Abstract:
A log splitter is disclosed as employing a fluid driven hammer adapted to impart successive log splitting movements to a log splitting element, a manually operable parallelogram linkage for supporting the hammer for vertical movement relative to an upper position for removably positioning the splitting element in engagement with a log to be split, and a control for controlling operation of the hammer.

Description:
FIELD OF THE INVENTION 
     The present invention relates to log splitters, and more particularly to a log splitter employing a fluid-powered hammer of known construction to split a log without requiring a user to manually manipulate and guide the hammer during use. 
     BACKGROUND OF THE INVENTION 
     Heretofore, it has been proposed in U.S. Pat. Nos. 4,669,552 and 5,107,911 to employ manually manipulate jack hammers to split logs. In each case, a user is required to lift the hammer, place the hammer in vertical alignment with a log to be split and thereafter manually support the hammer as it operates upon the log. Jack hammers used in this manner can place a substantial strain on the back of a user and can possibly result in injury to the user in the event the log to be split should tilt or slide from beneath the splitting point or wedge of the hammer at the outset of the splitting operation. 
     It has also been known to support a steam driven hammer on a framework for purposes of applying blows to an article supported on an anvil disposed below and in vertical alignment with the hammer. This construction is quite complicated and believed not to be readily adapted for use in the splitting of logs. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a relatively low cost and easily operated log splitter particularly adapted for use by home owner or small wood lot owner who wishes to split wood for home fireplace consumption. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The nature and mode of operation of the present invention will now be more fully described in the following detailed description taken with the accompanying drawings wherein: 
     FIG. 1 is a side elevational view of a log splitter formed in accordance with the present invention; 
     FIG. 2 is a side elevational view, as viewed from the left of FIG. 1; 
     FIG. 3 is an enlarged, partial side elevational view of the log splitter, as viewed from the right of FIG. 1; 
     FIG. 4 is a side elevational view of a two-stage splitting wedge assembly formed in accordance with an alternative form of the present invention; 
     FIG. 5 is a side elevational view thereof, as viewed from the right of FIG. 4; 
     FIG. 6 is a side elevational view of a chisel portion of the wedge assembly of FIG. 4; 
     FIG. 7 is a sectional view taken generally along the line  7 — 7  in FIG. 6; 
     FIG. 8 is a side elevational view of the chisel portion of the wedge assembly, as viewed from the right of FIG. 6; 
     FIG. 9 is an exploded vertical sectional view of a wedge portion of the wedge assembly of FIG. 4; 
     FIG. 10 is an exploded top plan view of the wedge portion; 
     FIG. 11 is a side elevational view of the wedge position in assembled condition; 
     FIG. 12 is a top plan view of the wedge portion of FIG. 10; 
     FIG. 13 is a side elevational view of the wedge assembly arranged in contact with a log to be split; 
     FIG. 14 is a view similar to FIG. 13, but showing the wedge assembly upon completion of initial penetration of a log by the chisel portion of the assembly; and 
     FIG. 15 is a view similar to FIGS. 13 and 14, but showing the wedge assembly during a further penetration of a log by the wedge portion of the assembly. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A log splitting device according to a preferred form of the present invention is generally designated as  10 , and shown as including a fluid powered impact hammer  12  supported for vertically directed movement relative to a base  14  by a linkage  16 , and a control  18  for controlling operation of the hammer. A log to be split is designated by the letter “L”. 
     Hammer  12  is preferably a conventional pressurized air powered hammer having a log splitting element in the form of a wedge  20  to which it is adapted to impart an impact force during each operational cycle of the hammer, as indicated by arrow  22  in FIG. 1. A hammer of this type may be supplied with air under pressure from a suitable air compressor, not shown. It is contemplated that in accordance with a preferred form of the invention, the trigger, not shown, of hammer  12  may be fixed in an on position, such that the hammer will operate through successive cycles, as long as pressurized air is supplied to the hammer, and that the flow of pressurized air to the hammer would be under the control of control  18 , which is best shown in FIG.  3 . It is, however, contemplated that other fluids, such as steam supplied by a suitable steam generator may be employed to operate hammer  12 . Moreover, it is contemplated that hammer  12  may be an electromagnetic hammer or a hammer powered by gases generated by burning of a combustible mixture within a cylinder forming an integral part of the hammer. In this latter case, control  18  could be arranged to permit its operation of a trigger mechanism of the hammer. 
     Base  14  preferably includes a ground or otherwise supported support plate  26  and a post  28  arranged to vertically upstand from the support plate. Alternatively, post  28  may be otherwise supported, such as being fixed to any suitable vertically extending, rigid object, such as a wall, and in this case a log “L” to be split would be simply arranged to upstand from the ground. 
