Patent Publication Number: US-8523035-B2

Title: Fastener driving apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present disclosure is a continuation in part of the U.S. Utility patent application Ser. No. 12/616,227 filed on Nov. 11, 2009 now U.S. Pat. No. 7,793,811, the disclosure of which is incorporated by reference. 
    
    
     FIELD OF THE DISCLOSURE 
     The present disclosure generally relates to apparatuses for driving fasteners into workpiece, and more particularly, to a fastener driving apparatus used as a portable hand tool. 
     BACKGROUND OF THE DISCLOSURE 
     A fastener driving apparatus is a tool used to drive fasteners, such as nails and staples into a workpiece. The fastener driving apparatus may be used for various operations, such as making wooden walls, positioning hang sheathings over the wooden walls, fastening baseboards over a lower portion of an interior wall and crown molding. 
     There are various fastener driving apparatuses known in the art. These fastener driving apparatuses operate utilize various means and mechanisms known in the art for their operation. For example, the prior art fastener driving apparatuses may be operated based on compressed air generated by an air compressor, fuel cells, electrical energy, a flywheel mechanism, and the like. 
     Although these fastener driving apparatuses are useful in driving fasteners into a workpiece, such apparatuses have numerous limitations. For example, the fastener driving apparatuses operated on the compressed air are bulkier, non-portable and costlier due to requirement of the air compressor and associated air-lines. Fastener driving apparatuses operated on the fuel cells are complicated in design and are expensive. Further, the apparatuses that are operated on fuel cells require both electrical energy and fuel. More specifically, a spark source required for combustion of the fuel derives its energy from various electric energy sources, such as batteries and the like. Furthermore, the fastener driving apparatuses operated on fuel cells generate a loud report and release combustion products. 
     Further, the fastener driving apparatuses operated on electrical energy are limited to fasteners of relatively short lengths, such as one inch or less. Further, fastener driving apparatuses operated on electrical energy generate a high reactionary force. Therefore, a prolonged use of such a fastener driving apparatus requires user to expend a substantial amount of effort in order to resist the reactionary force, which makes the utilization of the fastener driving apparatuses a tiring job. Further, the reactionary force may cause inaccurate driving of the fasteners into the workpiece in the subsequent drives done by the apparatus. The high reactionary force is typically a consequence of the comparatively longer time taken by such fastener driving apparatuses to drive the fasteners into the workpiece. Therefore, the fastener driving apparatuses operated on electrical energy are limited in their repetition rate because of the long time it takes to drive a fastener into the workpiece. 
     Moreover, although fastener driving apparatuses operated by flywheels are capable of driving the fasteners of longer sizes very quickly, these apparatuses are bulkier in size and weight. Further, drive mechanisms of these apparatuses are complicated in design, which results in a high cost of such apparatuses. Additionally, the fastener driving apparatuses operated by flywheel also generate high reactionary force. 
     Additionally, a majority of the above-mentioned fastener driving apparatuses includes a striker mechanism for driving the fasteners into the workpiece. The striker mechanism may be retracted to its initial position by means of various retracting mechanisms, such as a spring, a bungee and the like. Although such striker mechanisms are useful in driving the fasteners into the workpiece, these retracting mechanisms have numerous limitations. For example, the retracting mechanisms, due to inertia associated therewith, consume significant amounts of drive energy of the apparatuses and may prevent the fasteners from being fully driven into the workpiece. Accordingly, these retracting mechanisms may require an increase in power to drive the fasteners into the workpiece. Further, these retracting mechanisms reduce the drive speed of the fastener driving apparatuses. The existing retracting mechanisms may also bias the striker mechanism towards the workpiece, causing a safety hazard for the user. 
     Based on the foregoing, there exists a need for a fastener driving apparatus employing a retracting mechanism that precludes consumption of drive energy of the fastener driving apparatus and facilitates a fastener to be fully driven into a workpiece. The fastener driving apparatus should have the retracting mechanism that is capable of precluding reduction of drive speed of the fastener driving apparatus and that is capable of providing safety to a user. Further, the fastener driving apparatus should be portable in nature and should be capable of driving the fastener into the workpiece in a single stroke. Moreover, the fastener driving apparatus should provide a minimized reactionary force while operating the fastener driving apparatus. 
     SUMMARY OF THE DISCLOSURE 
     In view of the foregoing disadvantages inherent in the prior art, the general purpose of the present disclosure is to provide a fastener driving apparatus that is configured to include all the advantages of the prior art, and to overcome the drawbacks inherent therein. 
     Accordingly, an object of the present disclosure is to provide a fastener driving apparatus employing a retracting mechanism that precludes consumption of drive energy and reduction in drive speed of the fastener driving apparatus and facilitates a fastener being fully driven into a workpiece. 
     Another object of the present disclosure is to provide a fastener driving apparatus that is portable in nature and is capable of providing more safety to a user. 
     Yet another object of the present disclosure is to provide a fastener driving apparatus that is capable of driving a fastener into a workpiece in a single stroke and is capable of increasing efficiency of the fastener driving apparatus. 
     Still another object of the present disclosure is to provide a fastener driving apparatus that is capable of minimizing reactionary force generated during fastener driving operation. 
     In light of the above objects, a fastener driving apparatus for driving a fastener into a workpiece is disclosed. The fastener driving apparatus includes a power source, a control circuit, a motor, a first hollow guide member having a first volumetric capacity, a first piston, a linear motion converter, a second hollow guide member having a second volumetric capacity smaller than the first volumetric capacity, a second piston, an anvil, a valve arrangement and at least one sensor. The control circuit is electrically coupled to the power source. The motor is electrically coupled to the power source and is responsive to the control circuit. 
     The first piston is reciprocally movable within the first hollow guide member to execute a compression stroke and a return stroke. The first piston is configured to define a gas chamber within the first hollow guide member. The gas chamber is capable of accommodating gas therein. The first piston is operationally coupled to the linear motion converter. The linear motion converter is driven by the motor. The linear motion converter is configured to reciprocally move the first piston within the first hollow guide member. The first hollow guide member is pneumatically connected to the second hollow guide member. The second piston is reciprocally movable within the second hollow guide member. The anvil is coupled to the second piston. The anvil is capable of striking the fastener to drive the fastener into the workpiece. The valve arrangement is operationally disposed between the first hollow guide member and the second hollow guide member for pneumatically connecting the first hollow guide member and the second hollow guide member. The valve arrangement is configured to define a gas passageway between the first hollow guide member and the second hollow guide member in an open position. Further, the valve arrangement is also configured to block the gas passageway in a closed position. The at least one sensor is communicably coupled to the control circuit. The at least one sensor is configured to detect at least one position of the first piston in the first hollow guide member and communicate the detected position of the first piston to the control circuit. The control circuit is configured to stop an operation cycle of driving the fastener into the workpiece based on the detected position by the at least one sensor. 
     The control circuit is configured to actuate the valve arrangement to configure one of the open position and the closed position based on the detected position of the first piston. 
     During the compression stroke, the first piston is configured to move towards a top dead center of the first hollow guide member thereby compressing the gas in the gas chamber to a predetermined pressure. Further, the valve arrangement assumes the open position at the predetermined pressure for communicating the compressed gas to the second hollow guide member. The compressed gas communicated to the second hollow guide member causes the second piston to move linearly and enables the anvil to drive the fastener into the workpiece. During the return stroke, the valve arrangement assumes the closed position and the first piston is configured to move towards a bottom dead center of the first hollow guide member thereby creating a vacuum in the first hollow guide member between the top dead center of the first hollow guide member and the first piston. At a predetermined position of the first piston during the return stroke, the valve arrangement assumes the open position. The open position of the valve arrangement causes the vacuum created in the first hollow guide member to communicate to the second hollow guide member, thereby causing the second piston and the anvil to retract to initial positions of the second piston and the anvil. 
