US 7,467,739 B2
Combustion-powered, fastener-driving tool generating sparks in succession when triggered
Haruhisa Fujisawa, Hitachinaka (Japan); Yoshitaka Akiba, Hitachinaka (Japan); Nobuhiro Takano, Hitachinaka (Japan); Kenro Ishimaru, Hitachinaka (Japan); and Tomomasa Nishikawa, Hitachinaka (Japan)
Assigned to Hitachi Koki Co., Ltd., Tokyo (Japan)
Filed on Sep. 29, 2005, as Appl. No. 11/237,860.
Prior Publication US 2006/0065690 A1, Mar. 30, 2006
Int. Cl. B25C 1/08 (2006.01)
U.S. Cl. 227—10  [227/2; 227/156; 227/9] 14 Claims
OG exemplary drawing
 
1. A combustion-powered, fastener-driving tool comprising:
a housing;
a cylinder fixedly disposed in the housing;
a combustion chamber disposed on top of the cylinder, the combustion chamber accommodating a gaseous mixture of existing air in the combustion chamber and fuel injected therein;
a spark plug that is disposed in the combustion chamber and generates a spark to combust the gaseous mixture in the combustion chamber;
a trigger that produces the spark in the spark plug when operated;
a piston movably supported in the cylinder and driven by combustion in the combustion chamber;
a driving blade coupled to the piston for driving a fastener;
a spark controller that generates a plurality of sparks in succession with the spark plug; and
a temperature sensor that detects a tool temperature that is primarily increased by heat generated in the combustion chamber;
wherein the spark controller varies the number of sparks generated in the spark plug based on the temperature detected by the temperature sensor so as to provide at least one spark.