     Linkage  16  is preferably in the form of a parallelogram linkage having a pair of opposite vertically extending links, defined by hammer  12  and an upper end portion  28   a  of post  28 , a pair of vertically spaced links defined by an elongated upper link  30  and a lower link  32 . Post end portion  28   a  is pivotally coupled to first ends of upper link  30  and lower link  32  by a first pair of upper and lower pivot pins  34  and  36 , respectively, and hammer  12  is pivotally coupled to a mid-portion of upper link and a second end of lower link  32  by a second pair of upper and lower pivot pins  38  and  40 , respectively. Pivot pins  34 ,  36 ,  38  and  40  have parallel pivot axes, and the transverse spacing between pivot pins  34  and  36  is preferably equal to the transverse spacing between pivot pins  38  and  40 , and the transverse spacing between pivot pins  38  and  34  is preferably equal to the transverse spacing between pivot pins  40  and  36 . Alternatively, a separate vertically extending link, not shown, may be pivotally connected to links  30  and  32  by pivot pins  38  and  40 , and hammer  12  suitably fixed to such separate link. 
     By use of a parallelogram linkage, hammer  12  is constrained to be maintained in constant vertical orientation, e.g. parallel to post  28 , during vertical movements of the hammer downwardly from and during return to an inoperative or upper position shown in FIGS. 1 and 2. The inoperative upper position of hammer  12  may be variously defined, such as by providing post  28  with an abutment, not shown, arranged for engagement by upper link  30 , and a spring  44  shown only in FIG. 1, employed to normally bias the hammer to normally assume its inoperative position. 
     Preferably, the free swinging end  30   a  of upper link  30  is provided with a transversely extending handle  48 , which can be gripped by the hand of an operator whenever he wishes to initiate movement of hammer  12  downwardly away from its inoperative position. 
     Control  18  is best shown in FIG. 3 as including an air flow control valve  50  having an inlet conduit  52  connected to a source of air under pressure, not shown, and a discharge conduit  54  connected to hammer  12 . Valve  50  is normally maintained in closed or flow blocking condition by a return spring  56  acting on rotary valve part  58 , but may be moved into an open position, not shown, to place conduits  52  and  54  in flow communication for purposes of operating the hammer by operation of a control cable  62 . Cable  62  includes a sheaf  62   a  and a movable control wire  62   b,  which is slidably received within the sheaf and has its opposite ends connected to a rotatable valve part  58  and an operating lever  30   b,  which is pivotally supported by a bracket  30   c  in turn mounted on the free swinging end  30   a  of upper link  30  or on handle  48 , as desired. By pivoting lever  30   b  in a counterclockwise direction, as viewed in FIG. 1, valve part  58  is caused to rotate in a clockwise direction, as viewed in FIG. 3, to open valve  50  against the bias of spring  56 . If desired, lever  30   b  and bracket  30   c  may be similar in construction to a typical bicycle handle mounted brake operator. Also, it is contemplated that valve  50  may be dispensed with and lever  30   b  connected to the trigger of hammer  12  by control cable  12  or other suitable control linkage, such that a trigger operated flow control valve arranged internally of the hammer is used in place of valve  50 . 
     In operation of the preferred form of log splitter  10 , a log “L” is first placed on support plate  26  to upstand in vertical alignment with splitting element  20 , while hammer is maintained in its illustrated upper inoperative position by spring  44 . In this position of hammer  12 , return spring  56  is operative to maintain valve  50  in its closed condition, wherein flow of air from inlet conduit  52  to discharge conduit  54  is blocked, thereby resulting in the hammer being rendered inoperative for lack of pressurized air supplied thereto. 
     Thereafter, when an operator wishes to split log “L”, he grasps handle  48  and pulls downwardly to place splitting element  20  in engagement with the log. At some desired position of hammer  12 , the operator pivots lever  30   b  in order to cause sliding movement of control wire  62   b  within sheaf  62   a  with the result that valve part  58  is caused to rotate sufficiently to move valve  50  into an open position, thereby placing conduits  52  and  54  in flow communication. Thus, pressurized air is supplied to hammer  12  during an operator determined portion of the downward movement of the hammer away from its illustrated inoperative position for purposes of imparting successive blows to wedge  20 , as required to effect splitting of the log, and operation of the hammer continues until the lever  30   b  is released in order to permit spring  56  to return valve  50  to its original closed condition. Spring  44  in turn returns hammer  12  to its operative position upon release of handle  48 . 
     A modified form of the present invention is shown in FIGS. 4-15, wherein  100  designates a two-stage splitting wedge assembly adapted for use in splitting a log “L”. Assembly  100  includes a chisel portion  102  and a wedge portion  104  slidably mounted on the chisel portion for movement between a first position shown in FIGS. 4,  5  and  13 , and a second position shown in FIGS. 14 and 15. 
     Chisel portion  102  is best shown in FIGS. 6-8 as including an elongated shank  106  having a cylindrical mounting end portion  108  provided with an oval-shaped shoulder  110 , and a generally cylindrical opposite end portion  112  mounting a fork-shaped chisel  114  having a pair of chisel side surfaces  114   a  and  114   b,  which converge downwardly from a chiseled upper edge  114   c  to define a knife edge  114   d.  Opposite end portion  112  is separated from the mounting end portion by a round shoulder or abutment  116 . As best shown in FIGS. 6 and 7, opposite end portion  112  is provided with a flat surface  112   a  extending downwardly between shoulder  116  and chisel  114 . It will be understood that end portion  108  and oval-shaped shoulder  110  may be employed to removably mount assembly  100  on hammer  12 , as is known in the art relating to fluid-powered hammers. 