     This aspect together with other aspects of the present disclosure, along with the various features of novelty that characterize the present disclosure, are pointed out with particularity in the claims annexed hereto and form a part of this present disclosure. For a better understanding of the present disclosure, its operating advantages, and the specific objects attained by its uses, reference should be made to the accompanying drawings and descriptive matter in which there are illustrated exemplary embodiments of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The advantages and features of the present disclosure will become better understood with reference to the following detailed description and claims taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  illustrates a longitudinal cross-sectional view of a fastener driving apparatus depicting an initial stage of an operation cycle of driving a fastener from the fastener driving apparatus, in accordance with an embodiment of the present disclosure; 
         FIG. 2  illustrates a longitudinal cross-sectional view of the fastener driving apparatus depicting compression of gas in a gas chamber to a predetermined pressure, in accordance with an embodiment of the present disclosure; 
         FIGS. 3 and 4  illustrate longitudinal cross-sectional views of the fastener driving apparatus depicting rapidly expanding gas driving a second piston and an anvil in a downward direction for driving the fastener into a workpiece, in accordance with an embodiment of the present disclosure; 
         FIG. 5  illustrates a longitudinal cross-sectional view of the fastener driving apparatus depicting a closed position of a valve arrangement and a first piston performing a return stroke, in accordance with an embodiment of the present disclosure; 
         FIG. 6  illustrates a longitudinal cross-sectional view of the fastener driving apparatus depicting the closed position of the valve arrangement and the first piston generating vacuum in a first hollow guide member, in accordance with an embodiment of the present disclosure; 
         FIG. 7  illustrates a longitudinal cross-sectional view of the fastener driving apparatus depicting an open position of the valve arrangement communicating the vacuum created in the first hollow guide member to the second hollow guide member for retracting the second piston and the anvil to their initial positions, in accordance with an embodiment of the present disclosure; 
         FIG. 8  illustrates a longitudinal cross-sectional view of the fastener driving apparatus depicting vacuum retracted initial positions of the second hollow guide member and the anvil, in accordance with an embodiment of the present disclosure; 
         FIG. 9  illustrates a longitudinal cross-sectional view of the fastener driving apparatus, in accordance with another embodiment of the present disclosure; and 
         FIG. 10  illustrates a longitudinal cross-sectional view of the fastener driving apparatus, in accordance with yet another embodiment of the present disclosure; and 
         FIG. 11  illustrates a front view of a fastener driving apparatus, in accordance with still another embodiment of the present disclosure; and 
         FIG. 12  illustrates a cross-sectional view of a first hollow guide member and a second hollow guide member of the fastener driving apparatus of  FIG. 11  along an axis AA′, in accordance with an embodiment of the present disclosure, and  FIG. 13  shows a view of a fastener driving apparatus wherein a second hollow guide member is disposed within a first hollow guide member, in accordance with an embodiment of the present disclosure. 
     
    
    
     Like reference numerals refer to like parts throughout the description of several views of the drawings. 
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     The exemplary embodiments described herein detail for illustrative purposes are subject to many variations in structure and design. It should be emphasized, however, that the present disclosure is not limited to a particular fastener driving apparatus as shown and described. It is understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient, but these are intended to cover the application or implementation without departing from the spirit or scope of the claims of the present disclosure. 
     The terms “first,” “second,” and the like, herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another, and the terms “a” and “an” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. 
     The present disclosure provides a fastener driving apparatus for driving fasteners into a workpiece. As used herein, the term “fastener” refers to, but is not limited to, a nail, a staple, and the like. Further, the term “gas” as used herein, refers to, but is not limited to atmospheric air. Herein, the terms “gas” and “air” are interchangeably used throughout the description. Furthermore, an ‘operation cycle’ of driving a fastener refers to steps involved in driving the fastener completely into a workpiece from the fastener driving apparatus. The operation cycle may also be termed as a combination of a “compression stroke” and a “return stroke” of a first piston. 
     The fastener driving apparatus, disclosed in the present disclosure, includes a power source, a control circuit, a motor, a first hollow guide member, a first piston, a linear motion converter, a second hollow guide member, a second piston, an anvil, a valve arrangement and at least one sensor. The first piston is reciprocally movable within the first hollow guide member to execute a compression stroke and a return stroke. The first piston executes the compression stroke and return stroke with help of the motor and the linear motion converter. Operation of the motor is further controlled by the control circuit. The valve arrangement is configured to pneumatically connect the first hollow guide member and the second hollow guide member. The valve arrangement assumes one of an open position and a closed position during an operation cycle of driving a fastener into the workpiece. In the open position of the valve arrangement, the valve arrangement defines a gas passageway allowing any communication of gas between the first hollow guide member and the second hollow guide member. Further, in the closed position of the valve arrangement, the gas passageway is blocked to stop any communication of gas between the first and second hollow guide members. 
     During the compression stroke of the first piston in the first hollow guide member, the first piston is configured to move towards a top dead center of the first hollow guide member, thereby compressing gas in a gas chamber formed above an upper face of the first piston in the first hollow guide member to a predetermined pressure or a predetermined stroke of the first piston. Further, the valve arrangement assumes the open position at the predetermined pressure or the predetermined stroke and allows the compressed gas to communicate to the second hollow guide member. The compressed gas communicated to the second hollow guide member causes the second piston disposed in the second hollow guide member to move linearly. The anvil is coupled to the second piston. The anvil also moves linearly with the movement of the second piston and strikes the fastener thereby driving the fastener into the workpiece. 
     During the return stroke of the first piston in the first hollow guide member, the valve arrangement assumes the closed position, and the first piston is configured to move towards a bottom dead center of the first hollow guide member. Movement of the first piston towards the bottom dead center of the first hollow guide member creates a vacuum between the top dead center of the first hollow guide member and the first piston. When the first piston reaches a predetermined position in the first hollow guide member during the return stroke, the valve arrangement assumes the open position. The open position of the valve arrangement causes the vacuum created in the first hollow guide member to communicate to the second hollow guide member and thereby causes the second piston and the anvil to retract to their initial positions. Further, the fastener driving apparatus becomes ready for driving a next fastener from the fastener driving apparatus. The working mechanism and exemplary configurations of the fastener driving apparatus of the present disclosure is described herein in conjunction with  FIGS. 1 to 8 . 
     Referring to  FIGS. 1 to 8 , longitudinal cross-sectional views of a fastener driving apparatus  10  are illustrated. An operation cycle for driving a fastener  1000  from the fastener driving apparatus  10  will be described in conjunction with  FIGS. 1 to 8 . Referring particularly to  FIG. 1 , the fastener driving apparatus  10  includes a power source  100 , a control circuit  200 , a motor  300 , a first hollow guide member  400 , a first piston  500 , a linear motion converter  600 , a second hollow guide member  700 , a second piston  800 , an anvil  900 , a valve arrangement  2000  and a pair of sensors  3000 . 
     The power source  100  is configured to provide power for working of the fastener driving apparatus  10 . The power source  100  may be a rechargeable battery, a battery pack, or any other power source such as an AC power supply. The power source  100  is electrically coupled to the control circuit  200 . The power source  100  may be electrically coupled to the control circuit  200  by means of wired, wireless means or any other mechanism known in the art. 
