Abstract:
A hand-held power tool powered by a gas combustion mechanism comprising a combustion chamber, a second chamber within a cylinder having aft and fore ends. The combustion chamber in fluid communication with the second chamber, and a first supercharger including a driver assembly, a drive motor and a fan assembly, the driver assembly having a piston and driver movable within the cylinder between said aft and fore ends. In use, whilst the piston is at or near the fore end of the cylinder, the fan assembly introduces air into the combustion chamber and the second chamber thereby pressuring the air there within, and fuel gas is introduced into the combustion chamber from a first supply port, the air and fuel gas becoming an air/fuel gas mixture therein. The drive motor moves the piston to a position at or near the aft end thereby compressing the air/fuel gas mixture within the first combustion chamber so that it is ignites within the combustion chamber to impart motion onto the piston. A second supercharger is connected to the combustion chamber for supplying a fuel gas and air mixture from a second supply port.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to an internal combustion fastener driving tool. 
       BACKGROUND 
       [0002]    Fastener driving tools have been developed that use internal combustion as a power source to drive fasteners such as nails, pins and staples into a work piece or substrate made of wood, concrete or steel. The tools ignite a fuel/air mixture in a combustion chamber to forcibly drive a piston, which then ejects the fastener from the tool. The effectiveness of the prior art is largely limited to their efficiency in rapidly igniting the complete volume of fuel/air mixture. If insufficient volumes of fuel ignite, the device delivers unsuitable driving forces to the fastener. If the tool produces unreliable power outputs the fasteners may be driven to unsatisfactory depths or insufficiently seated. Prior art devices have attempted to address these inefficiencies by making a larger tool and wasting larger volumes of fuel. 
         [0003]    Some prior art tools also suffer from what is known as misfire (or non-fire). This occurs when the tool is operated in low temperature conditions or at high altitude and hot conditions. The cause of the phenomenon is; (a) insufficient atomization and mixing of the air/fuel; (b) an insufficient fuel/air ratio; (c) low air density. 
         [0004]    One such prior art tool is described in U.S. Pat. No. 5,213,247 (Gschwend et al). This device includes a network of mechanisms that operate to measure a specific quantity of fuel and then draw that fuel, along with air, into a combustion chamber by mechanically expanding the combustion chamber volume. A drawback of this device is that the fuel and gas are not mixed sufficiently, which decreases the efficiency of combustion. 
         [0005]    A further disadvantage of such prior art tools is the tool mass (weight and physical size) required for a given output of energy. Furthermore, such tools draw fuel and air into the combustion chamber with partial vacuum. As a consequence the fuel/air mixture is ignited at a low pressure, which leads to a low burn rate and further inefficiency. This is particularly problematic in that the less efficient an internal combustion fastener driving tool is, the more susceptible the device is to output fluctuations that result in ignition failures and unsatisfactory driving forces to the fastener. 
         [0006]    Also prior art impulse tools such as those used in nail and fixing in the building industry have limitations in their use. Such tools have the capability of producing 70 to 100 joules of output energy. These tools will only produce their manufactured claimed output under optimal conditions ie; 24C@sea level and a relevant humidity level of approximately 40%. If these optimum conditions change, so does the power output by as much as 25%, and in some cases they do not fire at all. This means that nails and fixers sometimes protrude and are only driven 80 to 90% of the manufactured depth, and thus the work piece may not meet building standards. This may also lead the operator to have to use a traditional hammer to finish the job. 
         [0007]    Some impulse tool manufactures have developed tools to produce in excess of 100 joules, but such tools have ended up being a far larger unit for consumers to reasonably expect to purchase. 
         [0008]    All prior art combustion tools used for fixing, suffer from gumming up and need to be cleaned regularly. This is caused by incomplete combustion in the tool. Carbon, lubricants and other bi-products of combustion and exhaust gases build up deposits within the combustion chamber, driver piston and head. 
         [0009]    A new and more powerful generation of cordless combustion impulse tools employing “supercharging” in their combustion processes have been developed. One such tool is described in our International Publication No. WO 2009/140728 (International Application No. PCT/AU2009/000629). 
