Patent Document

BACKGROUND 
     The present disclosure relates generally to powered, fastener-driving tools, wherein the tools may be electrically powered, pneumatically powered or powder activated, and more particularly to a combustion-powered fastener-driving tool having a trigger control mechanism that is operable in both a sequential actuation mode and a contact actuation mode. 
     Powered, fastener-driving tools of the type used to drive various fasteners, such as, for example, staples, nails, and the like, typically include a housing, a power source, a supply of fasteners, a trigger mechanism for initiating the actuation of the tool, and a workpiece contact element (also referred to herein as a “workpiece contacting element” or “WCE”). The workpiece contact element is configured to engage or contact a workpiece, and is operatively connected to the trigger mechanism, such that when the workpiece contact element is in fact disposed in contact with the workpiece, and depressed or moved inwardly a predetermined amount with respect to the tool, as a result of the tool being pressed against the workpiece a predetermined amount, the trigger mechanism is enabled to initiate actuation of the fastener-driving tool. 
     As is well-known in the art, powered, fastener-driving tools normally have two operational modes, and the tool is accordingly provided with some mechanism, such as, for example, a lever, a latch, a switch or the like, for enabling the operator to optionally select one of the two operational modes that the operator desires to use for installing the fasteners. More particularly, in accordance with a first one of the operational modes, known in the industry and art as the sequential or single-actuation mode of operation, the depression or actuation of the trigger mechanism will not in fact initiate the actuation of the tool and the driving of a fastener into the workpiece unless the workpiece contact element is initially depressed against the workpiece. Considered from a different point of view or perspective, in order to operate the powered, fastener-driving tool in accordance with the sequential or single-actuation mode of operation, the workpiece contact element must first be depressed against the workpiece followed by the depression or actuation of the trigger mechanism. Still further, once the particular fastener has in fact been driven into the workpiece, further or repeated depression or actuation of the trigger mechanism will not result in the subsequent driving of additional fasteners into the workpiece unless, and until, the workpiece contact element is permitted to effectively be reset to its original position and once again disposed in contact with, and pressed against, the workpiece prior to the depression or actuation of the trigger mechanism each time the tool is to be actuated so as to drive a fastener into the workpiece. 
     Alternatively, in accordance with a second operational mode, known in the industry and art as the contact actuation mode of operation, the operator can in fact maintain the trigger mechanism at its depressed position, and subsequently, each time the workpiece contact element is disposed in contact with, and pressed against, the workpiece, the tool will actuate, thereby driving a fastener into the workpiece. 
     Combustion-powered tools are known in the art. Exemplary tools are manufactured by Illinois Tool Works, Inc. of Glenview, Ill. for use in driving fasteners into workpieces, and are described in commonly assigned patents to Nikolich U.S. Pat. Re. No. 32,452 and U.S. Pat. Nos. 4,522,162; 4,483,473; 4,483,474; 4,403,722; 5,133,329; 5,197,646; 5,263,439; 6,145,724 and 7,383,974, all of which are incorporated by reference herein. 
     Such tools incorporate an external tool housing enclosing a small internal combustion engine. The engine is powered by a canister of pressurized fuel gas, also called a fuel cell. A battery-powered electronic power distribution unit produces a spark for ignition, and a fan located in a combustion chamber provides for both an efficient combustion within the chamber, while facilitating processes ancillary to the combustion operation of the device. Such ancillary processes include: cooling the engine, mixing the fuel and air within the chamber, and removing, or scavenging, combustion by-products. The engine includes a reciprocating piston with an elongated, rigid driver blade disposed within a single cylinder body. 
     A valve sleeve is axially reciprocable about the cylinder and, through a linkage, moves to close the combustion chamber when the workpiece contact element at the end of the linkage is pressed against a workpiece. This pressing action also triggers a fuel-metering valve to introduce a specified volume of fuel into the closed combustion chamber. This same movement of the tool against the workpiece causes the fan inside the combustion chamber to turn on and mix the fuel with the air inside the combustion chamber. 
