GB2487252A

GB2487252A - Gas nailer fuel container assembly comprising dip tube

Info

Publication number: GB2487252A
Application number: GB201103445A
Authority: GB
Inventors: Yu-Chuan Ho; Ryan Chen; Yi-Hung Wu
Original assignee: Superior Power Tool Co Ltd
Current assignee: Superior Power Tool Co Ltd
Priority date: 2010-12-24
Filing date: 2011-03-01
Publication date: 2012-07-18
Also published as: GB201103445D0; TWM406502U

Abstract

A fuel container assembly (100, Fig 1) for a gas nailer (200, Fig 3) comprises an outer container 10, and inner container 40, a metering valve set 20 and a dip tube 30. Metering valve set 20 comprises a valve rod 21 disposed outside outer container 10, and a connector 22 disposed inside outer container 10. Inner container 40 is sealed with connector 22, and contains liquid fuel L and gaseous fuel G, vaporised from the liquid fuel L. Dip tube 30 is connected to connector 22 in fluid communication with metering valve set 20, and is suspending inside inner container 40 and dipped in liquid L to guide liquid L to metering valve set 20. Metering valve set 20 may comprise a metering chamber (23, Fig 3), and dip tube 30 may be formed integrally or separately from connector 22. The propelling substance may have a gas phase and a liquid phase condensed from the gas phase. The fuel container assembly is intended to eliminate non-firing problems at a low-temperature and the drawbacks of overpressure and low firing capacity.

Description

FUEL CONTAINER ASSEMBLY FOR GAS NAILER

BACKGROUND OF THE INVENTION

I. Field of the Invention

The present invention relates to a gas nailer an.d more particularly, to a the! container assembly for use in a gas nailer.

2. Description of the Related Art

The firing power of a gas nailer comes from a fuel in a the! container installed therein. Conventional fuel container assemblies for gas nailer are disclosed in US Pat. Nos. 5,115,944; 4,522,162; 4,483,474; 4,403,722. These designs commonly include an outer container, a metering valve and an inner bag mounted inside the outer container and sealed with the metering valve. The inner bag contains a fuel (hydrocarbon fuel, such as liquefied petroleum gas). A propellant is provided between the outer container and the inner bag to squeeze the inner bag, forcing the liquefied fuel out of the inner bag into the metering valve and then into a combustion chamber in the gas nailer. At this time, the liquefied fuel is vaporized due. to a sudden pressure change. At the same time, the functioning of a fan. in the gas nailer causes the vaporized fuel to mix with air for ignition, enabling the explosion stroke to push the firing pin in driving out a nail.

Several tens of years have passed since the invention of gas nailer. However, regular fuel containers for gas nailer are not workable under a low temperature F environment. The problem is probably thought to be due to that: the substance having a relatively higher boiling point (for example, butane) in the fuel is not easy to vaporize at a low temperature, and will lower the concentration of the gas phase in the combustion chamber, causing the ignition unable to induce explosion. Further, the propellant between the outer container and the inner bag will be gradually liquefied at a low temperature. In consequence, the propellant pressure will be reduced, unable to force the fuel out of the inner bag into the metering valve. The aforesaid two factors may occur at the same time, subject to the types of the fuel and propellant used.

The common way to solve the aforesaid problems is to take the fuel container out of the gas nailer and then gently warm up the fuel container to the operable condition. This manner complicates the application. Further, changing the fuel composition can solve the problems. However, it will be difficult and expensive to obtain a specially formulated fuel. Other measures, such as increasing the pressure in between the outer container and the inner bag, or increasing the ratio of the relatively higher pressure liquefied substance (such as propane) in the liquid fuel, may be employed, however these measures have the drawback of overpressure (not in conformity with local safety mles) or low firing capacity.

After through several tests and corrections, the inventor found out that the use of a dip tube in the ftiel container effectively solves the problem of non-firing at a low temperature.

Similar structures that use a dip tube with an inner bag in conjunefion with the control of container pressure are seen in US Pat 6,439,430 and 7,198,179.

However, these two designs are adapted for cosmetics and medical aerosol containers.

The related content and the phase transition and fluid dynamics thereof, unlike the fuel to be used for gas nailer. Further, in the specifications of tb.e aforesaid two patents, the dip tube is simply adapted to assist flowing and discharge of the content, especially for viscous content. Further, the dip tube is not a requisite element in the aforesaid two patents. Further, these specifications do not mention any low temperature operation teachings.

SUMMARY OF TIlE INVENTION

The present invention has been accomplished under the circumstances in view. It is the main object of the present invention to provide a fuel container assembly S for gas nailer, which eliminates the problem of non-f'irin.g at a low-temperature and the drawbacks of overpressure and low firing capacity, and has the advantages of being easy and safe to use and easy to manufacture.

