CA2255102A1 - High velocity, combustion-powered fastener-driving tool - Google Patents
High velocity, combustion-powered fastener-driving tool Download PDFInfo
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- CA2255102A1 CA2255102A1 CA002255102A CA2255102A CA2255102A1 CA 2255102 A1 CA2255102 A1 CA 2255102A1 CA 002255102 A CA002255102 A CA 002255102A CA 2255102 A CA2255102 A CA 2255102A CA 2255102 A1 CA2255102 A1 CA 2255102A1
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Abstract
Disclosed is a combustion-powered, fastener-driving tool comprising structure defining a combustion chamber having a combustion chamber volume, structure defining a piston chamber communicating with the combustion chamber, a driving piston movable within the piston chamber between an initial position and a terminal position, and a driving blade mounted to the driving piston so as to be conjointly movable with the driving piston. The driving piston, the driving blade, and the piston chamber are arranged so that combustion in the combustion chamber imparts energy to the driving piston and the driving blade so as to drive the driving piston and the driving blade from the initial position toward the terminal position, through a piston displacement volume, with the driving blade preceding the driving piston. The ratio of the piston displacement volume to the combustion chamber volume is sufficient to enable the driving blade to transfer more than one half of the maximum, transferable energy to a fastener engaged by the driving blade as the driving piston and the driving blade approach the terminal position. Preferably the ratio is sufficient to enable the driving blade to transfer more than eight tenths of the maximum, transferable energy to a fastener engaged by the driving blade as the driving piston and the driving blade approach the terminal position.
Description
CA 022~102 1998-12-02 HIGH VELOCITY, COMBUSTION-POWERED, FASTENER-DRIVING TOOL
This application is a divisional of application File No. 2,182,340 filed July 30, 1996.
S Technical Field of the Invention This invention pertains to a high velocity, combustion-powered, fastener-driving tool, in which a driving piston, a driving blade, and a piston chamber are arranged so that combustion of a fuel in a combustion chamber imparts energy to the driving piston and the driving blade so as to drive the driving piston and the driving blade over a stroke having a length sufficient to enable the driving blade to transfer more than one half of the maximum, transferable energy to a fastener, and so that the driving piston and the driving blade are guided solely within the axial length of the driving piston, over at least substantially all of the stroke.
Background of the Invention Combustion-powered, fastener-driving tools of a type~exemplified in Nikolich U.S. Patent Re. 32,452 and Nikolich U.S. Patent No. 5,197,646 are available commercially from ITW Paslode (a unit of Illinois Tool Works Inc.) of Vernon Hills, Illinois, and are used widely in building construction.
Typically, such a tool comprises a combustion chamber, a piston chamber communicating with the combustion chamber, a driving piston movable within the piston chamber over a stroke between an initial position and a terminal position, and a driving blade mounted to the driving piston so as to be con~ointly movable with the driving piston. Combustion in the combustion chamber imparts energy to the driving piston and the driving blade so as to drive the driving piston and the driving blade over a stroke from an initial position toward a terminal position with the driving blade preceding the driving piston. Typically, the CA 022~102 1998-12-02 , driving blade is guided by passing through or between guides, over the entire stroke of the driving blade.
Generally, such a tool also comprises means for sensing when the tool is pressed against a workpiece, for enabling the tool when the tool is pressed against a workpiece, and for disabling the tool when the tool is not pressed against a workpiece, together with means including a trigger for initiating combustion in the combustion chamber when the tool is enabled and the trigger is actuated.
It has been found that such tools known heretofore transfer less than one half of the maximum, transferable energy to a fastener engaged by the driving blade as the driving piston and the driving blade approach the terminal position. It would be highly desirable to provide such a tool that could transfer substantially more of the maximum, transferable energy to a fastener engaged by the driving blade as the driving piston and the driving blade approach the terminal position.
Summary of the Invention A first aspect of this invention stems from a discovery that increasing the ratio of the piston displacement volume to the combustion chamber volume, as by lengthening the stroke of the piston, increases the fraction of the imparted energy that can be thus transferred until a maximum, transferable energy is approached, whereupon such fraction begins to fall as such ration is increased further. A second aspect of this invention stems from a discovery that, since friction within the tool affects the fraction of the imparted energy that can be thus transferred and since the driving blade tends to buckle if elongated excessively, it is advantageous for the driving piston and the driving blade to be guided solely within the axial length of the driving piston, over substantially CA 022~102 1998-12-02 all of the stroke, so as to minimize friction within the tool.
