Portable gas-powered tool with linear motor

Abstract

An efficient, portable, easy to operate tool employing a linear motor is disclosed that is powered by the gases produced from the internal combustion of a fuel and air mixture. A supply of liquified gas stored under pressure in a cylinder provides the source of power. The linear motor is slidably mounted within a cylinder to move reciprocally downwardly and upwardly through a driving and return stroke. A combustion chamber is formed at the upper end of the cylinder. A spark plug powered by a piezo-electric firing device is located within the combustion chamber. The combustion chamber features a turbulence generator, such as a fan, driven by an electric motor which is continuously in operation when the tool is in use. A main valve mechanism actuated by a set of lifting rods that are moved upwardly and downwardly when the tool is moved towards and away from the workpiece, is used to control the opening and closing of the combustion chamber and to control the flow of fresh air through the combustion chamber. When the combustion chamber is isolated from the atmosphere and the fuel and air are thoroughly mixed, the spark plug is fired to explode the fuel and air mixture and force the linear motor through its driving stroke. The linear motor is returned to its driving position by a spring or air acting against the underside of the linear motor. The unique use of the electric fan improves the overall operational efficiency of the tool and the utilization of the liquified combustible gas.

What is claimed is: 
     
       1. A self-starting portable tool comprising a housing, a cylinder in said housing, a piston in said cylinder and forming a motor member, a working member attached to said piston, a combustion chamber formed within said housing and having said piston defining a wall portion thereof, a turbulence generator in said chamber, means for supplying fuel and air to said chamber, means for operating said generator independent of said piston such that premixing and turbulence are imparted to the air and fuel in said chamber before initial ignition of the mixture in said chamber and before initial movement of said piston, and means for igniting and exploding said mixture in said combustion chamber to .[.deive.]. .Iadd.drive .Iaddend.said piston to operate said working member, whereby the initial and all subsequent strokes of the motor member are operated at .[.substantiall.]. .Iadd.substantially .Iaddend.full energy output and further wherein the turbulence generator consists of a fan disposed in said chamber and the means for operating said generator includes an electric motor self-contained within said housing and connected to said generator. 
     
     
       2. A portable tool in accordance with claim 1 including means for returning the piston to its driving position after it has been driven. 
     
     
       3. A portable tool in accordance with claim 2 including means for admitting air under ambient pressure to the underside of the piston when it is in its driven position such that the pressure differential between the ambient pressure on the underside of the piston and the lower pressure on the other side of the piston is effective to return the piston to its driving position. 
     
     
       4. A portable tool in accordance with claim 2 including means for retaining the piston in its driving position after it has been returned thereto. 
     
     
       5. A self-starting portable tool comprising a housing, a cylinder in said housing, a piston in said cylinder and forming a motor member, a working member connected to said piston, a combustion chamber formed within said housing and having said piston defining a wall portion thereof, means providing axially disposed inlet and exhaust ports to said combustion chamber for admitting air and for discharging the products of combustion, a turbulence generator in said chamber axially disposed between said inlet and exhaust ports, means for supplying fuel to said chamber, means for operating said generator independent of said piston such that premixing and turbulence are imparted to the air and fuel in said chamber before initial ignition of the fuel in said chamber and before initial movement of said piston, and means for igniting and exploding the mixture in said combustion chamber to drive said piston to operate said working member and further wherein the turbulence generator comprises a fan having its axis axially disposed in said chamber, which fan serves to scavenge said chamber after firing by directing air from said inlet port through said exhaust port, and the means for operating said generator includes an electric motor self-contained within said housing and connected to said generator. 
     
     
       6. Apparatus in accordance with claims 1 or 5 in which the means for supplying fuel to said chamber is a metering valve mechanism wherein a prescribed amount of fuel is supplied to said combustion chamber. 
     
     
       7. Apparatus in accordance with claims 1 or 5, wherein the means for igniting said fuel includes a spark plug powered by a piezo-electric device. 
     
     
       8. Apparatus in accordance with claims 1 or 5, including trigger operated means for operating the means for supplying fuel to said chamber and for igniting said fuel to drive said motor member. 
     
     
       9. A portable tool in accordance with claim 5 in which the combustion chamber is opened and closed by a valve means that coacts with said inlet and exhaust ports, and means for effecting movement of said valve means to close off said chamber prior to ignition and open said chamber after the working member has been driven to facilitate scavenging of said chamber. 
     
     
       10. A portable tool in accordance with claim 9 in which the valve means includes a slidable sleeve that cooperates with the housing to effect opening and closing of the inlet and exhaust ports. 
     