     Upon the pulling of a trigger, which closes a trigger switch, a spark is generated for igniting a charge of gas in the combustion chamber of the engine, the resulting high pressure inside the chamber causes the combined piston and driver blade to be forced downward to impact a positioned fastener and drive it into the workpiece. Just before the piston impacts a resilient bumper at a lower end of the cylinder, the piston passes an exhaust port, through which some of the exhaust gas is vented. Next, the tool valve sleeve and cylinder absorb heat from the combustion to generate vacuum pressure that pulls the piston back to its uppermost position in the cylinder for the next cycle. Fasteners are fed magazine-style into the nosepiece, where they are held in a properly positioned orientation for receiving the impact of the driver blade. 
     For efficient operation, it is preferred that the combustion chamber remains sealed until the piston returns to its uppermost or pre-firing position. The amount of time that the combustion chamber remains closed is a function of the operator&#39;s work rhythm and is often too short when attempting a repetitive cycle operation, where the trigger remains pulled and the workpiece contact element is rapidly pressed upon the workpiece for fastener driving, and then the tool is quickly lifted and moved to the next fastener location. 
     In cases where a tool is operated at a much higher cycle rate, the operator can open the combustion chamber during the piston return cycle by removing the tool from the workpiece. This causes the vacuum to be lost, however, and piston travel will stop before reaching the top of the cylinder. This leaves the driver blade in the guide channel of the nosepiece, thereby preventing the nail strip from advancing towards the nose. The net result is no nail in the firing channel and no nail fired in the next shot. 
     To assure adequate closed combustion chamber dwell time in the sequentially-operated combustion tools identified above, a chamber lockout device is known that is linked to the trigger. This mechanism holds the combustion chamber closed until the operator releases the trigger. This extends the dwell time (during which the combustion chamber is closed) by taking into account the operator&#39;s relatively slow musculature response time. In other words, the physical release of the trigger consumes enough time of the firing cycle to assure piston return. The mechanism also maintains a closed chamber in the event of a large recoil event created, for example, by firing into hard wood. 
     Conventional combustion-powered fastening tools typically operate in the sequential actuation mode. As a result, experienced carpenters typically use the sequentially actuated combustion tool for precision nailing and a different contact actuated tool for non-precision nailing, such as for roofing and decking. A need therefore exists for a single combustion fastener-driving tool that is operable in both a sequential actuation mode and a contact actuation mode. 
     SUMMARY 
     Various embodiments of present disclosure provide a new and improved combustion fastener-driving tool which has a trigger control mechanism for alternatively permitting sequential and contact actuation modes of operation. 
     In an embodiment, a fastener-driving tool has a housing including a combustion chamber, where the combustion chamber generates combustion for driving a fastener, and a processor associated with the housing and in communication with the combustion chamber. The processor is configured to cause an initial combustion in the combustion chamber and cause a fastener to be driven when a first actuation event and a second actuation event occur, and is configured to cause at least one subsequent combustion in the combustion chamber and cause at least one additional fastener to be driven when only the first actuation event occurs. 
     In another embodiment, a fastener-driving tool has a trigger control mechanism operable in a sequential actuation mode and a contact actuation mode. The tool includes a housing, a workpiece contact element movably connected to the housing, where the workpiece contact element is movable between a rest position and an activated position, a trigger movably connected to the housing, an actuation lever movably connected to the trigger and a control valve including an stem, where the stem is movable between a rest position and an activated position. In the sequential actuation mode, a single fastener is driven into a first location on a workpiece by pressing the workpiece contact element against the workpiece to move the workpiece contact element to the activated position followed by pressing the trigger and causing the actuation lever to contact and move the stem to the activated position. In the contact actuation mode, at least one additional fastener is driven into a second, different location on the workpiece by holding the trigger and pressing the workpiece contact element against the workpiece and causing the actuation lever to contact and move the stem to the activated position. 