         [0010]    Whilst the supercharged tools are more powerful than earlier prior art tools, they suffer from a number of disadvantages. 
         [0011]    Firstly there is a higher demand on battery power availability, resulting in less tool cycles per battery charge. 
         [0012]    Secondly inefficiencies with ignition processes may result in an incomplete burn. 
         [0013]    Thirdly, an unregulated fuel delivery system may result in an incorrect fuel ratio which may cause the tool to misfire (or non-fire). This occurs when the tool is operated in low temperature conditions or at high altitude and hot conditions. The cause of the phenomenon is insufficient atomization and mixing of the air/fuel and or an insufficient fuel/air/supercharging ratio. 
         [0014]    Fourthly, energy output and duration and energy fluctuations can be a disadvantage. In the prior art supercharged tools, a large amount of energy is created at the beginning (first 50%) of the driving stroke as opposed to the ending (latter 50%) of the driving stroke where a greater frictional force is acting on the nail or pin. 
         [0015]    The tool cycle time has been extended from 4 cycles per second to 2, as a result of the time delay created by the supercharging time delay. 
         [0016]    With these new technology&#39;s and higher outputs a larger tool is resulting. Supercharging pressures and tool output power are limited to the ability of the driver piston holding mechanism in conjunction with the driver piston return mechanism and overall tool construction. 
         [0017]    High output supercharging of cordless combustion impulse tools has also created new and in some cases catastrophic part overstress, failures and overheating. It has also been found that the internal circulation fan drive motor can fail due to the increase in ignition pressures and/or shock within a super-charged system. 
         [0018]    The present invention seeks to provide a fastener driving tool that will ameliorate or overcome at least one of the deficiencies of the prior art. 
       SUMMARY OF INVENTION 
       [0019]    According to a first aspect the present invention consists in a hand-held power tool, the operational power of which is provided by a gas combustion mechanism, said gas combustion mechanism comprising a first combustion chamber, a second chamber within a driving cylinder having an aft end and a fore end, said first combustion chamber in fluid communication with said second chamber via said aft end, a first supercharger including a driver assembly, a drive motor and at least one fan assembly, said driver assembly having a piston and driver movable within said driving cylinder between said aft end and said fore end, said drive motor operably connected to said driver assembly, wherein in use, whilst said piston is at or near said fore end of said driving cylinder, said fan assembly introduces air into said first combustion chamber and said second chamber thereby at least partially pressuring the air there within, fuel gas is introduced into said combustion chamber from a first fuel supply port, the air and fuel gas being mixed to form an air/fuel gas mixture therein, said drive motor operably moves said piston to a position at or near said aft end thereby compressing said air/fuel gas mixture within said first combustion chamber so that said air/fuel mixture is ignited within the combustion chamber to impart motion onto said piston and to facilitate the operation of the tool, characterized in that a second supercharger is operably connected to said combustion chamber for supplying a fuel gas and air mixture from a second supply port. 
         [0020]    Preferably both the first supercharger and second supercharger can be used in combination or independently to each other to supercharge said tool. 
         [0021]    Preferably fuel from said second supply port is a weaker fuel than the fuel being dispensed from said first supply port. 
         [0022]    Preferably fuel from said second supercharger cylinder may be introduced into said combustion chamber after or during ignition of fuel and air mixture supercharged by said first supercharger. 
         [0023]    Preferably said tool further comprises a movable tool nose assembly and a trigger assembly both operably connected to an ECM for the control and actuation of the fan assembly, drive motor and first and second gas supply ports. 
         [0024]    Preferably said tool has a selector switch operably connected to said ECM that allows said a user to select operation of said first supercharger and second supercharger to be used in combination or independently to each other. 
         [0025]    Preferably said ECM includes a programmed timing circuit to allow variation of the supercharging provided by said second supercharger to engage and disengage said secondary supercharger and also vary the amount of supercharging from said first supercharger. 
