Patent Publication Number: US-8991675-B2

Title: Dynamic clutch apparatus for electrical nail gun

Description:
BACKGROUND 
     1. Technical Field 
     The invention relates generally to an electrical nail gun, and more particularly, to a dynamic clutch apparatus that uses a flywheel to drive a firing pin set. 
     2. Related Art 
     An electrical nail gun is an electrical hand tool that uses electricity to drive a firing pin set to generate nail-percussion kinetic energy. The firing pin set must be capable of outputting tremendous liner nail-percussion kinetic energy instantaneously. Patents such as U.S. Pat. No. 5,098,004, EP1584418, EP1584419 have already disclosed electrical nail guns that use flywheels to drive firing pin sets so as to generate nail-percussion kinetic energy. 
     A person skilled in the relevant art knows how to make use of the characteristic that when a flywheel is driven to rotate, the flywheel can accumulate rotational kinetic energy. The person can place the firing pin set between the flywheel and a free roller (a.k.a. a pinch roller) that can move. A swinging arm mechanism can serve as a dynamic clutch apparatus, controlling the free roller to move by rotation and oscillation. The free roller than presses the firing pin set, causing the firing pin set to touch and press the flywheel. At the moment when the firing pin set touches and presses the flywheel, the flywheel passes the accumulated rotational kinetic energy to the firing pin set, causing the firing pin set to instantaneously output tremendous liner nail-percussion kinetic energy, successfully firing nail components one by one. 
     In addition, the U.S. Pat. No. 7,575,141 discloses an electrical nail gun unlike those disclosed by the aforementioned patents. Specifically, the U.S. Pat. No. 7,575,141 gives the free roller a fixed position, and the free roller only serves for guidance and support purposes when the firing pin set is having liner nail-percussion movement. The patent further uses a different swinging arm mechanism to serve as a dynamic clutch apparatus, controlling the rotating flywheel to move, and as a result to touch the firing pin set and to press the firing pin set to move to percuss a nail. 
     It deserves mentioning that the U.S. Pat. No. 7,575,141 prevents the free roller from deviating from the nail-percussion axial direction when it presses and touches the flywheel, which is a common problem of the U.S. Pat. No. 5,098,004, EP1584418, and EP1584419 patents. This problem is severe especially when a skid base of the firing pin set has worn out after multiple frictions. However, in the patents, including the U.S. Pat. No. 7,575,141, the swinging arm mechanism serves as a dynamic clutch apparatus. When the firing pin set is being pressed by the free roller and the flywheel on two sides to pass kinetic energy, the swinging arm and the gun body support inevitably suffer from tremendous bending moment applied by the free roller or the flywheel. The bending moment is a bending load of the swinging arm; the swinging arm mechanism and the gun body support must be thick and strong enough to cope with the bending load. As a result, the swinging arm mechanism and the gun body support occupy too much volume of the gun body and add too much additional weight. 
     BRIEF SUMMARY 
     The invention provides a dynamic clutch apparatus for an electrical nail gun. It omits the swinging arm of the related art, hence resolves the aforementioned bending load problem suffered by the swinging arm and the gun body support when the flywheel is driving the firing pin set and applying bending moments on the swinging arm and the gun body support. 
     A dynamic clutch apparatus for an electrical nail gun according to the invention comprises a pair of symmetric direct stroke apertures, formed on a gun body support and extending along a first direction; a firing pin set, slidably installed on a side of the gun body support on the first direction along a nail-percussion axial direction, wherein the first direction is not parallel to the nail-percussion axial direction; a guiding base, movably installed inside the gun body support, driven by an electromagnetic driver to move along a second direction, wherein the second direction is not parallel to the first direction; a pair of symmetric oblique stroke apertures, formed on the guiding base and extending along a third direction, wherein the third direction is situated between the first direction and the second direction, and aperture walls of the oblique stroke apertures and the direct stroke apertures encircle and form an interconnected through aperture; and a flywheel for accumulating kinetic energy, wherein two sides of the flywheel have two pivot bearings installed coaxially, the pivot bearings are slidably installed inside the through aperture, when the guiding base moves along the second direction, the through aperture restricts the pivot bearings so as to cause the flywheel to move along the first direction synchronously, as a result driving the firing pin set to pass nail-percussion kinetic energy along the nail-percussion axial direction. 
     The firing pin set receives contacted-based guidance from a positioning pulley and is slidably installed on the nail-percussion axial direction, and the positioning pulley is pivoted on a side of the gun body support. The positioning pulley is located on the first direction, separated by the firing pin set and being adjacent to the direct stroke apertures. The second direction is perpendicular to the first direction and parallel to the nail-percussion axial direction, and the third direction and the second direction have an included angle of 15 to 30 degrees. A first elastic component is installed between the guiding base and the gun body support, driving the guiding base to move along the second direction and then to restore position. A second elastic component is installed inside the gun body support on a direction opposite to the first direction, protecting and supporting the guiding base. The electromagnetic driver is fixed on the gun body support so as to drive the guiding base. The flywheel rotates by being driven by an electrical motor, the electrical motor is positioned on the gun body support. 
