Patent Publication Number: US-2023158653-A1

Title: Fastener-driving tool with chamber member retaining assembly

Description:
PRIORITY 
     This patent application is a continuation-in-part of and claims priority to and the benefit of U.S. patent application Ser. No. 17/687,154, filed Mar. 4, 2022, which claims priority to and the benefit of U.S. Provisional Patent Application Ser. No. 63/159,696, filed Mar. 11, 2021, the contents of which are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND 
     The present disclosure relates to powered fastener-driving tools. Powered fastener-driving tools employ one of several different types of power sources to drive a fastener (such as a nail or a staple) into a workpiece. Powered fastener-driving tools use a power source to drive a piston carrying a driver blade through a cylinder from a pre-firing position to a firing position. As the piston moves to the firing position, the driver blade travels through a nosepiece that guides the driver blade to contact a fastener housed in the nosepiece of the tool. Continued movement of the piston through the cylinder toward the firing position forces the driver blade to drive the fastener out of the nosepiece and into the workpiece. The piston is then forced back to the pre-firing position in a way that depends on the tool&#39;s construction and the power source the tool employs. A fastener-advancing device of the tool forces another fastener from a magazine of the tool into the nosepiece, and the tool is ready to fire this next fastener. 
     Combustion-powered fastener-driving tools are one type of powered fastener-driving tool. A combustion-powered fastener-driving tool uses a small internal combustion assembly as its power source. For various known combustion-powered fastener-driving tools, when an operator depresses a workpiece-contact element (“WCE”) of the tool onto a workpiece to move the WCE from an extended position to a retracted position, one or more mechanical linkages cause: (1) a chamber member to move to a sealed position to seal a combustion chamber that is in fluid communication with the cylinder; and (2) a fuel delivery system to dispense fuel from a fuel canister into the (now sealed) combustion chamber. When an operator pulls the trigger, the trigger actuates a trigger switch, thereby causing a spark plug to spark and ignite the fuel/air mixture in the combustion chamber. This generates high-pressure combustion gases that expand and force the piston to move through the cylinder from the pre-firing position to the firing position, thereby causing the driver blade to contact a fastener housed in the nosepiece and drive the fastener out of the nosepiece and into the workpiece. Just before the piston reaches the firing position, the piston passes exhaust check valves defined through the cylinder, and some of the combustion gases that propel the piston exhaust through the check valves to atmosphere. This combined with heat exchange to the atmosphere and the fact that the combustion chamber remains sealed during firing generates a vacuum pressure above the piston and causes the piston to retract to the pre-firing position. When the operator removes the WCE from the workpiece, a spring biases the WCE from the retracted position to the extended position, causing the one or more mechanical linkages to move the chamber member to an unsealed position to unseal the combustion chamber. 
     One issue with the operation of certain combustion-powered fastener-driving tools can occur if the chamber member moves and the combustion chamber unseals before the piston returns to the pre-firing position. For instance, if the operator removes the WCE from the workpiece after firing but before the piston returns to the pre-firing position, this can cause the chamber member to move to the unsealed position and unseal the combustion chamber. When this happens, at least some of the vacuum pressure can be lost. This can cause the piston to stop before reaching its pre-firing position, which in turn can cause the tool to not properly function the next time the operator attempts to use the tool to drive the next fastener. 
     Certain fastener-driving tools have two different types of operational modes and one or more mechanisms that enable the operator to optionally select one of the two different operational modes that the operator desires to use for driving the fasteners. One such operational mode is known in the industry as the sequential or single actuation operational mode. In this operational mode, the actuation of the trigger mechanism will not (by itself) initiate the actuation of the powered fastener driving tool (and the driving of a fastener into the workpiece) unless the WCE is sufficiently depressed against the workpiece. In other words, to operate the powered fastener driving tool in the sequential or single actuation operational mode, the WCE must first be depressed against the workpiece followed by the actuation of the trigger mechanism. Another operational mode is known in the industry as the contact actuation or bump-fire operational mode. In this operational mode, the operator can maintain the trigger mechanism at or in its actuated position, and subsequently, each time the WCE is in contact with and sufficiently pressed against the workpiece, the fastener-driving tool will actuate (thereby driving a fastener into the workpiece). 
