More particularly, this auto-ignition gas cutting machine discharges mixed gas of oxygen and gas through a nozzle tip to generate cutting flame, and has both an oxygen control valve and a gas control valve at its grip, thus feeding oxygen and gas while controlling the quantities of them, and has an ignition device inside the grip with an ignition button exposed outside the grip, thereby easily igniting the mixed gas from the nozzle tip to generate desired cutting flame, and has an oxygen and gas feeding structure used for feeding oxygen and gas to an ignition unit separately or after mixing in accordance with desired capacity and use of a cutting machine, thus allowing a user to effectively use the gas cutting machine while controlling the capacity of the machine to meet desired purposes.

This invention is to improve upon auto-ignition gas cutting machines previously applied by and allowed to the inventor of this invention.

Background Art Conventional gas cutting machines are not provided with a means for automatically igniting mixed gas to form cutting flame, and so the ignition of mixed gas when using such a conventional gas cutting machine must be manually performed and is attended with danger. That is, when it is desired to use a conventional gas cutting machine having no automatic ignition means, mixed gas discharged from the nozzle tip of the cutting machine must be fired by a separate lighting means, such as a conventional cigarette lighter, matches, or several types of industrial lighters. In such a case, the separate lighting means is primarily fired, and the lighting means with flame is moved toward the nozzle tip of the gas cutting machine while controlling both the oxygen control valve and the gas

control valve of the gas cutting machine such that the mixed gas discharged from the nozzle tip is ignited by the flame of the lighting means.

The conventional gas cutting machines, which are ignited manually as described above, are inconvenient to users since the machines force the users to carry a separate lighting means. In addition, as the user moves the lighting means with flame toward the nozzle tip of the machine discharging mixed gas, it is not easy to control the quantity of mixed gas discharged from the nozzle tip. The conventional gas cutting machines thus sometimes cause safety hazards, such as causing a user to be burned while igniting mixed gas using such a separate lighting means.

In an effort to overcome such problems of the conventional gas cutting machines, the inventor of this invention proposed auto-ignition gas cutting machines of Korean Utility Model Registration No. 40,791 and Korean patent No.

226,322.

The auto-ignition gas cutting machine of Korean Utility Model Registration No. 40,791 is designed such that ignition flame is automatically generated from an igniter by operating an ignition lever and lights the mixed gas discharged from a nozzle tip of the machine. However, it is not easy for a user to control the ignition lever with a hand holding the grip of the machine, and so the user must hold the grip with one hand and control the ignition lever with the other hand. In addition, it is necessary for the user to move his hand from the ignition lever to the gas control valve and the oxygen control valve after lighting the igniter. The above gas cutting machine is thus inconvenient to users while igniting the mixed gas.

In the above auto-ignition gas cutting machine, the ignition lever is rotatably mounted in the grip using a shaft and is pressed down by a user at one end thereof to activate a high voltage generating piezoelectric device, and lights the ignition gas discharged from the nozzle of the igniter. That is, when the end of the ignition lever is pressed down, the other end of the ignition lever is raised up to lift and open the nozzle of the igniter, and allows ignition gas to be discharged from the nozzle of the igniter. However, it is impossible for the user to control

the quantity of ignition gas discharged from the nozzle of the igniter. In addition, the igniter does not have any electric insulating means for preventing leakage of the high voltage from the piezoelectric device, and so the igniter sometimes fails to perform smooth ignition in addition to giving an electric shock to the user.

The auto-ignition gas cutting machine of Korean patent No. 226,322 was proposed to overcome the above-mentioned problems experienced in the gas cutting machine of Korean Utility Model Registration No. 40,791. That is, the gas cutting machine of Korean patent No. 226,322 is designed such that an ignition button is manipulated by the thumb of a hand holding the grip of the cutting machine, thus more easily igniting mixed gas from the nozzle tip of the machine.

The above ignition button is provided on the side surface of the grip, and so when it is desired to control the ignition button with the thumb of a hand holding the grip, the user must primarily hold the grip with the hand while unnaturally bending the wrist of the hand such that the palm comes into contact with the back of the grip and the thumb is allowed to reach the ignition button, and secondarily change the hand from such an unnatural holding position to a natural holding position after ignition. The auto-ignition gas cutting machine is thus inconvenient to users.

Disclosure of the Invention Accordingly, an object of the present invention is to provide an auto- ignition gas cutting machine, which is structurally improved to overcome the above problems occurring in the conventional auto-ignition gas cutting machines.

Another object of the present invention is to provide an auto-ignition gas cutting machine, which has an oxygen feed spout and a gas feed spout at the lower end of the grip, and feeds oxygen and gas from the two spouts to a nozzle tip of a head unit through an oxygen feed pipe and a gas feed pipe, and which is provided with a piezoelectric device (high voltage generating device) inside the grip for performing a mixed gas distribution and an ignition flame generation, and has an actuation button at the upper end or the back of the grip for actuating the piezoelectric device, and which also has a handle or a lever at the front surface or

the back surface of the top portion of the grip for actuating an oxygen feed control valve provided in the grip, thus feeding ignition gas and oxygen from the grip to the ignition unit of the head unit through a gas and oxygen feed structure separately or after mixing in accordance with desired capacity and use of the cutting machine, thus allowing a user to effectively use the gas cutting machine while controlling the capacity of the machine to meet desired purposes.

