IE20030771U1 - A gas powered heating tool - Google Patents

Abstract

for modulating the fuel gas supply in response to the temperature of the soldering tool tip

Description

"A gas powered heating tool" The present invention relates to a gas powered heating tool, and in particular, to a gas powered heating tool, for example, a soldering tool, a heated cutting knife for cutting plastics material, a hot gas blow torch.

Such gas powered heating tools are known. For example, European Patent Specification No. 0,118,282 of Oglesby, et al discloses a gas powered soldering tool which can be constructed in relatively slim compact form in the shape of a pen.

Providing a soldering tool in such a compact slim shape has many advantages, not least of which being that a tradesperson can readily easily carry the soldering tool in his or her pocket as they would a fountain pen or the like. The soldering tool of Oglesby, et al disclosed in the European specification comprises a handle in which a fuel gas reservoir is located. A tubular support member extending from the handle carries a body member at its free end, which terminates in a soldering tip. A combustion chamber is formed within the body member, and a catalytic combustion element is located in the combustion chamber for converting a fuel gas/air mixture to heat for heating the body member and in turn the soldering tip. A fuel gas regulating and control system is located in the handle which supplies a regulated supply of fuel gas from the reservoir to a venturi mixer where the fuel gas supply is mixed with air.

The fuel gas/air mixture is delivered through the tubular support member into the combustion chamber.

While the soldering tool disclosed in European Patent Specification No. 0,118,282 has many advantages, it suffers from one disadvantage in that the temperature of the soldering tip can only be regulated by manually regulating the supply of fuel gas to the combustion chamber. Thus, in general, it is not possible to operate the soldering tool at a substantially constant temperature during soldering without manually regulating the supply of fuel gas to the combustion chamber during the actual soldering operation. This is inconvenient, and in many cases impossible to achieve.

OPENTOPUBUClNSPEO'HON The provision of a gas powered heating tool with a temperature responsive valve for controlling the temperature of a working body member of such a tool is known. For example, PCT Specification No. WO 02/48591A of Oglesby, et al discloses both a temperature responsive valve for modulating flow of fuel gas in response to temperature, and a gas powered glue gun which includes the temperature responsive valve for modulating the flow of fuel gas to a combustion chamber in response to temperature. The glue gun comprises a main body member having a glue accommodating bore therethrough in which the glue is melted. The combustion chamber is also formed in the main body member, and a catalytic combustion element is located within the combustion chamber for converting fuel gas/air mixture to heat for heating the main body member for melting the glue. A venturi mixer supplies the fuel gas/air mixture to the combustion chamber. Fuel gas is supplied from a fuel gas reservoir in a handle of the glue gun to the venturi mixer through the temperature responsive valve. The temperature responsive valve modulates the supply of fuel gas to the venturi mixer in response to the temperature of the main body member. The temperature responsive valve comprises a circular bi—metal disc which is constrained within a valve chamber of the temperature responsive valve for modulating the flow of fuel gas through the valve chamber. However, while the construction of the gas powered heating tool with the temperature responsive valve disclosed in PCT Specification No. WO O2/48591A is suitable for glue guns, it is not particularly suitable for soldering tools. A soldering tool of the construction of the heating tool disclosed in PCT Specification No. WO 02/48591A would be relatively cumbersome.

There is therefore a need for a gas powered heating tool which comprises a temperature responsive valve for modulating the flow of fuel gas to a combustion chamber of the gas powered heating tool for maintaining a working body member of the gas powered heating tool at a substantially constant temperature during use, and which permits the gas powered heating tool to be supplied as a relatively compact, and preferably, slimline tool.

The present invention is directed towards providing such a gas powered heating tool.

According to the invention there is provided a gas powered heating tool comprising a body member having a combustion chamber formed therein, within which a fuel gas/air mixture is converted to heat, a venturi mixing means located upstream of the combustion chamber for mixing fuel gas with air to provide the fuel gas/air mixture, a first nozzle being provided from the venturi mixing means for delivering the fuel gas/air mixture to the combustion chamber, the first nozzle defining a delivery axis along which the fuel gas/air mixture is delivered from the venturi mixing means, a temperature responsive valve located upstream of the venturi mixing means for modulating the flow of fuel gas from a fuel gas source in response to the temperature of the body member, the temperature responsive valve having a valve seat and comprising a temperature responsive bi—metal member co—operating with the valve seat for modulating the flow of fuel gas through the valve, a fuel gas inlet being provided to the temperature responsive valve for delivering fuel gas from the fuel gas source to the valve, the fuel gas inlet defining a delivery axis along which fuel gas is delivered to the temperature responsive valve, and a second nozzle being provided from the temperature responsive valve for supplying the modulated fuel gas to the venturi mixing means, the second nozzle defining a delivery axis along which fuel gas is delivered to the venturi mixing means, wherein the delivery axes defined by the first and second nozzles and by the fuel gas inlet to the temperature responsive valve are parallel to each other.

Preferably, the respective delivery axes defined by the first and second nozzles and the fuel gas inlet to the temperature responsive valve coincide with each other.

In one embodiment of the invention the temperature responsive valve comprises a valve housing defining a valve chamber within which the bi—metal member is located, and the fuel gas inlet extends through the valve housing into the valve chamber.

Preferably, the valve housing of the temperature responsive valve defines a longitudinally extending central geometrical axis which coincides with the delivery axis of the fuel gas inlet thereof. Advantageously, the fuel gas inlet to the temperature responsive valve is formed by a fuel gas accommodating inlet bore IEOIQ77, extending through the valve housing into the valve chamber, the fuel gas accommodating inlet bore defining the delivery axis of the fuel gas inlet and terminating in the valve chamber in the valve seat.

In another embodiment of the invention a valving member is located in the valve chamber, and the valving member is co—operable with the bi—metal member and the valve seat for modulating the flow of fuel gas through the temperature responsive valve. Preferably, the valving member is located between the bi—metal member and the valve seat.

In another embodiment of the invention a fuel gas accommodating outlet bore extends through the valve housing from the valve chamber for delivering the modulated fuel gas from the valve chamber, the fuel gas accommodating outlet bore terminating in the second nozzle. Preferably, the fuel gas accommodating outlet bore of the temperature responsive valve defines the delivery axis of the second nozzle.