     One issue with various commercially available combustion-powered fastener-driving tools (that are sometimes called cordless framing nailers) is that they operate in the sequential firing mode but do not operate in the bump fire mode. Operating such tools only in the sequential firing mode can lead to operator fatigue. 
     Accordingly, there is a need for combustion-powered fastener-driving tools that address these issues. 
     SUMMARY 
     The present disclosure provides various embodiments of a combustion-powered fastener-driving tool that address the above issues by including a chamber member retaining assembly to ensure the chamber member doesn&#39;t move to an unsealed position and the combustion chamber remains sealed until the piston fully returns to its pre-firing position. The chamber member retaining assembly is controlled by a suitable controller and engageable with the chamber member thereby providing the controller with the ability to prevent certain undesired movement of the chamber member from the sealed position. 
     In various embodiments, the chamber member retaining assembly includes an electromagnet that directly holds the chamber member in a retained position. The controller of the tool selectively energizes the electromagnet to maintain the chamber member in a retained position. The electromagnet directly selectively prevents the chamber member from moving toward its unsealed position from its sealed position. In various embodiments, the controller de-energizes the electromagnet after a designated amount of time (thereby allowing the chamber member to move to the unsealed position) to give the piston time to fully return to its pre-firing position. This enables the tool to operate in a bump fire mode. The operational rate can be limited by various factors including the requisite electromagnet “on” time and the time between fastener driving cycles while the tool is repositioned, and the combustion chamber receives fresh air. The combustion-powered fastener-driving tool of various embodiments of the present disclosure is able to thus able to provide an automatic combustion chamber lock control feature and a bump-fire mode feature. 
     Various embodiments of the combustion-powered fastener-driving tool of the present disclosure operate in a default sequential mode and responsive to the user switching modes operate in a bump-fire mode. In various embodiments, the controller of the tool employs a time-out function in the bump-fire mode that prevents tool operation in the bump-fire mode after a designated idle period (such as, for example, five to ten seconds). The combustion-powered fastener-driving tool of various embodiments of the present disclosure enables the operator to rapidly select between the sequential or single actuation operational mode and the contact actuation or bump-fire operational mode. 
     Additional features and advantages are described in, and will be apparent from, the following Detailed Description and the Figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view of a combustion-powered fastener-driving tool of one example embodiment of the present disclosure. 
         FIGS.  2 A,  2 B,  2 C, and  2 D  are fragmentary partial cross-sectional views of the fastener-driving tool of  FIG.  1    in a rest state with the chamber member in an unsealed position, the piston in a fully retracted position, and the chamber member retaining assembly in an inactive state. 
         FIGS.  3 A,  3 B, and  3 C  are fragmentary partial cross-sectional views of the fastener-driving tool of  FIG.  1    in a ready to fire state with the chamber member in a sealed position, the piston in a fully retracted position, and the chamber member retaining member in an inactive state. 
         FIGS.  4 A,  4 B, and  4 C  are fragmentary partial cross-sectional views of the fastener-driving tool of  FIG.  1    that is in a fired state with the chamber member in the sealed position, the piston in a partially driven position, and the chamber member retaining assembly in an active state with actuation member retained position, the electromagnet energized and retaining the actuation member in the retained position, and the chamber member engagement lever positioned to engage the chamber member. 
         FIGS.  5 A,  5 B, and  5 C  are fragmentary partial cross-sectional views of the fastener-driving tool of  FIG.  1    that is in a fired state with the chamber member in the sealed position, the piston is fully driven and starting to move back toward the retracted position, and the chamber member retaining assembly in the active state with actuation member in the retained position, the electromagnet energized and retaining the actuation member in the retained position, and the chamber member engagement lever positioned to engage the chamber member. 