     The control circuit  200  is configured to actuate the power source  100  for initiating the operation cycle for driving the fastener  1000 . Similarly, the control circuit  200  is configured to deactivate the power source  100  after completion of the operation cycle. The control circuit  200  may be any of the various control circuits known in the art. In one embodiment of the present disclosure, the control circuit  200  may include a microprocessor, plurality of high power switching elements and control circuit inputs. Further, in another embodiment of the present disclosure, the control circuit  200  may include a limit switch coupled to cams and linkages. Further, the control circuit  200  may be configured to receive input signals from timers, sensors, and the like. Furthermore, the control circuit  200  may also be configured to provide an output signal to an interface, a LED, and the like. Moreover, in one embodiment of the present disclosure, the control circuit  200  may include at least one low battery indicator, a pulse control of motor power, a plurality of communication ports, a status display indicator, a fault lockout protection controller, and the like. The control circuit  200  is configured to control the working of the motor  300  by activating or deactivating the power source  100 . 
     The motor  300  is electrically connected to the power source  100 . The motor  300  may be electrically connected to the power source  100  by means of various means and mechanisms, such as an electric wire or a magnetic coupling. The motor  300  is further responsive to the control circuit  200 . More specifically, the control circuit  200  is configured to direct the power from the power source  100  to the motor  300  for initiating the operation cycle of driving the fastener such as the fastener  1000  into the workpiece. Similarly, the control circuit  200  is configured to disconnect the power from the power source  100  to the motor  300  after completion of the operation cycle. In one embodiment of the present disclosure, the motor  300  may include a dynamic braking system for halting the rotations of the motor  300 . Further, in one embodiment of the present disclosure, the fastener driving apparatus  10  may include a switch  302  for directing and disconnecting the power from the power source  100  to the motor  300  through the control circuit  200 . More specifically, the switch  302  may be controlled by the control circuit  200  for appropriately actuating the starting and stopping of the operation cycle of fastener drive apparatus  10 . The switch  302  may be an ON/OFF switch. The motor  300  is configured to impart a reciprocating movement to the first piston  500  in the first hollow guide member  400 . The motor  300  provides the reciprocating movement to the first piston  500  through the linear motion converter  600 . The linear motion converter  600  is configured to convert the rotational motion of the motor  300  into linear reciprocating movement of the first piston  500  within the first hollow guide member  400 . 
     The linear motion converter  600  is driven by the motor  300 . Without departing from the scope of the present disclosure, the linear motion converter  600  may be driven by the motor  300  through a speed reduction mechanism  4000 . The speed reduction mechanism  4000  is configured to reduce the revolutions per minute (rpm) of the motor  300  depending upon a required speed of reciprocating movement of the first piston  500 . In one embodiment of the present disclosure, the speed reduction mechanism  4000  may be a gear reduction mechanism. The speed reduction mechanism  4000  is connected to the linear motion converter  600  through a shaft  4002 . In the present embodiment of the present disclosure, the linear motion converter  600  is shown as a crankshaft mechanism. Herein, the linear motion converter  600  includes a crankshaft  602  and a connecting rod  604  connected to the crankshaft  602 . 
     The crankshaft  602  includes a first end portion  606 , a middle portion  608  and a second end portion  610 . The first end portion  606  of the crankshaft  602  is connected to a body portion  1100  of the fastener driving apparatus  10  and the second end portion  610  is coupled to the shaft  4002  that is coupled the speed reduction mechanism  4000 . The body portion  1100  refers to a structural framework on which various components of the fastener driving apparatus  10  may be disposed. Further, the speed reduction mechanism  4000  is coupled to the second end portion  610  of the crankshaft  602  for transmitting the rotational motion generated by the motor  300  to the crankshaft  602  and the connecting rod  604 . The connecting rod  604  is connected to the middle portion  608  of the crankshaft  602 . An upper end portion  612  of the connecting rod  604  is connected to the first piston  500 . In one embodiment of the present disclosure, the upper end portion  612  of the connecting rod  604  is connected to the first piston  500  by means of a piston pin (not shown). Further, a lower end portion  614  of the connecting rod is connected to the middle portion  608  of the crankshaft  602 . The lower end portion  614  of the connecting rod  604  may be connected to the middle portion  608  of the crankshaft  602  by means of various means and mechanisms, such as a nut and a bolt, a rivet, and the like. 
     Although, in the embodiment of the present disclosure shown in  FIG. 1 , the linear motion converter  600  is described in accordance with the crankshaft mechanism, the linear motion converter  600  may include other arrangements, such as a slider crank arrangement, a rack and pinion arrangement, a lead screw arrangement, and the like. 
     Further, the first hollow guide member  400  of the fastener driving apparatus  10  includes an upper end portion  402 , a lower end portion  404  and a cylinder end cap  406 . The cylinder end cap  406  is configured on the upper end portion  402 . The cylinder end cap  406  further includes an opening  408  configured thereon. The first hollow guide member  400  may have a volume that is proportional to the amount of energy required for driving the fastener  1000  into the workpiece. In one embodiment of the present disclosure, for driving an 18 gage fastener, the volume of the first hollow guide member  400  may be around 8 to 12 cubic inches at standard atmospheric temperature and pressure conditions. 
     The first piston  500  is disposed within the first hollow guide member  400 . The first piston  500  includes an upper face  502 , a lower face  504 , a body portion  506  and a check valve  508 . Further, the first piston  500  is configured to define a gas chamber  510  within the first hollow guide member  400 . More specifically, the first piston  500  is configured to define the gas chamber  510  between the upper face  502  of the first piston  500  and the cylinder end cap  406  of the first hollow guide member  400 . The gas chamber  510  is capable of accommodating gas therein. The first piston  500  is configured to reciprocally move within the first hollow guide member  400  to execute the compression stroke and the return stroke. During the compression stroke, the first piston  500  is configured to move from the lower end portion  404 , i.e., Bottom Dead Center (BDC) of the first hollow guide member  400  to the upper end portion  402 , i.e., Top Dead Center (TDC) of the first hollow guide member  400 . Further, during the return stroke, the first piston  500  is configured to move from the upper end portion  402  (TDC) of the first hollow guide member  400  to the lower end portion  404  (BDC) of the first hollow guide member  400 . 
     Before starting the compression stroke, the gas chamber  510  may have a volume of the gas stored therein, which is proportional to the amount of energy required for driving the fastener  1000  into the workpiece. In one specific embodiment of the present disclosure, for driving the 18 gage fastener, the gas chamber  510  may have a volume of about 9 to 11 cubic inches, before starting the compression stroke at standard atmospheric pressure and temperature conditions. More specifically, in this embodiment, for driving the 18 gage fastener, the gas chamber  510  may have a volume of about 10 cubic inches at standard atmospheric pressure and temperature conditions. The gas stored in the gas chamber  510  is prevented from flowing towards the lower face  504  of the first piston  500 , as the check valve  508  assumes the closed position. 
     The check valve  508  is disposed in the body portion  506 . More specifically, the check valve  508  may be disposed on a side portion of the body portion  506 . However, the present disclosure is not limited to a particular disposition of the check valve  508  within the body portion  506 . The check valve  508  is a unidirectional valve configured to allow atmospheric air to flow into the first hollow guide member  400  in an open position. 
     As shown in  FIG. 1 , the fastener driving apparatus  10  includes a vertical actuation member  5000  for the actuation of the check valve  508 . The vertical actuation member  5000  may be disposed on the body portion  1100  of the fastener driving apparatus  10 . More specifically, the vertical actuation member  5000  may be disposed adjacent to the connection of the first end portion  606  of the crankshaft  602  to the body portion  1100 . The vertical actuation member  5000  includes a first end portion  5002  and a second end portion  5004 . The first end portion  5002  of the vertical actuation member  5000  is connected to the body portion  1100 . The second end portion  5004  is configured to actuate the check valve  508  to configure the open position of the check valve  508 , when the first piston  500  reaches the lower end portion  404  of the first hollow guide member  400 . In one embodiment, the check valve  508  may be configured such that when the crankshaft  602  rotates till 30 degrees from a starting point of the crankshaft  602 , the gas chamber  510  is replenished with the atmospheric air. Herein, the starting point of the crankshaft  602  refers that when the crankshaft  602  is at the starting point, the first piston  500  is at the BDC of the first hollow guide member  400 . 