         [0026]    Preferably said second supercharger comprises a double acting cylinde 
         [0027]    Preferably said driving cylinder is directly connected to a cylinder head that supports said fan assembly. 
         [0028]    Preferably said driving cylinder has plurality of radially spaced apart inlet primary inlet ports around the driving cylinder near cylinder head, and a plurality of secondary transfer polarity ports radially spaced apart around said driving cylinder at a location further away from cylinder head and extending below annular chamber housing. 
         [0029]    Preferably an annular chamber housing surrounding said driving cylinder and connected thereto allows for a portion of said combustion chamber to extend radially beyond the external diameter of said driving cylinder. 
         [0030]    Preferably said fan assembly has a first external induction fan for introducing air into said first combustion chamber. 
         [0031]    Preferably said fan assembly has a fan motor which is of a pancake type. 
         [0032]    Preferably said fan assembly has a second internal circulation fan disposed within said first combustion chamber. 
         [0033]    Preferably said second internal circulation fan is in magnetic communication with a second drive motor. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0034]      FIG. 1  shows a schematic cross-sectional view of a hand held internal combustion nail fastener tool in accordance with a first embodiment of the present invention; 
           [0035]      FIG. 2   a  shows a schematic cross-sectional view of the hand held internal combustion nail fastener tool of  FIG. 1  and the air flow paths as air is introduced into the combustion chamber for charging using the primary supercharger. 
           [0036]      FIG. 2   b  shows a schematic cross-sectional view of the hand held internal combustion nail fastener tool of  FIG. 1  and the air flow paths as air is introduced into the combustion chamber for charging using the primary supercharger. 
           [0037]      FIG. 3  shows a schematic cross-sectional view of the hand held internal combustion nail fastener tool of  FIG. 2  with the driver and piston in a fully extended position where the piston abuts and compresses the bumper as a result of the firing trigger being fully depressed and air/fuel mixture being ignited; 
           [0038]      FIG. 4  shows a schematic cross-sectional view of the hand held internal combustion nail fastener tool of  FIG. 1  in the mode when a user has touched the trigger, thereby causing external air to be force fed (supercharged via primary supercharger) into the combustion and drive cylinder chambers and the piston has been driven to a positioning abutting the bumper and blocking the exhaust port; 
           [0039]      FIG. 5  shows a schematic cross-sectional view of the hand held internal combustion nail fastener tool of  FIG. 1  placed against the substrate and ten percent travel of the movable tool nose has occurred; 
           [0040]      FIG. 6  shows a schematic cross-sectional view of the hand held internal combustion nail fastener tool of  FIG. 1  placed against the substrate and one hundred percent travel of the movable tool nose has occurred; 
           [0041]      FIG. 7  shows a schematic cross-sectional view of the hand held internal combustion nail fastener tool of  FIG. 1  placed against the substrate and the firing trigger been activated about ten percent of its travel; 
           [0042]      FIG. 8  shows an enlarged schematic cross-sectional view of the top end (combustion chamber/fan assembly end) of the hand held internal combustion nail fastener tool of  FIG. 1 . 
           [0043]      FIG. 9  shows an enlarged side view detail of the two fuel cells and secondary supercharger of the hand held internal combustion nail fastener tool of  FIG. 1 . 
           [0044]      FIG. 10  shows an enlarged schematic cross-sectional view of the top end of the hand held internal combustion nail fastener tool of  FIG. 1 , with internal components extending into combustion chamber omitted to clearly indicate combustion chamber location. 
           [0045]      FIG. 11  is a typical graph representation of Output Energy (kgf/cm2) Vs Time (ms) that would be achieved relying on primary supercharging producing 70 joules of output energy. 
           [0046]      FIG. 12  is a typical graph representation of Output Energy (kgf/cm2) Vs Time (ms) that would be achieved relying on primary supercharging producing 140 joules of output energy. 
           [0047]      FIG. 13  is a graph representation of Output Energy (kgf/cm2) Vs Time (ms) that would be achieved relying on primary and secondary supercharging producing a 200 joules of output energy. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0048]      FIGS. 1-10  depict a hand held internal combustion nail fastener tool  100  which includes two superchargers, namely a “primary supercharger” and a “secondary supercharger”. 