According to the first aspect of this invention, this invention provides a combustion-powered, fastener-driving tool of the type noted above, wherein thedriving piston, the driving blade, and the piston chamber are arranged so that combustion in the combustion chamber having a combustion chamber volume imparts energy to the driving piston and the driving blade so as to drive the driving piston and the driving blade from the initial position toward the terminal position, through a piston displacement volume, with the driving blade preceding the driving piston, wherein the ratio of the piston displacement volume to the combustion chamber volume is sufficient to enable the driving blade to transfer more than one half of the maximum, transferable energy to a fastener engaged by the driving blade as the driving piston and the driving blade approach the terminal position, preferably being sufficient to enable the driving blade to transfer more than eight tenths of the maximum, transferable energy to a fastener engaged by the driving blade as the driving piston and the driving blade approach the terminal position. The ratio of the piston chamber volume to the combustion chamber volume can be advantageously increased by lengthening the stroke of the piston.
According to the second aspect of this invention, this invention provides a combustion-powered, fastener-driving tool of the type noted above, wherein thedriving piston, the driving blade, and the piston chamber are arranged so that the driving piston and the driving blade are guided solely within the axial length of the driving piston, over at least substantially all of the stroke.
CA 022~102 1998-12-02 - 3a-The invention to which the divisional application is directed provides a combustion-powered, fastener-driving tool comprising structure defining a combustion chamber having a combustion chamber volume, structure defining a piston chamber communicating with the combustion chamber, a driving piston movable within the piston chamber between an initial position and a terminal position, and a driving blade mounted to the driving piston so as to be conjointly movable with the driving piston. The driving piston, the driving blade, and the piston chamber are arranged so that combustion in the combustion chamber imparts energy to the driving piston and the driving blade so as to drive the driving piston and the driving blade from the initial position toward the terminal position, through a piston displacement volume, with the driving blade precedingthe driving piston. The ratio of the piston displacement volume to the combustion chamber volume is sufficient to enable the driving blade to transfer more than one half of the maximum, transferable energy to a fastener engaged by the driving blade as the driving piston and the driving blade approach the terminal position. Preferably the ratio is sufficient to enable the driving blade to transfer more than eight tenths of the maximum, transferable energy to a fastener engaged by the driving blade as the driving piston and the driving blade approach the terminal position.
CA 022~102 1998-12-02 cylindrical wall, and the driving piston has an annular portion with an annular groove, in which a piston ring is seated and engages the inner, cylindrical wall.
These and other objects, features, and advantages of this invention are evident from the following description of two contemplated embodiments of this invention with reference to the accompanying drawings.
Brief Description of the Drawings Figure 1 is a perspective, schematic view of elements of a high velocity, combustion-powered, fastener-driving tool constituting one contemplated embodiment of this invention.
Figure 2, on a larger scale, is a sectional view taken along line 2-2 of Figure 1, in a direction indicated by arrows.
Figure 3, on a similar scale, is a fragmentary, cross-sectional view taken through an axis of the tool shown in Figure 1.
Figure 4, on a similar scale, is a fragmentary, cross-sectional view taken through an axis of a high velocity, combustion-powered, fastener-driving tool constituting an alternative embodiment of this invention.
Figure 5 is a sectional view taken along line 5 -5 of Figure 4, in a direction indicated by arrows.
Figure 6 is a simplified, longitudinal section taken through a high velocity, combustion-powered, fastener-driving tool constituting a preferred embodiment of this invention.
Figure 7 is a graph of piston chamber volume versus energy (joules) for such tools having combustion chambers of six different volumes.
Figure 8 is a graph of (inches) versus energy (joules) for such tools having combustion chambers of six different volumes.
Detailed Description of the Illustrated Em~odiments CA 022~S102 1998-12-02 .
As shown schematically in Figures 1, 2, and 3, a high velocity, combustion-powered, fastener-driving tool 10 of the type noted above constitutes one contemplated embodiment of this invention. Except as illustrated and described herein, the tool 10 may be substantially similar to one of the combustion-powered, fastener-driving tools disclosed in ~ikolich U.S.
Patents Re. 32,452 and No. 5,197,646 the disclosures of which may be referred to for further detail.
Being of the type noted above and deriving motive power from combustion of a gaseous fuel, the tool 10 comprises a housing structure 20 and a cylinder body 22, which is mounted fixedly within the housing structure 20, and which defines a combustion chamber lS 30, a piston chamber 40 communicating with the combustion chamber 30, and a nosepiece 32 communicating with the piston chamber 40. The combustion chamber 30, the piston chamber 40, and the nosepiece 32 define an axis of the tool 10. The combustion chamber 30 is adapted to contain a mixture of such a fuel and air.
The nosepiece 32 is adapted to receive a fastener and to guide the fastener as the fastener is driven.
Moreover, the tool 10 comprises a driving piston 50 movable axially within the piston chamber 40 over a stroke between an initial position, which is an upper position in the drawings, and a terminal position, which is a lower position in the drawings. The driving piston 50 has an axial length, to which reference is to be later made. Furthermore, the tool 10 comprises a driving blade 60, which is mounted to the driving piston 50 so as to be conjointly movable with the driving piston S0. Generally, the terminal position is - defined by an annular, elastomeric bumper 90, which is arranged to arrest the driving piston S0 as the driving 3s piston S0 and the driving blade 60 approach the terminal position. The combustion chamber 30 has a CA 022~102 1998-12-02 volume, which is measured with the driving piston 50 and the driving blade 60 in the initial position. As the driving piston 50 and the driving blade 60 are moved from the initial position into the terminal position, the driving piston 50 is displaced through a volume, which may be conveniently called the piston displacement volume.