     In a further embodiment, a fastener-driving tool includes a housing, a combustion chamber in the housing, a workpiece contact element movably connected to the housing and movable between a rest position and an activated position, a trigger movably connected to the housing and an actuation lever movably connected to the trigger. In a sequential actuation mode, combustion is generated in the combustion chamber to drive a fastener into a workpiece each time the workpiece contact element and the trigger are each moved from the rest position to the activated position in a designated sequence. In a contact actuation mode, the trigger remains in the activated position and combustion is generated in the combustion chamber to drive at least one additional fastener into the workpiece each time the workpiece contact element is moved to an activated position by depressing the workpiece contact element on the workpiece. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front perspective view of a conventional fastener-driving tool; 
         FIG. 2  is a fragmentary vertical cross-section of the tool of  FIG. 1  shown in the rest position; 
         FIG. 3  is a cross-sectional view of a trigger control mechanism for a combustion-powered fastener-driving tool that includes a trigger assembly having an actuation lever where the trigger assembly and the workpiece contact element are in a rest position; 
         FIG. 4  is a cross-sectional view of the fastener-driving tool of  FIG. 3  showing the chamber lockout device in a non-activated position; 
         FIG. 5  is a cross-sectional view of the fastener-driving tool of  FIG. 3  in the sequential actuation mode, where the workpiece contact element is depressed against a workpiece, the actuation lever has moved to a position adjacent to the trigger assembly and the trigger has been depressed to drive a fastener into the workpiece; 
         FIG. 6  is a cross-sectional view of the fastener-driving tool of  FIG. 3  showing the chamber lockout device in the activated or lockout position; 
         FIG. 7  is a cross-sectional view of the fastener-driving tool of  FIG. 3  between actuations of the tool in the contact actuation mode, where the workpiece contact element has been removed from the workpiece causing the actuation lever to disengage from the actuation pin; 
         FIG. 8  is a cross-sectional view of the fastener-driving tool of  FIG. 3 , where the workpiece contact element is depressed against the workpiece and the trigger has been released thereby resetting the tool from the contact actuation mode to the sequential actuation mode. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to  FIGS. 1-2 , a combustion-powered fastener-driving tool is generally designated  10  and is of the general type described in detail in the patents listed above and incorporated by reference in the present application. A housing  12  of the tool  10  encloses a self-contained internal power source  14  ( FIG. 2 ) within a housing main chamber  16 . As is generally known in the art, the power source  14  is powered by internal combustion and includes a combustion chamber  18  that communicates with a cylinder  20 . A piston  22  reciprocally disposed within the cylinder  20  is connected to the upper end of a driver blade  24 . As shown in  FIG. 2 , an upper limit of the reciprocal travel of the piston  22  is referred to as a pre-firing or pre-actuating position, which occurs just prior to firing or actuation of the tool, or the ignition of the combustion gases which initiates the downward driving of the driver blade  24  to impact a fastener (not shown) to drive it into a workpiece. 
     Through depression of a trigger  26 , an operator induces combustion within the combustion chamber  18 , causing the driver blade  24  to be forcefully driven downward through a nosepiece  28  ( FIG. 1 ). The nosepiece  28  guides the driver blade  24  to strike a fastener that had been delivered into the nosepiece via a fastener magazine  30 . 
     Included in the nosepiece  28  is a workpiece contact element  32 , which is connected, through a linkage or upper probe  34  to a reciprocating valve sleeve  36 , an upper end of which partially defines the combustion chamber  18 . Depression of the tool housing  12  against the workpiece contact element  32  in a downward direction as seen in  FIG. 1  (other operational orientations are contemplated as are known in the art), causes the workpiece contact element to move from a rest position to a firing or actuation position. This movement overcomes the normally downward biased orientation of the workpiece contact element  32  caused by a spring  38  (shown hidden in  FIG. 1 ). It is contemplated that the location of the spring  38  may vary to suit the application, and locations displaced farther from the nosepiece  28  are envisioned. 
     Through the linkage  34 , the workpiece contact element  32  is connected to and reciprocally moves with, the valve sleeve  36 . In the rest position ( FIG. 2 ), the combustion chamber  18  is not sealed, since there is an annular gap  40  separating the valve sleeve  36  and a cylinder head  42 , which accommodates a chamber switch  44  and a spark plug  46 . Specifically, there is an upper gap  40 U near the cylinder head  42 , and a lower gap  40 L near the upper end of the cylinder  20 . In the preferred embodiment of the present tool  10 , the cylinder head  42  also is the mounting point for a cooling fan  48  and a fan motor  49  powering the cooling fan. The fan and at least a portion of the motor extend into the combustion chamber  18  as is known in the art and described in the patents which have been incorporated by reference above. In the rest position depicted in  FIG. 2 , the tool  10  is disabled from firing because the combustion chamber  18  is not sealed at the top with the cylinder head  42 , and the chamber switch  44  is open. 