     In the invention, an electromagnetic driver drives a guiding base to move along a second direction, causing a through aperture to move along a first direction and limiting a flywheel to move along the first direction synchronously. A firing pin set is installed on the first direction, so the flywheel can be driven to press and drive the firing pin set to move along a nail-percussion axial direction and percuss a nail component. This design does not involve a swinging arm, but instead uses direct stroke apertures to serve as a through aperture that restricts the flywheel&#39;s movement. When the flywheel drives the firing pin set, the outer walls of the pivot bearings have multiple contact-points with aperture walls of oblique stroke apertures and direct stroke apertures. As a result, load is shared. When the firing pin set is pressed by the positioning roller and the flywheel and kinetic energy is passed, the guiding base bears the pressure load and the gun body support bears the tension load. Therefore, the tremendous stress caused by bending load is effectively excluded. 
     Other features of the present invention will be apparent from the accompanying drawings and from the detailed description which follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is fully illustrated by the subsequent detailed description and the accompanying drawings, in which like references indicate similar elements. 
         FIG. 1  shows a pictorial view of an embodiment of the invention. 
         FIG. 2  shows an exploded pictorial view of the embodiment of  FIG. 1 . 
         FIG. 3  shows a sectional view of the embodiment of  FIG. 1 . 
         FIG. 4  shows a front view of the gun body support of  FIG. 1 . 
         FIG. 5  shows a sectional view of the embodiment of  FIG. 3 , illustrating how a guiding base  3  and other relevant components are installed inside the gun body support. 
         FIG. 5   a  shows a partial pictorial view of the embodiment of  FIG. 5 , illustrating how a second elastic component is installed in the gun body support. 
         FIG. 6  shows a sectional view illustrating how kinetic energy causes the flywheel of  FIG. 1  to depart from the firing pin set. 
         FIG. 6   a  illustrates the position of the through aperture in  FIG. 6 . 
         FIG. 6   b  illustrates the position of the pivot bearing in  FIG. 6 . 
         FIG. 7  shows a sectional view illustrating how the flywheel of  FIG. 1  uses kinetic energy to drive the firing pin set. 
         FIG. 7   a  illustrates the position of the pivot bearing in  FIG. 7 . 
         FIG. 8  shows a sectional view illustrating the position of the firing pin set after percussing a nail. 
     
    
    
     DETAILED DESCRIPTION 
     The directions mentioned in this detailed description are vectors. The vectors help define directional characteristics such as relative positions of relevant components, movements, and forces. In the figures dotted arrows are used to represent directions. 
     Please refer to  FIG. 1  to  FIG. 3 .  FIG. 1  shows a pictorial view of a dynamic clutch apparatus for an electrical nail gun according to an embodiment of the invention.  FIG. 2  shows an exploded pictorial view of the embodiment of  FIG. 1 .  FIG. 3  shows a sectional view of the embodiment of  FIG. 1 . The dynamic clutch apparatus of this embodiment includes a gun body support  1 , a firing pin set  2 , a guiding base  3 , and a flywheel  4 . 
     The gun body support  1  is a fixed support for components such as the firing pin set  2 , the guiding base  3 , and the flywheel  4  to be installed thereon; hence the gun body support  1  can be viewed as a fixed end inside the gun body. 
       FIG. 4  and  FIG. 5  together illustrate a pair of symmetric direct stroke apertures  11  formed on the gun body support  1 . On a coordinates system defined by coordinate axis X and coordinate axis Y, the direct stroke apertures  11  are formed on the gun body support  1  and extend along a first direction X. 
       FIG. 5  and  FIG. 6  together illustrate that the firing pin set  2  is located on the first direction X, and is slidably installed on a side of the gun body support  1  along a nail-percussion axial direction Y 1 . The first direction X is not parallel to the nail-percussion axial direction Y 1 . For example, the first direction X can be perpendicular to the nail-percussion axial direction Y 1 . More specifically, a pivot  18  is used to install a positioning pulley  12  pivotally on the gun body support  1 . The firing pin set  2  is contacted by and guided by the positioning pulley  12  and slidably installed on the nail-percussion axial direction Y 1 . For example, the positioning pulley  12  is located on the first direction X, separated by the firing pin set  2  and being adjacent to the direct stroke apertures  11 . 