A further object of the present invention is to provide an auto-ignition gas cutting machine, which allows a user to set the opening ratio of the oxygen feed control valve provided in the grip by an operation of the handle or lever, thus generating a cutting flame of predetermined intensity from the nozzle tip during an operation of the gas cutting machine.

Still another object of the present invention is to provide an auto-ignition gas cutting machine, which feeds oxygen and gas from the grip to the nozzle tip of the head unit while more effectively mixing the oxygen and gas to form mixed gas.

Still another object of the present invention is to provide an auto-ignition gas cutting machine, which feeds ignition gas and ignition oxygen from the grip to the ignition unit of the head unit separately or after mixing in accordance with desired purpose and desired capacity of the gas cutting machine in a way such that a mixed gas of oxygen and gas is fed to the ignition unit through a mixed gas feed pipe, in case of a small-capacity gas cutting machine; and the oxygen and gas are separately fed to the ignition unit through an oxygen feed pipe and a gas feed pipe in place of the mixed gas feed pipe in case of a large-or medium-capacity gas cutting machine, to secure operational safety.

In order to accomplish the above objects, the present invention provides an auto-ignition gas cutting machine 1,1-1 or 1-2, comprising: a valve unit 4 integrated with the lower end of a grip 3 and provided with both an oxygen feed spout 7 having a main oxygen control valve 5 and a gas feed spout 8 having a main gas control valve 6, thus feeding oxygen and gas from the oxygen feed spout 7 and the gas feed spout 8 to the interior of the grip 3 under the control of the oxygen control valve 5 and the gas control valve 6; a head unit 10 connected to the grip 3 through an oxygen feed pipe and a gas feed pipe so as to receive oxygen and gas

from the interior of the grip 3 through the oxygen feed pipe and the gas feed pipe and discharge the oxygen and gas through a nozzle tip 11 thereof; a piezoelectric device 52 installed in the grip 3 and operated by an ignition button 50 provided outside the grip 3; an ignition unit 9 provided in the head unit 10 and including an ignition coil 16 and an ignition pin 19 connected to the piezoelectric device 52 through an electric wire 24, thus generating ignition sparks at a gap between the ignition coil 16 and the ignition pin 19 by an operation of the piezoelectric device 52; and a mixed gas feed pipe 23 for feeding mixed gas from the interior of the grip 3 to an ignition gas nozzle 15 of the head unit 10 by an operation of the ignition button 50, thus allowing the mixed gas to be discharged from the ignition gas nozzle 15 and ignited by the ignition sparks generated at the gap between the ignition coil 16 and the ignition pin 19, wherein the oxygen feed pipe 20, the gas feed pipe 21 and a protection pipe 22 extend from the grip 3 to the head unit 10, with the mixed gas feed pipe 23 and the electric wire 24 housed in the protection pipe 22; an oxygen/gas mixing unit 30 is installed in the grip 3 and mixes the oxygen with the gas to form the mixed gas guided to the mixed gas feed pipe 23; the ignition button 50 for operating the piezoelectric device 52 is provided at the grip 3 such that the button 50 is exposed outside an upper end of the grip 3; an oxygen feed control valve 45 is provided in the valve unit 4 for controlling a flow of oxygen for cutting flame generation fed from the oxygen control valve 5 to the head unit, and an actuation unit for operating the oxygen feed control valve 45 is provided at the upper or lower portion of the back of the grip 3; an oxygen and gas supply means is provided in the grip 3 for feeding oxygen and gas for ignition flame generation from the grip 3 to the ignition gas nozzle 15 while separating the oxygen from the gas; and a lever 72 is rotatably mounted to the grip 3 by a shaft 75 at a position under the ignition button 50, with the piezoelectric device 52 and a gas distributor 70-1 provided at the lower and upper portions of the lever 72 respectively so as to be operated by the lever 72 at the same time.

Brief Description of the Drawings The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which : Fig. 1 is a partially sectioned front view of an auto-ignition gas cutting machine in accordance with the primary embodiment of the present invention; Figs. 2a, 2b and 2c are views showing the parts of the auto-ignition gas cutting machine of Fig. 1, in which: Fig. 2a is a view of a head unit of the auto-ignition gas cutting machine; and Figs. 2b and 2c are sectional views of an oxygen control unit provided at the grip of the auto-ignition gas cutting machine for controlling the amount of oxygen for cutting flame generation; Fig. 3 is a sectional view, showing an oxygen feed passage and a gas feed passage provided in the grip of the auto-ignition gas cutting machine of Fig. 1 ; Figs. 4a and 4b are sectional views, showing an ignition button provided at the grip of the auto-ignition gas cutting machine of Fig. 1; Fig. 5 is a front view of an auto-ignition gas cutting machine in accordance with the second embodiment of the present invention; Figs. 6a, 6b and 6c are sectional views showing the construction of a head unit and a grip unit of the auto-ignition gas cutting machine of Fig. 5; Figs. 7a and 7b are sectional views of an auto-ignition gas cutting machine in accordance with the third embodiment of the present invention; and Fig. 8 is a sectional view, showing the construction of a high voltage generation/gas distribution unit included in the auto-ignition gas cutting machine of Figs. 7a and 7b.

Best Mode for Carrying Out the Invention Reference should now be made to the drawings, in which the same

reference numerals are used throughout the different drawings to designate the same or similar components.