         FIGS.  6 A,  6 B, and  6 C  are fragmentary partial cross-sectional views of the fastener-driving tool of  FIG.  1    that is in a fired state with the chamber member still not moving (or substantially moving) from the sealed position, the piston moving back toward the fully retracted position, and the chamber member retaining assembly in the active state with actuation member in a retained position, the electromagnet energized and retaining the actuation member in the retained position, and the chamber member engagement lever engaging the chamber member to prevent movement of the chamber member. 
         FIGS.  7 A,  7 B, and  7 C  are fragmentary partial cross-sectional views of part of a combustion-powered fastener-driving tool of another example embodiment of the present disclosure, wherein the chamber member retaining assembly does not include a chamber member engagement lever and the engagement of the chamber member is directly engaged by the actuation member. 
         FIGS.  8 A and  8 B  are diagrammatic views of a chamber member retaining assembly of a combustion-powered fastener-driving tool of another example embodiments of the present disclosure. 
         FIGS.  9 A,  9 B, and  9 C  are diagrammatic views of a chamber member retaining assembly of a combustion-powered fastener-driving tool of another example embodiment of the present disclosure. 
         FIGS.  10 A and  10 B  are diagrammatic views of a chamber member retaining assembly of a combustion-powered fastener-driving tool of another example embodiments of the present disclosure. 
         FIGS.  11 A and  11 B  are fragmentary view of a part of a combustion-powered fastener-driving tool of another embodiment of the present disclosure and showing the potential locations of a chamber member retaining assembly thereof. 
         FIGS.  12 A and  12 B  are fragmentary view of a part of a combustion-powered fastener-driving tool of another embodiment of the present disclosure and showing the chamber member retaining assembly thereof. 
         FIGS.  13 A and  13 B  are fragmentary view of a part of a combustion-powered fastener-driving tool of another embodiment of the present disclosure and showing the chamber member retaining assembly thereof. 
         FIGS.  14 A and  14 B  are fragmentary view of a part of a combustion-powered fastener-driving tool of another embodiment of the present disclosure and showing the chamber member retaining assembly thereof. 
     
    
    
     DETAILED DESCRIPTION 
     While the systems, devices, and methods described herein may be embodied in various forms, the drawings show, and the specification describes certain exemplary and non-limiting embodiments. Not all components shown in the drawings and described in the specification may be required, and certain implementations may include additional, different, or fewer components. Variations in the arrangement and type of the components; the shapes, sizes, and materials of the components; and the manners of connections of the components may be made without departing from the spirit or scope of the claims. Unless otherwise indicated, any directions referred to in the specification reflect the orientations of the components shown in the corresponding drawings and do not limit the scope of the present disclosure. Further, terms that refer to mounting methods, such as mounted, connected, etc., are not intended to be limited to direct mounting methods but should be interpreted broadly to include indirect and operably mounted, connected, and like mounting methods. This specification is intended to be taken as a whole and interpreted in accordance with the principles of the present disclosure and as understood by one of ordinary skill in the art. 
     Turning now to the figures,  FIGS.  1  to  6 C  illustrate one example embodiment of a combustion-powered fastener-driving tool  100  of the present disclosure (sometimes called the “tool” for brevity). The tool  100  generally includes a multi-piece housing  110 , a nosepiece assembly  130  including a workpiece-contact element  136  supported by the housing  110 , a trigger assembly  140  supported by the housing  110 , a fastener magazine  150  supported by the housing  110  and connected to the nosepiece assembly  130 , an internal combustion assembly  200  at least partially within the housing  110 , and a chamber member retaining assembly  300  supported by the housing  110 . Since certain portions of the fastener-driving tool  100  such as the housing  110 , the nosepiece assembly  130 , the workpiece-contact element  126 , the fuel delivery system (not shown), and the fastener magazine  150  are well-known in the art, they are only partially shown in certain drawings and are not described herein for brevity. 
