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(11) | EP 0 062 145 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Powder actuated tool with gas venting handle |
| (57) A powder actuated fastener setting tool is provided with a gas venting and sound
muffling housing which extends laterally from the tool housing so as to be usable
as a gripping handle for the tool. The inside of the gas venting and sound muffling
housing is divided into a series of chambers through which combustion gases are bled,
there being openings between each of the chambers to allow combustion gases to pass
successively through the chambers. The cross sectional area of the respective openings
increases progressively away from the tool barrel. |
[0001] This invention relates to a powder actuated tool of the type used for setting fasteners in a supporting material, such as masonry, steel, wood, or the like, and more particularly to a gas venting and sound muffling mechanism for such a tool.
[0002] It has long been recognized that powder actuated fastener driving tools should desirably be provided with _a mechanism for venting combustion gases harmlessly and for muffling the sound generated when such tools are used.
[0003] Such venting and muffling mechanisms have taken a variety of forms in the prior art. For example, concentric barrels, tubes and housings have been used as shown in U.S. Patents Nos. 3,050,732 to Termet; 3,895,752 to Hatayama et al.; and 4,056,935 to Gassmann. Additionally, rather complicated side chambers have been suggested, such as shown in U.S. Patent No. 3,997,096 to Gloor et al. Box-type chambers attached to the tool housing have been suggested, as shown in U.S. Patent No. 4,093,110 to Johnson. Finally, usage of modified pre-existing tool structure, such as a piston returning pawl housing is shown in my U.S. Patent No. 4,218,005.
[0004] Since powder actuated tools used for driving fasteners are specifically designed to allied, yet different applications, a gas venting and sound muffling system which. is suitable for use in one tool, as for example, one used in low power applications, may not be suitable for use on another tool, as for example, one used in high power applications.
[0005] It is also advantageous to make dual use, if possible, of the tool structure which is used to form the gas venting and sound muffling mechanism, such as was done in my aforementioned U.S. Patent No. 4,218,005. To this end, the gas venting and sound muffling structure disclosed herein can be advantageously used as an auxiliary handle, in addition to the conventional pistol grip handle. Dual handle powder actuated fastener driving tools are known, as shown in U.S. Patent No. 2,925,601 to Pfaff et al.; however,the auxiliary handle does not also serve as a gas venting and sound muffling mechanism in the aforementioned patent.
[0006] The gas venting and sound muffling mechanism of this invention is particularly useful on higher power tools used in higher power applications because it has a high capacity for forming multiple serial gas expansion chambers which provide for controlled combustion gas expansion. This increased capacity for controlling combustion gas expansion increases the ability of the mechanism to muffle sound, and cool the expanding gases, while at the same time providing a greater surface area for deposit of fouling residue present in such combustion gases. The mechanism includes a housing which is elongated along its axis, which axis extends generally perpendicularly to the axis of the tool barrel. The housing is attached to the main housing of the tool and is subdivided along its axis into a plurality of serially arranged chambers. Each chamber communicates with the chamber next adjacent to it by means of a single venting hole. The venting holes increase in area from chamber to chamber as the combustion gases are bled away from the barrel of the tool. Furthermore, the venting holes are disposed at 1800 angles from the next adjacent venting holes on either side so that the expanding gases follow a tortuous path from chamber to chamber through the mechanism housing. The multiple chambers, the increasing vent hole size, and the tortuous expansion path all contribute to controlling the rate of gas.expansion so that increased cooling, muffling and residue deposit is achieved. In order to render the mechanism housing useful as an auxiliary handle, the housing includes an outer layer of insulating material such as urethane, neoprene, or the like mounted thereon, which outer layer is preferably contoured to serve as an auxiliary hand grip for the tool.
[0007] It is, therefore, an object of this invention to provide an improved combustion gas expansion and sound muffling mechanism for a powder actuated fastener driving tool.
[0008] It is a further object of this invention to provide a mechanism of the character described having a plurality of internal gas expansion chambers for providing controlled expansion of gases vented therethrough.
[0009] It is yet another object of this invention to provide a mechanism of the character described wherein the gas expansion chambers are vented one to the next by a series of single vent holes of progressively increasing area.
