Combustion-powered tool assembly

Abstract: In a combustion-powered, fastener-driving tool (10), a cylinder body (30) mounted fixedly within a housing structure (12) has a combustion chamber (70) defining an axis. A valve sleeve (62) functions to open and close the combustion chamber (70). A piston (40) operative within the combustion chamber (70) and a driving blade (42) moveable with the piston (40) function to drive a fastener (N) into a workpiece (W). An improved linkage for moving the valve sleeve (62) includes a workpiece-contacting (82) element and a pair of arms (100) attached to such element and disposed alongside the cylinder body (30) and the nosepiece (50). An improved, one-piece, interlocking member (130) prevents a trigger (120) from being actuated unless the combustion chamber (70) is closed. Thus, a simple, compact, lightweight tool is provided.

Description: Technical Field of the Invention This invention is directed to a combustion-powered tool for driving fasteners according to the preamble of claim 1 and 5, respectively. The preamble of claim 1 and 5 is based on the disclosure of the document US-A-4483474. Background of the Invention Typically, as exemplified in Nikolich U.S. Patent Re. 32,452, Nikolich U.S. Patent No. 4,522,162, Nikolich U.S. Patent No. 4,483,474, Nikolich U.S. Patent No. 4,403,722, and Wagdy U.S. Patent No. 4,483,473 a combustion-powered, fastener-driving tool comprises a combustion chamber, which is defined by a cylinder body and by a valve sleeve arranged for opening and closing the combustion chamber. Generally similar, combustion-powered, nail- and staple-driving tools are available commercially from ITW-Paslode (a unit of Illinois Tool Works Inc.) of Lincolnshire, Illinois, under its IMPULSE trademark. Particularly, as disclosed in US-A-4,483,474 and EP-A-0 123 716, respectively, a prior art tool comprises a housing structure within which a cylinder body is mounted fixedly. A piston is mounted operatively in the cylinder body. The piston is arranged to drive a driving plate extending axially from the cylinder body. A valve member is mounted in axially movable relation to the cylinder body, wherein the cylinder body and the valve member define a combustion chamber. The valve member is axially movable along the cylinder body, so as to open and close the combustion chamber. A nosepiece is mounted to the housing structure, in axially spaced relation to the cylinder body, via a separate piece defining a lower chamber between the cylinder body and the nosepiece. The linkage includes a workpiece-contacting element as used to close the combustion chamber, when the workpiece-contacting element contacts a workpiece. The linkage includes four arms connected to the valve member by fasteners. The linkage arms are connected to each other and to the workpiece-contacting element by an intermediate structure disposed within the lower chamber and across the tool axis. Further this document, particularly as shown in figures 16 to 18 of the publication, discloses a tool comprising a trigger operated cam means responsive to the movement of the valve means, whereby the tool cannot be fired until the combustion chamber is closed and the chamber cannot be opened until the trigger is released. The trigger cannot be operated until the cam interlock assembly is free to move. Movement of the cam interlock assembly is normally prevented by a U-shaped trigger rod mechanism, that is secured to the slidable cylinder. When the work sensitive probe assembly is in the extended position the U-shaped rod is located immediately adjacent the generally triangular shaped cam member. The trigger is associated with a pin extending from one end of the triangular cam, which cam is pivotally mounted relative to the housing by a pivot. The pin is located in an elongated slot found in the trigger bracket which facilitates upward movement of the trigger bracket while causing pivotal movement of the cam member. Thus the trigger cannot be moved upwardly to activate the piezo-electric system until the U-shaped rod located adjacent the cam has been moved out of abutting relationship therewith. Disengagement of the rod from the cam will occur upon upper movement of the slidable cylinder resulting from the upward movement of the work probe assembly resulting when it contacts a workpiece. Accordingly this tool is relatively complex regarding its construction, is relatively heavy, and is provided with a relatively long axial length. It is therefore an object of the invention, to provide a modified tool being reduced in its axial length and its overall weigth, and which is simple in construction. Even small reductions in the