Auto chain tensioner

Abstract

The invention relates to an auto tensioner of a chain saw. A spiral guide groove ( 16 ) of the disk ( 15 ) engages with a protrusion 10 a of a slider piece ( 10 ) and the slider piece ( 10 ) is slidably stored in a guide portion ( 9 ) formed in a chain cover ( 2 ) via a spring ( 14 ). A tensioner ( 11 ) comprising a protrusion ( 11 ) engaged with a guide bar is slidably stored in the slider piece 10 via a coin spring ( 12 ). The protrusion ( 10 a ) contacts an outer circumference face of the spiral guide groove on a diameter passing through a rotating center of the disk, and an unshown nut for engaging with a stud bolt 6 provided on an engine cover side is attached on the rotating center of the disk ( 15 ). A rotation of the disk enables to fix the chain cover ( 2 ) and move the guide bar.

1 - 15 . (canceled) 
   
   
       16 . A chain saw comprising:
 a guide bar for providing a tension or a relaxation to a saw chain running along the guide bar;   chain cover fixing means for pressing and holding the guide bar between an engine case and a chain cover and for fixing the chain cover to the engine case;   a contact face of the guide bar which contacts at least one of the engine case and a contact face of the chain cover to increase the friction at the contact face;   a slider piece which is disposed at one of the places between the chain cover and the guide bar and between an engine cover and the guide bar, and slides linearly in a back and forth moving direction of the guide bar for providing the tension or a relaxation to the saw chain; and   a tensioner which is connected to the slider piece via a spring and is slidable in a sliding direction of the slider piece;   wherein the chain cover fixing means further includes a sliding mechanism for allowing one of the slider piece and the tensioner to slide in the back and forth moving direction of the guide bar; and   wherein the other one of the tensioner and the slider piece is engaged with the guide bar.   
   
   
       17 . A chain saw comprising:
 a guide bar for providing a tension or a relaxation to a saw chain running along the guide bar;   chain cover fixing means for pressing and holding the guide bar between an engine case and a chain cover and for fixing the chain cover to the engine case;   a slider piece which is disposed at one of the places between the chain cover and the guide bar and between an engine cover and the guide bar, and slides linearly in a back and forth moving direction of the guide bar for providing the tension or a relaxation to the saw chain; and   a tensioner which is connected to the slider piece via a spring and is slidable in a sliding direction of the slider piece;   wherein the chain cover fixing means further includes a sliding mechanism for allowing one of the slider piece and the tensioner to slide in the back and forth moving direction of the guide bar;   wherein the other one of the tensioner and the slider piece is engaged with the guide bar; and   wherein a wedge face is formed where the contact face of the guide bar contacts with at least one of the engine case and the chain cover.   
   
   
       18 . A chain saw comprising:
 a guide bar for providing a tension or a relaxation to a saw chain running along the guide bar;   chain cover fixing means for pressing and holding the guide bar between an engine case and a chain cover and for fixing the chain cover to the engine case;   a slider piece which is disposed at one of the places between the chain cover and the guide bar and between an engine cover and the guide bar, and slides linearly in a back and forth moving direction of the guide bar for providing the tension or a relaxation to the saw chain; and   a tensioner which is connected to the slider piece via a spring and is slidable in a sliding direction of the slider piece;   wherein the chain cover fixing means further includes a sliding mechanism for allowing one of the slider piece and the tensioner to slide in the back and forth moving direction of the guide bar;   wherein the other one of the tensioner and the slider piece is engaged with the guide bar; and   wherein said chain cover fixing means comprises one or more fixing portion of the chain cover for enabling to fix the chain cover at plural portions in conjunction with operation of the chain cover fixing means in the chain cover.   
   
   
       19 . A chain saw comprising:
 a guide bar for providing a tension or a relaxation to a saw chain running along the guide bar;   chain cover fixing means for pressing and holding the guide bar between an engine case and a chain cover and for fixing the chain cover to the engine case;   a slider piece which is disposed at one of the places between the chain cover and the guide bar and between an engine cover and the guide bar, and slides linearly in a back and forth moving direction of the guide bar for providing the tension or a relaxation to the saw chain; and   a tensioner which is connected to the slider piece via a spring and is slidable in a sliding direction of the slider piece;   temporary fixing means for temporarily fixing the guide bar to the engine case so that a fixing face of the guide bar is in parallel with a fixing face of the engine case;   wherein the chain cover fixing means further includes a sliding mechanism for allowing one of the slider piece and the tensioner to slide in the back and forth moving direction of the guide bar; and   wherein the other one of the tensioner and the slider piece is engaged with the guide bar.