Advantageously, the bi-metal member extends transversely relative to the delivery axis defined by the fuel gas inlet to the temperature responsive valve. Ideally, the bi- metal member is provided by a circular bi—metal disc defining a central geometrical axis which extends coaxially with the delivery axis defined by the fuel gas inlet to the temperature responsive valve.

In one embodiment of the invention the venturi mixing means comprises a venturi mixing chamber within which the modulated fuel gas and air are mixed to form the fuel gas/air mixture, the venturi mixing chamber defining a longitudinally extending central geometrical axis which is coaxial with the delivery axis defined by the second nozzle. Preferably, the second nozzle terminates in the venturi mixing chamber of the venturi mixing means.

In one embodiment of the invention the bi-metal member is of the type having a predetermined transition temperature at which the bi-metal member transitions from lE03n77, a first configuration to a second configuration, the second configuration being substantially a mirror image of the first configuration.

In another embodiment of the invention the bi—metal member is constrained in the temperature responsive valve to prevent transitioning from the first configuration to the second configuration, but is permitted limited transitioning movement for cooperating with the valve seat of the temperature responsive valve for modulating the flow of fuel gas through the valve. Preferably, the bi—metal member is responsive to temperature within a predetermined temperature range adjacent the transition temperature for modulating the flow of fuel gas through the temperature responsive valve. in one embodiment of the invention the bi—metal member is responsive to temperature within a predetermined temperature range below the transition temperature of the bi—metal member for modulating the flow of fuel gas through the temperature responsive valve. Preferably, the bi—metal member is responsive to temperature within a predetermined temperature range which is just below the transition temperature of the bi—metal member for modulating the flow of fuel gas through the temperature responsive valve.

Additionally, or alternatively, the bi—metal member is responsive to temperature within a predetermined temperature range above the transition temperature of the bi- metal member for modulating the flow of fuel gas through the temperature responsive valve. Advantageously, the bi—metal member is responsive to temperature within a predetermined temperature range just above the transition temperature of the bi—metal member for modulating the flow of fuel gas through the temperature responsive valve.

In one embodiment of the invention the bi—metal member is selected to have a transition temperature which lies within the predetermined temperature range within which the bi—metal member is responsive for modulating the fiow of fuel gas through the temperature responsive valve. ln another embodiment of the invention the bi-metal member comprises a lower transition temperature and an upper transition temperature, the upper transition temperature being the temperature at which the bi-metal member would transition from the first configuration to the second configuration as the temperature is rising if the bi-metal member were unconstrained, and the lower transition temperature being the temperature at which the bi-metal member if unconstrained would transition from the second configuration to the first configuration as the temperature is falling. in a further embodiment of the invention the bi-metal member is responsive to temperature in a predetermined temperature range between the upper transition temperature and the lower transition temperature for modulating the flow rate of fuel gas through the temperature responsive valve.

Preferably, the bi-metal member is shaped for determining each predetermined transition temperature.

In one embodiment of the invention a gas catalytic combustion element is located in the combustion chamber for converting fuel gas to heat therein. Preferably, the first nozzle delivers the fuel gas/air mixture to a burner, the burner being located in an intermediate chamber formed by a sub—housing extending upstream from the body member and communicating with the combustion chamber, the burner and the intermediate chamber co—operating for burning the fuel gas/air mixture in a flame for initially raising the temperature of the gas catalytic combustion element in the combustion chamber to its ignition temperature. Advantageously, the burner is located relative to the combustion chamber and the gas catalytic Combustion element so that as the gas catalytic combustion element reaches its ignition temperature and commences to convert fuel gas to heat, the flame in the intermediate chamber is extinguished.

In another embodiment of the invention a spark ignition means is provided for igniting the fuel gas to initially burn in the intermediate chamber in a flame.

Preferably, the burner and the body member are electrically insulated from each other, and the spark ignition means is coupled to the burner and the body member for applying an EMF between the burner and the body member for generating a spark between the burner and the body member for igniting the fuel gas/air mixture to burn in a flame in the intermediate chamber.

In one embodiment of the invention the body member terminates in a working body member. in another embodiment of the invention the gas powered heating tool is a soldering tool, and the working body member forms a soldering tip of the soldering tool.

In an alternative embodiment of the invention the body member defines an outlet from the combustion chamber for providing a hot gas stream therefrom.

Additionally the invention provides a gas powered heating tool comprising a body member having a combustion chamber formed therein within which a fuel gas/air mixture is converted to heat, the combustion chamber defining a longitudinally extending central geometrical axis, a venturi mixing means located upstream of the combustion chamber for mixing fuel gas with air to provide the fuel gas/air mixture, the venturi mixing means defining a longitudinally extending central geometrical axis, a first nozzle being provided from the venturi mixing means for delivering the fuel gas/air mixture to the combustion chamber, the first nozzle defining a longitudinally extending central axis, a temperature responsive valve located upstream of the venturi mixing means for modulating the flow of fuel gas from a fuel gas source in response to the temperature of the body member, the temperature responsive valve having a valve seat and comprising a temperature responsive bi-metal member co- operating with the valve seat for modulating the flow of fuel gas through the valve, the temperature responsive valve defining a longitudinally extending central geometrical axis, a fuel gas inlet being provided to the temperature responsive valve for delivering fuel gas from the fuel gas source to the valve, and a second nozzle being provided from the temperature responsive valve for supplying the modulated fuel gas to the venturi mixing means, the second nozzle defining a longitudinally extending central axis, wherein the central axes defined by the venturi mixing means, the temperature responsive valve and the first and second nozzles extend parallel to each other. in one embodiment of the invention the respective central axes of the venturi mixing means, the temperature responsive valve and the first and second nozzles coincide with each other.

Preferably, the central axis defined by the combustion chamber extends parallel to the central axis defined by the temperature responsive valve, and advantageously, the central axis defined by the combustion chamber coincides with the central axis defined by the temperature responsive valve.