length and weigth of such a tool can meaningfully increase its versatility. Summary of the Invention According to a first aspect of this invention, this invention contemplates an improvement providing a simple, compact, lightweight, combustion-powered tool for driving fasteners. Thus, in one contemplated form, the tool comprises the features of claim 1. The arms provide operative connections to the valve sleeve. There is no need for a lower chamber to provide axial clearance for any part of the valve sleeve-actuating linkage. Therefore, as compared to combustion-powered tools known heretofore, the axial length of the tool and its overall weight can be meaningfully reduced. According to a second aspect of this invention a tool comprising the features of claim 5 is provided. Thereby actuation of the trigger is prevented unless the valve member has been moved to a position wherein the valve member closes a combustion chamber of the combustion-powered tool. This aim is achieved with a simple, lightweight tool as compared to the prior art. These and other objects, features, and advantages of this invention are evident from the following description of a preferred embodiment of this invention with reference to the accompanying drawings. Brief Description of the Drawings Figure 1 is a fragmentary, cross-sectional view taken along a vertical plane through a combustion-powered, nail-driving tool constituting a preferred embodiment of this invention. Figure 1 showws the tool with a workpiece-contacting member pressed against a workpiece, with a trigger actuated, and with a piston in an upper position. Figure 2 is a fragmentary, cross-sectional view taken along a vertical plane normal to the vertical plane along which Figure 1 is taken. The piston is shown in a lower position. Figure 3 is a view similar to Figure 1, taken along the same plane, and showing the tool with the workpiece-contacting member extended, with the trigger deactuated, and with the piston in the upper position. Figure 4 is a view similar to Figure 2, taken along the same plane, and showing the tool with the workpiece-contacting member extended. A cylinder body and related parts are shown in full elevation. Figure 5 is an enlarged, front elevation of the workpiece-contacting member, along with two biasing springs shown fragmentarily. Figure 6 is a similarly enlarged, side elevation of the workpiece-contacting member, along with the biasing springs shown fragmentarily. Portions of a cylinder body and a nosepiece, which are formed as a single piece, are shown in phantom lines. Figure 7 is a similarly enlarged, fragmentary, exploded view of a trigger, a one-piece interlocking member, and related parts, as used in the tool. Figure 8 is a perspective view of a cylinder body, a valve sleeve, a nosepiece, a workpiece-contacting member, and related components of a combustion-powered tool exemplifying the prior art. Figure 9 is a fragmentary, cross-sectional view of some of the tool components of Figure 8 with the workpiece-contacting member extended. A housing structure is shown fragmentarily. Figure 10 is a similar view of the components shown in Figure 9 with the workpiece-contacting member pressed against a workpiece. Brief Description of Prior Art Tool Before a detailed description is given of a combustion-powered tool embodying this invention, a brief description follows of a combustion-powered, fastener-driving tool 200 illustrated in Figures 8, 9, and 10 and exemplifying the prior art. The tool 200 is similar to combustion-powered, fastener-driving tools exemplified in the Nikolich patents identified above and to combustion-powered, fastener-driving tools available commercially from ITW-Paslode (a unit of Illinois Tool Works Inc.) of Lincolnshire, Illinois, under its IMPULSE trademark. The tool 200 comprises a housing structure 202 (see Figures 9 and 10) within which a cylinder body 204 is mounted fixedly. The cylinder body 204 defines a tool axis. A piston (not shown) is mounted operatively in the cylinder body 204. The piston is arranged to drive a driving blade 206 extending axially from the cylinder body 204. A valve sleeve 210 is mounted in axially movable relation to the cylinder body 204. The cylinder body 204 and the valve sleeve 210 define a combustion chamber 212. The valve sleeve 210 is moveable axially, along the cylinder body 204, so as to open and close the combustion chamber 212. A nosepiece 214 is mounted to the housing structure 202, in axially spaced relation to the cylinder body 204, via a separate piece 216 defining a lower chamber 218 between the cylinder body 204 and the nosepiece 214. A linkage 220, which includes a workpiece-contacting