An Improved Carburetter 6 Easy-starter " '1 1 1-1E success of certain carburetters
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of the type incorporating a separate device for supplying rich mixture for starting from cold, is sometimes marred by the carelessness of the driver. It is found that he may forget to put the device out of operation after the engine has started, or may use it unnecessarily when the engine is hot.
To overcome this weakness, Solex, Ltd., 223-231, Marylebone Road, London, N.W.1, has introduced a new carburetter of its well-known " selfstarting" type, which incorporates an ingenious thermostatic device that automatically performs the operation hitherto done by the driver.
A valve, incorporated in the carburetter body, puts the easy-starting part of the instrument into and out of communication with th5 induction pipe. It is operated, through a diaphragm, by engine suction, and controlled by a thermostatic valve attached to the exhaust manifold. The accompanying drawing, which shows the parts concerned in section, will enable the system to be understood.
The actuating element of the thermostat is a bimetal strip, held at one end by a spring-loaded fixing, and bearing against an adjustable screw which acts as a fulcrum. Its other end 1384 carries a valve that closes the orifice of a tube, communicating with the carburetter, when the temperature of the manifold rises. In this manner the " starter" is put out of action and remains inoperative until the engine cools and th.e element straightens out.
Referring to the carburetter part of the device, it will be seen that the connecting tube terminates here in a chamber, one wall of which is formed by a diaphragm. To the last-named is attached the horizontal stem of a mushroom-type valve. The " selfstarting " jet, etc., is seen below this valve and the small air-intake orifice immediately above it. When the valve is open, as shown, these are put into communication with the induction pipe, via a vacuum chamber. A passage —shown dotted—leads from the vacuum chamber to the diaphragm chamber.
When starting a cold engine, initial suction opens the mushroom valve, the depression behind the diaphragm chamber being negligible, as air can enter by the connecting tube. So :iron as the thermostatic element heeds, however, the orifice of the tube is closed, a vacuum is created in the diaphragm chaniber, and the mushroom valve (of smaller area than the diaphragm) is closed.