The invention also provides a thermostatically controlled burner unit for a gas powered heating tool, the thermostatically controlled burner unit comprising a burner, a venturi mixing means located upstream of the burner for mixing fuel gas with air to provide the fuel gas/air mixture for supply to the burner, a first nozzle being provided from the venturi mixing means for delivering the fuel gas/air mixture to the burner, the first nozzle defining a delivery axis along which the fuel gas/air mixture is delivered from the venturi mixing means, a temperature responsive valve located upstream of the venturi mixing means for modulating the flow of fuel gas from a fuel gas source in response to temperature, the temperature responsive valve having a valve seat and comprising a temperature responsive bi—metal member co—operating with the valve seat for modulating the flow of fuel gas through the valve, a fuel gas inlet being provided to the temperature responsive valve for delivering fuel gas from the fuel gas source to the valve, the fuel gas inlet defining a delivery axis along which fuel gas is delivered to the temperature responsive valve, and a second nozzle being provided from the temperature responsive valve for supplying the modulated fuel gas to the venturi mixing means, the second nozzle defining a delivery axis along which fuel gas is delivered to the venturi mixing means, wherein the delivery axes defined by the first and second nozzles and by the fuel gas inlet to the temperature responsive valve are parallel to each other.

In one embodiment of the invention the respective delivery axes defined by the first and second nozzles and the fuel gas inlet to the temperature responsive valve coincide with each other.

In another embodiment of the invention the burner defines a longitudinally extending central geometrical axis, which is coaxial with the delivery axis defined by the first nozzle.

In another embodiment of the invention the burner unit defines a longitudinally extending main central axis, and the respective delivery axes defined by the first and second nozzles and by the fuel gas inlet to the temperature responsive valve coincide with the main central axis of the burner unit.

The invention further provides a thermostatically controlled burner unit for a gas powered heating tool, the thermostatically controlled burner unit comprising a burner, the burner defining a longitudinally extending central geometrical axis, a venturi mixing means located upstream of the burner for mixing fuel gas with air to provide the fuel gas/air mixture, the venturi mixing means defining a longitudinally extending central geometrical axis, a first nozzle being provided from the venturi mixing means for delivering the fuel gas/air mixture to the burner, the first nozzle defining a longitudinally extending central axis, a temperature responsive valve located upstream of the venturi mixing means for modulating the flow of fuel gas from a fuel gas source in response to the temperature, the temperature responsive valve having a valve seat and comprising a temperature responsive bi—metal member co- operating with the valve seat for modulating the flow of fuel gas through the valve, the temperature responsive valve defining a longitudinally extending central geometrical axis, a fuel gas inlet being provided to the temperature responsive valve for delivering fuel gas from the fuel gas source to the valve, and a second nozzle being provided from the temperature responsive valve for supplying the modulated fuel gas to the venturi mixing means, the second nozzle defining a longitudinally extending central axis, wherein the central axes defined by the venturi mixing means, the temperature responsive valve and the first and second nozzles extend parallel to each other.

Preferably, the respective central axes of the venturi mixing means, the temperature responsive valve and the first and second nozzles coincide with each other.

Preferably, the central axis defined by the burner extends parallel to the central axis defined by the temperature responsive valve, and advantageously, the central axis defined by the burner coincides with the central axis defined by the temperature responsive valve.

The advantages of the invention are many. By virtue of the fact that the gas powered heating tool is provided with a temperature responsive valve for modulating the Supply of fuel gas to the combustion chamber of the body member in response to the temperature of the body member, the temperature of the body member can be maintained substantially constant during operation of the tool. Additionally, by virtue of the fact that the modulated supply of fuel gas is delivered to the venturi mixing means through a second nozzle, and the fuel gas/air mixture is delivered from the venturi mixing means through a first nozzle, and the fuel gas supply to the temperature responsive valve is supplied through a fuel gas inlet to the temperature responsive valve, and furthermore, by virtue of the fact that the first and second nozzles and the inlet to the temperature responsive valve are arranged with their respective delivery axes substantially parallel to each other, the temperature responsive valve, the venturi mixing means and the combustion chamber can be arranged substantially aligned with each other. This, thus, permits the gas powered heating tool to be provided in a relatively compact slimline manner. By locating the first and second nozzles and the fuel gas inlet to the temperature responsive valve with their delivery axes coinciding with each other, the temperature responsive valve, the venturi mixing means and the body member can be completely aligned with each other, thereby facilitating the implementation of the gas powered heating tool in a particularly compact slimline fashion. By providing the temperature responsive valve with a circular temperature responsive bi-metal member, and by locating the bi—metal member with its longitudinal central geometrical axis coinciding with the delivery axis defined by the fuel gas inlet to the temperature responsive valve, the gas powered heating tool can be provided with a temperature responsive valve without affecting the compact and slimline nature of the gas powered tool. in the aspect of the invention where the combustion chamber, the venturi mixing means, the first and second nozzles, the temperature responsive valve, the fuel gas inlet to the temperature responsive valve each define longitudinally extending central axes, and where the respective central axes extend parallel to each other, a gas powered heating tool of relatively compact and slimline construction is provided.

Furthermore, where the respective central axes coincide with each other, a particularly compact and slimline gas powered heating tool is provided, and the gas powered heating tool is particularly suitable for implementing as a gas powered soldering tool, or a hot gas stream delivery tool.

By providing the bi—metal member to be of the type having a predetermined transition temperature at which the bi~metal member transitions from a first configuration to a second configuration which is substantially a mirror image of the first configuration, and by constraining the bi—metal member to prevent it transitioning between its respective first and second configurations, particularly accurate modulation of the flow of fuel gas can be achieved, thereby permitting the temperature of the body member to be maintained substantially constant within relatively narrow upper and lower predetermined limits. Additionally, by constraining the bi—metal disc to prevent it transitioning between its respective first and second configurations, the modulation of the flow of fuel gas is essentially an analogue modulation, and is directly proportional to the temperature of the body member.

By providing the gas powered heating tool in the form of a soldering tool, a particularly compact and slimline soldering tool is provided, and indeed, the soldering tool can be provided in the shape of a fountain pen for clipping into a pocket of a tradesperson. The gas powered heating tool is also particularly suitable for use as a IE? 0:3 0 7 7 I heated knife and as a hot gas blower, and in both cases, can readily easily be provided in the shape of a fountain pen for clipping into a tradesperson’s pocket.