Figs. 1 to 8 show auto-ignition gas cutting machines 1, 1-1 and 1-2 in accordance with the primary to third embodiments of the present invention. That is, Fig. 1 is a partially sectioned front view of an auto-ignition gas cutting machine 1 according to the primary embodiment of this invention. Figs. 2a, 2b and 2c are views showing a head unit and an oxygen control unit of the auto-ignition gas cutting machine 1 of Fig. 1. Fig. 3 is a sectional view showing the construction of an oxygen/gas mixing unit 30 used for mixing oxygen and gas to form mixed gas. Figs. 4a and 4b are views showing the construction of an ignition device of the auto-ignition gas cutting machine 1.

Fig. 5 is a view showing an auto-ignition gas cutting machine 1-1 in accordance with the second embodiment of the present invention. Figs. 6a, 6b and 6c are views showing the construction of a head unit and a grip unit of the auto-ignition gas cutting machine 1-1.

Figs. 7a and 7b are sectional views of an auto-ignition gas cutting machine 1-2 in accordance with the third embodiment of the present invention.

Fig. 8 is a view showing the construction of a high voltage generation/gas distribution unit of the auto-ignition gas cutting machine 1-2.

The auto-ignition gas cutting machine 1 of Fig. 1 is designed to be preferably used as a small-or medium-capacity gas cutting machine.

In the auto-ignition gas cutting machine 1, the head unit 10 and the grip unit 2 are connected to each other through an oxygen feed pipe 20, a gas feed pipe 21 and a protection pipe 22. In such a case, the head unit 20 and the grip unit 2 are integrated into a single body by the three pipes 20,21 and 22. Oxygen and gas are fed from the grip unit 2 to the head unit 10.

The grip unit 2 has a grip 3, which is integrated with a valve unit 4 at its lower end.

The valve unit 4 includes an oxygen feed spout 7 provided with a main oxygen control valve 5, and a gas feed spout 8 provided with a main gas control valve 6. An oxygen feed control valve 45 having a conventional construction is

installed inside the valve unit 4.

The grip 3 integrated with the upper end of the valve unit 4 has a hollow structure, and receives a connector body 31 therein as shown in Figs. 2b, 3 and 4a.

Provided in the connector body 31 are an oxygen/gas mixing unit 30, an actuation unit for operating the oxygen feed control valve 45, and an ignition device for supplying ignition gas to an ignition unit 9 of the head unit 10 so as to generate ignition flame as will be described in detail later herein. A first oxygen feed tube 7-1, a second oxygen feed tube 7-2 and a gas feed tube 8-1 extend between the connector body 31 and the valve unit 4. In such a case, the first oxygen feed tube 7-1 is connected to the oxygen feed control valve 45, the second oxygen feed tube 7-2 is connected to the oxygen feed spout 7, and the gas feed tube 8-1 is connected to the gas feed spout 8, and so oxygen and gas are fed from the valve unit 4 to the connector body 31.

The actuation unit for operating the oxygen feed control valve 45 is installed inside the cavity 32 of the connector body 31 as shown in Figs. 2b and 2c.

That is, an L-shaped lever 42 is rotatably mounted in the cavity 32 of the connector body 31 using a shaft 43, while an oxygen control valve 40 is mounted to the back of the grip 3 at a position around the lever 42 for controlling the amount of oxygen for cutting flame generation. The above valve 40 is rotated in opposite directions to rotate the lever 42 around the shaft 43 : The oxygen control valve 40 has a lifting rod 41 at its inside end to normally push one arm of the lever 42 inward in a radial direction. An actuating rod 44 is axially set in the grip 3 while coming into contact with the other arm of the lever 42, thus actuating the oxygen feed control valve 45 in conjunction with a rotation of the valve-operated lever 42 around the shaft 43.

As shown in Fig. 3, the oxygen/gas mixing unit 30 is installed at the middle of the connector body 31, and mixes oxygen with gas to form mixed gas prior to feeding the mixed gas into a mixed gas feed pipe 23. The mixed gas is thus fed to the ignition unit 9 through the mixed gas feed pipe 23, and generates ignition flame.

The oxygen/gas mixing unit 30 includes a gas inlet chamber 35 formed at

the center of the connector body 31. The gas inlet chamber 35 is connected to the gas feed tube 8-1 through a gas inlet hole 34. A gas feed nozzle 33, fixed to the outlet end of the second oxygen feed tube 7-2, is inserted into the inlet of the gas inlet chamber 35. A spray nozzle body 36 connected to the gas feed pipe 21 is installed at the outlet of the gas inlet chamber 35. The gas feed nozzle 33 has a pointed end. The spray nozzle body 36 is designed such that the cross-sectional area of its channel is gradually increased in opposite directions from the center to opposite ends, and so'it is possible to more quickly and effectively mix oxygen with gas to form mixed gas.

As shown in Figs. 4a and 4b, an ignition device having a conventional construction is set within the connector body 31.

In order to form the ignition device, a push rod insert hole 31-1 is axially formed in the connector body 31, and receives a push rod 51 such that the push rod 51 is placed in the cavity 32 of the connector body 31. A stopper 53 is provided on the push rod 51, and holds one end of a compression coil spring 54 fitted over the push rod 51. The coil spring 54 normally biases the push rod 51 in a direction toward the head unit 10. A support ring 55 and a sealing ring 56 are sequentially fitted over the push rod 51 at positions under the spring 54. The upper end of the push rod 51 is exposed outside the connector body 31, with the ignition button 50 mounted to the exposed end of the push rod 51 such that a user is able to easily manipulate the button 50 outside the grip 3 during an operation of the gas cutting machine 1.