To achieve this and other objects of the present invention, a fuel container assembly comprises an outer container containing a propelling substance capable of generating a pressure, a metering valve set having a valve rod mounted outside the outer container and a connector mounted inside the outer container, an inner container mounted inside the outer container and sealed with the connector of the metering valve set and containing a liquid fuel and a gaseous fuel vaporized from the liquid fuel, and a dip tube connected to the connector in fluid communication with the metering valye set and dipped in the liquid fuel to guide the liquid fuel into the metering valve set.

Thus, the invention uses the dip tube to guide the liquid fuel out of the inner container independently without carrying the gaseous fuel into the metering valve set.

Therefore, either under a normal temperature condition or low temperature environment below the boiling point of the liquid fuel, the amount of the liquid fuel entered the metering valve is sufficient, arid no gaseous fuel will be mixed in the liquid fuel in the metering chamber. Further, when the liquid fuel is changed to gas phase, its volume expands several hundred times Therefore, when a sufficient amount of the liquid fuel entered the combustion chamber, the gas phase concentration will be much higher than the conventional designs, assuring positive ignition and explosion in the combustion chamber under a low temperature environment Further, the propellants filled in some commercial fuel containers for gas nailer may be liquefied under a low temperature environment, lowering the propellant pressure. Subject to the arrangement of the dip tube in the inner container, less propellant pressure is needed to force the liquid fuel out of the inner container into the metering valve set, and therefore the invention can still provide a sufficient amount of the liquid fuel to the metering valve set when under a low temperature environment, eliminating the problem of non-firing at a low temperature.

Other and further features, benefits and advantages and the assembly and use of the present invention will be understood by reference to the following description in conjunction with the accompanying drawings, in which like reference signs denote like elements of structure. However, it is to be understood to any person having skill in the art that the embodiments of the invention are for explanation only but not intended for use as a hmitatiorL

BRIEF DESCRIPTION OF THE DRAWINGS

FIG 1 is a perspective view of a fuel container assembly in accordance with the present invention.

FIG 2 is a sectional view of the fuel container assembly in accordance with the present invention.

FIG 3 is an enlarged view of a part of the fuel container assembly in accordance with the present invention.

FIG. 4 is similar to FIG I, illustrating the liquid fuel used up.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1 -3, a fuel container assembly 100 in accordance with the present invention is shown used in a gas nailer 200, and adapted to provide the necessary power dunng a nailing action of the gas nailer 200 The gas nailer 200 includes a combustion chamber 201 and a fan 202. Because the body structure of the gas nailer is not within the scope of the present invention, no further detailed description is necessary in this regard. The fuel container assembly 100 includes an* outer container 10, a metering valve set 20, a dip tube 30 and an inner container 40.

The outer container 10 is same as a conventional fuel container for gas nailer, having the inside space thereof filled with a propelling substance 11 capable of generating a pressure. The propelling substance 11 can be compressed air or carbon dioxide, or any other similar non-temperature-sensitive substance. Alternatively, the propelling substance 11 can be a temperature-sensitive substance, such as hydrocarbon fuel. According to the present preferred embodiment, the propelling substance 11 is compressed air.

The metering valve set 20 is mounted in the outer container 10. The metering valve set 20 can be any known design used in a fuel container for gas nailer. For easy understanding of the invention, the metering valve set 20 is explained hereinafter by way of an example. According to the present preferred embodiment, the metering valve set 20 includes a valve rod 21 disposed outside the outer container 10, a connector 22 disposed inside the outer container 10, and a metering chamber 23. With respect to the structural details, please refer to US Pat. 6,302,297.

The dip tube 30 according to the present preferred embodiment is a hollow tube detachably connected to the connector 22 (for example, by means of sleeve joint, plug joint, clamping, or bonding). Alternatively, the connector 22 and the dip tube 30 can be integrated dunng fabneation, enhancing air-tightness and reliability After connection between the dip tube 30 and the connector 22, the dip tube 30 is kept in F fluid commumeation with the metenng valve set 20 The inner container 40 according to the present preferred embodiment is a flexible bag mounted inside the outer container 10, and sealed with the connector 22 of the metering valve set 20. The inner container 40 can be any of a variety of flexible iimer containers for fuel container for gas nailer. For example, the inner container disclosed in US Pat. 6,681,955 can be used. However, it is not a limitation. Further, the inner container 40 contains therein a liquid fuel L, for example, but not limited to, propane-butane mixture. Any other liquid hydrocarbon fuel suitable for gas nailer, such as propylene, n-butene-1 or n-butane can be selectively used. Fuel composition similar to the relationship between propane and butane is bettet Further, due to the eflèct of vapor pressure, the inner container 40 also contains a gaseous thel G vaporized from the liquid fuel L. According to the present preferred embodiment, the gaseous fuel G is gaseous propane-butane mixture.

