Method for manufacturing a cylinder for internal combustion engine

Abstract

A method is provided for manufacturing a cylinder for an internal combustion engine, which makes it possible not only to manufacture the cylinder by a high-pressure die casting method at low cost and in high precision, but also to prevent relative misalignment among the scavenging port, suction port and exhaust port of the cylinder. This method is characterized by the steps of: preparing a cylinder liner made of an aluminum alloy pipe and provided with the scavenging port, and a bore-core die as well as cores for scavenging ducts both being uncollapsible and configured so as not to intrude into the scavenging ports; setting the cylinder liner in place in the bore-core die; and casting, by means of metal mold casting method, an aluminum alloy onto the outer peripheral surface of the cylinder liner to thereby mold a main body of the cylinder.

What is claimed is:  
     
         1 . A manufacturing method of a cylinder for an internal combustion engine provided with an inner wall-attached hollow scavenging duct having a scavenging port to be opened and closed by the movement of a piston, the method comprising the steps of: 
 preparing a cylinder liner made of an aluminum alloy pipe and provided with the scavenging port, and a bore-core die as well as a core for scavenging duct both being uncollapsible and configured so as not to intrude into the scavenging port;    setting the cylinder liner in place in the bore-core die; and    casting, by means of a metal mold casting method, an aluminum alloy as a raw material onto the outer peripheral surface of the cylinder liner to thereby mold a main body of the cylinder.    
     
     
         2 . The manufacturing method according to  claim 1 , wherein said cylinder liner is provided in advance with a suction port as well as an exhaust port in addition to the scavenging port.  
     
     
         3 . The manufacturing method according to  claim 1 , which further comprises a step of providing melt intrusion prevention means for preventing melt from entering into the scavenging port on the occasion of metal mold casting.  
     
     
         4 . The manufacturing method according to  claim 3 , wherein said melt intrusion prevention means is configured so as to prevent the generation of a step portion between the scavenging port and the scavenging duct of the main body of the cylinder.  
     
     
         5 . The manufacturing method according to  claim 3 , wherein said melt intrusion prevention means comprises a blocking member removably attached to the scavenging port.  
     
     
         6 . The manufacturing method according to  claim 3 , wherein said melt intrusion prevention means comprises a thick-walled portion or a rib portion configured to be in contact with the core for the scavenging duct and disposed all around an outer periphery of the cylinder liner excluding a lower side of the scavenging port in a manner to prevent the generation of a step portion relative to the scavenging port.  
     
     
         7 . The manufacturing method according to  claim 1 , wherein a chamfered portion is formed in advance on an inner periphery of an opening such as the scavenging port formed in the cylinder liner.  
     
     
         8 . The manufacturing method according to  claim 1 , wherein a portion of the outer peripheral surface of the cylinder liner, which contacts with the main body of the cylinder, is coated in advance with a metal having a lower melting point than that of the aluminum alloy.  
     
     
         9 . The manufacturing method according to  claim 1  further comprising preventing the generation of a step portion between the scavenging port and the scavenging duct of the main body of the cylinder.  
     
     
         10 . A cylinder for an internal combustion engine provided with an inner wall-attached hollow scavenging duct having a scavenging port to be opened and closed by the movement of a piston, the cylinder being manufactured by the steps of: 
 preparing a cylinder liner made of an aluminum alloy pipe and provided with the scavenging port, and a bore-core die as well as a core for scavenging duct-both being uncollapsible and configured so as not to intrude into the scavenging port;    setting the cylinder liner in place in the bore-core die; and    casting, by means of a metal mold casting method, an aluminum alloy as a raw material onto the outer peripheral surface of the cylinder liner to thereby mold a main body of the cylinder.    
     
     
         11 . The cylinder according to  claim 10 , wherein in the manufacturing of the cylinder, said cylinder liner is provided in advance with a suction port as well as an exhaust port in addition to the scavenging port.  
     
     
         12 . The cylinder according to  claim 10 , wherein the manufacturing of the cylinder further comprises a step of providing melt intrusion prevention means for preventing melt from entering into the scavenging port on the occasion of metal mold casting.  
     
     
         13 . The cylinder according to  claim 12 , wherein said melt intrusion prevention means in manufacturing the cylinder is configured so as to prevent the generation of a step portion between the scavenging port and the scavenging duct of the main body of the cylinder.  
     
     
         14 . The cylinder according to  claim 12 , wherein said melt intrusion prevention means in manufacturing the cylinder comprises a blocking member removably attached to the scavenging port.  
     
     
         15 . The cylinder according to  claim 12 , wherein said melt intrusion prevention means in manufacturing the cylinder comprises a thick-walled portion or a rib portion configured to be in contact with the core for the scavenging duct and disposed all around an outer periphery of the cylinder liner excluding a lower side of the scavenging port in a manner to prevent the generation of a step portion relative to the scavenging port.  
     
     
         16 . The cylinder according to  claim 10 , wherein in manufacturing the cylinder, a chamfered portion is formed in advance on an inner periphery of an opening such as the scavenging port formed in the cylinder liner.  
     
     
         17 . The cylinder according to  claim 10 , wherein a portion of the outer peripheral surface of the cylinder liner, which contacts with the main body of the cylinder, is coated in advance with a metal having a lower melting point than that of the aluminum alloy.  
     
     
         18 . The cylinder according to  claim 10 , wherein the manufacturing of the cylinder further comprises preventing the generation of a step portion between the scavenging port and the scavenging duct of the main body of the cylinder.