The provision of the gas powered heating tool as a soldering tool of relatively compact slimline construction provides a gas tool which is readily easy to operate, and in particular, facilitates accurate soldering of relatively small components in relatively confined spaces.

The invention will be more clearly understood from the following description of some preferred embodiments thereof, which are given by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a side elevational view of a gas powered heating tool according to the invention, Fig. 2 is a top plan view of the gas powered heating tool of Fig. 1, Fig. 3 is a transverse cross—sectional plan view of the heating tool of Fig. 1 on the line lll-Ill of Fig. 1, Fig. 4 is an enlarged transverse cr0ss—sectional view of a portion of the heating tool of Fig. 1 on the line Ill-lll of Fig. 1, Fig. 5 is a transverse cross—sectiona| view of a portion of the heating tool of Fig. 1 on the line V—V of Fig. 2, Fig. 6 is a transverse cross-sectional plan view of a portion of the heating tool of Fig. 1 on the line l|l—lll of Fig. 1, Fig. 7 is a side elevational view of a portion of the heating tool of Fig. 1, Fig. 8 is a transverse cross—secti0nal side elevational view of the portion of Fig. 7 on the line Vlll—Vlll of Fig. 7, Fig. 9 is an exploded side elevational view of the portion of Fig. 7, Fig. 10 is a side elevational view of another portion of the heating tool of Fig. 1, Fig. 11 is a transverse cross~sectional plan view of the portion of Fig. 10 on the line Xl—Xl of Fig. 10, Fig. 12 is an enlarged perspective view of a portion of the gas powered heating tool of Fig. 1, Fig. 13 is an enlarged sectional perspective view of a portion of the gas powered heating tool of Fig. 1, Fig. 14 is a transverse cross-sectional side elevational view of a portion of a gas powered heating tool according to another embodiment of the invention, Fig. 15 is a perspective view of a detail of the portion of Fig. 14, Fig. 16 is another perspective view of the detail of Fig. 15, Fig. 17 is a side elevational view of the detail of Fig. 15, Fig. 18 is a transverse cross—sectiona| plan view of the detail of Fig. 15 on the line XVll—XV|l of Fig. 17, and Fig. 19 is an end view of the detail of Fig. 15.

Referring to the drawings and initially to Figs. 1 to 13, there is illustrated a gas powered heating tool according to the invention which in this embodiment of the [E0307], invention is a soldering tool indicated generally by the reference numeral 1. The soldering tool 1 is a portable hand—held soldering tool and comprises a main housing 3 of plastics material of circular transverse cross—section, which defines a longitudinally extending main central axis 2. The main housing 3 forms a handle 4 for holding the soldering tool in use. The main housing 3 defines a rechargeable fuel gas reservoir 5 for fuel gas in liquid form. A charging valve 6 is located in an upstream end cap 7 of the main housing 3 for facilitating charging of the fuel gas reservoir 5 with liquid fuel gas. A body member 10 of circular transverse cross- section of nickel plated brass terminates in a working body member, namely, a soldering tool tip 11, and is secured to the main housing 3 by a tubular retaining member 12 of stainless steel and a gland nut 14, which secures the retaining member to a downstream end cap assembly 15. The downstream end cap assembly is secured to the main housing 3.

The body member 10 defines a combustion chamber 18 within which a cylindrical gas catalytic combustion element 19 is located for converting a fuel gas/air mixture to heat for heating the body member 10, and in turn the soldering tool tip 11. The body member 10 and the combustion chamber 18 define a longitudinally extending central geometrical axis which coincides with the main central axis 2 defined by the main housing 3. An exhaust port 20 from the combustion chamber 18 exhausts burnt gases therefrom. An open mouth 21 to the combustion chamber 18 accommodates a fuel gas/air mixture into the combustion chamber 18 to the catalytic element 19. A baffle plug 23 of brass located in the combustion chamber 18 within the catalytic element 19 is secured in tight heat transfer engagement in a bore 24 extending into the soldering tool tip 11 for transferring heat internally from the catalytic combustion element 19 to the soldering tool tip 11. The baffle plug 23 also acts as a thermal mass for increasing the thermal mass of the body member 10 and the soldering tool tip 11, and assists in minimising fluctuations in the temperature of the soldering tool tip 11 during soldering. In particular, the baffle plug 23 acts to distribute the fuel gas/air mixture to and throughout the catalytic combustion element 19 in order to achieve flameless combustion throughout the entire catalytic combustion element 19. Further, the baffle plug 23 acts to prevent any danger ofa ’E030]7’ flame during initial ignition of the fuel gas/air mixture in flame combustion for raising the temperature of the catalytic combustion element 19 to its ignition temperature burning outside the exhaust port 20, as will be described below.

A tubular upstream portion 25 of the body member 10 extends upstream from the combustion chamber 18, and forms a socket 26 for engaging a tubular sub—housing 28 of circular transverse cross-section and of heat conductive ceramics material of high aluminium content. The sub-housing 28 extends in an upstream direction from the body member 10 and abuts a portion 29 of the downstream end cap assembly . The tubular retaining member 12 terminates in its upstream end in an outwardly extending flange 30 which is retained captive between the gland nut 14 and the portion 29 of the downstream end cap assembly 15. The tubular retaining member 12 terminates at its downstream end in an inwardly directed flange 31 which engages a shoulder 32 of the body member 10 for retaining the body member 10 in abutment engagement with the sub—housing 28 for in turn retaining the body member captive. The retaining member 12 and the sub—housing 28 define respective central axes which coincide with the main central axis 2 defined by the main housing 3.

The sub—housing 28 forms an intermediate chamber 35. A burner 36 located in the intermediate chamber 35 delivers the fuel gas/air mixture into the intermediate chamber 35 where it is initially burnt in flame combustion as will be described below for raising the temperature of the catalytic combustion element 19 to its ignition temperature. The burner 36 is located in the intermediate chamber 35 upstream of the catalytic combustion element 19, and is located relative to the catalytic combustion element 19 so that when the catalytic combustion element 19 is raised to its ignition temperature and commences to convert fuel gas/air mixture to heat, the flame in the intermediate chamber 35 is extinguished, as a result of starvation of fuel gas/air mixture.