         [0049]    The first (or primary) supercharger is made up of driver assembly  7 , motor  101  and fans  103 , 104 . These components of the first primary supercharger are similar to those shown in our “prior art” International Publication No. WO 2009/140728. Whilst the operation of the “primary supercharger” differs to that of the abovementioned “prior art” tool, for ease of reference those components that are similar in the abovementioned prior art tool are numbered similarly in this embodiment. 
         [0050]    Hand-held internal combustion nail fastener tool  100  comprises a drive motor  101 , an induction/circulation motor  102 , an external induction fan  103 , an internal circulation fan  104 , a twenty-four volt battery pack  105 , a combustion chamber  106 , a driver cylinder chamber  107  within cylinder  13 , an exhaust (cooling) cavity  108 , a fuel cell cartridge  109   a  (see  FIG. 9 ), and igniters  110   a  and  110   b.  The combustion chamber housing  17  surrounding combustion chamber  106  and mounted to cylinder has a “annular shaped” (best seen in  FIG. 10 ) and is directly mounted to cylinder  13 . 
         [0051]    Tool  100  has an Electronic Control Module (ECM)  27  which controls various components of tool  100 . An output power selector switch  146  connected to ECM  27  allows a user (not shown) to select various operating configurations, “Normal Power” (only primary supercharger employed), “High Power” (both primary and secondary superchargers employed), and “Low Power” (only secondary supercharger employed). 
         [0052]    The operation of tool  100  will now be described. A user (not shown) holds tool  100  by support handle (pistol grip)  34 . Preferably the user&#39;s index finger is placed on firing trigger  3 . The touch sensor  35  alerts ECM  27  that tool  100  is to be operated. ECM  27  actuates the electrical circuit to the induction and circulation fan motor  102  to operate at twelve volts. This results in the external induction fan  103  and internal circulation fan  104  to drive air from external of tool  100  in through air intake filter  21 . External air is force fed into the combustion chamber  106  via a plurality of inlet ports  134  and driver cylinder chamber  107  (see  FIG. 1 ) has charged air. Simultaneously ECM  27  checks the position of drive motor  101 , which is in communication with driver  14  and piston  15  via drive motor gear  7  and driver gear rack  11 . The drive motor  101  repositions driver  14  and piston  15  so that the underside of piston  15  is resting on bumper  8 , see  FIG. 4 . In this position the piston  15  is blocking the exhaust port  10  and seals chambers  106  and  107 . Also at this same point of the tool cycle the combustion chamber housing  17  is in the one hundred percent (100%) open mode in communication with movable tool nose portion  5 . As external air is drawn in via fan  103 , seal  132  prevents the air now under pressure from fan  103  from entering cavity  108 , so one hundred percent (100%) of external air is directed into the combustion chamber  106 . Upon entering combustion chamber  106 , the incoming air is further accelerated by the internal circulation fan  104 . As the air passes through fan  104 , the air is forced to flow through baffle  139  and frusto-conically shaped circulation shroud  25 , which further speeds up the air flow. Air is then directed down the centre of driver chamber  107  via shroud  25 . At the base of chamber  107  (within cylinder  13 ), the air flow is split and redirected back up chamber  107  into the combustion chamber  106 , via the “toroidally” shaped concave aft surface of piston  15 , where the air flow is split by port mask  136  and approximately 95% exits chamber  106  via a plurality of exhaust transfer ports  133 , flowing into and along cavity  108  and exiting tool  100  via exhaust vent  9 . The remaining air flow in chamber  106  (approximately 5%) flows up to the top of the chamber  106  where it rejoins the incoming air flow through a plurality of holes/vents arranged around the side wall of circulation shroud  25  as seen in  FIG. 4 . 