     Actuation or firing is enabled when an operator presses the workpiece contact element  32  against a workpiece. This action overcomes the biasing force of the spring  38 , causes the valve sleeve  36  to move upward relative to the housing  12 , closing the gaps  40 U and  40 L and sealing the combustion chamber  18  until the chamber switch  44  is activated. This operation also induces a measured amount of fuel to be released into the combustion chamber  18  from a fuel canister  50  (shown in fragment). 
     Upon a pulling of the trigger  26 , the spark plug  46  is energized and produces a spark that ignites the fuel and air mixture in the combustion chamber  18  and propels the piston  22  and the driver blade  24  downward through the cylinder and toward the waiting fastener for entry into the workpiece. As the piston  22  travels down the cylinder, it pushes a rush of air which is exhausted through at least one petal or check valve  52  and at least one vent hole  53  located beyond piston displacement ( FIG. 2 ). At the bottom of the piston stroke or the maximum piston travel distance, the piston  22  impacts a resilient bumper  54  as is known in the art. With the piston  22  beyond the exhaust check valve  52 , high pressure gasses vent from the cylinder  20  until near atmospheric pressure conditions are obtained and the check valve  52  closes. Due to internal pressure differentials in the cylinder  20 , the piston  22  is returned to the pre-actuation position shown in  FIG. 2 . Because conventional combustion-powered fastener-driving tools typically only operate in a sequential actuation mode, the above process must be repeated to drive another fastener into the workpiece. 
     Referring now to  FIGS. 3-8 , an example combustion-powered nailer  100  includes a trigger control mechanism that enables the nailer to operate in both a sequential actuation mode and a contact actuation mode. 
     The trigger control mechanism or trigger control assembly, generally indicated by reference number  102 , is configured to be mounted upon a housing  104 . A workpiece contact element assembly  106  includes a workpiece contact element  108 , which is configured to be depressed on contact with a workpiece  101 , and a workpiece contact element linkage  110 , which is slidably mounted in a reciprocal manner upon the fastener-driving tool housing  104 . 
     A trigger switch assembly  114  is mounted to the housing  104  so as to initiate either a sequential or a contact actuation operational mode of the fastener-driving tool  100  when the trigger switch assembly is actuated by the trigger control mechanism  102  of the present disclosure as will be described below. More particularly, the trigger switch assembly  114  includes a switch housing  116  biased by a spring  118  and configured to be seated upon a switch seat  120 , and a stem  122  configured to be engaged by an actuation lever  124  of the trigger control mechanism  102 . The actuation lever  124  is movably connected to a trigger  126  by a pin  128  and is movable between a first position or rest position ( FIG. 3 ) and a second position or activated position ( FIG. 5 ). A bias member, such as spring  130  connected to the pin  128 , biases the actuation lever  124  to the rest position. 
     The operation of the structural components in the sequential actuation mode and the contact actuation mode will now be described. 
     Referring to  FIG. 3-5 , in the sequential operation mode, the workpiece contact element  108  of the combustion nailer  100  is pressed against a workpiece  101 , which is a first actuation event, causing the workpiece contact element and the linkage  110  attached of the workpiece contact element assembly  106  to move upwardly within the housing  104 . The linkage  110 , which is connected with or integrally formed with the valve sleeve  132 , reciprocally moves the sleeve upwardly and closes the combustion chamber  134 , which also activates a head switch (not shown) adjacent to the chamber. The linkage  110  also contacts the actuation lever  124  causing the actuation lever  24  to move from a rest position to an activated position as shown in  FIG. 5 . In a second actuation event, a user presses the trigger  126  inwardly, i.e., activates the trigger, which in turn, depresses the stem  122  inwardly to activate it. After both the head switch and the stem  122  are activated, a spark is initiated to ignite the fuel mixture in the combustion chamber  134  thereby generating combustion. The combustion explosion within the chamber  134  drives piston  136  and driver blade  138  through cylinder  139  and into contact with a fastener  140  located in drive channel  141  to drive the fastener into a workpiece  101 . 
