Cylinder and manufacturing method therefor

Abstract

A cylinder minimizes the friction between an inner peripheral surface of a cylinder bore and a piston by substantially providing no plating on a portion of the inner peripheral surface of the cylinder bore where a cross sectional configuration of the inner periphery of the cylinder bore is prone to deform and which does not interfere with a predetermined operation performed in cooperation with a piston that reciprocates in slidable contact with the inner peripheral surface of the cylinder bore.

What is claimed is:  
     
         1 . A cylinder in which the friction between an inner peripheral surface of a cylinder bore and a piston is controlled to a minimum possible level by decreasing the thickness of a plating layer on a portion of an inner peripheral surface of a cylinder bore where a cross sectional configuration of the inner periphery is prone to deformation and which does not interfere with a predetermined operation performed in cooperation with a piston that reciprocates in slidable contact with the inner peripheral surface of the cylinder bore.  
     
     
         2 . A cylinder in which the friction between an inner peripheral surface of a cylinder bore and a piston is controlled to a minimum possible level by substantially eliminating a plating layer on a portion of an inner peripheral surface of a cylinder bore where a cross sectional configuration of the inner periphery is prone to deformation and which does not interfere with a predetermined operation performed in cooperation with a piston that reciprocates in slidable contact with the inner peripheral surface of the cylinder bore.  
     
     
         3 . A cylinder having an inner peripheral surface of a cylinder bore thereof furnished with plating, wherein a portion of the inner peripheral surface at an opening end of the cylinder is substantially formed of a non-plated portion.  
     
     
         4 . A cylinder which has an inner peripheral surface of a cylinder bore thereof furnished with plating, and slidably receives a piston from an opening end portion thereof, wherein a portion of the inner peripheral surface of the opening end portion is substantially formed of a non-plated portion so as to allow an annular clearance between the inner peripheral surface and a skirt of the piston that is located lower than the position of a piston ring when the piston is at bottom dead center.  
     
     
         5 . A manufacturing method for a cylinder having a non-plated portion, comprising: 
 a step of disposing an electrode, which is composed of an insulator and has a partial mask, so that the electrode opposes an inner peripheral surface of a cylinder bore;    a step for passing electric current from the electrode to the cylinder; and    a step for supplying a plating solution between the electrode and the inner peripheral surface of the cylinder bore.    
     
     
         6 . A manufacturing method for a cylinder having a non-plated portion according to    claim 5   , wherein the electrode is provided with masking so as to form a non-plated portion at the opening end of the inner peripheral surface of the cylinder bore.  
     
     
         7 . A plating method for a cylinder, comprising: 
 a step of disposing an electrode, which is composed of an insulator and has a mask, at a position of an inner peripheral surface of a cylinder bore, where no plating is required, such that the electrode opposes the inner peripheral surface of a cylinder bore;    a step for passing electric current from the electrode to the cylinder; and    a step for supplying a plating solution between the electrode and the inner surface of the cylinder bore.    
     
     
         8 . A plating apparatus for a cylinder, comprising: 
 a detachable anode that has a mask composed of an insulator and is disposed at the position of a portion of an inner peripheral surface of a cylinder bore, the portion requiring no plating, so that it opposes the inner peripheral surface of the cylinder bore;    a cathode electrically connected to the cylinder; and    a plating solution supplied between the anode, which is inserted so that it opposes the inner peripheral surface of the cylinder bore, and the inner peripheral surface of the cylinder bore.