[0010] It is an additional object of this invention to provide a mechanism of the character described wherein a tortuous gas flow path is provided from chamber to chamber.
[0011] It is yet a further object of this invention to provide a mechanism of the character described wherein the mechanism is structured so as to serve as an auxiliary hand grip for the tool.
[0012] These and other objects and advantages of the mechanism of this invention will be more readily apparent from the following detailed description of a preferred embodiment thereof taken in conjunction with the accompanying drawing which is a side elevational view of a tool employing the mechanism of this invention, said view being partially in section.
[0013] Referring now to the drawing, there is shown a powder actuated fastener driving tool denoted generally by the numeral 2. The tool 2 includes a housing 4 having a breechward pistol grip 6, and supporting a trigger 8 and firing pin assembly 10 of conventional construction. The housing 4 carries a barrel 12 which is reciprocally slidably mounted in the housing 4 for relative movement in the breechward and muzzleward directions. A firing chamber 14 is disposed in the breechward end of the barrel 12. A cartridge extractor 16 is mounted in the breechward end of the barrel 12, the extractor 16 including an operating rod portion 18 which projects into a slot 20 formed in the lower portion of the barrel 12. An extractor-operating pawl 22 is secured to the housing 4 and extends into the slot 20 in the barrel 12. The pawl 22 engages the extractor rod 18 when the barrel 12 is displaced muzzleward, so as to operate the extractor 16 by displacing the latter in a breechward direction. The slot 20 is outwardly closed off by the housing 4.
[0014] The barrel 12 includes a bore 24 in which there is slidably disposed a piston 26 which is driven through the bore 24 by combustion gases produced by firing a blank cartridge positioned in the firing chamber 14. The piston 26 is driven from a breechward firing position, shown in the drawing, to a muzzleward fired position, to drive a fastener positioned in the muzzle of the tool. There are two slots 28 and 30 which extend through the bottom of the pawl slot 20 and open into the barrel bore 24. An opening 32 is formed in the bottom of the housing 4 in registry with the pawl slot 20.
[0015] Secured to the housing 4 and surrounding the opening 32 is the venting and muffler housing 34. It will be noted that the venting and muffler housing 34 is elongated along its axis in a direction generally perpendicular to the barrel axis so as to be suitable for use as an auxiliary hand grip. Thus the tool 2 may be gripped by the operator with two hands during use, i.e., by the pistol grip 6 and the venting and muffler housing 34. A preferably shock absorbing and insulating layer 36 of neoprene, urethane, or the like material is mounted on the exterior of the venting and muffler housing 34, the layer 36 being appropriately contoured for manual gripping by the tool operator.
[0016] The interior of the venting and muffler housing 34 is subdivided into a plurality of serially disposed chambers 38, 40, 42, 44 and 46. The chambers 38 and 40 are formed by a sleeve insert member 48 having a median transverse web 50. The successive chambers 42, 44 and 46 are formed by cup-shaped members 52, 54 and 56, each having transverse webs 58, 60 and 62 respectively, which cup-shaped members 52, 54 and 56 are stacked on top of each other within the housing 34. The sleeve 48 and cup-shaped members 52, 54 and 56 are held in place within the housing 34 by means of a bolt 64 and nuts 66 cooperating with the bottom closure 68 of the housing 34.
[0017] The transverse web 50 is provided with an opening 70 of predetermined size which allows gas flow to occur between the first chamber 38 and the second chamber 40. Likewise, the transverse webs 58, 60 and 62 are each provided with openings 72, 74 and 76 respectively which allow gas flow to occur between the remaining chambers 42, 44 and 46. The size of the openings 70, 72, 74 and 76 increases progressively with the opening 70 being the smallest and the opening 76 being the largest. It will be noted that successive ones of the openings 70, 72, 74 and 76 are disposed on opposite sides of the bolt 64, 180° from each other, so as to provide a tortuous flow path for gases vented into the housing 34. There extends through the bottom closure 68 of the housing 34 a vent port 78 which directs exhausting gases to be deflected by a disk 79 prior to venting to the open atmosphere.