     The user may now remove the tool from the workpiece  101  and repeat the above steps to continue in the sequential operational mode. Alternatively, to initiate the contact actuation mode (also referred to herein as the bump actuation mode), the user keeps the trigger  126  depressed or in the activated position. Upon this action, a processor  137  ( FIG. 3 ) to activate a chamber lockout device  142  ( FIG. 4 ), such as the lockout device described in commonly owned U.S. Pat. No. 7,383,974 and U.S. application Ser. No. 13/469,795, which are both herein incorporated by reference in their entireties. It should be appreciated that the lockout device  142  may be any suitable lockout device. In the illustrated embodiment, the lockout device  142  includes a pivot arm  144  that pivots between a lockout position ( FIG. 6 ) where the pivot arm contacts and holds the valve sleeve  132  in the closed position so that the combustion chamber  134  remains closed, and a released position ( FIG. 4 ) where the pivot arm is dis-engaged from the sleeve  132  so that the sleeve  132  may move to the open position. 
     Referring now to  FIGS. 6-9 , upon activation of the lockout device  142 , the pivot arm  142  moves from the released position to the lockout position ( FIG. 6 ). In the lockout position, an end of the pivot arm  142  engages and temporarily holds the sleeve  132  in the closed position and thereby keeps the combustion chamber  134  in the closed position to allow time for the piston to reach the top position in the cylinder. As discussed below, the processor is programmed to activate the lockout device for a designated period of time that is equal to or greater than the time needed for the piston to return to the top position of the cylinder. In the contact actuation mode, the processor bypasses the head switch so that the sequential sequence of first activating the head switch and then depressing the trigger  126  is not required to further actuate the combustion nailer  100  and drive fasteners  140  into the workpiece  101 . Thus, in the contact actuation mode, the nailer  100  can be moved from one location to another location relative to the workpiece  101  without needing to repeat the actuation sequence discussed above. 
     When the nailer  100 , and more specifically, the workpiece contact element  108 , is removed from the workpiece  101  and the lockout device has been de-activated and disengaged from the sleeve, the workpiece contact element moves from the depressed or activated position to the non-depressed or rest position shown in  FIG. 7 . The nailer  100  is then moved, if needed, to a different location on the workpiece  101  and pressed against the workpiece. As described above, when the workpiece contact element  108  is pressed against the workpiece  101 , the workpiece contact element  108  and the associated linkage  110  moves upwardly. When the linkage  110  moves upwardly, it contacts the actuation lever  124  and pushes the actuation lever to the activated position ( FIG. 8 ) where it contacts and presses the stem  122  inwardly to initiate the combustion sequence described above. The combustion generated in the combustion chamber  134  causes the piston  136  and driver blade  138  to be driven through the cylinder to drive a fastener  140  into the workpiece  101 . 
     As described above, the processor is programmed with a preset or designated lockout time period so that the lockout device  142  remains activated for the designated period of time to lock the valve sleeve  132  in position and keep the combustion chamber  134  closed. In an embodiment, the lockout device is activated for 100 msec in each actuation of the tool. It should be appreciated that the lockout time period may be any suitable amount of time. 
     The combustion nailer  100  remains in the bump actuation mode until a reset event occurs. Upon an occurrence of a reset event, the nailer  100  is reset to operate in the sequential operation mode. For example, a reset event may occur when the trigger  126  is released ( FIG. 8 ) or when a fastener  140  has not been driven into the workpiece  101  (i.e., the tool has been inactive) for a designated amount of time, i.e., the reset time period. The processor is programmed with the reset time period where the reset time period may be any suitable amount of time. A user must now press the workpiece contact element  110  against the workpiece  101  or another workpiece and press the trigger  126  in this sequence to initiate the sequential actuation mode or the bump actuation mode. 
     The combination of the present trigger assembly  102  and the lockout device  142  enables the combustion nailer  100  to be operated in both a sequential activation mode and a bump actuation mode. Such flexibility in operation of the nailer  100  enables users to be able to easily switch from a sequential operation mode to a bump actuation mode at a jobsite without having to switch tools thereby saving significant time and cost. 
     While a particular embodiment of a combustion-powered fastener-driving tool has been described herein, it will be appreciated by those skilled in the art that changes and modifications may be made thereto without departing from the invention in its broader aspects and as set forth in the following claims.

Technology Category: 7