A temperature responsive valve 38 located within the sub—housing 28 receives fuel gas from the reservoir 5 through a fuel gas supply system 39 as will be described below, and modulates the supply of fuel gas to the combustion chamber 18 in response to the temperature of the body member 10, as will also be described below, for maintaining the temperature of the soldering tool tip 11 substantially constant within a narrow predetermined temperature range. The temperature responsive valve 38 delivers the modulated fuel gas to a mixing chamber 40 of a venturi mixing means, provided by a venturi mixer 41, where it is mixed with air drawn into the mixing chamber 40 through a port 42 in the venturi mixer 41, and through ports 44 and 45 in the sub-housing 28 and the retaining member 12, respectively. The venturi mixer 41 is of brass, and is located securely in the sub- housing 28 adjacent the intermediate chamber 35, and terminates in the burner 36.

A first nozzle 47 from the venturi mixer 41 delivers the fuel gas/air mixture to the burner 36. Radially extending ports 48 in the burner 36 deliver the fuel gas/air mixture from the first nozzle 47 into an annular outlet 49 defined between the burner 36 and the sub~housing 28. The fuel gas/air mixture issuing from the annular outlet 49 is initially burnt with flame combustion in the intermediate chamber 35, and on the flame being extinguished, the fuel gas/air mixture is converted to heat in the combustion chamber 18 by the catalytic element 19.

Referring now in particular to Figs. 7, 8 and 13, the temperature responsive valve 38 which is somewhat similar to the temperature responsive valves disclosed in PCT Specification No. WO O2/48591A of Oglesby, et al, the disclosure of which is incorporated herein by reference, will now be described. The temperature responsive valve 38 comprises a valve housing 52 formed by an outer housing 53 of brass and an inner housing 54 also of brass, which together define a valve chamber 55. The outer and inner housings 53 and 54 are of circular transverse cross- sectional area and define a longitudinally extending central geometrical axis of the temperature responsive valve 38 which coincides with the main central axis 2. A fuel gas inlet 56 which receives fuel gas from the fuel gas supply system 39 delivers the fuel gas into the valve chamber 55. The fuel gas inlet 58 is formed by a bore which terminates in the valve chamber 55in an annular valve seat 57. A valving member 58 provided by a circular disc of nitrite rubber material co-operates with the valve seat 57 for modulating the flow of fuel gas into the valve chamber 55. A bi—metal ’EU3[]77’ member, in this embodiment of the invention a circular bi—metal disc 59 located in the valve chamber 55, is responsive to the temperature of the body member 10, and co— operates with the valving member 58 for modulating the flow of fuel gas into the valve chamber 55 in response to the temperature of the body member 10 for maintaining the temperature of the soldering tool tip 11 substantially constant within the predetermined temperature range as will be described below.

A portion 50 of the inner housing 54 of the temperature responsive valve 38 engages a socket 51 in the venturi mixer 41. An outlet bore 61 extending through the inner housing 54 delivers fuel gas from the valve chamber 55, and terminates in a second nozzle 60, which delivers fuel gas into the mixing chamber 40 of the venturi mixer 41. A filter 62 in the bore 61 of the inner housing 54 filters the fuel gas to the second nozzle 60. A spigot 63 extends from the outer housing 53 of the temperature responsive valve 38 into the fuel gas supply system 39, and a bore 64 extending through the spigot 63 accommodates fuel gas from the fuel gas supply system 39 to the fuel gas inlet 56 of the temperature responsive valve 38.

In this embodiment of the invention the bi—metal disc 59 is substantially similar to the bi—metal disc of the temperature responsive valve disclosed by Oglesby, et al in PCT Specification No. WO 02/48591A, and is of the type which transitions with a snap action from a first concave configuration when viewed in one direction to a second convex configuration, which is a mirror image of the first configuration, when viewed from the same direction at a first predetermined transition temperature as the temperature of the bi—metal disc 59 is rising. Similarly, when the temperature of the bi-metal disc 59 is falling, the disc transitions with a snap action from the second convex configuration to the first concave configuration at a second predetermined transition temperature, which is lower than the first transition temperature. Such bi- metal discs as the bi—metal disc 59 will be well known to those skilled in the art.

When such bi—metal discs are free to transition between their respective first and second configurations, the bi~meta| discs, in general, operate with a digital action, in other words, if they were controlling a valving member, they would operate the valving member between an open state when in one configuration of the bi—metal FEUSQ77, disc, and a closed state, when in the other configuration of the bi-metal disc.

Furthermore, when transitioning from one of the configurations to the other with the snap action, such bi-metal discs operate the valving member with a similar snap action between the open and closed states. ln this embodiment of the invention the bi-metal disc 59 is constrained in the valve chamber 55 between the inner housing 54 and the outer housing 53 so that its transitioning movement is restricted to prevent transitioning between its respective first and second configurations. However, the bi-metal disc is located so that it is permitted limited transitioning movement as the temperature of the bi-metal disc 59 is increasing towards its first transition temperature. ln this way the bi-metal disc 59 acts with an analogue action within a temperature range just below its first transition temperature for operating the valving member 58 with a corresponding analogue action, rather than a digital action. Thus, the bi~metal disc 59 modulates the flow of the fuel gas by gradually increasing or decreasing the flow of the fuel gas in response to temperature variation in the body member 10 for maintaining the temperature of the soldering tool tip 11 substantially constant within the narrow predetermined temperature range. Additionally, the bi-metal disc 59 is located in the valve chamber 55 so that fuel gas can pass through the valve chamber 55 past the bi-metal disc 59 from the fuel gas inlet 56 to the outlet bore 61.

The temperature of the valve housing 52 and in turn the temperature of the bi-metal disc 59 are maintained substantially at the temperature of the body member 10 and in turn the temperature of the soldering tool tip, less a small temperature drop, by heat transfer from the body member 10. Heat is conducted from the body member through the sub—housing 28 to the valve housing 52, as well as through the retaining member 12 and through the venturi mixer 41. Heat is conducted and radiated to the bi-metal disc 59 from the valve housing 52.