As disclosed in Nikolich U.S. Patent No. 5,197,646 noted above, the tool 10 comprises means including a workpiece-contacting element for sensing when the tool is pressed against a workpiece, for enabling the tool 10 when the tool 10 is pressed against a workpiece, and for disabling the tool 10 when the tool 10 is not pressed against a workpiece, means including a trigger for initiating combustion of a gaseous fuel mixed with air in the combustion chamber 30 when the trigger is actuated. Details of these means and other elements of the tool 10 are outside the scope of this invention and can be readily supplied by persons having ordinary skill in the art from the Nikolich patents noted above and from other sources.
As discussed above, the first aspect of this invention stems from the discovery that increasing the ratio of the piston displacement volume to the combustion chamber volume, as by lengthening the stroke of the piston, increases the fraction of the imparted energy that can be thus transferred until a maximum, transferable energy is approached, whereupon such fraction begins to fall. This discovery is illustrated by the graph of Figure 7, which shows the energy transferable by a driving blade to a fastener at strokes of different lengths, for combustion-powered, fastener-driving tools of the type noted above with different com~ustion chamber volumes, and by the graph of Figure 8, which shows the energy transferable by a driving blade to a fastener at different piston CA 022~102 1998-12-02 displacement volumes for combustion-powered, fastener-driving tools of the type noted above with different combustion chamber volumes. All numbers shown on the graphs (Figures 7 and 8) are approximate.
According to the first aspect of this invention, the driving piston 50, the driving blade 60, and the piston chamber 40 are arranged so that combustion in the combustion chamber 30 imparts energy to the driving piston 50 and the driving blade 60 so as to drive the driving piston 50 and the driving blade 60 from the initial position toward the terminal position with the driving blade 60 preceding the driving piston 50, over a stroke having a length sufficient to enable the driving blade 60 to transfer more than one half of the maximum, transferable energy to a fastener engaged by the driving blade 60 as the driving piston 50 and the driving blade 60 approach the terminal position, preferably over a stroke having a length sufficient to enable the driving blade 60 to transfer more than eight tenths of the maximum, transferable energy to a fastener engaged by the driving blade 60 as the driving piston 50 and the driving blade 60 approach the terminal position.
As an example of such tools known heretofore, one model of a combustion-powered, fastener-driving tool available commercially from Illinois Tool Works Inc.
has a combustion chamber with a volume of approximately 17 cubic inches and a stroke of approximately 3.5 inches, utilizes a given quantity of a gaseous fuel, and is capable of transferring approximately 50 joules to a fastener, which energy (50 joules) is approximately 0.417 (less than one half) of the maximum energy (120 joules) transferable in such a tool. As an example of such tools embodying this invention, an experimental, combustion-powered, fastener-driving tool having a combustion chamber with a volume of CA 022~102 1998-12-02 ,~
approximately 17 cubic inches but a stroke of approximately seven inches and utilizing approximately the same quantity of the same fuel is capable of transferring approximately 100 joules to a fastener, which energy (100 joules) is approximately 0.833 times (more than eight tenths) of the m~;mum energy (120 joules) transferable in such a tool.
As discussed above, the second aspect of this invention stems from a discovery that for reducing friction within such a tool so as to increase the fraction of the maximum, transferable energy that can be thus transferred it is advantageous for the driving piston 50 and the driving blade 60 to be guided solely within the axial length of the driving piston 50, over substantially all of the stroke.
Thus, the piston chamber 40 has an inner, cylindrical wall 42, and the driving piston 50 has an annular portion 52 with an annular groove 54, in which a piston ring 56 is seated. The piston ring 56 engages the inner, cylindrical wall 42, so as to provide a gas- -tight seal between the driving piston 50 and the cylindrical wall 42 as the driving piston 50 and the driving blade 60 are driven axially. The driving piston 50, which has a small mass, has a central hub 70, which trails the annular portion 52, three radial arms 72, which radiate from the central hub 70, and three axially extending guides 74, each of which is connected to the central hub 70 by one of the radial arms 72 and each of which has an outer face 76 conforming to the cylindrical wall 42. As the driving piston 50 and the driving blade 60 are driven axially, these axially extending guides 74 help to guide the driving piston 50 and the driving blade 60 along the cylindrical wall 42 and serve to prevent tilting of the driving piston 50 and the driving blade 60 from the axis to any significant degree.
CA 022~102 1998-12-02 As shown schematically in Figures 4 and 5, a high velocity, combustion-powered, fastener-driving tool 100 of the type noted above constitutes an alternative embodiment of this invention. The tool 100 is designed to drive fasteners exemplified by the illustrated fastener F of a type exemplified in Almeras et al . U . S .