A piezoelectric device 52 is installed in the grip 3 at a position under the lower end of the push rod 51. An electric wire 24, connected to the piezoelectric device 52, extends through a wire passage hole 26 and the protection pipe 22 as will be described in more detail later herein.

A gas feed hole 58 connected to the gas feed tube 8-1, an oxygen feed hole 59 connected to the second oxygen feed tube 7-2, and a mixed gas discharge hole 60 connected to the mixed gas feed pipe 23 through a mixed gas guide hole 25 are formed in the connector body 31 such that they communicate with the push rod insert hole 31-1. The above holes 58, 59 and 60 are spaced apart from each

other at regular intervals. A plurality of sealing rings 61 are fitted over the push rod 51 at positions outside the gas feed hole 58 and the mixed gas discharge hole 60, in addition to positions between the gas feed hole 58, the oxygen feed hole 59 and the mixed gas discharge hole 60. Due to the sealing rings 61, it is possible to separately feed oxygen and gas to the ignition unit 9 without allowing a mixing or leaking of the oxygen and gas. Of course, it is also possible to mix oxygen with gas to form mixed gas by axially moving the push rod 51 in the push rod insert hole prior to feeding the mixed gas to the ignition unit 9.

The oxygen feed pipe 20 connected to the oxygen feed control valve 45, the gas feed pipe 21 connected to the spray nozzle body 36 of the oxygen/gas mixing unit 30, and the protection pipe 22 housing and protecting both the mixed gas feed pipe 23 and the electric wire 24 extend from the upper end of the grip 3 to the head unit 10 while being parallel to each other.

The head unit 10, to which the oxygen feed pipe 20, the gas feed pipe 21, and the protection pipe 22 are connected, has a flame nozzle tip 11 having a conventional construction. In the head unit 10, the oxygen feed pipe 20 is connected to an oxygen feed hole 12, thus feeding oxygen for cutting flame generation to the nozzle tip 11. The gas feed pipe 21 is connected to a gas feed hole 13, thus feeding gas for cutting flame generation to the nozzle tip 11.

The ignition gas nozzle 15, having an ignition coil 16 at its front end, is installed in the nozzle chamber 10-2, with a nozzle cap 14 covering the chamber 10-2. The mixed gas feed pipe 23 extending through the protection pipe 22 feeds mixed gas to the ignition gas nozzle 15 through a first mixed gas feed hole 17 and into the nozzle chamber 10-2 through a second mixed gas feed hole 18. The electric wire 24 extending through the protection pipe 22 is connected to an ignition pin 19, which projects into the nozzle chamber 10-2 at its end and is surrounded by a ceramic ring 26 so as to prevent leakage of voltage.

Figs. 5,6a, 6b and 6c show an auto-ignition gas cutting machine 1-1 in accordance with the second embodiment of the present invention. In the second embodiment, the gas cutting machine 1-1 is designed such that oxygen and gas for each of ignition and cutting flame generation are separately fed to the head unit 10

without being mixed together, different from the primary embodiment. This gas cutting machine 1-1 is designed to be used as a large-capacity gas cutting machine.

In the gas cutting machine 1-1 according to the second embodiment, the construction of the grip 3 of the grip unit 2 and the valve unit 4 assembled with the grip unit 2 remains the same as that of the primary embodiment of Figs. 1,2a and 2b. However, this gas cutting machine 1-1 does not have the oxygen/gas mixing unit 30 in the grip 3, different from the primary embodiment of Fig. 3, since the gas cutting machine 1-1 is designed such that oxygen and gas for ignition are separately fed to the ignition unit 9 of the head unit 10 without being mixed together.

In the gas cutting machine 1-1, the head unit 10 has a nozzle tip 11 and an oxygen feed pipe 20 as shown in Figs. 5,6a and 6b.

As best seen in Fig. 6a, a tip mounting chamber 10-1, a gas inlet chamber 10-5, an oxygen inlet chamber 10-4, and a high pressure oxygen inlet chamber 10- 3 are sequentially formed along the central axis in a direction from the front to the back of the head unit 10. In such a case, the diameters of the chambers are sequentially reduced in the same direction to form a stepped interior.

The tip mounting chamber 10-1 has internal threads, and so a locking nut 11-1 having external threads is tightened to the chamber 10-1 when installing the nozzle tip 11 in the chamber 10-1. In the head unit 10, the gas inlet chamber 10-5 communicates with a gas feed pipe 21-2 through a gas feed hole 13-2, the oxygen inlet chamber 10-4 communicates with a oxygen feed pipe 21-1 through a first oxygen feed hole 13-1, and the high pressure oxygen inlet chamber 10-3 communicates with a high pressure oxygen feed pipe 20 through a second oxygen feed hole 12.

A nozzle chamber 10-2 is formed in the head unit 10 at a position under the tip mounting chamber 10-1. An ignition gas nozzle 15 is installed in the nozzle chamber 10-2, with a nozzle cap 14 covering the chamber 10-2. An ignition oxygen feed pipe 23-2 is connected to the ignition gas nozzle 15 through an oxygen feed hole 17-1, thus feeding ignition oxygen to the nozzle 15. An ignition gas feed pipe 23-1 is connected to the nozzle chamber 10-2 through a gas

feed hole 17-2, thus feeding ignition gas into the nozzle chamber 10-2. The electric wire 24 extending through the protection pipe 22 is connected to an ignition pin 19, which projects into the nozzle chamber 10-2 at its end and is surrounded by a ceramic ring 26 so as to prevent leakage of voltage.