     In another embodiment, instead of using the check valve  508 , the diameter of the lower end portion  404  of the first hollow guide member  400  may be larger than remaining portion of the first hollow guide member  400 . Further, the first piston  500  may include O rings formed on lateral surfaces thereof. When the first piston  500  moves towards the TDC of the first hollow guide member  400  from the BDC of the first hollow guide member  400 , there are inlets formed between either sides of the first piston  500  and the lower end portion  404  of the first hollow guide member  400 . The atmospheric air enters the gas chamber  510  through the inlets. Further, during the movement of the first piston  500  towards the TDC, when the O rings go past the lower end portion  404 , i.e., an enlarged section of the first hollow guide member  400 , the inlets are closed as O rings come in physical contact with walls of the remaining portion of the first hollow guide member  400 . In one embodiment, positioning of the O rings on the first piston  500  and the dimensions of the lower end portion  404  may be such that with the rotation of the crankshaft  602  by 30 degrees from the starting point of the crankshaft  602 , the gas chamber  510  is replenished with the atmospheric air. 
     Further, the fastener driving apparatus  10  may include at least one sensor such as a first sensor  3002  and a second sensor  3004 , disposed on the first hollow guide member  400 . More specifically, the first sensor  3002  is disposed on the upper end portion  402  of the first hollow guide member  400  and the second sensor  3004  is disposed on the lower end portion  404  of the first hollow guide member  400 . The sensors  3002  and  3004  are communicably coupled to the control circuit  200 . The sensors  3002  and  3004  are communicably coupled to the control circuit  200  by means of various wired or wireless means known to the person skilled in the art. Further, the sensors  3002  and  3004  are configured to detect at least one position of the first piston  500 . More specifically, the first sensor  3002  is configured to detect position of the first piston  500  when the first piston  500  approaches the TDC of the first hollow guide member  400 . Similarly, the second sensor  3004  is configured to detect position of the first piston  500  when the first piston  500  approaches the BDC of the first hollow guide member  400 . Further, the first sensor  3002  and the second sensor  3004  are configured to communicate the detected position of the first piston  500  to the control circuit  200 . Based on the detected position by the sensor  3004 , the control circuit  200  is configured to disconnect the power source  100  from the motor  300  to stop the operation cycle. In one embodiment, the control circuit  200  is configured to actuate the valve arrangement  2000  to configure one of the open position and the closed position based on the detected position of the first piston  500 . 
     The sensors  3002  and  3004  may be selected from, but not limited to, one of or a combination of a limit switch, a Hall Effect sensor, a photo sensor, a reed switch, a timer and a current or voltage sensor without departing from the scope of the disclosure. The sensors  3002  and  3004  may also include hall sensors combined with at least one magnet. The sensors  3002  and  3004  are shown as disposed on the upper end portion  402  and the lower end portion  404  in  FIG. 1 , however it should not be considered limiting. In another embodiment, the pair of sensors  3000  may also be disposed on the first piston  500 . 
     Further, the valve arrangement  2000  is operationally disposed between the first hollow guide member  400  and the second hollow guide member  700 . The valve arrangement  2000  is disposed in a manner such that the valve arrangement  2000  acts as a medium for communicating gas between the first hollow guide member  400  and the second hollow guide member  700 . The valve arrangement  2000  is configured to assume one of the open position and the closed position. The valve arrangement  2000  is configured to define a gas passageway  2005  between the first hollow guide member  400  and the second hollow guide member  700  in the open position. In one embodiment of the present disclosure, a volume of the gas passageway  2005  is less than 15% of the volume of the first hollow guide member  400 . The volume of the gas passageway  2005  may be less than 15% of the volume of the first hollow guide member  400  for minimizing losses related to accumulation of the gas in the gas passageway  2005 , and thereby increasing the efficiency of the fastener driving apparatus  10 . The valve arrangement  2000  is configured to block the gas passageway  2005  in the closed position of the valve arrangement  2000 . 
     The valve arrangement  2000  includes a valve spool  2006  and a valve body  2008 . The valve spool  2006  is slidably disposed in the valve body  2008 . The valve spool  2006  may include an elongated groove  2010  configured on a central portion thereof. Further, in one embodiment of the present disclosure, the valve spool  2006  may be held in position by means of a spring (not shown) and pressure balance between two o-rings (not shown). The valve body  2008  may further include an opening  2012  configured thereon. In the closed position of the valve arrangement  2000 , the opening  2012  is configured to receive gas from the elongated groove  2010  and pass the gas to atmosphere. 
     The valve arrangement  2000  assumes the open position and the closed position by utilizing a coupling member  2050 . The coupling member  2050  is operably coupled between the motor  300  and the valve arrangement  2000 . In one embodiment, the coupling member  2050  may be operatively connected between the speed reduction mechanism  4000  and the valve spool  2006 . The coupling member  2050  is configured such that it imparts a linear movement to the valve spool  2006  in response to the rotation movement of the motor  300  for covering/uncovering the opening  408 , thereby defining the gas passageway  2005 . Accordingly, the valve arrangement  2000  may assume the open position or the closed position. 
     In one embodiment, the coupling member  2050  may include a cam  2052 , a pushrod  2054 , a rocker arm  2056  and a cam guide  2066 . In one form, the cam  2052  may be coupled to the shaft  4002  that is coupled to the speed reduction mechanism  4000 , so that the cam  2052  may rotate about axis of the shaft  4002 . The pushrod  2054  operably couples the cam  2052  to the rocker arm  2056 . The rocker arm  2056  has a first arm  2058  and a second arm  2060 . The first arm  2058  is connected to a rear portion of the valve spool  2006  and the second arm  2060  is connected to the pushrod  2054 . The first arm  2058  and the second arm  2060  are pivotally connected to each other at a pivot point  2062 . Further, the second arm  2060  is also pivotally connected to the pushrod  2054 . The cam guide  2066  guides the upward and downward movement of the pushrod  2054 . 
     The cam  2052  has a suitable profile such that with the rotation of the cam  2052 , the pushrod  2054  is moved towards and away from the shaft  4002  and acts on the rocker arm  2056  such that the rocker arm  2056  actuates the valve spool  2006  for the valve arrangement  2000  to assume the open position and the closed position. In one form, the cam  2052  has a profile having two rises and two falls in 360 degrees rotation about the shaft  4002  in one operation cycle. When the pushrod  2054  is pushed away from the shaft  4002 , the pushrod  2054  pushes the second arm  2060  to rotate in a clockwise manner about the pivot point  2062 . Due to the clockwise rotation of the second arm  2060  about the pivot point  2062 , the first arm  2058  pulls the valve spool  2006  away from the opening  408  and compresses a valve spool return spring  2064 . Accordingly, the valve spool  2006  unblocks the opening  408 , thereby causing the valve arrangement  2000  to assume the open position. 