element 222, is used to close the combustion chamber 212 when the element 222 contacts a workpiece P . The linkage 220 includes four arms 224 connected to the valve sleeve 210 by fasteners 226. The linkage arms 224 are connected to each other and to the workpiece-contacting element 222 by an intermediate structure 228 disposed within the lower chamber 218 and across the tool axis. The linkage arms 224 are shaped so as to extend outwardly from the lower chamber 218 and upwardly along the cylinder body 204. A coiled spring 230 is disposed within the lower chamber 218, between the cylinder body 204 and the intermediate structure 228, so as to bias the valve sleeve, via the linkage 220, to a position wherein the combustion chamber 212 is opened. The lower chamber 218 provides axial clearance, e.g. about one inch of axial clearance, to permit axial movement of the linkage arms 224 and the intermediate structure 228 relative to the cylinder body 204, the nosepiece 214, and the housing structure 202. This invention eliminates the lower chamber providing axial clearance for the coiled spring and the elements connecting the workpiece-contacting element to the valve sleeve. Consequently, this invention provides a simple, compact, lightweight tool. Detailed Description of Preferred Embodiment As shown in Figures 1 through 4, a combustion-powered, nail-driving tool 10 constitutes a preferred embodiment of this invention. Because of the improvements provided by this invention, the tool 10 is simple, compact, and lightweight. Except as illustrated and described herein, the tool 10 may be substantially similar in its structure and functions to prior combustion-powered tools disclosed in the Nikolich patents noted above, the disclosures of which are incorporated herein by reference. Herein, directional terms including "upper", "lower", and terms of similar import are used to refer to the tool 10 in a convenient orientation, in which the tool 10 is shown in the drawings. It should be understood that this invention is not limited to any particular orientation. The tool 10 includes a generally hollow housing structure 12 molded from a suitable engineering polymer. The housing structure 12 has a principal portion 14 and a handle portion 16. The housing structure 12 mounts a nail-feeding mechanism 20 shown fragmentarily. The nail-feeding mechanism 20 is used to feed nails N (one shown in Figure 1) successively into the tool 10. As shown in Figure 1, the nail N is a known nail having an elongate, pointed shank and an offset or clipped head. The tool 10 comprises a cylinder body 30 mounted fixedly within the housing structure 12. The cylinder body 30 has a piston chamber 32, which defines an axis, and a blade orifice 34. The cylinder body 30 has integral cooling fins 36 extending laterally from the cylinder body 30. The cylinder body 30 is open at its upper end, as shown, so as to define a gas inlet and outlet passage 38. A piston 40 is moveable axially within the piston chamber 32 between an upper position, in which the piston 40 is shown in Figures 1 and 3, and a lower position, in which the piston 40 is shown in Figure 4. A driving blade 42 is attached to the piston 40 so as to extend axially from the piston 40 and so as to be axially and conjointly moveable with the piston 40. The driving blade 42 is arranged to be forcibly and rapidly driven downwardly from the upper position, in a manner to be later described, so as to drive a nail, such as the nail N shown in Figure 1, from the tool 10 into a workpiece W . As shown in Figure 4, a muffler 44, which included a reed valve 46, is mounted to one side of the cylinder body 30. The tool 10 includes a nosepiece 50 extending below the housing structure 12. A wear plate 52 is mounted fixedly to the nosepiece 50 via screws 54 (one shown in Figures 1 and 3) which also function to mount the nail-feeding mechanism 20 to the nosepiece 50. The nail-feeding mechanism 20 is mounted elsewhere to the handle portion 16 of the housing structure 12. The nosepiece 50 functions for receiving a nail from the nail-feeding mechanism 20, before the nail is engaged by the driving blade 42, and for guiding the nail as the nail is driven by the driving blade 42. Advantageously, the cylinder body 30 and the nosepiece 50 are made in a single piece, which may be a steel casting that can be suitably machined so as to interfit with other components of the tool 10. The wear plate 52, which may be a steel stamping, prevents the nosepiece 50, as a portion of a cast piece, from wearing excessively as nails are driven by the driving blade 42. The tool 10 includes a valve member 60 disposed within the housing structure 