Patent No. 4,824,003 and Dewey et al. U.S. Patent No.
5,193,729. Except as illustrated and described herein, the tool 100 may be substantially similar to the tool 10 and to one of the combustion-powered, fastener-driving tools disclosed in Nikolich U.S. Patents Re.
32,452 and No. 5,197,646, supra.
The tool 100 comprises structure defining a combustion chamber (not shown) along with structure defining a piston chamber 120 having an inner, cylindrical wall 122, a driying piston 130 movable axially within the piston chamber 120 over a stroke between an initial position, which is an upper position in the drawings, and a terminal position, which is a -lower position in the drawings. The driving piston 130 is shown in the terminal position.
Furthermore, the tool 100 comprises a driving blade 160, which is mounted to the driving piston 130 so as to be conjointly movable with the driving piston 130. Generally, the terminal position is defined by an annular, elastomeric bumper 170, which is arranged to arrest the driving piston 130 as the driving piston 130 and the driving blade 160 approach the terminal position.
As shown, the driving piston 130 has a central hub 132 between two axially spaced, annular portions 134, 136, a leading one of which 134 has an annular groove 138 with a piston ring 170 seated in the annular groove 138 and engaging the inner, cylindrical wall 122.
Also, the trailing portion 136 has four generally cylindrical openings 180, so as to reduce the mass of CA 022~102 1998-12-02 ,, ~
the driving piston 130.
As shown in Figure 6, a combustion-powered, fastener-driving tool 200 for driving fasteners like the fastener F shown in Figure 4 constitutes a preferred embodiment of this invention. The tool 200 is similar to the tools described above, particularly the tool 10, and comprises structure defining a combustion chamber 210, structure defining a piston chamber 220 having an inner, cylindrical wall 222, a driving piston 230 movable axially within the piston chamber 220 over a stroke between an initial position, which is an upper position in the drawings, and a terminal position, which is a lower position in the drawings.
Being similar to the driving piston 50, the driving piston 230 has an annular portion 232 with an annular groove 234, in which a piston ring 236 is seated. The piston ring 236 engages the inner, cylindrical wall 222, so as to provide a gas-tight seal - 20 between the driving piston 230 and the cylindrical wall 222 as the driving piston 230 and the driving blade 260 are driven axially. The driving piston 230, which has a small mass, has a central hub 240, which trails the annular portion 232, three radial arms 242, which radiate from the central hub 240, and three axially extending guides 244, each of which is connected to the central hub 240 by one of the radial arms 242 and each of which has an outer face 246 conforming to the cylindrical wall 222.
The tool 200 comprises means including a workpiece-contacting element 240 for sensing when the tool 200 is pressed against a workpiece, for enabling the tool 200 when the tool 200 is pressed against a workpiece, and for disabling the tool 200 when the tool 200 is not pressed against a workpiece, means including a trigger 250 for initiating combustion of a gaseous CA 022~102 1998-12-02 fuel mixed with air in the combustion chamber 30 when the trigger is actuated. Details of the means including the workpiece-contacting element 240, the means including the trigger 240, and other elements of the tool 200 are outside the scope of this invention and can be readily supplied by persons having ordinary skill in the art from the Nikolich patents noted above and from other sources.
Furthermore, the tool 200 comprises a driving blade 260, which is mounted to the driving piston 230 so as to be conjointly movable with the driving piston 230. Generally, the terminal position is defined by an annular, elastomeric bumper 270, which is arranged to arrest the driving piston 230 as the driving piston 230 and the driving blade 260 approach the terminal pos itlon .
The second aspect of this invention, as described above, may prove to be also advantageous in a pneumatically powered, fastener-driving tool of a type exemplified in Golsch~U.S. Patent No. 4,932,480, as well as in a combustion-powered, fastener-driving tool.
Various modifications may be made in the illustrated embodiments described above without departing from the scope and spirit of this invention.
This application is a divisional of application File No. 2,182,340 filed July 30, 1996.
S Technical Field of the Invention This invention pertains to a high velocity, combustion-powered, fastener-driving tool, in which a driving piston, a driving blade, and a piston chamber are arranged so that combustion of a fuel in a combustion chamber imparts energy to the driving piston and the driving blade so as to drive the driving piston and the driving blade over a stroke having a length sufficient to enable the driving blade to transfer more than one half of the maximum, transferable energy to a fastener, and so that the driving piston and the driving blade are guided solely within the axial length of the driving piston, over at least substantially all of the stroke.
Background of the Invention Combustion-powered, fastener-driving tools of a type~exemplified in Nikolich U.S. Patent Re. 32,452 and Nikolich U.S. Patent No. 5,197,646 are available commercially from ITW Paslode (a unit of Illinois Tool Works Inc.) of Vernon Hills, Illinois, and are used widely in building construction.