[0018] The tool operates as follows. A cartridge is placed in the firing chamber 14 with the piston 26 being in its firing position as shown in the drawing. A fastener is placed in the muzzle end of the tool. The tool is then pressed against a work surface to cock the firing pin 10 and position the breech end of the barrel 12 so that the cartridge can be fired by actuation of the trigger 8 which releases the cocked firing pin 10.
[0019] When the cartridge is fired, high pressure combustion gases are produced on the breechward side of the piston 26 which propel the piston 26 muzzleward through the barrel bore 24. When the piston 26 has moved muzzleward sufficiently to pass the slot 28, the combustion gases will then be free to enter the barrel slot 28, and pass through the pawl slot 20. From the pawl slot 20, the combustion gases pass through the tool housing opening 32 and into the venting and muffler housing 34, and specifically into the first chamber 38 therein. When the piston 26 has reached its driven position, both barrel slots 28 and 30 will be opened to passage of combustion gases into the venting and muffler housing 34.
[0020] The gases entering the venting and muffler housing 34 will be hot and will be expanding. They will also contain primer and powder residue which will precipitate out of the gases as the latter cool and decompress. Thus, the gases entering the first chamber 38 will be at high pressure and will be hot. These gases will bleed out of the first chamber 38 through the small hole 70 and will enter the second chamber 40. The gases entering the second chamber 40 will be expanding into the second chamber and will thus be cooling. The surface area of the chambers 38 and 40 will provide heat transfer means, and will provide surfaces upon which fouling residue can deposit from the gases. The gases which pass into the chamber 40 will not immediately exit therefrom due to the 1800 displacement of the hole 72 from the preceding hole 70. Thus the gases will swirl in the chamber 40 before exiting therefrom through the hole 72 into the subsequent chamber 42. The larger area of the hole 72 permits ready passage of the gases from the chamber 40 to the subsequent chamber 42. It will be appreciated that the gases passing through the venting and muffler housing 34 will have a relatively long dwell period in the housing 34 due to the multiple chambers and tortuous flow path therein. Thus a delayed and gradual expansion and cooling of the combustion gases is achieved whereby the sound of firing the tool is markedly muffled, and combustion product residue in the combustion gases will be deposited over a relatively large surface area of non-moving parts of the tool. The vent hole 78 permits escape of ambient air and expanded relatively residue-free combustion gases therethrough.
[0021] The venting and muffling mechanism of this invention has been found to be remarkably efficient in cleaning, cooling and muffling combustion gases in a powder actuated tool. The elongated configuration of the housing permits its dual use as an auxiliary hand grip, and also permits the formation of an internal series of chambers into which combustion gases can sequentially flow and expand. The outer layer of insulating material on the venting and muffler housing helps to protect the operator's hand from heat emanating from the housing and provides a comfortable gripping surface.
a) A tool housing comprising a pistol grip handle;
b) a barrel mounted on said housing, said barrel having a bore;
c) A fastener driving piston reciprocally movably mounted in said barrel bore;
d) cartridge support means disposed at a breechward end of said barrel;
e) means forming a hollow combustion gas venting and sound muffling housing secured to said tool housing and extending in elongated fashion substantially perpendicularly to the axis of said barrel;
f) means dividing the interior of said hollow housing into a plurality of serially arranged chambers;
g) means forming a series of restricted gas flow openings between each of said chambers to permit combustion gases to flow sequentially from one of said chambers to the next, said gas flow openings being angularly offset one from the next so that combustion gases flow in a tortuous path through said serially arranged chambers to increase the dwell period of the combustion gases in each of said chambers; and
h) means providing a gas flow path from said barrel bore into an initial one of said serially arranged chambers.