12 so as to be axially moveable between an upper position, in which the valve member 60 is shown in Figures 1 and 4, and a lower position, in which the valve member 60 is shown in Figure 3. The valve member 60 has a sleeve portion 62, which is disposed around an upper portion 64 of the cylinder body 30 in the upper position of the valve member 60, as shown in Figures 1 and 4. An O-ring 66 is seated in an annular recess 68 in the upper portion 64 of the cylinder body 30. The O-ring 66 forms a generally gas-tight seal between the upper portion 64 of the cylinder body 30 and the sleeve portion 62 of the valve member 60, so as to close the gas inlet and outlet passage 38, when the valve member 60 is moved from its lower position into its upper position, which may be thus regarded as its combustion chamber-closing position. The valve member 60 moves away from the O-ring 66 so as to open the gas inlet and outlet passage 38 and the combustion chamber 70 when the valve member 60 is moved from its upper position into its lower position, which may be thus regarded as its combustion chamber-opening position. The valve member 60 and the cylinder body 30 define a combustion chamber 70. A fan 72, which is driven by a battery-powered, electric motor 74, is mounted operatively in the combustion chamber 70. When the gas inlet and outlet passage 38 is closed, the combustion chamber 70 is closed. When the gas inlet and outlet passage 38 is opened, the combustion chamber 70 is opened. An annular, elastomeric bumper 76 is disposed within the piston chamber 32, on an annular ledge 78, below the piston 40. The bumper 76 functions, in a known manner, to arrest downward movement of the piston 40 and the driving blade 42 and to absorb resultant shocks. The tool 10 includes a linkage 80 for engaging the workpiece and for moving the valve member 60. The linkage 80 includes a workpiece-contacting element 82 and a valve sleeve-actuating element 84. The workpiece-contacting element 82 is mounted movably to the nosepiece 50 so as to permit the workpiece-contacting element 82 to move between an extended position, in which the workpiece-contacting element 82 is shown in Figures 1 and 4 and a displaced position, in which the workpiece-contacting element 82 is shown in Figures 2 and 3. The valve sleeve-actuating element 84 is connected to the workpiece-contacting element 82 so as to be conjointly moveable with the workpiece-contacting element 82. The workpiece-contacting element 82 has an elongate, axially extending slot 86, and the valve sleeve-actuating element 84 has two small apertures 88 behind the slot 86. Two screws 90 are passed through the slot 86, and through the respective apertures 88, and are threaded into two respective, threaded sockets 92 in a block 94 behind the valve sleeve-actuating element 84 so as to connect the workpiece-contacting element 82 adjustably to the valve sleeve-actuating element 84. Thus, the slot 86 permits a limited range of adjustments, which permit the tool 10 to be used to drive nails of a given length into a workpiece at any selected depth within a similar range of depths. As shown in greater detail in Figures 5 and 6, the valve sleeve-actuating element 84 has an element 98 disposed alongside the nosepiece 50 and is bifurcated so as to have two arms 100 interconnected by the element 98. The arms 100 are disposed alongside the cylinder body 30, on opposite sides of such body 30. Each arm 100 has an end flange 102, near which such arm 100 is connected to the sleeve portion 62 of the valve member 60 via a screw 104. The arms 100 are arranged to push the sleeve portion 62 so as to push the valve member 60 from the lower, combustion chamber-opening position into the upper, combustion chamber-closing position when the workpiece-contacting element 82 is pressed against the workpiece W . As shown in Figures 2 and 4, the cylinder body 30 has two outer ears 106, one on each side of the cylinder body 30 above the respective end flanges 102 of the arms 100. Two coiled springs 110 are provided, each being compressed axially between one of the outer ears 106 and the end flange 102 of one of the arms 100, so as to bias the valve member 60 downwardly into the combustion chamber-opening position and so as to bias the workpiece-contacting element 82 and the valve sleeve-actuating element 84 downwardly into the extended position. The coiled springs 110 permit the workpiece-contacting element 82 and the valve sleeve-actuating element 84 to be conjointly moved from the extended position into the displaced position. Unlike the prior art construction of Figures 8, 9, and 10, the valve-actuating element 84 of the invention is