| 摘要 |
PURPOSE:To enhance the operation performance of an engine with the full opening of a secondary valve immediately after the start of the engine, by providing a solenoid valve in an atmosphere communication passage, and connecting the passage to a negative pressure passage for operating a diaphragm for opening the secondary valve, which is operated by the negative pressure at both the primary and secondary Venturi portions of a combined carburetor, so as to open the solenoid valve to keep the secondary valve from being opened when the temperature of the engine is low. CONSTITUTION:Pieces of negative pressure, which are obtained through negative pressure takeout ports 48, 50 opened into the Venturi portions of primary passage 14 and secondary passage 16 of a combined carburetor 10, are applied to the chamber 58 of a diaphragm 54 through a passage 62 to open a secondary throttle valve 38 depending on the pieces of negative pressure. An atmosphere communication passage 66 is connected to the passage 62. A solenoid valve 68 is provided for an orifice 70 in the passage 66. When the temperature of an engine is low, the solenoid valve 68 is opened to apply the atmospheric pressure to the chamber 58 of the diaphragm 54 to keep the secondary throttle valve 38 from being opened. Therefore, the secondary throttle valve 38 is not opened though a primary throttle valve is fully opened immediately after the start of the engine at the low temperature, so as to prevent the decrease in the ratio of fuel to air to enhance the operation performance of the engine. |