As shown in Fig. 6c, the gas cutting machine 1-1 has an oxygen and gas supply means for separately feeding oxygen and gas for ignition flame generation or cutting flame generation from the grip 3 to the ignition gas nozzle 15 or the nozzle tip 11 of the head unit 10. In order to form the oxygen and gas supply means, an oxygen pass hole 31-2 and a gas pass hole 31-3 are parallely formed in the connector body 31. The oxygen feed pipe 21-1 and an oxygen feed tube 7-1 are connected to opposite ends of the oxygen pass hole 31-2, respectively. The gas feed pipe 21-2 and a gas feed tube 8-1 are connected to opposite ends of the gas pass hole 31-3, respectively.

The oxygen pass hole 31-2 and the gas pass hole 31-3 communicate with a push rod insert hole 31-1 through an ignition oxygen passage hole 66-1 and an ignition gas passage hole 65-1, respectively. An ignition oxygen control valve 66, having a pointed end and external threads, is transversely set in the connector body 31 through a screw-type engagement at a position aligned with the ignition oxygen passage hole 66-1. The pointed end of the control valve 66 controls the opening ratio of the ignition oxygen passage hole 66-1. The outside end of the ignition oxygen control valve 66 is exposed to the outside of the grip 3 through an opening 66-2, and so a user easily tightens or loosens the ignition oxygen control valve 66 as desired at the outside of the grip 3. In addition, an oxygen blocking valve 65, having a pointed end and external threads, is transversely set in the connector body 31 through a screw-type engagement at a position aligned with the ignition gas passage hole 65-1. The pointed end of the control valve 65 controls the opening ratio of the ignition gas passage hole 65-1. That is, this control valve 65 can prevent gas flowing in the gas pass hole 31-3 from flowing into the oxygen pass hole 31-2.

A push rod 51 is inserted into the push rod insert hole 31-1 of the connector body 31, and actuates a piezoelectric device 52, with washers 62,62-1

and 0-rings 56 and 61 fitted over the push rod 51 so as to seal the gap between the insert hole 31-1 and the push rod 51. The push rod 51 is reduced in its diameter at several portions corresponding to the washers 62, thus having small-diameter parts 51-1 and 51-2. The ignition gas feed pipe 23-1 and the ignition oxygen feed pipe 23-2 are connected to push rod insert hole 31-1 at positions corresponding to the washers 62 and 62-1. The upper end of the push rod 51 is exposed outside the connector body 31, with a support ring 55, a spring 54 and a stopper 53 sequentially fitted over the push rod 51. In such a case, the stopper 53 is placed at the upper portion of the push rod 51. An ignition button 50 is mounted to the exposed upper end of the push rod 51.

An actuation unit for operating an oxygen feed control valve 45 is installed inside the valve unit 4. That is, an L-shaped oxygen control lever 42 is hinged to the grip 3 using a shaft 47, and has an actuating rod 44 connected to an actuation part 46-1. When a user rotates the lever 42 counterclockwise around the shaft 47, the actuating rod 44 actuates the oxygen feed control valve 45.

The first oxygen feed pipe 20 connected to the oxygen feed control valve 45, the second oxygen feed pipe 21-1 connected to the oxygen feed spout 7 of the valve unit 4, and the gas feed pipe 21-2 connected to the gas feed spout 8 of the valve unit 4 parallely extend from the grip 3 to the head unit 10. It is thus possible to separately feed oxygen and gas for cutting flame generation to the head unit 10. In addition, the ignition gas feed pipe 23-1 and the ignition oxygen feed pipe 23-2 extend through the protection pipe 22, and so it is possible to separately feed gas and oxygen for ignition. to the head unit 10.

Figs. 7a, 7b and 8 show an auto-ignition gas cutting machine 1-2 in accordance with the third embodiment of the present invention. This gas cutting machine 1-2 is designed as a small-capacity gas cutting machine.

The auto-ignition gas cutting machine 1-2 of Figs. 7a and 7b comprises a grip 3 provided with a high voltage generation/gas distribution unit 70. A distribution body 3-1 is mounted to the upper end of the grip 3, with an oxygen feed pipe 20, a gas feed pipe 21 and a mixed gas feed pipe 23 extending upward from the top of the distribution body 3-1 to a head unit 10. The head unit 10 also

has an ignition unit 9 and a nozzle tip 11.

The bottom of the grip 3 is provided with an oxygen feed spout 7 and a gas feed spout 8 for feeding oxygen and gas to the grip 3, with a main gas control valve 6 provided at the gas feed spout 8 for controlling the amount of gas flowing through the gas feed spout 8. A cap body 71 is integrated with the upper portion of the grip 3, with the high voltage generation/gas distribution unit 70 provided at the junction of the grip 3 and the cap body 71, as will be described herein below.

That is, the high voltage generation/gas distribution unit 70 comprises a button 50 provided at the upper end of the grip 3. This button 50 is exposed outside the grip 3. An L-shaped lever 72 is hinged to the grip 3 by a shaft 75 at a position under the button 50. This lever 72 has a pressure arm 77 at its upper end.