     Further, with the rotation of the cam  2052  and due to a fall profile of the cam  2052 , the pushrod  2054  comes towards the shaft  4002 , thereby causing the second arm  2060  to make a counter clockwise rotation about the pivot point  2062 . Further, the first arm  2058  moves away from the valve spool return spring  2064 , which is in compressed state. The release of the valve spool return spring  2064  further helps the valve spool  2006  to come toward the opening  408  and thereby closes the opening  408 . Accordingly, the valve arrangement  2000  assumes the closed position. In one embodiment, the valve spool  2006  includes a slot  2070  configured in the rear portion of the valve spool  2006 . In this embodiment, the valve spool return spring  2064  which is in compressed state when the valve arrangement  2000  is in open position, expands and pushes the valve spool  2006  to cover the opening  408 . In this embodiment, the first arm  2058  moves within the slot  2070 . The slot  2070  provides the valve spool  2006  for lost motion control as the valve spool  2006  opens at high speed in relation to speed of the rocker arm  2056 . More specifically, the slot  2070  allows the valve spool  2006  to open rapidly after the valve spool  2006  is tripped by the rocker arm  2056 . 
     In one embodiment of the present disclosure, the valve arrangement  2000  has a flow coefficient (Cv) greater than one. The flow coefficient describes the relationship between the pressure drop across a valve and corresponding flow rate. A valve arrangement having higher flow coefficient provides a larger flow of gas through valve arrangement at a given pressure drop. Further, the valve arrangement  2000  is configured as a snap acting valve. The snap acting valve may be defined as a valve that has an opening time of less than 20 milliseconds. Herein, the opening time of the valve represents a time involved in opening of the valve from the initial closed position to a position at which about 70 percent of full flow of the compressed gas in the valve may be achieved. 
     The second hollow guide member  700  is pneumatically connected to the first hollow guide member  400  via the valve arrangement  2000 . The second hollow guide member  700  may be positioned parallel to the first hollow guide member  400 , and may be positioned outside the first hollow guide member  400  or contained within the first hollow guide member  400 . The second hollow guide member  700  acts as an expansion hollow guide member, where the compressed gas within the first hollow guide member  400  is allowed to expand when the valve arrangement  2000  assumes the open position after the compression stroke of the first piston  500 . The second hollow guide member  700  includes a proximal end portion  702 , a distal end portion  704  and a top plate  706 . Further, a bumper  708  may be disposed in the distal end portion  704  of the second hollow guide member  700 . The bumper  708  is configured to absorb excess energy at the end of an expansion stroke, i.e., when the anvil  900  strikes the fastener  1000 . The bumper  708  may be composed of various impact energy absorbing materials, such as an elastomer, and the like. 
     The second piston  800  is disposed within the second hollow guide member  700 . The second piston  800  is configured to reciprocally move within the second hollow guide member  700 . The anvil  900  is coupled to a rear face  804  of the second piston  800  by means of a connector  806  coupled to the rear face  804 . The connector  806  may be coupled to the rear face  804  by means of various means and mechanisms, such as a nut and bolt arrangement, a rivet, welding and other arrangements known in the art. The anvil  900  may be secured in a central groove (not shown) of the connector  806 , by use of suitable means, such as a nut and bolt arrangement, a rivet, welding, and the like known in the art. Further, in one embodiment of the present disclosure, the connector  806  and the anvil  900  may also be configured as a single unit. 
     The anvil  900  is configured to reciprocally move along with the second piston  800 . The anvil  900  is capable of linearly moving within the second hollow guide member  700  and a fastener guide  1010 . Further, the anvil  900  is capable of striking the fastener  1000  to drive the fastener  1000  into the workpiece. The fastener guide  1010  is configured to receive the fastener  1000  from a fastener feeder  1020 . 
     Further, in one embodiment of the present disclosure, the second hollow guide member  700  may further include a second bumper disposed on the proximal end portion  702  of the second hollow guide member  700  for absorbing excess energy when the second piston  800  is retracted to its initial position. Furthermore, in one embodiment of the present disclosure, the second hollow guide member  700  may include an o-ring or a recess in the top plate  706  for maintaining the second piston  800  and the anvil  900  to their initial positions (pre-fastener driving positions as shown in  FIG. 1 ). Moreover, in one embodiment of the present disclosure, the second hollow guide member  700  may include a magnet disposed on the top plate  706  and a piece of ferrous material in the anvil  900  for maintaining the second piston  800  and the anvil  900  to their initial positions. Accordingly, by maintaining the second piston  800  and the anvil  900  in their upper positions and ensuring that there is little or no extra dead volume between the second piston  800  and the top plate  706 , maximum efficiency may be achieved as the expansion of the gas after the compression stroke acts directly on the second piston  800 . Further, such arrangement precludes any accidental release of the anvil  900  and thereby facilitates more safety to the user. 
     The operation cycle of the fastener driving apparatus  10  is shown in a progressive manner in  FIGS. 1 to 8 , and will now be described with reference to  FIGS. 1 to 8 . 
     Referring again to  FIG. 1 , a first stage of the operation cycle of the fastener driving apparatus  10  is shown. At this stage of the operation cycle, the first piston  500  is at the BDC of the first hollow guide member  400 , and the second piston  800  and the anvil  900  are at the proximal end portion  702  of the second hollow guide member  700 , the valve arrangement  2000  is in the closed position, the fastener  1000  is disposed in the fastener guide  1010  and the motor  300  is in an OFF state. Positioning of the second piston  800  and the anvil  900  at the proximal end portion  702  represent ‘initial positions’ of the second piston  800  and the anvil  900  at the beginning of the operation cycle. As the first piston  500  is at the BDC, the vertical actuation member  5000  keeps the check valve  508  in the open position. In the open position of the check valve  508 , the atmospheric air gets filled in the gas chamber  510  from the check valve  508  as shown by arrows ‘A 1 ’ in  FIG. 1 . Alternatively, in another embodiment of the present disclosure, the atmospheric air may be filled in the gas chamber  510  by means of the series of holes or the enlarged opening configured in the lower end portion  404  of the first hollow guide member  400 . Further, the check valve  508  in its closed position prevents any exit of gas from the gas chamber  510 . 
     Further, for initiating the operation cycle of the fastener driving apparatus  10 , the user may actuate the switch  302 . The control circuit  200  by means of the second sensor  3004  ensures that the first piston  500  is at the BDC of the first hollow guide member  400 . After ensuring that the first piston  500  is at the BDC of the first hollow guide member  400 , the control circuit  200  actuates the power source  100  to supply power to the motor  300 . The motor  300  then drives the linear motion converter  600 , which in turn facilitates the first piston  500  to execute the compression stroke. The valve arrangement  2000  is in the closed position and the first piston  500  moves from the lower end portion  404 , i.e., BDC of the first hollow guide member  400  towards the upper end portion  402 , i.e., TDC of the first hollow guide member  400 . Further, as the first piston  500  moves towards the TDC, the vertical actuation member  5000  causes the check valve  508  to assume the closed position. More specifically, due to a pressure difference on both sides of the check valve  508  (inside and outside of the first hollow guide member  400 ), the check valve  508  is configured to assume the closed position. Further, as valve arrangement  2000  is in the closed position, the first piston  500  compresses the gas in the gas chamber  510 . During the compression stroke, due to the cam rise profile of the cam  2052  that is rotating, the second arm  2060  starts rotating in the clockwise direction about the pivot point  2062 . Accordingly, the first arm  2058  starts pulling the valve spool  2006  rearward in order to uncover the opening  408 . Further, the valve spool return spring  2064  also starts compressing as the valve spool  2006  moves rearward. 