configured and disposed so as to operate outside the peripheral surfaces or envelope of the unitary cylinder body 30 and nosepiece 50 of the tool and thus not contribute to the length of the tool. More specifically, and as shown in Figures 2 and 6, the arms 100 and associated springs 110 are disposed outside the cylinder body 30 and the integral interconnecting portion 98 is disposed alongside the nosepiece 50. Moreover, it has been found that the simplicity of the element 84 contributed to the simplification of the tool in other respects including the novel single-piece casting of the body 30 and nosepiece 50. Thus, as compared to prior combustion-powered tools having similar capabilities, the tool 10 can be notably lighter, notably shorter, and much less expensive to produce. As shown in Figures 1, 3, and 7, the tool 10 includes a manual trigger 120, which is mounted operatively to the housing structure 16. The trigger 120 is biased by a coiled spring 122 into an outer position, in which the trigger 120 is spaced from a normally opened, trigger switch 124 having an actuator 126 and (unless disabled in a manner described below) can be manually pulled from the outer position into an inner position, in which the trigger 120 actuates the trigger switch 124 via the actuator 126. A pawl 130, which comprises a generally U-shaped wire, is mounted pivotally to the trigger 120. As shown in Figure 7, the pawl 130 is formed to include a bight portion 131 from which extend two legs 134 having inwardly bent ends 136. The ends 136 are pivotally connected to the trigger 120 as shown assembled in Figures 1 and 3. The pawl 130 extends slidably and pivotally along opposed grooves 132 embossed in opposite sides of the handle portion 16, between the trigger 120 and the sleeve portion 62 of the valve member 60. The grooves 132 loosely receive the legs 134 and permit the pawl 130 to pivot and to be forwardly pushed when the trigger 120 is pulled inwardly by a user and permit the pawl 130 to pivot and to be backwardly pulled when the trigger 120 is pushed outwardly by the spring 122. The sleeve portion 62 of the valve member 60 has a pawl-admitting aperture 140, which is disposed to admit the pawl 130 if the trigger 120 is pulled inwardly when the valve member 60 is in the combustion chamber-closing position, as shown in Figure 1. The cylinder body 30 provides sufficient clearance for the pawl 130 between the upper portion 62 and the cooling fins 36. As best shown in Figure 7, a wear plate 142 having an upper lip 144 is affixed to the sleeve portion 62 so as to cover an upper margin of the aperture 140 and so as to cover an outer area above the aperture 140. The aperture 140 is disposed so that if an attempt is made to pull the trigger 120 inwardly when the valve member 60 is in the combustion chamber-opening position, the bight 131 of the pawl 130 cannot enter the aperture 140 but engages the wear plate 142 at the lip 144, which arrests inward movement of the trigger 120 before the trigger 120 can actuate the trigger switch 124. As shown in Figure 1, the tool 10 includes a normally opened head switch 150 having an actuator 152. The head switch 150 is arranged to be closed via a flexible member 154 when the valve member 60 is moved into the combustion chamber-closing position. The member 154 is mounted within the housing structure 12 via a pin 156, so as to fix a lower end of the member 154, and tends to be normally disposed in a position wherein the member 154 is spaced from the actuator 152. The member 154 is provided at an upper end with a roller 158. The valve member 60 has an upper ear 160 disposed to engage the roller 158, so as to flex the member 154 backwardly to a position where the member 154 depresses the actuator 152, when the valve member 60 is moved into the combustion chamber-closing position. The trigger switch 124 and the head switch 150 are components of an ignition system of the tool 10. After the fan 72 has been actuated, and after the workpiece-contacting element 82 has been pressed against a workpiece so that the valve member 60 is moved from its combustion chamber-opening position into its combustion chamber-closing position and so that the head switch 150 is closed, the trigger 120 may be then pulled so as to initiate combustion of a fuel-air mixture in the combustion chamber 32, whereby the piston 40 is driven forcibly from its retracted position so that the driving blade 42 can drive a nail from the nosepiece 50 into a workpiece. As described above, this invention provides a simple, compact, lightweight tool, which offers significant advantages over combustion-powered, fastener-driving tools known heretofore.