The pressure arm 77 of the lever 72 projects from the grip 3, and is covered with the button 50, which projects outside the grip 3. A push part 74 is provided at the lower end of the lever 72, while a piezoelectric device 52 is installed inside the grip 3 at a position under the push part 74. In such a case, an actuation button 52- 1 of the piezoelectric device 52 comes into contact with the lower surface of the push part 74. Provided in the cap body 71 at a position above the push part 74 is a gas distributor 70-1 used for distributing gas from the gas feed spout 8 to the ignition unit 9 of the head unit 10.

In order to form the gas distributor 70-1, a cylinder chamber 83 is formed in the cap body 71, and communicates with a first gas feed path 81 through a gas guide path 82. The first gas feed path 81 connects the gas feed tube 8-1 to the gas feed pipe 21 of the distribution body 3-1. The cylinder chamber 83 is also connected to the mixed gas feed pipe 23 through a second gas feed path 95. A cylinder housing 88, having open ends, is assembled with the cylinder chamber 83 through a screw-type engagement using threaded parts 89. In such a case, an outside 0-ring 92 is placed at the junction of the chamber 83 and the housing 88 so as to accomplish a desired sealing effect at the junction. A piston 84, having a sealing ring 87 at its front end, is axially inserted into the cylinder housing 88. In such a case, a spring 90, a support ring 91 and an inside O-ring 92-1 are sequentially installed at the gap between the flange 86 of the piston 84 and the

stopper 88-1 of the cylinder housing 88. A valve shaft 85 axially extends from the outside end of the piston 84, and is connected at its lower end to the push part 74 of the lever 72 through a shaft 76.

In order to prevent undesired vibration and maintain desired balance during an operation of the piston 84, a balance spring 93 is provided between the inside surface of the cap body 71 and the shaft 76. In such a case, a spring holder 93-1 is formed on the inside surface of the cap body 71, and supports one end of the balance spring 93, while the other end of the spring 93 is supported by the shaft 76.

An electric wire 24, connected to the piezoelectric device 52, extends through the mixed gas feed pipe 23 supported by both the distribution body 3-1 and the cap body 71. In such a case, a seal packing 94 is fitted into the lower end of the mixed gas feed pipe 23, and the lower end of the pipe 23 is compressed to form an annular seal groove 23-1 accomplishing desired sealing effect at the gap between the pipe 23 and the packing 94.

The head unit 10, connected to the top ends of the oxygen feed pipe 20, the gas feed pipe 21 and the mixed gas feed pipe 23, has a tip mounting chamber 10-1, an oxygen feed hole 12, a gas feed hole 13 and a mixed gas feed hole 17.

In such a case, the oxygen feed hole 12 and the gas feed hole 13 communicate with the tip mounting chamber 10-1, while the ignition unit 9 is provided at the upper end of the mixed gas feed hole 17. The ignition unit 9 comprises an ignition gas nozzle 15, which is set in the upper end of the mixed gas feed hole 17 and is provided with an ignition coil 16. The electric wire 24, extending through the mixed gas feed pipe 23, is connected to an ignition pin 19 installed in the ignition unit 9 at a position under the ignition coil 16.

The auto-ignition gas cutting machines 1,1-1 and 1-2 of this invention are operated as follows.

Each of the auto-ignition gas cutting machines 1,1-1 and 1-2 of this invention is connected to an oxygen supply hose (not shown) and a gas supply hose (not shown) at the oxygen feed spout 7 and the gas feed spout 8, and so oxygen and gas are supplied to the gas cutting machine during an operation

thereof.

The auto-ignition gas cutting machine 1 according to the primary embodiment of Figs. 1 to 4b is operated as follows.

In an operation of the auto-ignition gas cutting machine 1, oxygen and gas are supplied to the gas cutting machine 1 through an oxygen supply hose (not shown) and a gas supply hose (not shown) connected to the oxygen feed spout 7 and the gas feed spout 8, respectively. In such a case, it is possible for a user to appropriately control the amounts of oxygen and gas by manipulating the main oxygen control valve 5 and the main gas control valve 6.

When appropriate amounts of oxygen and gas are supplied to the cutting machine 1 under the control of the main oxygen control valve 5 and the main gas control valve 6, the oxygen and gas are primarily fed to the oxygen/gas mixing unit 30 through the second oxygen feed tube 7-2 and the gas feed tube 8-1. In such a case, oxygen from the second oxygen feed tube 7-2 is guided into the gas feed nozzle 33, and is sprayed into the gas inlet chamber 35, while gas from the gas feed tube 8-1 is guided into the gas inlet chamber 35 through the gas inlet hole 34.

The oxygen and gas inside the gas inlet chamber 35 are mixed to form mixed gas while passing through the spray nozzle body 36, and the mixed gas is guided into the gas feed pipe 21. The mixed gas is thus fed from the gas feed pipe 21 to the nozzle tip 11 of the head unit 10 through the gas feed hole 13 When a user pushes the ignition button 50 of the grip 3 while the mixed gas is fed to the nozzle tip 11, the push rod 51 is retracted to actuate the piezoelectric device 52, thus allowing the piezoelectric device 52 to generate a high voltage. This high voltage is applied to the ignition pin 19 of the ignition unit 9 through the electric wire 24, and generates ignition sparks at the gap between the ignition coil 16 and the ignition pin 19.