         [0053]      FIG. 5  depicts tool  100  placed onto a substrate where ten percent (10%) travel of movable tool nose portion  5  has occurred. Tool nose portion  5 , which is in communication with housing  17 , has caused housing  17  to shut off the exhaust transfer ports  133  allowing one hundred percent (100%) of air flow to circulate around chambers  106  and  107 . At this same point the ECM  27  has switched motor  102  to twenty-four volts, 200% of the normal manufacturer duty-cycle voltage for motor  102 . This causes motor  102  to greatly increase its rotation (rpm) momentarily thus increasing the volume and speed of air flow into chambers  106  and  107 , as exhaust port  16  is closed the increase in air flow into chambers  106  and  107  causes an increase in air pressure there within. In prior art impulse tools the exhaust port and air inlet would close off simultaneously, however in this embodiment of the invention, after exhaust ports  133  closes, the increased rotation of motor  102  continues to introduce “supercharged” air into chambers  106  and  107 . This is because the closure of exhaust ports  133  is in or near the first ten percent (10%) of travel of housing  17 , leaving the inlet side open to receive charged air. 
         [0054]      FIG. 6  depicts tool nose  5 , in communication with the housing  17 , has operated (travelled) at one hundred percent (100%). At this point of the tool cycle, air flow from fan  103  has been redirected into cavity  108 . During the last say five percent (5%) of travel of chamber housing  17 , seals  17 A and  17 B cause chambers  106  and  107  to be sealed. When chamber housing  17 , has operated (travelled) at one hundred percent (100%) and therefore chambers  106  and  107  are sealed, a metered amount of gas from first fuel cell  109 A via gas regulator valve head  23 A and gas regulator valve actuator  24 , in communication with  17 , has entered chamber  106  through jet/manifold  153 . 
         [0055]    As the fuel exits jet/manifold  153  the rapidly rotating blades of fan  104  accelerate the vaporization and expansion reaction of the fuel gas as well as rapidly circulating and mixing the air and fuel together in chambers  106  and  107 . 
         [0056]      FIG. 7  also depicts that the firing trigger  3  has been actuated ten percent (10%) of its travel. At this point the ECM  27  in communication with trigger  3  switches electrical circuit on to drive motor  101 , causing piston  15  and driver  14  in conjunction with rack  11  and gear  7 , to travel one hundred percent (100%) to the top of driver cylinder  13 . If “High Power” setting is selected via tool output power selector  146 , simultaneously ECM  27  switches electrical circuit on momentarily to driver motor  132  and secondary supercharger assembly  131  also delivering air or air/fuel mixture to further boost supercharged pressures. 
         [0057]    As chamber  106  is sealed all the air mass in chamber  107  is compressed in to chamber  106 , creating a pressure greater than ambient (pressure difference). Also, as the driver assembly  14  and piston  15  achieve one hundred percent (100%) of travel up to the top of cylinder  13 , a nail  40  has been placed into the fixed tool nose  6  from fastener magazine  4 . Air and fuel now contained in chamber  106  circulates rapidly, shroud  25  directs the fuel/air mixture across the igniters  110   a  and  110   b,  by means of vents/holes (not shown) at the base of shroud  25 . 