     Wedge portion  104  is best shown in FIGS. 9-12 as being of a two-part construction consisting of first and second wedge halves  120  and  122  formed with planar, oppositely-facing and downwardly convergent wedge surfaces  120   a  and  122   a;  planar, facing surfaces  120   b  and  122   b;  coplanar upper end abutment surfaces  120   c  and  122   c;  and coplanar lower end abutment surfaces  120   d  and  122   d.  Facing guide recesses  120   e  and  122   e  are arranged to open through facing surfaces  120   b  and  122   b,  respectively, and are shaped and sized to slidably engage with opposite end portion  112  for purposes of mounting wedge portion  104  for sliding movements between its first and second positions. It will be noted by viewing FIGS. 10 and 12 that recess  120   e  is formed with a lengthwise extending flat surface  120   e′,  which is arranged to slidably engage with flat surface  112   a  in order to constrain wedge portion  104  from rotation about the axis of shank end portion  112  away from its position or orientation shown in FIG. 4, wherein facing surfaces  120   b  and  122   b  are disposed parallel to a bisection plane  126  extending vertically through the chisel cutting edge  114   d.  It will also be noted that guide recesses  120   e  and  122   e  are of sufficient depth, such that they cooperate with wedge surfaces  120   a  and  122   a  to define wedge surface cut outs  130  and  132 , which extend upwardly from lower abutment surfaces  120   d  and  122   d,  as best shown in FIGS. 4,  5  and  9 . Preferably, the widths of wedge halves  120  and  122  correspond to the width of chisel  114 , as shown in FIG. 5, and the sum of the thicknesses of lower end abutment surfaces  120   d  and  122   d  is less than the maximum thickness of the upper edge  114   c  of chisel  114 , as shown in FIG.  4 . 
     After forming wedge halves  120  and  122  as separate parts, as shown in FIGS. 9 and 10, the halves are placed about end portion  112  and thereafter joined, as in welding, to form an unitary structure arranged to surround shank end portion  112  intermediate chisel  114  and shoulder  116 . 
     In use of a log splitter fitted with assembly  100 , the assembly is first mounted on hammer  12  and a log “L” then placed on support plate  26  to upstand in vertical alignment with chisel  114 , while the hammer is maintained in its upper inoperative position. Thereafter, an operator grasps handle  48  and pulls downwardly thereon to place chisel  114  in engagement with the previously positioned log “L”, as shown in FIG.  13 . Upon placement of chisel  114  in engagement with log “L”, or if desired, as an incident to downward movement of hammer  12 , lever  30   b  is operated to open valve  50  and supply pressurized air or other fluid to the hammer. Up to this point, wedge portion  104  rests in its lower or first position under the influence of gravity, wherein lower abutment surfaces  120   d  and  122   d  rest on or abut against the chisel upper edge surface  114   c,  as shown in FIG.  13 . Operation of hammer  12  with chisel  114  engaged with log “L” serves to drive the chisel downwardly into the log to first place those portions of wedge surfaces  120   a  and  122   a,  which are disposed adjacent the upper ends of wedge surface cutouts  130  and  132 , in engagement with adjacent edges  140  and  142  of the log “L”, which bound the split or opening  144  created in the log by chisel  114 . Thereafter, wedge portion  104  is forced to slide upwardly relative shank lower portion  112  until upper abutment surfaces  120   c  and  122   c  move into engagement with enlargement  116  to complete a first stage of a log splitting operation as shown in FIG.  14 . 
     Upon continued operation of hammer  12 , wedge portion  104  is forced by enlargement  116  to move further downwardly into split  144 , whereupon wedge surfaces  120   a  and  122   a  serve to progressively enlarge or increase the width of the split until a second stage of the log splitting operation is completed with the final separation of the log into lengthwise extending pieces, as shown in FIG.  15 . 
     Various further modifications in the construction of the present log splitter are contemplated without departing from the present invention. In this respect, the length of post  28  may be made adjustable, as desired to compensate for varying lengths of logs to be split, and the upper and lower links of linkage  16  may be reversed, if desired to increase the stability of the log splitter. Further, in that wedge  20  follows an arculate path when hammer  12  is supported by a parallelogram, it may be desirable, particularly when splitting longer logs, to mount support plate  26  for horizontal sliding movement in order to reduce any tendency of a log to tilt, as the wedge moves downwardly through a log. Alternately, wedge may be mounted to permit horizontal sliding displacements thereof in order to prevent tilting of a log during splitting thereof. Still further, operation of hammer  12  may be automatically controlled as an incident to vertical movement of hammer  12 . In this respect, lever  30   b  and bracket  30   c  may be dispensed with and an end of control wire  62   b  connected directly to the free swinging end of the upper link  30 , such that valve  50  is forced to open incident to movement of hammer  12  downwardly away from its inoperative position and permitted to close under the influence of spring  56 , as the hammer is returned to its inoperative position by spring  44 .