     Further, as shown in  FIG. 2 , as the first piston  500  reaches the TDC of the first hollow guide member  400 , the gas is compressed to a predetermined pressure. In one embodiment of the present disclosure, for driving a standard 18 gages and 2 inches long fastener  1000 , the gas in the gas chamber  510  may be compressed to a predetermined pressure of 160 psi (pounds per square inch) with a volume of the compressed gas being approximately one cubic inch. The first piston  500  is configured to compress the gas in the gas chamber  510  at the predetermined pressure in a single rapid linear stroke, i.e., the compression stroke. By compressing the gas in the gas chamber  510  in the single rapid linear stroke, the gas is compressed in a way such that the pressure of the compressed gas exceeds a pressure that will be predicted by the formula P 1 V 1 =P 2 V 2 . Herein, P 1  and P 2  represent pressure of the gas and V 1  and V 2  represent volume of the gas. Such increase in the pressure may be modeled with a compression exponent greater than 1.05. Compression exponents greater than 1.05 yield higher gas pressures for a given compression ratio than the gas pressure for a compression done in a normal manner. More specifically, such a compression exponent allows more energy to be stored in the compressed gas than the energy stored if the compression were done via a normal multi-stroke compressor (in which the heat of compression may be lost to the environment.) 
     A formula for compression exponent greater than 1.05 may be written as: PV n =K, where P is pressure of the compressed gas, V is volume of the compressed gas, n is the compression exponent and K is a constant. For air in an isothermal compression, the compression exponent is 1.05, and for an adiabatic compression the compression exponent is about 1.4. In an embodiment of the present disclosure, as the compression cycle is sufficiently short, the gas in the gas chamber  510  may be compressed to the predetermined pressure at a compression exponent of approximately at least 1.1. 
     Further, as the first piston  500  reaches towards the TDC of the first hollow guide member  400 , due to the rise profile of the rotating cam  2052 , the second arm  2060  continues rotating in the clockwise direction about the pivot point  2062 . Accordingly, the first arm  2058  pulls the valve spool  2006  rearward in order to uncover the opening  408  for configuring the open position of the valve arrangement  2000 , which is shown in  FIGS. 3 and 4 . 
     Now referring to  FIG. 3  and  FIG. 4 , next stages of the operation cycle are shown. Particularly as shown in  FIG. 3 , the valve arrangement  2000  assumes the open position after completion of the compression stroke. As the valve arrangement  2000  is in the open position, the compressed gas at the predetermined pressure in the first hollow guide member  400  is communicated to the second hollow guide member  700  through the gas passageway  2005 . The compressed gas is then allowed to expand in the second hollow guide member  700  causing the second piston  800  and the anvil  900  to move linearly in a downward direction. Further, the anvil  900  extends along a longitudinal axis of the second hollow guide member  700  into the fastener guide  1010  for striking the fastener  1000 . The anvil  900 , upon striking the fastener  1000 , is capable of driving the fastener  1000  into the workpiece as shown in  FIG. 4 . 
     As the compressed gas from the first hollow guide member  400  is rapidly communicated to the second hollow guide member  700  through the gas passageway  2005 , such rapid communication of the compressed gas from first hollow guide member  400  to the second hollow guide member  700  yields a rapid acceleration of the second piston  800  and the anvil  900  in the downward direction. Such rapid acceleration of the second piston  800  and the anvil  900  results in a quick fastener drive stroke with a low reaction force. Additionally, the linear movement of the anvil  900  through the fastener guide  1010  enables in jam clearing of the fastener guide  1010 . Such jam clearing removes the fastener fragments or other debris inside the fastener guide  1010  and thereby avoids the need of any manual operation for cleaning the fastener guide  1010 . Accordingly, this would automatically make the fastener guide  1010  ready for a next operation cycle of driving the fastener  1000 . 
     After the fastener  1000  is fully driven into the workpiece, the valve arrangement  2000  is configured to assume the closed position. Due to the fall profile of the rotating cam  2052 , the second arm  2060  is free to rotate in the counter clockwise direction about the pivot point  2062 . Further, the valve spool return spring  2064  which is in the compressed state during the open position of the valve arrangement  2000 , starts expanding and thereby pushes the valve spool  2006  forward in order to cover the opening  408 . Accordingly, the valve arrangement  2000  assumes the closed position, as shown in  FIG. 5 . Further, due to continuous rotation of the motor  300 , the first piston  500  is configured to execute the return stroke. During the return stroke, the first piston  500  moves downwardly from the upper end portion  402 , i.e., the TDC of the first hollow guide member  400  towards the lower end portion  404 , i.e., the BDC of the first hollow guide member  400 . Further, due to the closed position of the valve arrangement  2000  and the closed position of the check valve  508 , a vacuum is created between the TDC of the first hollow guide member  400  and the first piston  500 . More specifically, the vacuum is created between the upper face  502  of the first piston  500  and the cylinder end cap  406 . 
     Further, as shown in  FIG. 5 , excess gas in the second hollow guide member  700  may be vented to the atmosphere. The excess gas in the second hollow guide member  700  may be vented to the atmosphere by means of the elongated groove  2010  of the valve spool  2006  and the opening  2012  configured on the valve body  2008 . Accordingly, such venting of the excess gas in the second hollow guide member  700  facilitates reduction of gas pressure above the front face  802  of the second piston  800 . Furthermore, in the case that the movement of the first piston  500  is impeded to any extent, such venting releases the pressure on the second piston  800  and the anvil  900 , thus providing safety to the user. 
     Further, as shown in  FIG. 6 , during the return stroke of the first piston  500 , when the first piston  500  reaches a predetermined position, the vacuum created within the first hollow guide member  400  is sufficient such that the second piston  800  and the anvil  900  may be retracted to their initial positions (as shown in  FIG. 1 ), if the vacuum is communicated to the second hollow guide member  700 . Accordingly, when the first piston  500  reaches the predetermined position in the first hollow guide member  400 , the rocker arm  2056  continues rotating in the clockwise direction about the pivot point  2062  due to the cam rise profile of the rotating cam  2052 . Accordingly, the first arm  2058  pulls the valve spool  2006  rearward in order to uncover the opening  408  for configuring the open position of the valve arrangement  2000 , which is shown in  FIG. 7 . 
     Further, a next stage of the operation cycle is illustrated in  FIG. 7 . The first arm  2058  pulls the valve spool  2006  rearward and uncovers the opening  408  configured on the cylinder end cap  406  of the first hollow guide member  400  to configure the open position of the valve arrangement  2000 . Thereafter, the vacuum created in the first hollow guide member  400  is communicated to the second hollow guide member  700 . More specifically, the vacuum created in the first hollow guide member  400  is filled by the gas communicated from the second hollow guide member  700 , when the valve arrangement  2000  assumes the open position. 
     Furthermore, as shown in  FIG. 8 , the vacuum communicated to the second hollow guide member  700  causes the second piston  800  and the anvil  900  to retract to their initial positions. Further, as the first piston  500  is configured to reach to the BDC of the first hollow guide member  400 , the second piston  800  and the anvil  900  are returned to their initial positions. It would be apparent to those skilled in the art that the second piston  800  and the anvil  900  are retracted to their initial positions without utilizing any drive energy of the fastener driving apparatus  10 . Further, a person skilled in the art would appreciate that virtually all energy from the fastener driving apparatus  10  is utilized to drive the fastener  1000  into the workpiece, as the retraction of the second piston  800  and the anvil  900  is performed automatically as the first piston  500  moves towards the BDC of the first hollow guide member  400  during the return stroke. More specifically, the return of the second piston  800  and the anvil  900  is vacuum actuated, and does not utilize any energy used for driving the fastener  1000 . 
     Hence, a person skilled in the art would appreciate that the vacuum generated in the first hollow guide member  400  acts as ‘the retracting mechanism’ in the fastener driving apparatus  10  of the present disclosure. It would be apparent to those skilled in that art that the anvil  900  of the present disclosure do not require any specific retracting mechanism such as compressing an anvil return spring or a bungee, the fastener driving apparatus  10  of the present disclosure increases the drive speed of the present disclosure. Further, the kinetic energy caused by the axial movement of the second piston  800 , the connector  806  and the anvil  900  is absorbed by the bumper  708 . 