Typically, such a tool comprises a combustion chamber, a piston chamber communicating with the combustion chamber, a driving piston movable within the piston chamber over a stroke between an initial position and a terminal position, and a driving blade mounted to the driving piston so as to be con~ointly movable with the driving piston. Combustion in the combustion chamber imparts energy to the driving piston and the driving blade so as to drive the driving piston and the driving blade over a stroke from an initial position toward a terminal position with the driving blade preceding the driving piston. Typically, the CA 022~102 1998-12-02 , driving blade is guided by passing through or between guides, over the entire stroke of the driving blade.
Generally, such a tool also comprises means for sensing when the tool is pressed against a workpiece, for enabling the tool when the tool is pressed against a workpiece, and for disabling the tool when the tool is not pressed against a workpiece, together with means including a trigger for initiating combustion in the combustion chamber when the tool is enabled and the trigger is actuated.
It has been found that such tools known heretofore transfer less than one half of the maximum, transferable energy to a fastener engaged by the driving blade as the driving piston and the driving blade approach the terminal position. It would be highly desirable to provide such a tool that could transfer substantially more of the maximum, transferable energy to a fastener engaged by the driving blade as the driving piston and the driving blade approach the terminal position.
Summary of the Invention A first aspect of this invention stems from a discovery that increasing the ratio of the piston displacement volume to the combustion chamber volume, as by lengthening the stroke of the piston, increases the fraction of the imparted energy that can be thus transferred until a maximum, transferable energy is approached, whereupon such fraction begins to fall as such ration is increased further. A second aspect of this invention stems from a discovery that, since friction within the tool affects the fraction of the imparted energy that can be thus transferred and since the driving blade tends to buckle if elongated excessively, it is advantageous for the driving piston and the driving blade to be guided solely within the axial length of the driving piston, over substantially CA 022~102 1998-12-02 all of the stroke, so as to minimize friction within the tool.
According to the first aspect of this invention, this invention provides a combustion-powered, fastener-driving tool of the type noted above, wherein thedriving piston, the driving blade, and the piston chamber are arranged so that combustion in the combustion chamber having a combustion chamber volume imparts energy to the driving piston and the driving blade so as to drive the driving piston and the driving blade from the initial position toward the terminal position, through a piston displacement volume, with the driving blade preceding the driving piston, wherein the ratio of the piston displacement volume to the combustion chamber volume is sufficient to enable the driving blade to transfer more than one half of the maximum, transferable energy to a fastener engaged by the driving blade as the driving piston and the driving blade approach the terminal position, preferably being sufficient to enable the driving blade to transfer more than eight tenths of the maximum, transferable energy to a fastener engaged by the driving blade as the driving piston and the driving blade approach the terminal position. The ratio of the piston chamber volume to the combustion chamber volume can be advantageously increased by lengthening the stroke of the piston.
According to the second aspect of this invention, this invention provides a combustion-powered, fastener-driving tool of the type noted above, wherein thedriving piston, the driving blade, and the piston chamber are arranged so that the driving piston and the driving blade are guided solely within the axial length of the driving piston, over at least substantially all of the stroke.
CA 022~102 1998-12-02 - 3a-The invention to which the divisional application is directed provides a combustion-powered, fastener-driving tool comprising structure defining a combustion chamber having a combustion chamber volume, structure defining a piston chamber communicating with the combustion chamber, a driving piston movable within the piston chamber between an initial position and a terminal position, and a driving blade mounted to the driving piston so as to be conjointly movable with the driving piston. The driving piston, the driving blade, and the piston chamber are arranged so that combustion in the combustion chamber imparts energy to the driving piston and the driving blade so as to drive the driving piston and the driving blade from the initial position toward the terminal position, through a piston displacement volume, with the driving blade precedingthe driving piston. The ratio of the piston displacement volume to the combustion chamber volume is sufficient to enable the driving blade to transfer more than one half of the maximum, transferable energy to a fastener engaged by the driving blade as the driving piston and the driving blade approach the terminal position. Preferably the ratio is sufficient to enable the driving blade to transfer more than eight tenths of the maximum, transferable energy to a fastener engaged by the driving blade as the driving piston and the driving blade approach the terminal position.
CA 022~102 1998-12-02 cylindrical wall, and the driving piston has an annular portion with an annular groove, in which a piston ring is seated and engages the inner, cylindrical wall.
These and other objects, features, and advantages of this invention are evident from the following description of two contemplated embodiments of this invention with reference to the accompanying drawings.
Brief Description of the Drawings Figure 1 is a perspective, schematic view of elements of a high velocity, combustion-powered, fastener-driving tool constituting one contemplated embodiment of this invention.
Figure 2, on a larger scale, is a sectional view taken along line 2-2 of Figure 1, in a direction indicated by arrows.
Figure 3, on a similar scale, is a fragmentary, cross-sectional view taken through an axis of the tool shown in Figure 1.