When the fuel container assembly 100 is assembled, the dip tube 30 is dipped in the liquid fuel L so that the liquid fuel L can flow through the dip tube 30 into the metering valve set 20. Preferably, the dip tube 30 extends to an area in proximity to the bottom wall of the inner container 40, enabling the liquid fuel L to be fully utilized.

During actual use of the fuel container assembly 100 in a gas nailer, the pressure in between the outer container 10 and the inner container 40 squeezes the inner container 40 to force the liquid fuel L into the dip tube 30 and then into the metering chamber 23 via the connector 22. Thus, the metering chamber 23 is fully filled with a constant volume of the liquid fuel L without containing the gaseous fuel G. When the nailer 200 is stopped against the work surface, the valve rod 21 of the metering valve set 20 is pressed, enabling the liquid fuel L to flow from the metering chamber 23 through the hole in the valve rod 21 into the combustion chamber 201 of the gas nailer 200. At this time, the liquid fuel L is vaporized due to a sudden pressure change. At the same time, the functioning of the fan 202 of the gas nailer 20 causes the vaporized the! to mix with air for ignition, enabling the explosion stroke to push the firing pin in driving out a nail. As stated above, subject to the use of the dip tube, the liquid fuel is independently guided out without carrying the gaseous fuel into the metering chamber. Thus, the invention eliminates the problem of guiding the liquid fuel with the gaseous fuel into the metering valve set as commonly seen in conventional fuel container designs. Therefore, either at room temperature or under a low temperature environment below the boiling point of the liquid fuel, the amount of the liquid fuel that enters the metering valve set is sufficient, ad no gaseous fuel will be mixed in the liquid fuel in the metering valve set Further, when the liquid fuel is changed to gas phase, the volume is expanded. Therefore, the gas-phase concentration in the combustion chamber in accordance with the present invention is much greater than what a conventional fuel container assembly can provide, enabling the concentration of the gas mixture in the combustion chamber to be controlled within an optimal range for ignition and explosion efficiently. Thus, the invention eliminates the non-firing problem at a low-temperature. When using the gas nailer under a low temperature environment, it is not necessary to warm the fuel container assembly, enhancing use convenience. Further, because it is not necessary to change the fuel composition, the invention facilitates fuel supply, saving the cost. Subject to the arrangement of the dip tube, it is not necessary to increase the container pressure or the ratio of the substance in the liquid fuel that requires a relatively higher pressure (such as propane), and the total fill pressure can be minimized. Therefore, the invention has the advantages of low container pressure and high firing capacity.

Further, as shown in FIG 4, when the liquid fuel L is being used up, the propelling substance 11 squeezes the inner container 40 against the periphery of the dip tube 30, causing the residual liquid fuel L to be forced through the dip tube 30 into the metering valve set 20. Therefore, the invention improves the! utilization efficiency and greatly increases the number of nails being driven.

Further, if the aforesaid propelling substance is temperature sensitive to induce a phase transition under a low temperature environment, the propelling substance changes from simple gas phase to a part of gas phase and a part of liquid phase, the pressure applied to the inner container is relatively reduced, Subject to the arrangement of the dip tube, the pressure required to force the liquid fuel to the metering valve set is relatively reduced, and therefore the fuel container assembly still can provide a sufficient amount of the liquid fuel to the metering valve set at a low temperature condition. Further, the dip tube can prevent the gas fuel from entering the metering valve set. Thus, the fuel container assembly works effectively under a low temperature environment, elimthatthg the non-firing problem of a gas nailer equipped with a prior art fuel container assembly when operating under a low temperature environment.

Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.

Claims

WHAT IS CLAIMED IS: I. A fuel container assembly for use in a gas nailer, comprising: an outer container containing a propelling substance capable of generating a pressure; a metering valve set mounted in said outer container, said metering valve set comprising a valve rod disposed outside said outer container and a connector disposed inside said outer container; an inner container mounted inside said outer container and sealed with said connector of said metering valve set, said inner container containing a liquid fuel and a gaseous fuel vaporized from said liquid fuel; and a dip tube connected to said connector in fluid communication with said metering valve set and suspending inside said inner container and dipped in said liquid fuel to guide said liquid fuel into sai.d metering valve set. iS
2. The fuel container assembly as claimed in claim 1, wherein said metering valve set comprises a metering chamber adapted for accommodating a predetermined volume of said liquid fuel.
3. The fuel container assembly as claimed in claim 1, wherein said dip tube is formed integral with said connector.

4 The fuel container assembly as claimed in claim 1., wherein said dip tube is detachably connected to said connector 5. The fuel container assembly as claimed in claim 1, wherein said propelling substance has a gas phase and a liquid phase changed from said gas phase.. Jo