Method and apparatus for control of engine idling circuit
FIELD OF THE INVENTION 
     The invention relates to a circuit for controlling fuel consumption in an engine with a carburetor. 
     BACKGROUND OF THE INVENTION 
     Known engine carburetors contain an idling circuit which operates at starting and during idle speed of the engine, but is not needed during normal driving conditions. There are situations during normal driving conditions, however, when high vacuum pressure in the manifold drastically increases fuel consumption from the idling circuit even though the engine does not require extra power. Such situations include deceleration from high speed, driving on a downward slope, shifting gears, applying the brake, or releasing the accelerator pedal. In these cases, fuel is wasted and additional air pollution results. 
     It would therefore be advantageous to disable the idling circuit when the engine is running at speeds in excess of idle. If this is accomplished, fuel can be conserved, and air pollution minimized. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a means for disabling the idling circuit of a carbureted engine to thereby conserve fuel and minimize air pollution. 
     The present invention accomplishes this object by a control circuit responsive to engine speed which activates a solenoid valve for blocking the idling circuit whenever engine speed exceeds a preset value. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     With these and other objects in view, which will become apparent in the following detailed description, the present invention, which is shown by example only, will be clearly understood in connection with the accompanying drawing, in which: 
     FIG. 1 is a schematic diagram of a closed circuit according to the invention under the control of a tachometer; 
     FIG. 2 is a view similar to FIG. 1, but showing an open circuit; 
     FIG. 3 is a schematic diagram of a closed circuit according to the invention under the control of the high tension wire of the engine&#39;s ignition system; 
     FIG. 4 is a view similar to FIG. 3, but showing an open circuit; 
     FIG. 5 is a schematic diagram of a closed circuit according to the invention under the control of the platinum contact of the engine&#39;s ignition system; 
     FIG. 6 is a view similar to FIG. 5, but showing an open circuit; 
     FIG. 7 is a cross sectional schematic view of the solenoid valve of the invention with the idling circuit enabled; 
     FIG. 8 is a cross sectional schematic view of the solenoid valve of the invention with the idling circuit disabled; 
     FIG. 9 is a cross sectional schematic view of an embodiment of the inventive solenoid valve suitable for installation in a motorcycle; 
     FIG. 10 is a view combining aspects of FIGS. 3 and 7; and 
     FIG. 11 is a view combining aspects of FIGS. 4 and 8. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The inventive concept of the present invention is illustrated herein by reference to three preferred embodiments, namely a tachometer controlled circuit, a high tension controlled circuit, and a platinum contact controlled circuit. Each circuit has the object of activating a solenoid valve in the idling circuit of a carburetor in accordance with engine speed. 
     Referring generally to FIGS. 1 and 2, a tachometer controlled circuit includes a control plate 17 in the tachometer (not shown) which responds to engine speed, i.e. needle movement of the tachometer. The control plate has an extended portion 18 which block light transmitted by LED from being sensed by optical sensor 20. When the engine speed is below a preset value, the extended portion 18 of plate 17 blocks the sensor 20 and thereby (via amplifier 21) closes the contacts A and B of relay 22. When engine speed is higher than the preset value, the extended portion 18 of plate 17 is rotated out of position allowing light from LED 19 to reach sensor 20 which, via amplifier 21 causes relay 22 to open the A - B contact. See FIG. 2. The relay 22 controls power to the solenoid discussed in detail hereinbelow. 
     Referring now to FIGS. 3 and 4, a high tension wire induction-type controlled circuit includes a coil 14 installed on the high tension wire 15 of the engine&#39;s ignition coil. Thereby, a current is induced in coil 14 whenever high tension is present in wire 15. The induced signal results in a positive current when the engine speed is lower than a preset value and thereby closes the contact A - B by way of the circuit shown in FIG. 3. When the engine speed is higher than a preset value, positive current to the solenoid S is cut off as shown in FIG. 4. 
     FIGS. 5 and 6 show a circuit for platinum contact control of solenoid S. This circuit utilizes the platinum contact P (negative terminal) of the engine&#39;s high tension ignition coil. The circuit provides positive current to solenoid S, when the signal supplied by the platinum contact is smaller than a preset value. When the engine speed is increased. the signal supplied by P reaches VR1, a preset value, and the circuit cuts off positive current to the solenoid valve S. 
     The idling solenoid valve according to the invention is shown by way of example in FIGS. 7 and 8. The valve is preferably installed at the passage of the idling circuit 11 of the carburetor, at the idle adjustment screw 3. When one of the circuits described above supplies current to contact S of coil 6, the adjusting screw 3, shown in FIG. 7, becomes magnetic and absorbs the spindle 2 so that there is no obstruction in the idling circuit. When the power to coil 6 is cut off, adjusting screw 3 is no longer magnetic and spindle 2 is pushed back in position by spring 5, as shown in FIG. 8. The gap between the spindle 2 and the idling nozzle 11 (FIG. 7) can be adjusted by screw 3, which serves as idle adjustment for the carburetor. 
     Thus, the solenoid valve keeps the idling circuit working when the power is on and disconnects the idling circuit when the power is off. 
     When the invention is in a motorcycle carburetor, an arrangement as shown in FIG. 9 can be used. In this embodiment an oil resistant rubber cap 2A can be provided on the tip of spindle 2 to enhance its sealing ability in blocking the idling circuit. 
     A preferred embodiment of the invention, shown in FIGS. 10 and 11, operates as follows: 
     Idle speed can be set at 600 rpm and the preset value at which the solenoid is activated can be set for 1200 rpm. When the ignition switch is turned on, positive current flows from D to A, B, and then S. There is an induction in coil 6 and the adjusting screw 3 becomes magnetic and attracts the spindle 2 to maintain the idling circuit so that the engine may be started and idle at the set idle speed. 
     When the engine speed is increased, the signal provided by P eventually reaches a value corresponding to the preset value at VR1. When the signal at P exceeds the value preset at VR1, the relay operates to disconnect A and B and power to the solenoid valve is cut off. The adjusting screw is no longer magnetic and no longer attracts spindle 2. Spindle 2 is forced by spring 5 to close the opening 11 of the idling circuit of the carburetor (FIG. 11). Thereafter, as long as engine speed remains above this preset limit, no fuel will be absorbed through the idling nozzle regardless of the vacuum in the manifold. 
     When the engine speed slows down to below the preset limit, the signal at P falls below the level preset at VR1, the relay stops operating, and current is restored to coil 6. The idling circuit is restored to function and keep the engine running at normal idling speed. 
     Although the invention is described and illustrated with reference to a plurality of embodiments thereof, it is to be expressly understood that it is in no way limited to the disclosure of such preferred embodiments but is capable of numerous modifications within the scope of the appended claims.