     The internal combustion assembly  200  of the tool  100  includes: (1) a cylinder  210  at least partially within and supported by the housing  110 ; (2) a piston  220  slidably disposed within the cylinder  210 ; (3) a driver blade  230  attached to and extending below the piston  220 ; and (4) a bumper  240  positioned within and at the bottom of the cylinder  210 . The piston  220  attached to the driver blade  230  is movable relative to the cylinder  210  between a pre-firing position and a firing position. The cylinder  210  includes an exhaust check or petal valve (not shown) near its bottom and defines a vent port  252  below the exhaust check valve. The exhaust check valve  250  and the vent port  252  fluidically connect the cylinder  210  with the atmosphere. 
     A chamber member (which is sometimes called a valve sleeve in the art)  260  is at least partially within, supported by, and movable relative to the housing  110 . The chamber member or valve sleeve  260  partially surrounds the cylinder  210 . The chamber member or valve sleeve  260  is movable relative to the housing  110 , the cylinder head  212 , and the cylinder  210  (among other components) between an unsealed position and a sealed position. The chamber member or valve sleeve  260 , the cylinder head  212 , the cylinder  210 , and the piston  220  collectively define a combustion chamber (not labeled). When the chamber member or valve sleeve  260  is in the sealed position, the combustion chamber is sealed. Conversely, when the chamber member or valve sleeve  260  is in the unsealed position, the combustion chamber is unsealed. 
     A suitable linkage (not shown) connects the chamber member or valve sleeve  260  and the workpiece-contact element  136 . The workpiece-contact element  136  is movable relative to the housing  110 , the cylinder head  212 , and the cylinder  210  (among other elements) between an extended position and a retracted position. A biasing element (not shown), such as a spring, biases the workpiece contact element  136  to the extended position. Movement of the workpiece-contact element  136  from the extended position to the retracted position causes the chamber member or valve sleeve  260  (via the linkage) to move from the unsealed position (see  FIGS.  2 A and  2 B ) to the sealed position (see  FIGS.  3 A,  3 B,  4 A,  4 B,  5 A,  5 B,  6 A, and  6 B ), and vice-versa. 
     In this example embodiment, the chamber member retaining assembly  300  of the tool  100  generally includes a housing  310 , a gas assisted actuation member  330  positioned in the housing  310 , and an electromagnet  360  positioned in the housing  310  and configured to hold the actuation member  330  in a retained position under control of the controller (not shown) of the tool  100 . The actuation member  330  includes an actuation pin  334  and an actuation plunger  338  connected to the distal end of the actuation pin  334 . The tool  100  provides gas that causes the actuation member  330  to move from an unretained position toward ( FIGS.  2 C,  2 D, and  3 C ) and to a retained position ( FIGS.  4 C,  5 C and  6 C ). The controller of the tool  100  is configured to selectively energize the electromagnet  360  to maintain the actuation member  330  in the retained position ( FIGS.  5 C and  6 C ). The actuation member  330  in turn causes a chamber member engagement lever  400  to prevent the chamber member  260  from moving toward its unsealed position from its sealed position. The controller energizes the electromagnet  360  for a designated amount of time (such as 100 to 160 milli-seconds) to give the piston  220  time to fully return to its pre-firing position before allowing the chamber member  260  to move to its unsealed position. Thus, in this example embodiment, the chamber member retaining assembly  300  ensures that the chamber member  260  does not move to an unsealed position and the combustion chamber remains sealed until the piston  220  fully returns to the pre-firing position. This partly enables the tool  100  to operate in a bump fire mode. 
