Choke valve structure

A choke valve structure for opening and closing an opening on an inlet side of an air inlet passage communicating with a carburetor provided in an engine, the choke valve structure comprising:

• an air cleaner body connected to the carburetor, the air cleaner body having an end wall and a suction pipe portion provided on the end wall and included in at least a portion of the air inlet passage;
• a choke valve having a valve body to adhere to a sealing surface formed around the opening;
• a movement mechanism configured to move the choke valve along a direction parallel to the sealing surface such that the valve body moves in a closing direction in which the opening is closed and an opening direction in which the opening is opened;
• a blowing back prevention plate is provided integrally with the air cleaner body, the blowing back prevention plate having a disc shape and being disposed on an axial line of the suction pipe portion to face the opening;
• and
• a protrusion provided on the valve body of the choke valve, the protrusion protruding in a direction of the axial line from the valve body and configured to come into sliding contact with the blowing back prevention plate when the movement mechanism operates and the valve body moves in the closing direction;
• wherein the valve body is pressed against the sealing surface to adhere to the sealing surface when the protrusion comes into contact with the blowing back prevention plate, the blowing back prevention plate has a contact surface on a side of the opening with which the protrusion comes into contact,
• wherein the blowing back prevention plate has a thickness which gradually increases from an upper part where the protrusion first comes into contact with the blowing back prevention plate toward a lower part where the protrusion remains in contact with the blowing back prevention plate when the valve body moves in the closing direction, such that the contact surface is inclined with respect to the direction parallel to the sealing surface to press the valve body against the sealing surface as the valve body moves in the closing direction,
• wherein the contact surface of the blowing back prevention plate having a width which is greater than the thickness, and
• wherein a diameter of the blowing back prevention plate is equal to an inner diameter of the suction pipe portion, and wherein the protrusion is configured to make sliding contact with the blowing back prevention plate along substantially an entire length of the diameter of the blowing back prevention plate.

A choke valve structure for opening and closing an opening on an inlet side of an air inlet passage communicating with a carburetor provided in an engine, the choke valve structure comprising:

• an air cleaner body connected to the carburetor, the air cleaner body having an end wall and a suction pipe portion provided on the end wall and included in at least a portion of the air inlet passage;
• a choke valve having a valve body to adhere to a sealing surface formed around the opening;
• a movement mechanism configured to move the choke valve along a direction parallel to the sealing surface such that the valve body moves in a closing direction in which the opening is closed and an opening direction in which the opening is opened;
• a blowing back prevention plate provided integrally with the air cleaner body, the blowing back prevention plate having a disc shape and being disposed on an axial line of the suction pipe portion to face the opening;
• a protrusion provided on the valve body of the choke valve, the protrusion protruding in a direction of the axial line from the valve body and configured to come into contact with the blowing back prevention plate when the movement mechanism operates and the valve body moves in the closing direction,
• wherein the valve body is pressed against the sealing surface to adhere to the sealing surface when the protrusion comes into contact with the blowing back prevention plate,
• wherein the blowing back prevention plate has a first surface on a side of the opening with which the protrusion comes into contact and a second surface on an opposite side from the first surface;
• and
• a rib for reinforcement provided on the second surface of the blowing back prevention plate, the rib extending in the opening and the closing direction,
• wherein a diameter of the blowing back prevention plate is equal to an inner diameter of the suction pipe portion, and wherein the protrusion is configured to make sliding contact with the blowing back prevention plate along substantially an entire length of the diameter of the blowing back prevention plate.