During such a retraction of the push rod 51, gas from the gas feed hole 58 and oxygen from the oxygen feed hole 59 are mixed together inside the push rod insert hole 31-1 to form mixed gas. The mixed gas is, thereafter, discharged from the push rod insert hole 31-1 through the mixed gas discharge hole 60, and is guided into the mixed gas feed pipe 23 through the mixed gas guide hole 25. The

mixed gas feed pipe 23 thus feeds the mixed gas to the ignition gas nozzle 15 through the first mixed gas feed hole 17 and into the nozzle chamber 10-2 through the second mixed gas feed hole 18.

When the mixed gas from the mixed gas feed pipe 23 is fed to the ignition gas nozzle 15 through the first mixed gas feed hole 17 and into the nozzle chamber 10-2 through the second mixed gas feed hole 18 as described above, the mixed gas is ignited by the sparks generated at the gap between the ignition coil 16 and the ignition pin 19, thus generating ignition flame at the mouth of the nozzle cap 14.

When the ignition flame reaches the outside of the nozzle cap 14 of the ignition unit 9 as described above, the mixed gas ejected from the nozzle tip 11 is ignited by the ignition flame, thus generating intense cutting flame.

When the mixed gas ejected from the nozzle tip 11 is ignited by the ignition flame to generate cutting flame as described above, the intensity of the cutting flame is controlled by operating the oxygen control valve 40 and a desired cutting work using the gas cutting machine 1 is performed.

The auto-ignition gas cutting machine 1-1 according to the second embodiment of Figs. 5 to 6c is operated as follows.

In an operation of the auto-ignition gas cutting machine 1-1, oxygen and gas is supplied to the gas cutting machine 1 through the oxygen feed spout 7 and the gas feed spout 8, respectively. In such a case, a part of the oxygen from the oxygen feed spout 7 is fed to the head unit 10 through the oxygen feed pipe 20 and the oxygen feed hole 12 of the head unit 10, while the remaining oxygen sequentially flows through the oxygen feed tube 7-1, the oxygen pass hole 31-2 and the oxygen feed pipe 21-1, and is fed into the oxygen inlet chamber 10-4 through the first oxygen feed hole 13-1. In addition, the gas from the gas feed spout 8 sequentially flows through the gas feed tube 8-1, the gas pass hole 31-3 and the gas feed pipe 21-2, and is fed to the nozzle tip 11 through the gas feed hole 13.

When oxygen and gas from the oxygen feed spout 7 and the gas feed spout 8 pass the oxygen pass hole 31-2 and the gas pass hole 31-3 of the connector body 31 respectively, parts of them reach the ignition oxygen passage hole 66-1

and the ignition gas passage hole 65-1, respectively.

When a user operates the ignition button 50 in such a case, the push rod 51 actuates the piezoelectric device 52, thus causing the piezoelectric device 52 to generate a high voltage. This high voltage is applied to the ignition pin 19 of the ignition unit 9 through the electric wire 24, and generates ignition sparks at the gap between the ignition coil 16 and the ignition pin 19.

During a movement of the push rod 51 by an operation of the ignition button 50, the small-diameter parts 51-1 and 51-2 of the push rod 51 reach the ignition oxygen passage hole 66-1 and the ignition gas passage hole 65-1, respectively. In such a case, oxygen and gas supplied to the ignition oxygen passage hole 66-1 and the ignition gas passage hole 65-1 are fed into the push rod insert hole 31-1 at positions around the small-diameter parts 51-1 and 51-2 of the push rod 51. The oxygen and gas, fed into the push rod insert hole 31-1 at positions around the small-diameter parts 51-1 and 51-2 of the push rod 51, are discharged from the push rod insert hole 31-1 through an ignition oxygen discharge hole 63 and an ignition gas discharge hole 64, respectively.

The oxygen and gas, discharged from the push rod insert hole 31-1 through the ignition oxygen discharge hole 63 and the ignition gas discharge hole 64, flow through the ignition oxygen feed pipe 23-2 and the ignition gas feed pipe 23-1 housed in the protection pipe 22. Thereafter, the oxygen is fed to the ignition gas nozzle 15 through the oxygen feed hole 17-1, while the gas is fed into the nozzle chamber 10-2 through the gas feed hole 17-2. The oxygen from the ignition gas nozzle 15 and the gas from the gas feed hole 17-2 are thus mixed inside the nozzle chamber 10-2.

When the oxygen from the ignition gas nozzle 15 is mixed with the gas from the gas feed hole 17-2 to form mixed gas inside the nozzle chamber 10-2, the mixed gas is ignited by the sparks generated at the gap between the ignition coil 16 and the ignition pin 19, thus generating ignition flame at the mouth of the nozzle cap 14. When the ignition flame is rushed to the outside of the nozzle cap 14 of the ignition unit 9 as described above, the mixed gas, formed by a mixing of the oxygen from the ignition oxygen feed pipe 23-2 with the gas from the ignition gas

feed pipe 23-1 and ejected from the nozzle tip 11, is ignited by the ignition flame, thus generating intense cutting flame.

After the mixed gas from the nozzle tip 11 is ignited by the ignition flame to generate cutting flame as described above, it is possible to control the intensity of the cutting flame by operating the oxygen control lever 46 of the grip 3. That is, when a user presses the lever 46, the actuation part 46-1 of the lever 46 pushes the actuating rod 44, and so the rod 44 actuates the oxygen feed control valve 45.

It is thus possible to generate hotter cutting flame from the nozzle tip 11, and a desired cutting work using the gas cutting machine 1-1 is performed.