a) a tool housing comprising a pistol grip handle;
b) a barrel mounted on said housing, said barrel having a bore;
c) a fastener driving piston reciprocally movably mounted in said barrel bore;
d) cartridge support means disposed at a breechward end of said barrel;
e) means forming a hollow combustion gas venting and sound muffling housing secured to said tool housing and extending in elongated fashion substantially perpendicularly to the axis of said barrel;
f) means dividing the interior of said hollow housing into a plurality of serially arranged chambers;
g) - means forming a series of restricted gas flow openings between each of said chambers to permit combustion gases to flow sequentially from one of said chambers to the next, said gas flow openings progressively increasing in size in the downstream direction of gas flow through said hollow housing; and
h) means providing a gas flow path from said barrel bore into an initial one of said serially arranged chambers.
a) a tool housing comprising a pistol grip handle at a breechward end of said tool housing;
b) a barrel mounted on said tool housing, said barrel having a bore;
c) a fastener driving piston reciprocally movably mounted in said barrel bore;
d) cartridge support means disposed at a breechward end of said barrel;
e) means forming a hollow secondary hand grip secured to said housing and extending in elongated fashion generally perpendicularly to the axis of said barrel, said secondary hand grip being disposed muzzleward of said pistol grip;
f) means dividing the interior of said secondary hand grip into a plurality of serially arranged chambers;
g) restricted means providing for combustion gas flow between said serially arranged chambers whereby combustion gases flowing - through said chambers will gradually expand and cool while within the confines of said secondary hand grip; and
h) means providing a gas flow path from said barrel bore into an initial one of said serially arranged chambers.
a) a tool housing comprising a pistol grip handle at a breechward end of said tool housing;
b) a barrel mounted on said tool housing, said barrel having a bore;
c) a fastener driving piston reciprocally movably mounted in said barrel bore;
d) cartridge support means disposed at a breechward end of said barrel;
e) means forming a hollow secondary hand grip secured to said housing and extending in elongated fashion generally perpendicularly to the axis of said barrel, said secondary hand grip being disposed muzzleward of said pistol grip;
f) means dividing the interior of said secondary hand grip into a plurality of serially arranged chambers;
g) means forming a series of restricted gas flow openings between each of said chambers to permit combustion gases to flow sequentially from one of said chambers to the next, said gas flow openings being angularly offset one from the next so that combustion gases flow in a tortuous path through said serially arranged chambers to increase the dwell period of the combustion gases in each of said chambers; and
h) means providing a gas flow path from said barrel bore into an initial one of said serially arranged chambers.
a) a tool housing comprising a pistol grip handle at a breechward end of said tool housing;
b) a barrel mounted on said tool housing, said barrel having a bore;
c) a fastener driving piston reciprocally movably mounted in said barrel bore;
d) cartridge support means disposed at a breechward end of said barrel;
e) means forming a hollow secondary hand grip secured to said housing and extending in elongated fashion generally perpendicularly to the axis of said barrel, said secondary hand grip being disposed muzzleward of said pistol grip;
f) means dividing the interior of said secondary hand grip into a plurality of serially arranged chambers;
g) means forming a series of restricted gas flow openings between each of said chambers to permit combustion gases to flow sequentially from one of said chambers to the next, said gas flow openings progressively increasing in size in the downstream direction of gas flow through said secondary handgrip; and
h) means providing a gas flow path from said barrel bore into an initial one of said serially arranged chambers.
a) a tool housing comprising a pistol grip handle at a breechward end of said tool housing;
b) a barrel mounted on said tool housing, said barrel having a bore;
c) a fastener driving piston reciprocally movably mounted in said barrel bore;
d) cartridge support means disposed at a breechward end of said barrel;
e) means forming a hollow secondary hand grip secured to said housing and extending in elongated fashion generally perpendicularly to the axis of said barrel, said secondary hand grip being disposed muzzleward of said pistol grip;
f) means dividing the interior of said secondary hand grip into a plurality of serially arranged chambers;
g) means forming a series of restricted gas flow openings between each of said chambers to permit combustion gases to flow sequentially from one of said chambers to the next, said gas flow openings being angularly offset one from the next so that combustion gases flow in a tortuous path through said serially arranged chambers to increase the dwell period of the combustion gases in each of said chambers, and said gas flow openings progressively increasing in size in the downstream direction of gas flow through said secondary hand grip; and
h) means providing a gas flow path from said barrel bore into an initial one of said serially arranged chambers.