The valve housing 52 of the temperature responsive valve 38 and the venturi mixer 41 are of circular transverse cross-section and define respective longitudinally extending central geometrical axes, which coincide with the main central axis 2 defined by the main housing 3. Additionally, the bi—metal disc 59 defines a central geometrical axis which also coincides with the main central axis 2 defined by the main housing 3. The fuel gas inlet 56 to the temperature responsive valve 38 defines a delivery axis along which the fuel gas is delivered to the temperature responsive valve 38. The first noale 47 defines a delivery axis along which fuel gas is delivered to the burner 36, and the second nozzle 60 defines a delivery axis along which fuel gas is delivered to the venturi mixer 41. The delivery axes defined by the fuel gas inlet 56, the first nozzle 47 and the second nozzle 60 are all axially aligned with each other, and all coincide with the main central axis 2 defined by the main housing 3. The burner 36 also defines a longitudinally extending central geometrical axis which coincides with the main central axis 2. Accordingly, the temperature responsive valve 38, the second nozzle 60, the venturi mixer 41, the first nozzle 47 and in turn the burner 36 are sequentially located one after the other in a generally downstream direction, and are axially aligned with each other. This permits the soldering tool 1 according to the invention to be provided as a relatively compact slimline soldering tool, while at the same time relatively accurate temperature control of the soldering tool tip 11 for maintaining the temperature of the soldering tool tip 11 substantially constant within a relatively narrow temperature range.

Returning now to the fuel gas supply system 39, a fuel gas outlet 65 from the fuel gas reservoir 5 accommodates fuel gas therefrom. A pressure reduction filter 66 in the fuel gas outlet 65 filters the fuel gas and reduces the pressure so that having passed through the filter 66 the fuel gas is in gaseous form. An on/off flow control valve 67 controls the flow of fuel gas from the fuel gas outlet 65. The fuel gas outlet 65 defines a valve seat 68, and a valving member 69 of the on/off flow control valve 67 co—operates with the valve seat 68 for switching on and off the supply of fuel gas from the fuel gas outlet 65. The valving member 69 is axially slideable within the main housing 3 for co—operating with the valve seat 68 and for switching on and off the fuel gas supply from the fuel gas outlet 65. A thumb operated slider switch 70 mounted externally on the main housing 3 co—operates with the valving member 69 for axially sliding the valving member 69 in the main housing 3 through a cam operated mechanism which is not illustrated in detail. However, such a cam lEU3o77, operated mechanism through which a thumb operated slider switch on a main housing of a soldering tool operates the valving member of an on/off flow control valve is illustrated and described in European Patent Specification No.

EP-A—O,1‘l8,282. A compression spring 71 co—operating with the downstream end cap assembly 15 of the main housing 3 urges the valving member 69 into engagement with the valve seat 68 for closing the on/off flow control valve 67. A bore 73 extends through the valving member 69 for accommodating fuel gas from the on/off flow control valve 67 to a central bore 74 of the main housing 3. An in—line filter 75 is located in the bore 73 for filtering the fuel gas. Radial ports (not shown) at the upstream end of the valving member 69 accommodate fuel gas from the on/off flow control valve 67 into the bore 73.

The spigot 63 extending axially upstream from the outer housing 53 of the temperature responsive valve 38 extends into the central bore 74 of the main housing 3, and the bore 64 extending through the spigot 63 delivers fuel gas from the central bore 74 to the temperature responsive valve 38.

An ignition means for igniting the fuel gas/air mixture from the burner 36 in the intermediate chamber 35 to burn in a flame is provided by a piezo—electric igniter (not shown) located in the main housing 3. The piezo—electric igniter (not shown) generates an EMF for providing a spark in the intermediate chamber 35 for igniting the fuel gas/air mixture to initially burn with a flame. In this embodiment of the invention the positive output of the piezo—electric igniter is connected to the fuel gas supply system 39, which is in electrical continuity with the burner 36, so that the burner 36 acts as one electrode. The negative output of the piezo—electric igniter is connected to the gland nut 14, which is in electrical continuity with the body member , so that the body member 10 acts as another electrode. Thus, when the EMF from the piezoelectric igniter is applied to the burner 36 and the body member 10, a spark arcs between the burner 36 and the body member 10, thereby igniting the fuel gas/air mixture issuing from the annular outlet 49. The valve housing 52 including the outer and inner housings 53 and 54 as well as the venturi mixer 41 and the burner 36 are electrically isolated from the body member 10, the retaining member and the gland nut 14 by the sub—housing 28. An actuator button 76 mounted externally on the main housing 3 is provided for actuating the piezo—electric igniter (not shown). in use, the bi—metal disc 59 is selected to have a first predetermined transition temperature of appropriate value to allow for the normal slight temperature drop from the body member 10 to the valve housing 52 of the temperature responsive valve 38 so that the soldering tool tip 11 is maintained at the desired temperature within a narrow predetermined temperature range. In this embodiment of the invention the temperature of the soldering tool tip 11 can be maintained substantially constant at a desired temperature within plus or minus 5°C, and in many cases within narrower limits. Thus, depending on the temperature at which it is desired to operate the soldering tool tip 11, the bi—metal disc 59 is selected to have the appropriate first predetermined transition temperature.

A typical temperature drop between the soldering tool tip 11 and the bi—metal disc 59 is 5°C, and thus, the bi—metal disc 59 is selected to have a first predetermined transition temperature of just above the desired temperature at which it is desired to maintain the soldering tip portion 11 less the temperature drop of 5°C. For example, where it is desired to maintain the temperature of the soldering tool tip at a temperature of approximately 280°C, the bi—metal disc 59 would be selected to have a first predetermined transition temperature of approximately 280°C. Thus, the bi- metal disc operates at a temperature around 275°C for controlling the flow rate of the fuel gas through the temperature responsive valve 38, which is just below its first predetermined transition temperature, and above its second predetermined transition temperature, which in general would be 10°C to 20°C below its first predetermined transition temperature.

Initially the thumb switch 70 is operated for switching on the on/off flow control valve 67 for supplying fuel gas to the temperature responsive valve 38. The fuel gas flows through the temperature responsive valve 38, and is delivered from the second nozzle 60 into the venturi mixer 41 where it is mixed with air and delivered through lE03u77, the first nozzle 47 to the burner 36. After the thumb switch 70 has been operated, the actuator button 76 is depressed for actuating the piezo—electric igniter (not shown) for generating the spark in the intermediate chamber 35 for igniting the fuel gas/air mixture, which commences to burn with a flame in the intermediate chamber , and extends into the combustion chamber 18. The flame raises the temperature of the catalytic combustion element 19 to its ignition temperature, at which stage the catalytic combustion element 19 commences to convert the fuel gas/air mixture to heat, thereby starving the flame of fuel gas and thus extinguishing the flame.