     In this example embodiment, the chamber member engagement lever  400  includes an upper arm  410 , a central pivot member  430 , and a lower arm  450 . The upper arm  410  is connected to the central pivot member  430  and extends upwardly from the central pivot member  430 . The upper arm  410  includes a chamber member engagement hand  415  configured to engage the chamber member  260  to prevent the movement of the chamber member  260  to the unsealed position. The lower arm  450  is connected to the central pivot member  430  and extends downwardly from the central pivot member  430 . The lower arm  450  includes a connection hand  455  that facilitates a pivotal connection to actuation member  330 . The central pivot member  430  is pivotally attached to a lever support  490  attached to the housing  310  by a pivot pin  435 . The upper arm  410 , the central pivot member  430 , and the lower arm  450  of the chamber member engagement lever  400  are thus pivotally connected to the actuation member  330  and the movement of the chamber member engagement lever  400  is thus controlled by the actuation member  330  and the chamber member retaining assembly  300  under control of the controller of the tool  100 . It should be appreciated that the pivot point for the chamber member engagement lever can vary in accordance with the present disclosure. It should also be appreciated that the configuration (including the shape and/or size) of the chamber member engagement lever (including the upper arm, the central pivot member, and/or the lower arm) can vary in accordance with the present disclosure. 
       FIGS.  2 A,  2 B,  2 C, and  2 D  show the tool  100  in a rest state with the chamber member  260  in an unsealed position, the piston  220  in a fully retracted position, and the chamber member retaining assembly  300  in an inactive state. In this example embodiment, the chamber member retaining assembly  300  includes a rubber bumper  370  that provides damping behind the electromagnet  360 . This allows for an amount of compression due to the gas pressure on the actuation member  330 , allows for adjustment of the stroke of the actuation member  330 , and allows for accommodations of material thickness of the housing  310  of the chamber member retaining assembly  300 . In this example embodiment, the chamber member retaining assembly  300  includes a biasing member such as spring  380  biases the actuation member  330  to the unretained position as shown in  FIGS.  2 C and  2 D . 
       FIGS.  3 A,  3 B, and  3 C  show the tool  100  in a ready to fire state with the chamber member  260  in a sealed position, the piston  220  in a fully retracted position, and the chamber member retaining assembly  300  in the inactive state. 
       FIGS.  4 A,  4 B, and  4 C  show the tool  100  in a fired state with the chamber member  260  in the sealed position, the piston  220  in a partially driven position, and the chamber member retaining assembly  300  in an active state with actuation member  330  in a retained position (against the bias of the spring  380 ), the electromagnet  360  energized and retaining the actuation member  330  in the retained position, and the chamber member engagement lever  400  positioned to engage the chamber member  260 . In this state, the actuation member  330  has caused the lower arm  450  of the chamber member engagement lever  400  to move toward the electromagnet  360 , the entire chamber member engagement lever  400  to pivot about the pivot pin  435 , and the upper arm  410  of the chamber member engagement lever  400  to pivot inwardly such that the chamber member engagement hand  415  of the chamber member engagement lever  400  can engage or be engaged by the chamber member  260  to prevent the chamber member  260  from moving to its unsealed position. 
       FIGS.  5 A,  5 B, and  5 C  show the tool  100  in a fired state with the chamber member  260  in the sealed position, the piston  220  in fully driven and starting to move back toward its retracted position, and the chamber member retaining assembly  300  in the active state with actuation member  330  in a retained position, the electromagnet  360  energized and retaining the actuation member  330  in the retained position, and the chamber member engagement hand  415  of the chamber member engagement lever  400  positioned to engage or be engaged by the chamber member  260 . 
       FIGS.  6 A,  6 B, and  6 C  show the tool  100  in a fired state with the chamber member  260  starting to move from the sealed position, the piston  220  moving back toward the fully retracted position, and the chamber member retaining assembly  300  in the active state with actuation member  330  in the retained position, the electromagnet  360  energized and retaining the actuation member  330  in the retained position, and the chamber member engagement hand  415  of the chamber member engagement lever  400  engaging or being engaged by the chamber member  260  to prevent further movement of the chamber member  260  until the piston  220  returns to its fully retracted position. After piston  220  has returned to its fully retracted position, the chamber member retaining assembly  300  will return to its inactive state such as shown in  FIGS.  2 A,  2 B,  2 C and  2 D . To do so, the controller will cause the electromagnet  360  to be de-energized and thus release the actuation member  330  such that the spring  380  will cause the actuation member to return to its un-retained position. This will cause the lower arm  450  of the chamber member engagement lever  400  to move away from the electromagnet  360 , the entire chamber member engagement lever  400  to pivot back about the pivot pin  435 , and the upper arm  410  of the chamber member engagement lever  400  to pivot outwardly such that the chamber member engagement hand  415  of the chamber member engagement lever  400  is no longer in position to engage or be engaged by the chamber member  260  and thus allow the chamber member  260  to move to its unsealed position. 