Claims: A combustion-powered tool (10) for driving fasteners comprising: a housing structure (12), a cylinder body (30) disposed within said housing structure (12) and having a gas inlet and outlet passage (38), and defining a longitudinal axis of said tool (10), a valve sleeve (60) movably disposed within said housing structure (12) and mounted movably around the cylinder body for opening and closing said passage, a nosepiece (50) extending axially from said cylinder body (30), said cylinder body (30) and said valve sleeve (60) defining a combustion chamber (70), a workpiece contacting-element (82) being spring biased into its normal inoperative position and movably mounted to said nosepiece (50), said valve sleeve (60) being movable by said workpiece-contacting element (82) from a combustion chamber-opening position into a combustion chamber-closing position when said workpiece contacting-element (82) engages a workpiece (W), characterized by a valve sleeve-actuating linkage (80) comprising said workpiece-contacting element (82) and a valve sleeve-actuating element (84) having a pair of arms (100) disposed alongside the cylinder body (30) and interconnected by an element (98) disposed alongside the nosepiece (50), the arms being connected to said valve sleeve (60) and said valve-actuating element (84, 98) being configured and disposed alongside said nosepiece (50), so as to operate outside the housing structure (12). Tool according to claim 1, characterized in that said cylinder body (30) and said nosepiece (50) are formed integrally as a single component. Tool according to claim 1, characterized by two coiled springs (110) each being disposed between one end of said arms (100) and said cylinder body (30). Tool according to claim 3, characterized in that said cylinder body (30) has two outer ears (106), each coiled spring (110) being disposed between one of said arms (100) and one of said ears (106). A combustion-powered tool (10) for driving fasteners comprising: a housing structure (12), a cylinder body (30) disposed within said housing structure (12) and having a gas inlet and outlet passage (38) and defining a longitudinal axis of said tool (10), a valve sleeve (60) movably disposed within said housing structure (12), a nosepiece (50) extending axially from said cylinder body (30), said cylinder body (30) and said valve sleeve (60) defining a combustion chamber (70), a workpiece contacting-element (82) being movably mounted to said nosepiece (50), said valve sleeve being movable by said workpiece-contacting element (82) in a combustion chamber-closing position when said workpiece contacting-element (82) engages a workpiece, and a trigger (120) actuable to initiate combustion within said combustion chamber (70) when said workpiece-contacting element (82) engages said workpiece characterized by an aperture (140) within said valve sleeve (60) and a one-piece interlocking member connected between said trigger (120) and said valve sleeve (60), such that one end of said interlocking member will be receivable by said aperture (140) when said valve sleeve (60) is disposed in a combustion chamber-closing position so as to permit actuation of the trigger (120), said aperture (140) being disposed such that the one end of said one-piece interlocking member (130) cannot enter the aperture when the valve sleeve (60) is disposed in the combustion chamber-opening position. Tool according to claim 5, characterized in that said valve sleeve (60) is arranged to block the interlocking member except when the interlocking member is received by the aperture (140). Tool according to claim 6, characterized in that said housing structure (12) comprises means for guiding the interlocking member so as to enable the interlocking member to be moved inwardly into the aperture (140), with a rocking motion, when the trigger (120) is actuated with the valve sleeve (60) in the combustion chamber-closing position. Tool according to claim 7, characterized in that said guiding means include two spaced elements, e.g. grooves (132), extending fixedly from the housing structure (12), and in that the interlocking member is formed from a single piece of metal wire having two leg portions (134) and a bight portion (131), the leg portions (134) being attached pivotally to the trigger (120) and extending loosely between the spaced elements of the guiding means, the bight portion (131) being movable inwardly into the aperture (140) when the trigger (120) is actuated with the valve sleeve (60) in the combustion chamber-closing position.

Inventors: NIKOLICH MILOVAN A, NIKOLICH, MILOVAN A., Nikolich, Milovan A., c/o KEIL &amp; SCHAAFHAUSEN
Applicants: ILLINOIS TOOL WORKS, ILLINOIS TOOL WORKS INC.
Application year: 1993
Main classification: B25C1
IPC codes: B25C1