     
       11. Apparatus in accordance with claims 9 or 10, including trigger operated means for (1) operating said valve means to control the opening and closing of said combustion chamber, (2) operating the means for supplying fuel to said chamber, and (3) for igniting said fuel to drive said motor member. 
     
     
       12. A portable tool in accordance with claims 9 or 10 including trigger operated means for operating said valve means to control the opening and closing of said combustion chamber. .Iadd. 
     
     
       13.  A self-starting portable tool comprising a housing,   an elongated cylinder in said housing,   a piston having an upper face and a lower face, said piston being mounted in said cylinder to be driven between an upper position of rest and a lowermost position and forming a motor member,   a working member attached to said piston,   a combustion chamber formed within said housing and having the upper face of said piston defining a wall portion of said combustion chamber,   means for providing a fuel and air mixture in said chamber,   means for igniting and exploding said mixture in said combustion chamber to drive said piston through a driving stroke from said upper position to said lowermost position to operate said working member,   and return means for causing said piston to move upwardly from said lowermost position to said upper position of rest, said return means including outlet means in said elongated cylinder between its ends for communicating said cylinder with ambient atmosphere and being disposed below said upper position of rest and above said lowermost position of said piston, such that when said piston is driven towards said lowermost position, said piston moves past said outlet means thereby to place said combustion chamber in communication with said outlet means to exhaust a portion of combustion gases from said combustion chamber to ambient atmosphere and cause a reduction in temperature of the combustion gases remaining in the combustion chamber, and   said return means further including bumper means at the lower end of the cylinder for initially moving said piston upwardly from said lowermost position, said combustion chamber above said upper face being out of communication with ambient atmosphere during the further return of said piston to said upper position of rest, said further return of said piston to said upper position of rest being substantially caused by throughout further such return, said return means producing an upwardly acting pressure differential on said upper and lower faces of said piston induced by the reduction in temperature of the combustion gases above the upper face to produce a sharp reduction of pressure in said combustion chamber to below ambient pressure. .Iaddend. .Iadd.14. A self-starting portable tool in accordance with claim 13, and wherein said outlet means comprises a plurality of ports. .Iaddend. .Iadd.15. A self-starting portable tool in accordance with claim 13, and wherein said outlet means is located in the lower end of the cylinder. .Iaddend. .Iadd.16. A self-starting portable tool in accordance with claim 13, and wherein said outlet means is in communication with ambient atmosphere when said piston is both thereabove and therebelow through an exhaust valve which opens in response to an elevation in the pressure internally of said cylinder at said outlet means above ambient pressure, which closes in response to a reduction to ambient pressure internally of the cylinder in the zone of said outlet means, and which remains closed under the influence of the reduction of pressure during the further return of the piston to the upper position of rest. .Iaddend. .Iadd.17. A self-starting portable tool in accordance with claim 16, and wherein said exhaust valve is adapted to open in response to movement of said piston downwardly during the driving stroke towards said outlet means, as well as in response to exposure to the elevated pressure of the combustion gases in said combustion chamber when said piston moves   
     
     
        downwardly past said outlet means. .Iaddend. .Iadd.18.  A self-starting portable tool in accordance with claim 13, and wherein said bumper means comprises a superatmospheric air bumper in the lower end of said cylinder which is generated after said piston moves downwardly past said outlet means, and one-way valve means in said cylinder below said outlet means for opening and communicating with ambient atmosphere when the pressure in the cylinder below the piston drops below ambient pressure. .Iaddend. .Iadd.19. A self-starting portable tool in accordance with claim 16, and wherein when the piston moves downwardly past said outlet means, there is rapid exhausting of the combustion gases therethrough and the exhaust valve is rapidly reclosed, rapid further temperature reduction of remaining combustion gases in the combustion chamber causing a sharp reduction in the pressure of the combustion gases above the piston, the differential between that pressure and ambient pressure below the piston inducing said further return of the piston to its upper position of rest. .Iaddend. .Iadd.20. A self-starting portable tool as set forth in claim 13, including exhaust valve means in communication with said outlet means for exhausting air beneath the piston as it moves through its driving stroke, the portion of the cylinder below said exhaust valve means, the piston lower face and the housing adjacent the bottom of the cylinder providing a sealed compression chamber whereby the air below the piston and exhaust valve means is compressed to form an air bumper to prevent the piston from contacting the housing adjacent the bottom of the cylinder, 
     
     
        said air bumper comprising said bumper means. .Iaddend. 21. A self-starting portable tool as set forth in claim 20, in which the portion of the housing adjacent the bottom of the cylinder includes at least one one-way check valve which opens to introduce ambient air to assist in returning the piston to its upper position of rest after it has been driven and the combustion gases have been exhausted and a pressure below ambient pressure exists above the upper face of the piston.