Figure 4, on a similar scale, is a fragmentary, cross-sectional view taken through an axis of a high velocity, combustion-powered, fastener-driving tool constituting an alternative embodiment of this invention.
Figure 5 is a sectional view taken along line 5 -5 of Figure 4, in a direction indicated by arrows.
Figure 6 is a simplified, longitudinal section taken through a high velocity, combustion-powered, fastener-driving tool constituting a preferred embodiment of this invention.
Figure 7 is a graph of piston chamber volume versus energy (joules) for such tools having combustion chambers of six different volumes.
Figure 8 is a graph of (inches) versus energy (joules) for such tools having combustion chambers of six different volumes.
Detailed Description of the Illustrated Em~odiments CA 022~S102 1998-12-02 .
As shown schematically in Figures 1, 2, and 3, a high velocity, combustion-powered, fastener-driving tool 10 of the type noted above constitutes one contemplated embodiment of this invention. Except as illustrated and described herein, the tool 10 may be substantially similar to one of the combustion-powered, fastener-driving tools disclosed in ~ikolich U.S.
Patents Re. 32,452 and No. 5,197,646 the disclosures of which may be referred to for further detail.
Being of the type noted above and deriving motive power from combustion of a gaseous fuel, the tool 10 comprises a housing structure 20 and a cylinder body 22, which is mounted fixedly within the housing structure 20, and which defines a combustion chamber lS 30, a piston chamber 40 communicating with the combustion chamber 30, and a nosepiece 32 communicating with the piston chamber 40. The combustion chamber 30, the piston chamber 40, and the nosepiece 32 define an axis of the tool 10. The combustion chamber 30 is adapted to contain a mixture of such a fuel and air.
The nosepiece 32 is adapted to receive a fastener and to guide the fastener as the fastener is driven.
Moreover, the tool 10 comprises a driving piston 50 movable axially within the piston chamber 40 over a stroke between an initial position, which is an upper position in the drawings, and a terminal position, which is a lower position in the drawings. The driving piston 50 has an axial length, to which reference is to be later made. Furthermore, the tool 10 comprises a driving blade 60, which is mounted to the driving piston 50 so as to be conjointly movable with the driving piston S0. Generally, the terminal position is - defined by an annular, elastomeric bumper 90, which is arranged to arrest the driving piston S0 as the driving 3s piston S0 and the driving blade 60 approach the terminal position. The combustion chamber 30 has a CA 022~102 1998-12-02 volume, which is measured with the driving piston 50 and the driving blade 60 in the initial position. As the driving piston 50 and the driving blade 60 are moved from the initial position into the terminal position, the driving piston 50 is displaced through a volume, which may be conveniently called the piston displacement volume.
As disclosed in Nikolich U.S. Patent No. 5,197,646 noted above, the tool 10 comprises means including a workpiece-contacting element for sensing when the tool is pressed against a workpiece, for enabling the tool 10 when the tool 10 is pressed against a workpiece, and for disabling the tool 10 when the tool 10 is not pressed against a workpiece, means including a trigger for initiating combustion of a gaseous fuel mixed with air in the combustion chamber 30 when the trigger is actuated. Details of these means and other elements of the tool 10 are outside the scope of this invention and can be readily supplied by persons having ordinary skill in the art from the Nikolich patents noted above and from other sources.
As discussed above, the first aspect of this invention stems from the discovery that increasing the ratio of the piston displacement volume to the combustion chamber volume, as by lengthening the stroke of the piston, increases the fraction of the imparted energy that can be thus transferred until a maximum, transferable energy is approached, whereupon such fraction begins to fall. This discovery is illustrated by the graph of Figure 7, which shows the energy transferable by a driving blade to a fastener at strokes of different lengths, for combustion-powered, fastener-driving tools of the type noted above with different com~ustion chamber volumes, and by the graph of Figure 8, which shows the energy transferable by a driving blade to a fastener at different piston CA 022~102 1998-12-02 displacement volumes for combustion-powered, fastener-driving tools of the type noted above with different combustion chamber volumes. All numbers shown on the graphs (Figures 7 and 8) are approximate.
According to the first aspect of this invention, the driving piston 50, the driving blade 60, and the piston chamber 40 are arranged so that combustion in the combustion chamber 30 imparts energy to the driving piston 50 and the driving blade 60 so as to drive the driving piston 50 and the driving blade 60 from the initial position toward the terminal position with the driving blade 60 preceding the driving piston 50, over a stroke having a length sufficient to enable the driving blade 60 to transfer more than one half of the maximum, transferable energy to a fastener engaged by the driving blade 60 as the driving piston 50 and the driving blade 60 approach the terminal position, preferably over a stroke having a length sufficient to enable the driving blade 60 to transfer more than eight tenths of the maximum, transferable energy to a fastener engaged by the driving blade 60 as the driving piston 50 and the driving blade 60 approach the terminal position.