     As shown in  FIG. 2 , the firing pin set  2  includes a fixed base  21 , two guide pillars  22 , a skid base  23 , two elastic rings  24 , and a firing pin  25 . Please refer to both  FIG. 1  and  FIG. 6 . The fixed base  21  is fixed on a side of the gun body support  1 . The two guide pillars  22  are fixed parallel to a side of the fixed base  21 . The skid base  23  is guided and held by the guide pillars  22  and is slidably installed on the nail-percussion axial direction Y 1 . On a surface of the skid base  23  adjacent to the flywheel  4 , there are concave-convex embedding slots  26 . The two elastic rings  24  encircle and lie between the skid base  23  and the fixed base  21 , enabling the skid base  23  to load spring pressure and slide along the nail-percussion axial direction Y 1  and then restore its original position. More specifically, the firing pin set  2  is contacted and guided by the positioning pulley  12  via the skid base  23 , and is slidably installed on the nail-percussion axial direction Y 1 . The firing pin  25  is installed on the skid base  23  along the nail-percussion axial direction Y 1 , so as to allow the firing pin  25  to be slidably installed on the gun body support  1  along the nail-percussion axial direction Y 1 , and to percuss and release nail components inside the nail gun. 
     As shown in  FIG. 3  and  FIG. 5 , the guiding base  3  is movably installed inside the gun body support  1  along a second direction Y. On the second direction Y inside the gun body support  1  there is an electromagnetic driver  31 . The electromagnetic driver  31  can be an electromagnet, driven by a power of the electrical nail gun to output driving force via an axis component. The axis component of the electromagnetic driver  31  is connected to the guiding base  3  and hence can drive the guiding base  3  to move along the second direction Y. 
     As shown in  FIG. 2 ,  FIG. 3 , and  FIG. 5 , the guiding base  3  has a pair of symmetric end walls  30 . Between the guiding base  3  and the gun body support  1  there is a first elastic component  32  and a second elastic component  34 . The first elastic component  32  can be a spiral spring. On two sides of the guiding base  3  and along the second direction Y there is a guiding-holding base  33  that can encircle an end of the first elastic component  32 . The guiding-holding base  33  causes another end of the first elastic component  32  to tightly contact a positioning end  13  inside the gun body support  1 . As a result, the electromagnetic driver  31  can drive the guiding base  3  to load spring pressure and move along a second direction Y when the electromagnetic driver  31  has been turned on. When the electromagnetic driver  31  has been turned off and has been demagnetized, the guiding base  3  can restore its original position. The second elastic component  34  is installed inside the gun body support on a direction opposite to the first direction by loading spring pressure, and can protect and hold the guiding base  3 . For example, the second elastic component  34  can be an L-shaped flat spring, having two rod parts  34   a  on two sides and a baffle part  34   b  in the middle. The baffle part  34   b  contacts a positioning end  14  inside the gun body support  1 . The rod parts  34   a  contact a positioning rib  15  (please refer to  FIG. 5   a ), causing the second elastic component  34  to load spring pressure and stretch tightly between the positioning end  14  and the positioning rib  15  of the gun body support  1 . In addition, the second elastic component  34  is located on a side  30   a  of the end walls  30  of the guiding base  3 , so as to pre-store a restraining force on a direction −X opposite to the first direction X to protect and hold the guiding base  3 . 
     As shown in  FIG. 4 , the second direction Y is not parallel to the first direction X. For example, the second direction Y can be perpendicular to the first direction X and has an intersection point O with the first direction X. As another example, the second direction Y can be parallel to the nail-percussion axial direction Y 1 . 
     As  FIG. 2  and  FIG. 5  indicate, two symmetric oblique stroke apertures  35  are formed on the end wall  30  of the guiding base  3 . More specifically, as  FIG. 4  and  FIG. 5  indicate, the oblique stroke apertures  35  extend along a third direction XY, where the third direction XY lies between the first direction X and the second direction Y, and the three directions intersect on the aforementioned intersection point O. For example, the third direction XY and the second direction Y can have an included angle of 15 to 30 degrees. This causes the aperture walls of the oblique stroke apertures  35  and the direct stroke apertures  11  to surround and form an interconnected through aperture  90 , which is shown in  FIG. 6   a . More specifically, as  FIG. 6   b  indicates, the through aperture  90  is formed by being surrounded by the aperture wall  35   a  of the oblique stroke apertures  35  and the aperture wall  11   a  of the direct stroke apertures  11 . This allows two pivot bearings  42 , each has a proper circle outer wall contour, to be slidably installed inside the through aperture  90 . The centers of the pivot bearings  42  happen to be located on the intersection point O. The pivot bearings  42  receive restriction, guidance, and support from the oblique stroke apertures  35  and the direct stroke apertures  11  to generate liner movement, which will be explained later. 