       FIGS.  7 A,  7 B, and  7 C  are fragmentary partial cross-sectional views of certain components of another example embodiment of a combustion-powered fastener-driving tool  1100  of the present disclosure, wherein the chamber member retaining assembly  1300  does not include a chamber member engagement lever  400  and the engagement of the chamber member  1260  is directly by the actuation member  1330 . In this example embodiment, the chamber member retaining assembly  1300  can include a solenoid or gas assisted actuation member  1330  and may include an electromagnet  1360  that holds the actuation member  1330  in a retained position. The tool  1100  causes the actuation member  1330  to move from an unretained position ( FIG.  7 C ) to a retained position ( FIGS.  7 A and  7 B ). The controller (not shown) of the tool  1100  energizes the electromagnet  1360  to maintain the actuation member  1330  in the retained position ( FIGS.  7 A and  7 B ). In this embodiment, the actuation member  1330  directly prevents the chamber member  1260  from moving toward its unsealed position from its sealed position when the actuation member  1330  is in its unretained position ( FIG.  7 C ). This operates in a reverse manner to the above embodiment. If this embodiment includes an electromagnet  1360 , the controller can de-energize the electromagnet  1360  to cause the actuation member to engage the chamber member  1260  to prevent to give the piston  1220  time to fully return to its pre-firing position. If this embodiment includes a solenoid, the controller can energize the solenoid to cause the actuation member to engage the chamber member  1260  to prevent to give the piston  1220  time to fully return to its pre-firing position. If various such embodiments, the spring may be eliminated. 
       FIGS.  8 A and  8 B  show another example embodiment of certain components of the chamber member retaining assembly  2300  of another example combustion-powered fastener-driving tool of the present disclosure. in this example embodiment, the actuation member  2330  is integrated into the engine sleeve  2310 . In this example embodiment, the chamber member retaining assembly  2300  includes a gas assisted actuation member  2330  positioned in and movable in the engine sleeve  2310  and an electromagnet  2360  (and electric leads  2362  thereof) positioned adjacent to the actuation member  2330  and supported by the housing (not shown). The electromagnet  2360  is configured, under control of the controller (not shown) of the tool, to hold the actuation member  2330  position in a retained position shown in  FIG.  8 A . The chamber member retaining assembly  2300  further includes a gas pressure feed tube  2420  that is configured to supply gas to move the actuation member  2330  to the retained position. In certain embodiments this gas pressure feed tube  2420  is optional. The chamber member retaining assembly  2300  further includes a gas pressure inlet valve  2440  configured to enable combusted gas to move the actuation member  2330  to the retained position. The chamber member retaining assembly  2300  further includes a biasing member such as a wave spring  2380  configured to bias the actuation member  2330  to the un-retained position shown in  FIG.  8 B . The chamber member retaining assembly  2300  further includes a rubber bumper  370  that provides damping behind the electromagnet  3360 . The chamber member retaining assembly  2300  further includes a retaining ring  2450  connected to the engine sleeve  2310  and configured to limit the outward movement of the actuation member  2330 . The chamber member retaining assembly  2300  further includes one or more seals  2460  configured to provide a gas tight seal between the actuation member  2330  and the engine sleeve  2310 . The chamber member retaining assembly  2300  further includes a spring retainer such as a stainless steel washer configured to retain the wave spring  2380 . In this example embodiment, when chamber member retaining assembly  2300  is active, the actuation member  2330  is moved toward the electromagnet  2360 , and the electromagnet  2360  holds the actuation member  2330  in a retained position to prevent downward movement of the chamber member or valve sleeve  2260  as shown in  FIG.  8 A . In this example embodiment, part of the chamber member or valve sleeve  2260  moves between the actuation member  2330  and the electromagnet  2360  when chamber member retaining assembly  2300  is not active as shown in  FIG.  8 B . 