     As the second piston  800  and the anvil  900  reach to their initial positions, the valve arrangement  2000  is configured to assume the closed position as shown in  FIG. 1 . When the first piston  500  reaches the BDC of the first hollow guide member  400 , the second sensor  3004  detects the presence of the first piston  500  at the BDC, and the control circuit  200  receives the detected position from the second sensor  3004 . Further, the control circuit  200  is configured to disconnect the power source  100  from the motor  300  to stop the operation cycle based on feedback from the second sensor  3004 . More specifically, the control circuit  200  disconnects the power from the power source  100  to the motor  300  so that motor  300  stops actuating the linear motion converter  600  for linearly moving the first piston  500  inside the first hollow guide member  400 . In one embodiment of the present disclosure, the motor  300  may be stopped by means of dynamic braking mechanism. It would be apparent to those ordinary skilled in the art that in this condition, the fastener driving apparatus  10  is in a ready position for performing a next operation cycle of the fastener driving operation. Accordingly, in a single stroke of the first piston  500  the operation cycle of the fastener driving is completed by the fastener driving apparatus  10 . Accordingly, with each triggering (i.e., powering of the switch  302 ), one fastener, such as the fastener  1000 , is driven into the workpiece. It would be apparent to those ordinary skilled in the art that in case of continuous driving of fasteners  1000 , the motor  300  may be continued as running in order to execute the successive operation cycles in a continuous manner. 
     Referring now to  FIG. 9 , in another embodiment of the present invention, a fastener driving apparatus  20  having a valve arrangement such as a valve arrangement  6000  and a coupling member such as a coupling member  6050 , is shown. The valve arrangement  6000  includes a valve spool  6010 , which has a cam ramp  6012  configured on a rear portion  6014  of the valve spool  6010 . The rear portion  6114  of the valve arrangement  6000  is also operably coupled to a valve spool return spring such as the valve spool return spring  2064 . 
     The coupling member  6050  includes a cam such as the cam  2052 , a pushrod  6052  and a cam guide such as the cam guide  2066 . The pushrod  6052  is operatively coupled to the cam  2052 . With the rotation of the cam  2052 , the pushrod  6052  executes an upward and downward movement, i.e., towards and away from the shaft  4002 . As shown in  FIG. 9 , the pushrod  6052  acts against a cam ramp  6012  on the valve spool  6010  to configure the open position or the closed position of the valve arrangement  2000 . The valve spool return spring  2064  also aids in closing the opening  408  when the pushrod  6052  retracts, i.e., goes towards the shaft  4002 . 
     For example, as shown in  FIG. 9 , due to variable profile of the cam  2052 , when the pushrod  6052  is in contact with the cam ramp  6012  at a point  6016 , the valve arrangement  6000  is in the closed position. Due to the cam rise profile of the cam  2052 , the pushrod  6052  is driven in the upward direction, i.e., away from the shaft  4002 . As the pushrod  6052  acts against the cam ramp  6012  to proceed in the upward direction, a resultant force is applied that pushes the valve spool  6010  in the rearward direction in order to uncover the opening  408  (when the pushrod  6052  is in contact with the cam ramp  6012  at a point  6018 ). Accordingly, the valve arrangement  6000  assumes the open position and simultaneously the valve spool return spring  2064  also compresses. It would be apparent to those skilled in the art that in an operation cycle, the cam  2052  will rotate by 360 degrees, and the cam  2052  will have a profile having two rises and two falls. 
     Referring now to  FIG. 10 , yet another embodiment of the present invention having a valve arrangement such as a valve arrangement  7000  utilized in a fastener driving apparatus  30 , is shown. The fastener driving apparatus  30  does not utilize any coupling member such as the coupling member  2050  operatively coupled between the valve arrangement  7000  and the motor  300 . 
     The valve arrangement  7000  may include a pneumatic valve  7002  and a valve solenoid  7004 . The valve solenoid  7004  is configured to actuate the pneumatic valve  7002 . The pneumatic valve  7002  includes a valve spool  7006  and a valve body  7008 . The valve spool  7006  is slidably disposed in the valve body  7008 . The valve spool  7006  may include an elongated groove  7010  configured on a central portion thereof. Further, in one embodiment of the present disclosure, the valve spool  7006  may be held in position by means of a spring (not shown) and pressure balance between two o-rings (not shown). The valve body  7008  may further include an opening  7012  configured thereon. In the closed position of the valve arrangement  7000 , the opening  7012  is configured to receive gas from the elongated groove  7010  and pass the gas to atmosphere. 
     Further, the valve solenoid  7004  includes an actuating member  7014 , a solenoid return spring  7016 , and a solenoid member  7018 . The actuating member  7014  is configured to actuate the valve spool  7006  to configure one of the closed position and the open position of the valve spool  7006 . The solenoid return spring  7016  is functionally coupled to the actuating member  7014 . The solenoid member  7018  is configured to actuate the actuating member  7014  and the solenoid return spring  7016  such that the valve spool  7006  may assume one of the open position and the closed position. The solenoid member  7018  is electrically coupled to the control circuit  200  that is configured to actuate the solenoid member  7018 . The solenoid member  7018  may be electrically coupled to the control circuit  200  by means of wired, wireless or any other means known in the art. The control circuit  200  may actuate the solenoid member  7018  for configuring the valve arrangement to assume one of the open position and the closed position based on the position of the first piston  500  detected within the first hollow guide member  400  and timings of start and stop of an operation cycle of the fastener driving apparatus  30 . 
     More specifically, for configuring the open position of the valve arrangement  7000 , i.e., the open position of the valve spool  7006 , the solenoid member  7018  actuates the actuating member  7014 . Further, the actuating member  7014  moves the valve spool  7006  towards the solenoid member  7018  and unblocks the opening  408  configured on the cylinder end cap  406  of the first hollow guide member  400 . More specifically, once the valve spool  7006  is cracked open by the solenoid member  7018 , the gas pressure may act on a front face (not shown) of the valve spool  7006  and moves the valve spool  7006  towards the solenoid member  7018  very fast and snaps the valve spool  7006  to assume the open position. While moving the valve spool  7006  towards the solenoid member  7018 , the actuating member  7014  compresses the solenoid return spring  7016 . Further, the solenoid member  7018  is configured to retain the open position of the valve spool  7006  even when the pressure in the gas chamber  510  drops. Such characteristics of the solenoid member  7018  to retain the open position of the valve spool  7006  even when the pressure in the gas chamber  510  drops, increases efficiency of the valve arrangement  7000  and facilitates a complete driving of the fastener  1000  into the workpiece. Further, the opening force required for configuring the open position of the valve arrangement  7000  is at least 1.5 times of the force required for maintaining the closed position of the valve arrangement  7000 . 
     Similarly, for configuring the closed position of the valve arrangement  7000 , i.e., the closed position of the valve spool  7006 , the solenoid member  7018  actuates the actuating member  7014  to move towards the second hollow guide member  700  by means of release of potential energy stored in the solenoid return spring  7016 . Accordingly, the actuating member  7014  moves the valve spool  7006  towards the second hollow guide member  700 , and thereby blocks the opening  408  configured on the cylinder end cap  406  of the first hollow guide member  400 . 
