Small engine and engine work machine including the same

摘要

An engine includes: a carburetor configured to supply an air-fuel mixture of fuel and air; a crank case defining a crank chamber; a cylinder block which includes: a cylinder bore in which a reciprocable piston is disposed; and an intake port which supplies the air-fuel mixture supplied from the carburetor to the crank chamber; a control valve configured to open and close the intake port; and a controller configured to control the control valve. The controller controls the number of times that the control valve closes the intake port with respect to the number of times that the piston moves up to thereby reduce pressure of the crank chamber.

主权项

1. An engine comprising:
a carburetor configured to supply an air-fuel mixture of fuel and air; a crank case defining a crank chamber; a cylinder block including:
a cylinder bore in which a reciprocable piston is disposed; andan air-fuel mixture passage communicating the carburetor with a combustion chamber of the cylinder block to supply the air-fuel mixture from the carburetor to the combustion chamber; a magnetic flux generator including a coil and being configured to generate a magnetic flux by applying a current to the coil, the application of the current to the coil starting when the pressure at the cylinder bore is equal to or greater than the pressure at the carburetor; and a reed valve configured to open the air-fuel mixture passage and close at least a part of the air-fuel mixture passage in response to the pressure difference between pressure at the carburetor and pressure at the cylinder bore and configured to maintain an at least partial closure of the air-fuel mixture passage while the current is applied to the coil.