         [0058]      FIG. 4  depicts that firing trigger  3  has operated 100% of its travel. ECM  27  switches circuit on to high tension ignition coil  1 , thereby operating same very rapidly, at approximately twenty-five to fifty applications. The resulting pulses of high voltage created by the ignition coil  1  are in communication with igniters  110   a  and  110   b.  The resulting multiple high-tension sparks from igniters  110   a  and  110   b  ignite the fuel/air mixture in combustion chamber  106  simultaneously. ECM  27  switches driver motor  101  to a separate electrical circuit converting driver motor  101  to a generator. As the fuel/air mixture ignites in chamber  106 , a rapid rise in pressure occurs forcing the driver assembly  14  and piston  15  down cylinder  13  ejecting nail  40  into the substrate (or work piece). As the driver assembly  14  and piston  15  progresses down cylinder  13  reaches 50% fifty present. If “High Power” setting is selected via tool output power selector  146 , ECM  27  switches electrical circuit back on momentarily to drive motor  132  and secondary supercharger  131  to engage for a second time to deliver air/fuel mixture to permit a further secondary supercharged power event to take place . To assist the secondary supercharged power event baffle  139  holds up (interrupts) the incoming air/fuel mixture and separates it from the preceding flame front. The igniters  110   a  and  110   b  are then reactivated by ECM  27  resulting in a secondary additional power cycle in the same tool  100  cycle. As the driver assembly  14  and piston  15  progress down the cylinder  13 , motor  101  now acting as a generator is in communication with driver assembly  14 , via rack  11  and gear  7 . The resulting charge is sent back into the battery pack  105 , increasing battery/tool cycles between charges. As the driver assembly (driver  14  and piston  15 ) reach 90% of travel, the underside of piston  15  comes into contact with bumper shock absorber  8 , which reduces the kinetic energy of driver  14  and piston  15 , bringing them to a steady controlled stop in cylinder  13 . At this stage of the tool/combustion cycle the exhaust ports  10  configured in plurality at the base of cylinder  13 , are uncovered by piston  15 . The exhaust gases in chambers  106  and  107  escape/evacuate through exhaust ports  10 , reducing the gas pressure in chambers  106  and  107  to a partial vacuum (lower pressure) than ambient. The stored energy in bumper  8  then repels the driver assembly (driver  14  and piston  15 ) approximately thirty percent (30%) back up bore  13 . ECM  27  then switches fan motor  102  back to normal running mode at 12V. Simultaneously ECM  27  in communication with driver motor  101  checks the position of the driver assembly (driver  14  and piston  15 ) and adjusts as required, at the bottom of the bore  13  with underside of piston  15  resting on bumper  8  also “closing off” the exhaust ports  10 . 
         [0059]    Tool  100  is then raised off the substrate allowing movable tool nose portion  5  to extend. Tool nose portion  5  in communication with housing  17  slides forward, allowing air to circulate around  106  and  107  and exit through exhaust ports  16 . The firing trigger  3  is then released resetting the ECM  27  back to the start cycle status. 
         [0060]    Various features of note of this embodiment will now be discussed in further detail. 
         [0061]    It should be noted that as “main” cylinder  13  continues right through tool  100  and connects directly to a more robustly constructed cylinder head  31 , tool  100  is more robust. Additionally cooling fins  133  have also been added for additional strength and cooling. These combined features significantly minimize the stresses transmitted through the body which are encountered in the prior art tool of International Publication No. WO 2009/140728. An advantage is that secondary supercharger  131  may also be operated simultaneously with the primary supercharger mechanism for extreme “High Power” output used to drive pins into steel and high density 6000 psi concrete. 
         [0062]    A varying degree of “secondary supercharging” is also achieved by having the ability to vary the supercharge pressure by means of a programmed timing circuit within ECM  27  to engage and disengage or turn on and off the double acting secondary supercharger  131  and also vary the amount of supercharging from primary supercharger mechanism, this in turn varies the tool energy output. 
         [0063]    To also achieve these overall improvements it is necessary for tool  100  to be equipped with two fuel gas cells  109 A,  109 B and metering valves  23 A and  23 B as best seen in  FIG. 9 . A ‘rich fuel” is preferably delivered directly into the cylinder  13  from “primary” fuel gas cell  109 A, via valve  23 A, fuel gallery  140 A, primary fuel manifold  138  and charge manifold  153 . “Secondary” fuel cartridge  109 B dispenses a weaker fuel mixture directly into the secondary supercharger  131  via fuel gallery  140 B. 
         [0064]    To overcome the battery power availability and tool cycle time, the present embodiment employs a secondary supercharger  131  having a modified double acting piston and cylinder mechanism  131  in which improves supercharging time and efficiency by up to 200% by closing off the rear of the cylinder, introducing a bearing/seal  142  for connecting rod  143  to operate within and air inlet valve V 2  and outlet valve V 1  in conjunction with manifold  140 C. 