       FIGS.  9 A,  9 B, and  9 C  show another example embodiment of certain components of the chamber member retaining assembly  3300  of another example combustion-powered fastener-driving tool of the present disclosure. In this example embodiment, the actuation member  3330  is moveable toward the electromagnet  3360 , the electromagnet  3360  holds the actuation member  3330  in a position to prevent downward movement of the chamber member or valve sleeve  3260 . In this example embodiment, the chamber member retaining assembly  3300  includes a lockout bar  3400  that is configured to engage one or multiple parts of the chamber member or valve sleeve  3260  when in the retained position as shown in  9 B. 
       FIGS.  10 A and  10 B  show another example embodiment of certain components of the chamber member retaining assembly  4300  of another example combustion-powered fastener-driving tool of the present disclosure. This example embodiment is somewhat similar to the embodiment of  FIGS.  8 A and  8 B  except that the electromagnet  4360  is relocated. In this example embodiment, the electromagnet  4360  is located entirely or partially around the actuation member  4330 , but in a biased direction toward the chamber member  4260  when in the inactive state. In this example embodiment, the actuation member  4330  is integrated into the engine sleeve  4310 . In this example embodiment, the electromagnet  4360  is located around the actuation member  4330  for compactness. In this example embodiment, the actuation member  4330  is moveable relative to the electromagnet  4360 , the electromagnet  4360  holds the actuation member or piston  4330  in a position to prevent downward movement of the chamber member or valve  4260  sleeve as shown in  FIG.  11 B . This embodiment also takes advantage of a stronger magnetic field position (i.e., the actuation member  4330  operates closer to the center of the electromagnet  4360  for less drop off in force). In this example embodiment, part of the chamber member or valve sleeve  4260  moves between the actuation member  4330  and the bumper  4370  of the chamber member retaining assembly  4300  when not active as shown in  FIG.  11 A . 
       FIGS.  11 A and  11 B  show an example combustion-powered fastener-driving tool  5100  showing in the phantom boxes indicated by numerals  5200 A and  5300 B the potential locations of a chamber member retaining assembly  5300  of the present disclosure. 
       FIGS.  12 A and  12 B  show another example embodiment of certain components of the chamber member retaining assembly  6300  of another example combustion-powered fastener-driving tool of the present disclosure. In this example embodiment, the electromagnet  6360  is configured to directly engage the chamber member  6260  to maintain the chamber member in the retained position. In this example embodiment, the electromagnet  6360  holds the chamber member or valve  6260  in the retained (upper) position as shown in  FIG.  12 B , and can release the chamber member or valve  6260  into an unretained (lower) position as shown in  FIG.  12 A . This embodiment also takes advantage of a strong magnetic field position because the forces of the electromagnet  6360  directly act on the chamber member  6260 . 
     More specifically, in this example embodiment, the electromagnet  6260  is supported by a wall  6110  of the housing (not shown) of the tool in a fixed position transverse to the movement of the chamber member  6260 . This transverse position of the electromagnet  6260  maximizes the time that the electromagnet  6260  can retain the chamber member  6260  in the retained position during the piston movement. In this example embodiment, a steel magnetic or electromagnet interface plate  6262  is connected to a wall of the chamber member  6260  by two fasteners  6264  and  6266  to enhance the interaction between the chamber member  6260  and the electromagnet  6260 . Thus, the electromagnet  6260  can, under control of a controller of the tool, delay the return of the chamber member  6260  until the piston returns to its starting position. This device also semi-automates the return part of the chamber member  6260  movement under control of the controller. 