The auto-ignition gas cutting machine 1-2 according to the third embodiment of Figs. 7a to 8 is operated as follows.

The auto-ignition gas cutting machine 1-2 is designed such that desired cutting flame is generated from the nozzle tip 11 by operating the ignition button 50 of the high voltage generation/gas distribution unit 70 while oxygen and gas are fed from the oxygen feed spout and the gas feed spout to the machine.

That is, in an operation of the auto-ignition gas cutting machine 1-2, oxygen and gas are supplied to the gas cutting machine 1 from the oxygen feed spout 7 and the gas feed spout 8, respectively. In such a case, a user appropriately controls the amounts of oxygen and gas by manipulating the main oxygen control valve 5, the main gas control valve 6 and the oxygen control valve 40. The oxygen and gas are mixed to each other to form mixed gas, and the mixed gas is discharged from the nozzle tip 11 of the head unit 10 and is ignited to generate cutting flame.

The gas from the gas feed spout 8 is fed to the gas feed pipe 21 through the gas feed tube 8-1 and the first gas feed path 81. The gas is, thereafter, fed form the gas feed pipe 21 into the tip mounting chamber 10-1 through the gas feed hole 13 of the head unit 10, and is discharged from chamber 10-1 through the nozzle tip 11. When the gas passes through the first gas feed path 81, a part of the gas is introduced into the gas guide path 82.

After a part of the gas is introduced into the gas guide path 82 as described above, the ignition button 50 of the high voltage generation/gas

distribution unit 70 is operated by a hand holding the grip 3. In such a case, the lever 72 is rotated counterclockwise around the shaft 75, and so the push part 74 of the lever 72 actuates the actuation button 52-1 of the piezoelectric device 52. The piezoelectric device 52 generates a high voltage, and this high voltage is applied to the ignition pin 19 of the ignition unit 9 through the electric wire 24, and generates ignition sparks at the gap between the ignition coil 16 and the ignition pin 19.

During such a rotation of the lever 72, the valve shaft 85 connected at its lower end to the push part 74 of the lever 72 through the shaft 76 is also pulled by the lever 72. Therefore, the piston 84 is moved downward within the cylinder housing 88 while compressing the spring 90. When the piston 84 is moved downward from the cylinder housing 88 as described above, the sealing ring 87 of the piston 84 is moved in the same direction to open the gas guide path 82.

Therefore, gas is introduced from the gas guide path 82 into the cylinder chamber 83. The gas is, thereafter, guided from the cylinder chamber 83 to the mixed gas feed pipe 23 through the second gas feed path 95, and flows in the mixed gas feed pipe 23 to be fed to the ignition gas nozzle 15 through the mixed gas feed hole 17.

This mixed gas is thus ejected from the ignition gas nozzle 15.

When the ignition button 50 of the high voltage generation/gas distribution unit 70 is operated to move the lever 72, the ignition sparks are generated at the gap between the ignition coil 16 and the ignition pin 19. In addition, the mixed gas is ejected from the ignition nozzle 15 at the same time.

The mixed gas from the ignition nozzle 15 is thus ignited by the sparks generated at the gap between the ignition coil 16 and the ignition pin 19, and so ignition flame is generated and rushed to the outside of the nozzle cap 14.

When the ignition flame is rushed to the outside of the nozzle cap 14 of the ignition unit 9 as described above, the gas cutting machine 1-2 is moved such that the nozzle tip 11 is positioned close to a sheet (not shown), such as a steel sheet, while controlling the gas control valve 80 and the oxygen control valve 40 to increase the opening ratios of them. Therefore, the mixed gas ejected from the nozzle tip 11 is directed against the sheet to be diffused and ignited by the ignition flame from the nozzle cap 14, thus generating intense cutting flame.

After the ignition flame ignites the mixed gas ejected from the nozzle tip 11 to generate intense cutting flame as described above, the user removes his finger from the ignition button 50. The actuation button 52-1 of the piezoelectric device 52 is thus moved to its original position by the restoring force of a spring (not shown) installed in the piezoelectric device 52, and so the lever 72 is rotated around the shaft 75 to restore its original position. When the lever 72 completely restores its original position, the compressed spring 90 of the gas distributor 70-1 is elastically returned to its original position while pushing the flange 86 of the piston 84. The piston 84 is thus moved to its original position inside the cylinder housing 88, and the sealing ring 87 of the piston 84 closes the gas guide path 82, thus cutting the flow of mixed gas for the ignition unit. The ignition flame ejected from the nozzle cap 14 is thus automatically extinguished.

Therefore, the gas cutting machine only generates intense cutting flame from the nozzle tip 11.

Industrial Applicability As described above, the present invention provides an auto-ignition gas cutting machine. This gas cutting machine is designed to feed gas and oxygen for each of ignition and cutting flame generation from the grip to the ignition unit of a head unit separately or after mixing in accordance with desired capacity and use of the cutting machine, thus allowing a user to effectively use the gas cutting machine while controlling the capacity of the machine to meet desired purposes. In the gas cutting machine of this invention, the gas and oxygen for ignition are mixed while being ejected, and so it is possible to enhance the intensity of ignition flame.

In addition, this gas cutting'machine is designed such that a user can easily manipulate the ignition button. Another advantage of this invention resides in that the gas and oxygen for ignition are fed to the ignition unit while being prevented from undesirably leaking from the machine, thus securing operational safety of the gas cutting machine.