The dividing element 51 contacts the compressible member 54 as a result of the pressure of filling exerted by the first volume 52 on the dividing element 51. In Fig. 5c, the dividing element 51 is further pushed in direction to the second volume 53 (and compressible member 54) by the vapour pressure of the liquefied gas with increased temperature. The balance between the pressure differences within the first volume 52 and the second volume 53 is guaranteed by the flexion property of the dividing element 51 and the compression property of the compressible member 54. The risk of over pressurization of the container 50 is maintained to a minimum, therefore the risk of bursting is limited.

[0041] The volume proportions disclosed above also apply for the embodiment of Figs. 5a to 5c. In the empty state (uncompressed state), the second volume 53 defined by the dividing element 51 and / or the compressible member 54 may occupy at least 10% of the total volume of the container 50, or at least 20%, or at least 30%. In the filled state (first compressed state), the liquefied gas exerts a pressure on the dividing element 51 of, for example, 250 kPa higher than the ambient pressure at 23°C, which leads the dividing element 51 to bend in direction of the second volume 53, i.e. the compressible member 54, 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 51, which brings it to an equilibrium position within the container 50. Ideally, at this state, the second volume 53 occupies approximately 15% of the total volume of the container 50 to assure enough volume for the liquefied gas to expand.

[0042] Alternatively, the second volume can occupy not more than 20% of the total volume of the container, or not more than 15%, or not more than 10%. Finally, in the pressurized state (second compressed state), the pressure exerted on the compressible member 54 further increases and can for example reach 1700 kPa above the ambient pressure or more, which leads the second volume 53 to reduce even more; the compressible member 54 occupies not more than 10% of the total volume of the container 50, or not more than 8%, or not more than 5%.

[0043] Any other characteristic disclosed for the previous embodiments may apply to the embodiment of Figs. 5a to 5c.

Claims

1. A lighter comprising a container (30, 50) 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 (31, 51) dividing the container volume in fluid-tight and gas-tight manner into a first volume (32, 52) containing the liquefied gas or the mixture of liquid and gas and into a second separate volume (33, 53), wherein the pressure differences between the first volume (32, 52) and the second volume (33, 53) are balanced within the container by deformation of the dividing element (31, 51), wherein the total container volume comprising the first volume (32, 52) and the second volume (33, 53) is constant at a given ambient pressure and a given ambient temperature, wherein the second separate volume (33, 53) can be reduced by expanding the first volume (32, 52), characterized in that the dividing element (31, 51) is fixed to the inner surface of the container (30, 50), and the dividing element (31, 51) is a membrane.

2. The lighter according to claim 1, wherein the compression state of the second separate volume (33, 53) depends on the amount of the liquefied gas or the mixture of liquid and gas contained in the first volume (32, 52), wherein the second separate volume (33, 53) is compressed from an uncompressed state in which the pressure in the container (30, 50) is identical to the ambient pressure, to a first compressed state when the container (30, 50) is filled with a pre-set maximum amount of liquefied gas or of the mixture of liquid and gas.

3. The lighter according to claim 2, wherein the first compressed state of the second separate volume (33, 53) is achieved when the container (30, 50) is filled with an amount of liquefied gas or of the mixture of liquid and gas at a pressure of 250 kPa above the ambient pressure.

4. The lighter according to claim 2 or 3, wherein the second separate volume can 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 60° or 90°C, compared to the temperature, in particular 23°C, 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.

5. The lighter according to one of the preceding claims, wherein the second separate volume (33, 53) occupies at least 10% of the total volume of the container (30, 50) when the pressure in the container (30, 50) is identical to the ambient pressure surrounding the lighter, in particular at least 20%, more particular at least 30%.

6. The lighter according to one of the preceding claims, wherein the second separate volume (33, 53) occupies not more than 20% of the total volume of the container (30, 50) when the pressure in the container (30, 50) is 250 kPa higher than the ambient pressure surrounding the lighter, in particular not more than 15%, more particular not more than 10%.

7. The lighter according to one of the preceding claims, wherein the second separate volume (33, 53) occupies not more than 10% of the total volume of the container (30, 50) when the pressure in the container (30, 50) is 1700 kPa higher than the ambient pressure surrounding the lighter, in particular not more than 8%, more particular not more than 5%.

8. The lighter according to one of the preceding claims, further comprising a compressible member (54) arranged in the second separate volume (33, 53).

9. The lighter according to one of the preceding claims, wherein the liquefied gas of the mixture of liquid and gas has a vapour pressure at 23°C that is equal or greater than 104 kPa.

10. The lighter according to one of the preceding claims, wherein the container (30, 50) can be refilled with liquefied gas or a mixture of liquid and gas, the lighter comprising: a first valve device (21) for refilling the container (30, 50), a second valve device (22) for withdrawing gas from the container (30, 50), and an igniting device (23) for igniting the gas exiting the container (30, 50) through the second valve (22), wherein the total container volume is in the range of 2 to 200 cm3, in particular in the range of 3 to 100 cm3, more particular in the range of 3 to 20 cm3.