     It would be apparent to those skilled in the art that the valve arrangement  700  may be configured to assume the open position or the closed position based on the signal received from the control circuit  200 . For example, during the compression stroke of the compression stroke of the operation cycle, when the first piston  500  reaches the TDC of the first hollow guide member  400 , the first sensor  3002  detects the position of the first piston  500  and communicates the detected position of the first piston  500  to the control circuit  200 . Thereafter, the control circuit  200  actuates the solenoid member  7018  of the valve arrangement  7000 . The solenoid member  7018  then actuates the actuating member  7014  for configuring the open position of the valve spool  7006 . Similarly, during the return stroke of the operation cycle, positioning of the first piston  500  at the predetermined position may be detected by the second sensor  3004 . More specifically, the second sensor  3004  is configured to detect the predetermined position of the first piston  500  on the return stroke so as to control the timing when the valve arrangement  7000  should assume the open position. The second sensor  3004  communicates this detected position of the first piston  500  to the control circuit  200 . Further, the control circuit  200  actuates the solenoid member  7018  to configure the open position of the valve arrangement  7000 . Further, as the valve arrangement  7000  assumes the open position, the vacuum is utilized to retract the second piston  800  and the anvil  900  to their initial positions in the second hollow guide member  700 . 
     Although in the present embodiment of the present disclosure, the valve arrangement  7000  includes the valve solenoid  7004  for configuring the open position and the closed position of the valve arrangement  7000 , the present disclosure is not limited to this particular arrangement only. In another embodiment of the present disclosure may include a valve arrangement having a pneumatic valve, similar to the pneumatic valve  7002  actuated by a plurality of sensors. Such valve arrangement may be designed by considering various parameters such as pressure drop through the valve arrangement, the opening time of the valve arrangement, and the volume of gas contained in a gas passageway of the valve arrangement. 
     Referring now to  FIG. 11 , a front view of still another embodiment of a fastener driving apparatus  40  is shown. The fastener driving apparatus  40  may be similar to the fastener driving apparatus  30 , which is explained in conjunction with  FIG. 10 . However, the fastener driving apparatus  40  includes a first hollow guide member  4400  and a second hollow guide member  4700  having different sizes. More specifically, the first hollow guide member  4400  is configured to have a first volumetric capacity and the second hollow guide member  4700  is configured to have a second volumetric capacity which is smaller as compare to the first volumetric capacity. For example, the first volumetric capacity of the first hollow guide member  4400  may be at least 10 percent greater than the second volumetric capacity of the second hollow guide member  4700 . 
     The second hollow guide member  4700  may be positioned parallel to the first hollow guide member  4400 , and may be positioned outside the first hollow guide member  4400  or contained within the first hollow guide member  4400 . 
     Due to such configuration of the first hollow guide member  4400  and the second hollow guide member  4700 , the fastener driving apparatus  40  may be capable of sufficiently driving the fastener  1000  (as shown in  FIG. 10 ) into a workpiece. More specifically, a pressure of the air at the end of an expansion stroke is always greater then the atmospheric pressure when the first hollow guide member  4400  is larger as compare to the second hollow guide member  4700 . For example, the pressure of the air is greater then the atmospheric pressure at the end of the expansion stroke when the anvil  900  (as shown in  FIG. 10 ) strikes the fastener  1000  for being sufficiently driven into the workpiece. Accordingly, such differences in the sizes of the first hollow guide member  4400  and the second hollow guide member  4700  provides required pressure and volume for sufficiently driving the fastener  1000  into the workpiece. 
     Further, due to such configuration of the first hollow guide member  4400  and the second hollow guide member  4700 , the vacuum retracting mechanism of the fastener driving apparatus  40  becomes more efficient. More specifically, the retraction of the second piston  800  (as shown in  FIG. 10 ) and the anvil  900  by a vacuum generated in the first hollow guide member  4200  may be achieved efficiently. For example, when the first hollow guide member  4400  is larger as compare to the second hollow guide member  4700 , the vacuum created in the first hollow guide member  4400  with the return stroke of the first piston  500  (as shown in  FIG. 10 ) is communicated to the second hollow guide member  4700  for retracting the second piston  800  and the anvil  900  to their initial positions. In the present embodiment, it would be apparent to person skilled in the art that the vacuum created in the first hollow guide member  4400  may cause a comparatively smaller volume of the second hollow guide member  4700  to evacuate faster and thereby creating a larger vacuum force for efficiently retracting the second piston  800  and the anvil  900  to their initial positions. 
     In the present embodiment, the first hollow guide member  4400  and the second hollow guide member  4700  of the fastener driving apparatus  40  may be further configured to have a cross section of one of an oval shape and an elliptical shape. For example, as shown in  FIG. 12 , the first hollow guide member  4400  and the second hollow guide member  4700  is configured to have an elliptical shaped cross section. Specifically,  FIG. 12  illustrates a cross sectional view of the first hollow guide member  4400  and the second hollow guide member  4700  along an axis AA′ of  FIG. 11 . Further, in one embodiment, the elliptical shaped cross section may include the following dimensions, i.e., a length of a major axis of the elliptical shaped cross section may be at least 10 percent greater then a length of minor axis of elliptical shaped cross section. 
     The elliptical cross section of the first hollow guide member  4400  and the second hollow guide member  4700  may reduce a distance between a user&#39;s hand and a firing point of the fastener driving apparatus  40 . More specifically, a distance ‘D’ (as shown in  FIG. 11 ) between the switch  302  and the fastener guide  1010  of the fastener driving apparatus  40  is reduced due to the elliptical cross section of the first hollow guide member  400  and the second hollow guide member  700 . The reduced distances between the switch  302  and the fastener guide  1010  allows the user to experience minimized reactionary force while operating the fastener driving apparatus  40 . Accordingly, the fastener driving apparatus  40  may enable in accurately driving the fasteners  1000  into the workpiece in the subsequent drives of the fastener driving apparatus  40 . Further, the operation of the fastener driving apparatus  40  becomes a less tiring job due to the minimized reactionary force. 
     It will be apparent to a person skilled in the art that, the fastener driving apparatus  40  is explained in conjunction with the fastener driving apparatus  30 . However, the fastener driving apparatus  40  may be similar to the fastener driving apparatuses  10  and  20 . Specifically, the fastener driving apparatuses  10  and  20  may include a first hollow guide member, such as the first hollow guide member  4200  and a second hollow guide member, a second hollow guide member  4700 , having different sizes, particularly different volumetric capacities, and having an elliptical or oval cross section. 
     Various embodiments of the present disclosure offer following advantages. The fastener driving apparatus, such as the fastener driving apparatuses  10   10 ,  20 ,  30  and  40 , utilizing valve arrangements such as valve arrangements  2000 ,  6000  and  7000 , respectively. Such fastener driving apparatuses, as described herein, provide retracting mechanisms that precludes consumption of drive energy of the fastener driving apparatuses and facilitates a fastener to be fully driven into a workpiece. Further, the retracting mechanisms of the fastener driving apparatuses of the present disclosure are capable of providing more safety to a user. Furthermore, the retracting mechanisms preclude reduction of drive speed of the fastener driving apparatuses. Moreover, the fastener driving apparatuses of the present disclosure are portable in nature. Further, the fastener driving apparatuses are inexpensive. Furthermore, the fastener driving apparatuses are simple in construction. Still further, the fastener driving apparatuses are capable of minimizing reactionary force and thereby providing more comfort to the user. Additionally, the fastener driving apparatus are capable of driving the fastener into the workpiece in a single stroke. 
     The foregoing descriptions of specific embodiments of the present disclosure have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present disclosure to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present disclosure and its practical application, and to thereby enable others skilled in the art to best utilize the present disclosure and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient, but such omissions and substitutions are intended to cover the application or implementation without departing from the spirit or scope of the claims of the present disclosure.