       FIGS.  13 A and  13 B  show another example embodiment of certain components of the chamber member retaining assembly  7300  of another example combustion-powered fastener-driving tool of the present disclosure. In this example embodiment, the electromagnet  7360  is configured to directly engage the chamber member  7260  to maintain the chamber member in the retained position. In this example embodiment, the electromagnet  7360  holds the chamber member or valve  7260  in the retained (upper) position as shown in  FIG.  13 B , and can release the chamber member or valve  7260  into an unretained (lower) position as shown in  FIG.  13 A . This embodiment also takes advantage of a strong magnetic field position because the forces of the electromagnet  7360  directly act on the chamber member  7260 . 
     More specifically, in this example embodiment, the electromagnet  7260  is supported by a wall  6110  of the housing (not shown) of the tool and one or more biasing members (such as the upper biasing member  7112 U and lower biasing member  7112 L) in a moveable position transverse to the movement of the chamber member  7260 . These transverse positions of the electromagnet  7260  maximize the time that the electromagnet  7260  can retain the chamber member  7260  in the retained position during the piston movement. In this example embodiment, a steel magnetic or electromagnet interface plate  7262  is connected to a wall of the chamber member  7260  by two fasteners  7264  and  7266  to enhance the interaction between the chamber member  7260  and the electromagnet  7260 . Thus, the electromagnet  7260  can, under control of a controller of the tool, delay the return of the chamber member  7260  until the piston returns to its starting position. This device also semi-automates the return part of the chamber member  7260  movement under control of the controller. 
       FIGS.  14 A and  14 B  show another example embodiment of certain components of the chamber member retaining assembly  8300  of another example combustion-powered fastener-driving tool of the present disclosure. In this example embodiment, the electromagnet  8360  is configured to directly engage the chamber member  8260  to maintain the chamber member in the retained position. In this example embodiment, the electromagnet  8360  holds the chamber member or valve  8260  in the retained (upper) position as shown in  FIG.  14 B , and can release the chamber member or valve  8260  into an unretained (lower) position as shown in  FIG.  14 A . This embodiment also takes advantage of a strong magnetic field position because the forces of the electromagnet  8360  directly act on the chamber member  8260 . 
     More specifically, in this example embodiment, the electromagnet  8260  is supported by a wall  8110  of the housing (not shown) of the tool in a fixed position transverse to the movement of the chamber member  8260 . This transverse position of the electromagnet  8360  maximizes the time that the electromagnet  8360  can retain the chamber member  8260  in the retained position during the piston movement. 
     In this example embodiment, the wall of the chamber member  8260  is configured with a step  8266  for enhancing the interaction between the chamber member  8260  and the electromagnet  8360  in the retained position as shown in  FIG.  14 B . The step  8266  can be configured in any suitable manner. A suitable spring (not shown) can be employed with this example embodiment to cause engagement or release of the chamber member  8260 . Thus, the electromagnet  8360  can, under control of a controller of the tool, delay the return of the chamber member  8260  until the piston returns to its starting position. This device also semi-automates the return part of the chamber member  8260  movement under control of the controller. 
     Various modifications to the above-described embodiments will be apparent to those skilled in the art. These modifications can be made without departing from the spirit and scope of this present subject matter and without diminishing its intended advantages. Not all of the depicted components described in this disclosure may be required, and some implementations may include additional, different, or fewer components as compared to those described herein. Variations in the arrangement and type of the components; the shapes, sizes, and materials of the components; and the manners of attachment and connections of the components may be made without departing from the spirit or scope of the claims set forth herein. Also, unless otherwise indicated, any directions referred to herein reflect the orientations of the components shown in the corresponding drawings and do not limit the scope of the present disclosure. This specification is intended to be taken as a whole and interpreted in accordance with the principles of the invention as taught herein and understood by one of ordinary skill in the art.