     As shown in  FIG. 1  to  FIG. 3 , the wheel surface of the flywheel  4  has concave-convex wheel slots  48  that correspond to the embedding slots  26  of the skid base  23 . The wheel center of the flywheel  4  has an axis component  41  that allows the pivot bearings  42  to be installed coaxially on two sides of the flywheel  4 , so that the circular outer walls of the pivot bearings  42  can be slidably installed inside the through aperture  90 . In addition, an end of the axis component  41  has a fixed driven belt wheel  43 . An electrical motor  44  is fixed on the gun body support  1 . An active belt wheel  45  is fixed on the axle center of the electrical motor  44 . A belt  46  encircles both the active belt wheel  45  and the driven belt wheel  43  and is tightened by an elastic press roller  47  on the gun body support  1 , so that the belt  46  can have a tension to avoid slipping. The belt  46  passes kinetic energy from the electrical motor  44  to the flywheel  4 , allowing the electrical motor  44  to drive the flywheel  4  to rotate and accumulate rotational kinetic energy. 
     As  FIG. 6  and  FIG. 6   b  indicate, when no electricity is supplied to the electromagnetic driver  31 , the guiding base  3  is tightened by the first elastic component  32  and slidably installed on a bottom position S 1 , causing the pivot bearings  42  to lie between the oblique aperture section A 1  on the upper right side of the oblique stroke apertures  35  and the direct aperture section B 1  on the right side of the direct stroke apertures  11 . The rotating and kinetic-energy-accumulating flywheel  4 &#39;s wheel slots  48  have a distance T apart from the embedding slots  26  of the skid base  23 . Hence, the flywheel  4  rotates with no load and does not pass rotational kinetic energy to the skid base  23 . 
     As  FIG. 7  and  FIG. 7   a  indicate, when a user turns on the power of the electrical nail gun and as a result causing the electromagnetic driver  31  to function, the guiding base  3  will load the elastic force of the first elastic component  32 , and be driven by the axis component of the electromagnetic driver  31  to move along the second direction Y. As a result the guiding base  3  moves to a top position S 2 . A specific stroke S lies between the top position S 2  and the bottom position S 1 . Because the pivot bearings  42  are restricted by the through aperture  90 , the flywheel  4  moves along the first direction X. More specifically, the circular outer walls of the pivot bearings  42  have point contacts with the aperture walls  11   a  and  35   a  of the direct stroke apertures  11  and the oblique stroke apertures  35 . The pivot bearings  42  are pushed when the aperture wall  35   a  of the oblique stroke apertures  35  is moving along the specific stroke S, and are restrained by the aperture wall  11   a  of the direct stroke apertures  11 . As a result the pivot bearings  42  move towards the aperture section A 2  on the lower left side of the oblique stroke apertures  35  and the aperture section B 2  on the left side of the direct stroke apertures  11 . As a result, the pivot bearings  42  and the flywheel  4  are driven to move along a first direction X, i.e. the skid base  23 &#39;s direction. The wheel slots  48  of the rotating and kinetic-energy-accumulating flywheel  4  can engage with the embedding slots  26  of the skid base  23 . In the meantime, the second elastic component  34  holds and protects the guiding base  3  on a direction −X opposite to the first direction X, preventing the guiding base  3  from having lateral movement along direction −X opposite to the first direction X when the flywheel  4  engages with the embedding slots  26 . This is true even if the contact surface of the embedding slots  26  is not even. More specifically, the second elastic component  34  drives the flywheel  4  to more stably contact and press the skid base  23 , so that the flywheel  4  can drive the skid base  23  to pass nail-percussion kinetic energy towards the nail-percussion axial direction Y 1 . As shown in  FIG. 8 , the result is that the firing pin  25  percusses a nail along the nail-percussion axial direction Y 1 . Afterward, the electromagnetic driver  31  is turned off and demagnetized, causing the guiding base  3  to be pushed by the first elastic component  32  and move back to the bottom position S 1  as depicted in  FIG. 6 . 
     The aforementioned upper right, lower left, left, and right directions are based on the directions appear in the figures of the invention. 
     Based upon above, the embodiment uses the direct stroke apertures  11  to restrict the moving track of the flywheel  4 . Furthermore, when the flywheel  4  drives the firing pin set  2 , the embodiment uses the aperture walls  35   a  and  11   a  of the oblique stroke apertures  35  and the direct stroke apertures  11  to provide multiple contact points and as a result to share load and prolong the components&#39; endurance and life. This also avoids the requirement of thick and strong swinging arms and gun body support, and as a result reduces the electrical nail gun&#39;s volume and weight. In addition, the embodiment further prevents the damages that might have been caused by bending loads. 
     In the foregoing detailed description, the invention has been described with reference to specific exemplary embodiments thereof. It will be evident that various modifications may be made thereto without departing from the spirit and scope of the invention as set forth in the following claims. The detailed description and drawings are, accordingly, to be regarded in an illustrative sense rather than a restrictive sense.