NZ272267A - Safety interlock for combustion powered tool: trigger locked until chamber closed - Google Patents

Description

272267 Priority Date(s): ..

Complete Specification Filed: Class: {§L.&23.3).%l±Q+.\ik\ Publication Date* 2..8..MAY... ;P.O. Journal No: ;UrxJer the provisions of Regulation 23 (1) ths — ;9|p6ctficaUon has be^n ;Initiate fLZ. PATWT OFFICE ;-1 JUN1995 ;receivo ;Patents Form No. 5 ;Our Ref: EG204792 ;This is a divisional out of application number 247074 dated 5 March 1993. ;NEW ZEALAND PATENTS ACT 1953 ;COMPLETE SPECIFICATION ;COMBUSTION—POWERED TOOL ASSEMBLY ;We, ILLINOIS TOOL WORKS INC., a corporation under the state of Delaware, U.S.A of 3600 West Lake Avenue, Glenview, Illinois 60025, United States Of America, hereby declare the invention, for which we pray that a patent may be granted to us emd the method by which it is to be performed, to be particularly described in and by the following statement: ;PT0510899 ;-1- ;(followed by page la) ;272 ;- /Cf- ;2TW Case 6441 ;COMBUSTION-POWERED TOOL ASSEMBLY ;I ;This invention provides improvements in a combustion-powered tool for driving fasteners, such as nails or staples. ;An improved, one-piece interlocking member is provided, which is useful to prevent actuation of a trigger unless a valve member has been moved to a position'wherein a combustion chamber is closed. ;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. ;Typically, in such a tool, a housing structure encloses a cylinder body, which defines a tool axis, and within which a piston is mounted operatively. A valve sleeve is mounted in movable relation to the cylinder body so as to open and close a combustion chamber defined by the cylinder body and the valve sleeve. A nosepiece is mounted to the housing structure, in ;(followed by page 2) ;- 2 ;7 ;axially spaced relation to the cylinder body, via a separate piece defining a lower chamber between the cylinder body and the nosepiece. ;This invention has resulted from efforts to redesign such a tool so as to reduce its axial length and its overall weight. Even small reductions in the length and weight of such a tool can meaningfully increase its versatility. ;It is an object of the invention to provide a simple, compact, lightweight, combustion powered tool for driving fasteners, or to at least provide the public with a useful choice. ;There is thus provided a combustion-powered tool for driving fasteners, the tool including a combustion chamber, a valve member movable along the combustion chamber to and from a chamber-closing position, the valve member being arranged to close the combustion chamber when moved to the camber-closing position, and a trigger actuatable to initiate combustion within the combustion chamber, the tool comprising: ;a one-piece interlocking member connected between the trigger and the valve member and arranged to prevent actuation of the trigger unless the valve member has been moved to the chamber-closing position. ;- 3 - ;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 shows 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 ;2722 ;- 4 - ;deactivated, 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-cpntacting 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 ;1 2722 ;- 5 - ;-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 p ;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 £. 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. ;• 27 ;- 6 - ;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. ;P^taUed Peseription pff 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 E (one shown in Figure 1) successively into the tool 10. As shown in Figure 1, the nail K is a ;272267 ;- 7 - ;known nail having an elongate, pointed shank and an offset or clipped head. Preferably, the nail-feeding mechanism 20 conforms to the nail-feeding mechanism disclosed in a copending application assigned commonly 5 herewith and filed October 21, 1991, under U.S Patent ;No. 5,197,647 , for FASTENER-DRIVING TOOL WITH IMPROVED FEEDING MECHANISM. ;The tool 10 comprises a cylinder body 30 mounted fixedly within the housing structure 12. The 10 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 15 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 20 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, 25 such as the nail £[ shown in Figure 1, from the tool 10 ;into a workpiece H- 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 30 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 35 handle portion 16 of the housing structure 12. The ;2722 ;- 8 - ;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 €0 ;r 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 ;2722 ;- 9 - ;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 c ;'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 ;2722 ;- 10 - ;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 workf .»*• -?e Jj.

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 2722 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 neen 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. r 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 272287' 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 13 0 to pivot and to be 5 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 10 when the valve member 60 is in the combustion chamber-closing position, as shown in Figure l. 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 15 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 20 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. 25 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 30 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 35 158. The valve member 60 has an upper ear 160 disposed 272267 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.

Details of the head and trigger switches and of the ignition system are found in two copending patent applications assigned commonly herewith, namely one filed June 17, 1991, under U.S Patent No. 5,191,209 for PHOTOELECTRIC SWITCH SEALED AGAINST INFILTRATION OF CONTAMINANTS, and another filed December 9, 1991, under U.S. No. 5,133,329, for IMPROVED IGNITION SYSTEM FOR COMBUSTION-POWERED TOOL.

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 70, 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.

Various modifications may be made in the tool described above without departing from the scope of this invention as defined in the claims. t 1 272267

Claims (7)

WHAT WE CLAIM IS:

1. A combustion-powered tool for driving fasteners, the tool including a combustion chamber, a valve member movable along the combustion chamber to and from a chamber-closing position, the valve member being arranged to close the combustion chamber when moved to the chamber-closing position, and a trigger actuatable to initiate combustion within the combustion chamber, the tool comprising: a one-piece interlocking member connected between the trigger and the valve member and arranged to prevent actuation of the trigger unless the valve member has been moved to the chamber-closing position.

2. The tool of claim 1 wherein the valve member has an aperture disposed to receive the interlocking member when the valve member has been moved to the chamber-closing position, the valve member being arranged to block the interlocking member except when the interlocking member is received by the aperture.

3. The tool of claim 2 further comprising a housing structure, within which a cylinder body is mounted fixedly and to which the trigger is mounted operatively, the housing structure comprising means for guiding the interlocking member so as to enable the interlocking member to be moved inwardly into the aperture, with a rocking motion, when the trigger is actuated with the valve member in the chamber-closing position.

4. The tool of claim 3 wherein the guiding means included two spaced elements extending fixedly from the housing structure and wherein the interlocking member is formed from a single piece of metal wire having two leg 272267 attached pivotally to the trigger and extending loosely between the spaced elements of the guiding means, the bight portion being movable inwardly into the aperture when the trigger is actuated with the valve member in the chamber-closing position. I

5. A tool as set forth in claim 4, wherein said spaced elements comprise laterally spaced guide grooves. sleeve; and said aperture is defined within a sidewall portion of said cylindrical valve sleeve. member and including a lip portion for engaging said interlocking member so as to prevent actuation of said trigger.

6. A tool as set forth in claim 3, wherein said valve member comprises a cylindrical valve

7. A tool as set forth in claim 3, wherein said non-actuated portion of said valve member comprises a wear plate fixedly attached to said valve CNOtS TOOL WORKS, INC Attorneys SON & CAREY