Thereafter the fuel gas/air mixture is delivered from the burner 36 directly through the open mouth 21 into the combustion chamber 18 where it is converted to heat by the catalytic reaction in the catalytic element 19, thereby raising the temperature of the soldering tool tip 11 to the desired operating temperature. Heat is transferred into the soldering tool tip 11 directly from the catalytic combustion element 19 through the body member 10 and through the baffle plug 23. As the temperature of the soldering tool tip 11 reaches the desired operating temperature, the bi—metal disc 59 within the temperature responsive valve 38 operates for modulating the flow of fuel gas through the temperature responsive valve 38 for maintaining the temperature of the soldering tool tip 11 substantially constant within the desired temperature range.

The baffle plug 23, as well as conducting heat from the combustion chamber 18 into the soldering tool tip 11, and distributing the fuel gas/air mixture throughout the catalytic combustion element 19 also increases the thermal mass of the body member 10, thereby rendering the soldering tool tip 11 less prone to temperature fluctuations.

In certain cases, it is envisaged that one or more radial grooves (not shown) may be provided in the valve seat 57 or in the valving member 58 of the temperature responsive valve 38 for facilitating continuity of flow of fuel gas through the temperature responsive valve 38 even when the valving member 58 is abutting the valve seat 57. The sizing of the grooves would be such as to permit the fuel gas to flow at a relatively low flow rate for merely maintaining the catalytic combustion lEn307 element at orjust above its ignition temperature.

Referring now to Figs. 14 to 19, there is illustrated a portion of a soldering tool according to another embodiment of the invention, indicated generally by the reference numeral 80. The soldering tool 80 is substantially similar to the soldering tool 1 and similar components are identified by the same reference numerals. The main difference between the soldering tool 80 and the soldering tool 1 is in the construction of the burner 36. The burner 36 in this embodiment of the invention is provided with a plurality of outlet ports 81 which are spaced apart circumferentially around a centrally extending electrode 82. A communicating duct 83 communicates the outlet ports 81 with the first nozzle 47 for delivering the fuel gas/air mixture from the first nozzle 47 to the outlet ports 81. Othenivise, the soldering tool 80 is similar to the soldering tool 1. However, in this embodiment of the invention the EMF generated by the piezo-electric igniter (not shown) is applied between the body member 10 and the electrode 82. A spark thus arcs between the electrode 82 and the body member 10, which ignites the fuel gas/air mixture issuing from the outlet ports 81 to burn in a flame in the intermediate chamber 35. Thereafter operation of the soldering tool 80 is similar to that of the soldering tool 1.

While the bi—metal disc 59 in the temperature responsive valve 38 has been described as being constrained so that it is prevented from transitioning from its first configuration to its second configuration as the temperature increases, it will be appreciated that in certain cases, the bi—metal disc may be located in the valve chamber of the temperature responsive valve to permit transitioning between its first and second configurations. In which case, the modulation of the flow of fuel gas would not be quite as accurate as when the bi—metal disc is constrained to operate with an analogue action, nonetheless, it is envisaged that in many cases, digital operation of the bi—metal disc as it transitions from its first to its second configuration as the temperature increases, and vice versa when it transitions from its second to its first configuration at the second lower predetermined transition temperature, the modulation of the flow of fuel gas would be sufficient to maintain the temperature of the soldering tool tip at the desired temperature, within a reasonable temperature lE0507 range.

It will also be appreciated that in certain cases where the bi-metal disc is constrained to prevent it transitioning from its first to its second configuration, the bi—metal disc may be selected to operate just above or just below its second predetermined transition temperature. Needless to say, the bi-metal disc could also be selected to operate just above its first predetermined transition temperature.

It is also envisaged in certain cases that the bi—metal disc may be selected to operate around either its first or its second predetermined transition temperatures, even when the bi-metal disc is constrained to prevent it actually transitioning from its first to its second or its second to its first configurations, as the case may be.

It is also envisaged that the bi—meta| disc itself may act as the valving member, and would co—operate directly with the valve seat extending around the fuel gas inlet 56.

It is also envisaged that the temperature responsive valve 38 and the venturi mixer 41 as well as the burner 36 may be supplied as one single unit plug-in in the form illustrated in Figs. 7 and 8 and Figs. 15 to 19, so that the plug-in unit could readily easily be replaced with another such plug-in unit, by releasing the gland nut 14 from the end cap assembly 15, for in turn releasing the tubular retaining member 12. The spigot 63 would be disengaged from the central bore 74, and the valve housing 52 and the venturi mixer 41 would be disengaged from the sub—housing 28. Each such unit would be provided with a bi—metal disc which would control the flow rate of the fuel gas for operating the soldering tool tip at different temperatures. For example, a range of the units may be provided which would modulate the flow of the fuel gas such that the soldering tool tip would operate at the following temperatures, 100°C, 250°C, 280°C, 315°C, 350°C and 370°C. Each unit would have the temperature at which it maintained the soldering tool tip engraved on the unit. Thus, if it were desired to operate the soldering tool at a temperature of, for example, 250°C, the appropriate unit for controlling the temperature of the soldering tool tip at 250°C would be inserted in the soldering tool. On the other hand, if it were desired to lEn5077p control the temperature of the soldering tool tip at 280°C, then the appropriate unit would be selected and inserted in the soldering tool. To replace one of the units with another unit would merely require removing the body member 10, the retaining member 12 and the sub—housing 28 by releasing the gland nut 14. The unit comprising the temperature responsive valve 38 and the venturi mixer 41 as well as the burner 36 would then be replaced with the unit which would control the temperature of the soldering tool tip at the desired temperature.

While the ignition means for igniting the fuel gas to burn in a flame has been described as being provided by a piezo—electric igniter, any other suitable means for igniting the fuel gas may be provided, for example, a flint igniter, which could be provided as an external ignition arrangement. it will of course be appreciated that other suitable ignition arrangements for raising the gas catalytic combustion element to its ignition temperature could be provided.