As an example of such tools known heretofore, one model of a combustion-powered, fastener-driving tool available commercially from Illinois Tool Works Inc.
has a combustion chamber with a volume of approximately 17 cubic inches and a stroke of approximately 3.5 inches, utilizes a given quantity of a gaseous fuel, and is capable of transferring approximately 50 joules to a fastener, which energy (50 joules) is approximately 0.417 (less than one half) of the maximum energy (120 joules) transferable in such a tool. As an example of such tools embodying this invention, an experimental, combustion-powered, fastener-driving tool having a combustion chamber with a volume of CA 022~102 1998-12-02 ,~
approximately 17 cubic inches but a stroke of approximately seven inches and utilizing approximately the same quantity of the same fuel is capable of transferring approximately 100 joules to a fastener, which energy (100 joules) is approximately 0.833 times (more than eight tenths) of the m~;mum energy (120 joules) transferable in such a tool.
As discussed above, the second aspect of this invention stems from a discovery that for reducing friction within such a tool so as to increase the fraction of the maximum, transferable energy that can be thus transferred it is advantageous for the driving piston 50 and the driving blade 60 to be guided solely within the axial length of the driving piston 50, over substantially all of the stroke.
Thus, the piston chamber 40 has an inner, cylindrical wall 42, and the driving piston 50 has an annular portion 52 with an annular groove 54, in which a piston ring 56 is seated. The piston ring 56 engages the inner, cylindrical wall 42, so as to provide a gas- -tight seal between the driving piston 50 and the cylindrical wall 42 as the driving piston 50 and the driving blade 60 are driven axially. The driving piston 50, which has a small mass, has a central hub 70, which trails the annular portion 52, three radial arms 72, which radiate from the central hub 70, and three axially extending guides 74, each of which is connected to the central hub 70 by one of the radial arms 72 and each of which has an outer face 76 conforming to the cylindrical wall 42. As the driving piston 50 and the driving blade 60 are driven axially, these axially extending guides 74 help to guide the driving piston 50 and the driving blade 60 along the cylindrical wall 42 and serve to prevent tilting of the driving piston 50 and the driving blade 60 from the axis to any significant degree.
CA 022~102 1998-12-02 As shown schematically in Figures 4 and 5, a high velocity, combustion-powered, fastener-driving tool 100 of the type noted above constitutes an alternative embodiment of this invention. The tool 100 is designed to drive fasteners exemplified by the illustrated fastener F of a type exemplified in Almeras et al . U . S .
Patent No. 4,824,003 and Dewey et al. U.S. Patent No.
5,193,729. Except as illustrated and described herein, the tool 100 may be substantially similar to the tool 10 and to one of the combustion-powered, fastener-driving tools disclosed in Nikolich U.S. Patents Re.
32,452 and No. 5,197,646, supra.
The tool 100 comprises structure defining a combustion chamber (not shown) along with structure defining a piston chamber 120 having an inner, cylindrical wall 122, a driying piston 130 movable axially within the piston chamber 120 over a stroke between an initial position, which is an upper position in the drawings, and a terminal position, which is a -lower position in the drawings. The driving piston 130 is shown in the terminal position.
Furthermore, the tool 100 comprises a driving blade 160, which is mounted to the driving piston 130 so as to be conjointly movable with the driving piston 130. Generally, the terminal position is defined by an annular, elastomeric bumper 170, which is arranged to arrest the driving piston 130 as the driving piston 130 and the driving blade 160 approach the terminal position.
As shown, the driving piston 130 has a central hub 132 between two axially spaced, annular portions 134, 136, a leading one of which 134 has an annular groove 138 with a piston ring 170 seated in the annular groove 138 and engaging the inner, cylindrical wall 122.
Also, the trailing portion 136 has four generally cylindrical openings 180, so as to reduce the mass of CA 022~102 1998-12-02 ,, ~
the driving piston 130.
As shown in Figure 6, a combustion-powered, fastener-driving tool 200 for driving fasteners like the fastener F shown in Figure 4 constitutes a preferred embodiment of this invention. The tool 200 is similar to the tools described above, particularly the tool 10, and comprises structure defining a combustion chamber 210, structure defining a piston chamber 220 having an inner, cylindrical wall 222, a driving piston 230 movable axially within the piston chamber 220 over a stroke between an initial position, which is an upper position in the drawings, and a terminal position, which is a lower position in the drawings.
Being similar to the driving piston 50, the driving piston 230 has an annular portion 232 with an annular groove 234, in which a piston ring 236 is seated. The piston ring 236 engages the inner, cylindrical wall 222, so as to provide a gas-tight seal - 20 between the driving piston 230 and the cylindrical wall 222 as the driving piston 230 and the driving blade 260 are driven axially. The driving piston 230, which has a small mass, has a central hub 240, which trails the annular portion 232, three radial arms 242, which radiate from the central hub 240, and three axially extending guides 244, each of which is connected to the central hub 240 by one of the radial arms 242 and each of which has an outer face 246 conforming to the cylindrical wall 222.