         [0065]    In addition the double acting secondary supercharger  131  having fuel dispensed directly into its cylinder via fuel supply manifold  140 B and the secondary fuel cartridge  109 B and metering valve  23 B can also be re-tasked to operate after the primary combustion cycle, having the ability of achieving a delayed secondary supercharged combustion cycle providing a prolonged power delivery duration as indicated in the “Power Output Vs Time” graph shown in  FIG. 13 . This delayed secondary supercharged combustion cycle may occur about 4 ms after commencing the primary supercharger. 
         [0066]    To better understand  FIG. 13 , it is best to first view “Power Output Vs Time” graphs shown in  FIGS. 11 and 12  which each show the power output of a primary supercharged tool. These  FIGS. 11 and 12  are typical representations of the prior art supercharged tools, or where only the primary supercharger is employed in tool  100  of the present embodiment. As can be seen in both of  FIGS. 11 and 12 , a large amount of energy is created at the beginning (first 50%) of the driving stroke as opposed to the ending (latter 50%) of the driving stroke where a greater frictional force is acting on the nail or pin. 
         [0067]    Where a delayed secondary supercharged combustion cycle (or secondary firing cycle) is provided, a prolonged power delivery duration is achievable as demonstrated in  FIG. 13 . 
         [0068]    The secondary firing cycle is further assisted by the introduction of baffle plate  139  with small holes strategically placed in the combustion chamber shroud as to interrupt or hold up the incoming secondary fresh charge of fuel/air mixture via the charge manifold  153  from the secondary supercharger  131  and or separating the new charge from the primary flame front. 
         [0069]    Tool  100  of the present embodiment includes multiple ignition points  110 A and  110 B (or more than one igniter), in addition multiple applications (cycles) of the ignition points (20+) for 1 to 20 milliseconds duration are applied per tool cycle. This ensures a more complete burn in all climatic and fuel/air state conditions. 
         [0070]    To allow these new features to operate efficiently it is important to note the function of annular smooth “aerodynamic” chamber housing  17  in conjunction with primary inlet polarity ports  134  and secondary transfer polarity ports  133 , which allows the fresh incoming air flow to pass into and circulate around the combustion area and drive cylinder  13 . The primary inlet ports  134  are radially spaced apart around the driving cylinder  13  near cylinder head  31 , whilst secondary transfer polarity ports  133  are also radially spaced apart around the driving cylinder  13  but at a location further away from cylinder head  31  extending below housing  17 . 
         [0071]    The overall height of tool  100  is significantly reduced when compared to the prior art, firstly by utilizing an annular combustion chamber housing  17  that “bulges” outwardly a portion of combustion chamber  106  beyond the external diameter of cylinder  13 . Secondly by adopting fan motor  102  to be of a “pancake type” this may also significantly reduces overall height of tool  100 . 
         [0072]    In the abovementioned first embodiment, the internal circulation fan  104  of tool  100  is driven directly by motor  102 . However, in an alternative not shown “fan drive system” embodiment that can be used in tool  100 , the internal circulation fan drive motor is in magnetic communication (drive) with an internal circulation fan via spaced apart magnetic drive components. Such alternative “fan drive system” would allow the fan drive motor and its associated magnetic drive component to be isolated from the combustion chamber side where internal circulation fan and its magnetic drive component are disposed. This arrangement would minimise the risk of failure to the fan drive motor due to increases in ignition pressures and/or shock within a super-charged system. 
         [0073]    In a further not shown embodiment it should be understood that a battery charging docking station built into the tool carry case could be employed so that when the tool is placed in its home position within the case electrical contacts on the tool marry up with contacts in the case to facilitate boost or recharging of the tool battery (s). This would assist in extending battery usage. The tool carry-case may also have a solar photovoltaic panel built into the lid for the purpose of battery charging 
         [0074]    Additionally in a further embodiment the tool is fitted with an audible and or visual information system for product (sales) tool status information for the consumer and product servicing and warranty; a touch pad may be incorporated for tool security purposes. 
         [0075]    The terms “comprising” and “including” (and their grammatical variations) as used herein are used in inclusive sense and not in the exclusive sense of “consisting only of’.