While the gas powered heating tool has been described as being a soldering tool, it will be readily apparent to those skilled in the art that the gas powered heating tool may be provided in many other forms. For example, the gas powered heating tool may be provided as a heated knife for cutting, for example, sheets of plastics material, ropes of plastics material and the like. In which case, the body member instead of terminating in a soldering tool tip, would terminate in an appropriately shaped and formed knife, which would be heated in similar fashion as the soldering tool tip is heated.

It is also envisaged that the gas powered heating tool may be provided in the form of a glue gun, whereby the body member would be an enlarged body member which as well as defining the combustion chamber, would also define a glue accommodating bore in which glue from a glue stick would be melted, and discharged through a nozzle. it is also envisaged that the gas powered heating tool may be provided as a blow lE0507 torch for providing a hot gas stream, for example, removing paint, melting solder in solder incorporated plumbing fittings, for example, plumbing fittings for connecting pipes together, and for any other purposes where a hot gas stream is required.

Claims (5)

Claims

1. A gas powered heating tool comprising a body member having a combustion chamber formed therein, within which a fuel gas/air mixture is converted to heat, a venturi mixing means located upstream of the combustion chamber for mixing fuel gas with air to provide the fuel gas/air mixture, a first nozzle being provided from the venturi mixing means for delivering the fuel gas/air mixture to the combustion chamber, the first nozzle defining a delivery axis along which the fuel gas/air mixture is delivered from the venturi mixing means, a temperature responsive valve located upstream of the venturi mixing means for modulating the flow of fuel gas from a fuel gas source in response to the temperature of the body member, the temperature responsive valve having a valve seat and comprising a temperature responsive bi- metal member co-operating with the valve seat for modulating the flow of fuel gas through the valve, a fuel gas inlet being provided to the temperature responsive valve for delivering fuel gas from the fuel gas source to the valve, the fuel gas inlet defining a delivery axis along which fuel gas is delivered to the temperature responsive valve, and a second nozzle being provided from the temperature responsive valve for supplying the modulated fuel gas to the venturi mixing means, the second nozzle defining a delivery axis along which fuel gas is delivered to the venturi mixing means, characterised in that the delivery axes defined by the first and second nozzles and by the fuel gas inlet to the temperature responsive valve are parallel to each other.

2. A gas powered heating tool comprising a body member having a combustion chamber formed therein within which a fuel gas/air mixture is converted to heat, the combustion chamber defining a longitudinally extending central geometrical axis, a venturi mixing means located upstream of the combustion chamber for mixing fuel gas with air to provide the fuel gas/air mixture, the venturi mixing means defining a longitudinally extending central geometrical axis, a first nozzle being provided from the venturi mixing means for delivering the fuel gas/air mixture to the combustion chamber, the first nozzle defining a longitudinally extending central axis, a temperature responsive valve located upstream of the venturi mixing means for modulating the flow of fuel gas from a fuel gas source in response to the temperature of the body member, the temperature responsive valve having a valve seat and comprising a temperature responsive bi—metal member co-operating with the valve seat for modulating the flow of fuel gas through the valve, the temperature responsive valve defining a longitudinally extending central geometrical axis, a fuel gas inlet being provided to the temperature responsive valve for delivering fuel gas from the fuel gas source to the valve, and a second nozzle being provided from the temperature responsive valve for supplying the modulated fuel gas to the venturi mixing means, the second nozzle defining a longitudinally extending central axis, characterised in that the central axes defined by the venturi mixing means, the temperature responsive valve and the first and second nozzles extend parallel to each other.

3. A gas powered heating tool substantially as described herein with reference to and as illustrated in the accompanying drawings.

4. A thermostatically controlled burner unit for a gas powered heating tool, the thermostatically controlled burner unit comprising a burner, a venturi mixing means located upstream of the burner for mixing fuel gas with air to provide the fuel gas/air mixture for supply to the burner, a first nozzle being provided from the venturi mixing means for delivering the fuel gas/air mixture to the burner, the first nozzle defining a delivery axis along which the fuel gas/air mixture is delivered from the venturi mixing means, a temperature responsive valve located upstream of the venturi mixing means for modulating the flow of fuel gas from a fuel gas source in response to temperature, the temperature responsive valve having a valve seat and comprising a temperature responsive bi—metal member co—operating with the valve seat for modulating the flow of fuel gas through the valve, a fuel gas inlet being provided to the temperature responsive valve for delivering fuel gas from the fuel gas source to the valve, the fuel gas inlet defining a delivery axis along which fuel gas is delivered to the temperature responsive valve, and a second nozzle being provided from the temperature responsive valve for supplying the modulated fuel gas to the venturi mixing means, the second nozzle defining a delivery axis along which fuel gas is delivered to the venturi mixing means, characterised in that the delivery axes defined by the first and second nozzles and by the fuel gas inlet to the temperature responsive valve are parallel to each other.

5. A thermostatically controlled burner unit for a gas powered heating tool, the thermostatically controlled burner unit comprising a burner, the burner defining a longitudinally extending central geometrical axis, a venturi mixing means located upstream of the burner for mixing fuel gas with air to provide the fuel gas/air mixture, the venturi mixing means defining a longitudinally extending central geometrical axis, a first nozzle being provided from the venturi mixing means for delivering the fuel gas/air mixture to the burner, the first nozzle defining a longitudinally extending central axis, a temperature responsive valve located upstream of the venturi mixing means for modulating the flow of fuel gas from a fuel gas source in response to the temperature, the temperature responsive valve having a valve seat and comprising a temperature responsive bi—metal member co—operating with the valve seat for modulating the flow of fuel gas through the valve, the temperature responsive valve defining a longitudinally extending central geometrical axis, a fuel gas inlet being provided to the temperature responsive valve for delivering fuel gas from the fuel gas source to the valve, and a second nozzle being provided from the temperature responsive valve for supplying the modulated fuel gas to the venturi mixing means, the second nozzle defining a longitudinally extending central axis, characterised in that the central axes defined by the venturi mixing means, the temperature responsive valve and the first and second nozzles extend parallel to each other. F.F.