The tool 200 comprises means including a workpiece-contacting element 240 for sensing when the tool 200 is pressed against a workpiece, for enabling the tool 200 when the tool 200 is pressed against a workpiece, and for disabling the tool 200 when the tool 200 is not pressed against a workpiece, means including a trigger 250 for initiating combustion of a gaseous CA 022~102 1998-12-02 fuel mixed with air in the combustion chamber 30 when the trigger is actuated. Details of the means including the workpiece-contacting element 240, the means including the trigger 240, and other elements of the tool 200 are outside the scope of this invention and can be readily supplied by persons having ordinary skill in the art from the Nikolich patents noted above and from other sources.
Furthermore, the tool 200 comprises a driving blade 260, which is mounted to the driving piston 230 so as to be conjointly movable with the driving piston 230. Generally, the terminal position is defined by an annular, elastomeric bumper 270, which is arranged to arrest the driving piston 230 as the driving piston 230 and the driving blade 260 approach the terminal pos itlon .
The second aspect of this invention, as described above, may prove to be also advantageous in a pneumatically powered, fastener-driving tool of a type exemplified in Golsch~U.S. Patent No. 4,932,480, as well as in a combustion-powered, fastener-driving tool.
Various modifications may be made in the illustrated embodiments described above without departing from the scope and spirit of this invention.
Claims (7)
1. A combustion-powered, fastener-driving tool comprising structure defining a combustion chamber having a combustion chamber volume, structure defining a piston chamber communicating with the combustion chamber, a driving piston movable within the piston chamber between an initial position anda terminal position, and a driving blade mounted to the driving piston so as to be conjointly movable with the driving piston, wherein the driving piston, the driving blade, and the piston chamber are arranged so that combustion in the combustion chamber imparts energy to the driving piston and the driving blade so as to drive the driving piston and the driving blade from the initial position toward the terminal position, through a piston displacement volume, with the driving blade preceding the driving piston, wherein the ratio of the piston displacement volume to the combustion chamber volume is sufficient to enable the driving blade to transfer more than one half of the maximum, transferable energy to a fastener engaged by the driving blade as the driving piston and the driving blade approach the terminal position.
2. The tool of claim 1 wherein the ratio of the piston displacement volume to the combustion chamber volume is sufficient to enable the driving blade to transfer more than eight tenths of the maximum, transferable energy to a fastener engaged by the driving blade as the driving piston and the driving blade approach the terminal position.
3. A combustion-powered, fastener-driving tool comprising structure defining a combustion chamber having a combustion chamber volume, structure defining a piston chamber communicating with the combustion chamber, a driving piston movable within the piston chamber between an initial position anda terminal position, and a driving blade mounted to the driving piston so as to be conjointly movable with the driving piston, wherein the driving piston, the driving blade, and the piston chamber are arranged so that combustion in the combustion chamber imparts energy to the driving piston and the driving blade so as to drive the driving piston and the driving blade from the initial position toward the terminal position with the driving blade preceding the driving piston, over a stroke having a length sufficient to enable the driving blade to transfermore than one half of the maximum, transferable energy to a fastener engaged by the driving blade as the driving piston and the driving blade approach the terminal position.
4. The tool of claim 3 wherein the stroke has a length sufficient to enable the driving blade to transfer more than eight tenths of the maximum, transferable energy to a fastener engaged by the driving blade as the driving piston and the driving blade approach the terminal position.
5. The tool of claim 3 or 4 wherein the driving piston has an axial length and wherein the driving piston, the driving blade, and the piston chamberare arranged so that the driving piston and the driving blade are guided solely within the axial length of the driving piston, over at least substantially all of the stroke.
6. The tool of claim 5 wherein the piston chamber has an inner, cylindrical wall and wherein the driving piston has an annular portion with an annular groove, in which a piston ring is seated and engages the inner, cylindrical wall.
7. The tool of claim 5 wherein the piston chamber has an inner, cylindrical wall and wherein the driving piston has two axially spaced, annular portions, at least one of which has an annular groove with a piston ring seated in the annular groove and engaging the inner, cylindrical wall.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/536,854 | 1995-09-29 | ||
| US08/536,854 US5722578A (en) | 1995-09-29 | 1995-09-29 | High velocity, combustion-powered, fastener-driving tool |
| CA002182340A CA2182340C (en) | 1995-09-29 | 1996-07-30 | High velocity, combustion-powered fastener-driving tool |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002182340A Division CA2182340C (en) | 1995-09-29 | 1996-07-30 | High velocity, combustion-powered fastener-driving tool |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2255102A1 true CA2255102A1 (en) | 1997-03-30 |
Family
ID=25678589
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002255102A Abandoned CA2255102A1 (en) | 1995-09-29 | 1996-07-30 | High velocity, combustion-powered fastener-driving tool |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2255102A1 (en) |
-
1996
- 1996-07-30 CA CA002255102A patent/CA2255102A1/en not_active Abandoned
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |