Patent GB-390968-A (GB)
Title: Improvements in and relating to bi-fuel vaporiser systems for internal combustion engines
IPC: F02M1/00
Filed: 1932-05-26
Abstract: 390,968. Spray carburetters; vaporizers. MERCER, A. A., 123A, Walmer Road, North Kensington, London. May 26, 1932, No. 15000. [Class 7 (iii).] In a carburetter having a heated float chamber for heavy fuel and a separate chamber for carburetting air with light fuel, a single throttle control governs the delivery into the induction tract of a light fuel combustible mixture when the throttle is completely or nearly closed and a heavy fuel combustible mixture at greater throttle openings, the light fuel mixture being cut off. Initial heating of the heavy fuel may be effected electrically, the heater being energized and de-energized under the control of the throttle as it is opened. The system includes a device, shown in Fig. 5, for supplying light fuel to a throttle chamber A, Fig. 1, disposed above a float chamber B for heavy fuel and communicating with a tubular vaporizer C which is heated by exhaust gases in passing through it to a conduit D associated with an air intake 51 and the float chamber. The spindle 3, Fig. 2, of a throttle valve 2 is bored to receive a rod 4 having a squared end adapted to support a disc 13 formed with apertures of different sizes, any one of which may be arranged to co-operate with a channel 21 according to the setting of the disc on the rod 4. Secured to the other end of the rod and angularly adjustable thereon is a crank arm 7 connected to a control arm 5 for the throttle, the control arm being itself angularly adjustable on the throttle spindle 3. When the throttle valve 2 is in the nearly closed position shown, air is sucked through an adjustable orifice 34, Fig. 5, into a chamber 37 containing fine gauze and disposed near the bottom of a petrol can, the combustible mixture thus formed passing through an outlet 35 and pipe (not shown) to a chamber 16 formed on the wall 23 of the throttle chamber and containing the disc 13 through one of the apertures in which it passes to the channel 21 and thence into the throttle passage 1. The disc 13 cuts off the light fuel supply as the throttle is opened and heavier fuel supplied. The heavy fuel is fed to a float chamber 50 past an adjustable heavy needle valve 59 controlled by a light float 63 connected to it through a lever 61 the pivot of which may be mounted on an eccentric to make the leverage adjustable from outside the float chamber. Air is drawn in past a butterfly valve 91 in the air intake 51 to a bowl-shaped depression 52 surrounding a fuel nozzle 70. The butterfly valve 91 is connected to the control arm 5 of the throttle 2 by an arm on the butterfly valve which is shorter than the control arm 5 and linked to it by a rod with which the arm 5 has a resilient sliding connection, the arrangement constituting a lost motion device which keeps the butterfly valve closed at the commencement of the throttle opening, then opens it rapidly to its full position before the throttle itself is fully opened. Normally, exhaust gases in the conduit D heat the fuel in the float chamber but before the throttle is sufficiently opened to permit of this being adequately achieved, an electric resistance coil 111 mounted between a central electrode and the body of a plug 110 is switched on by a control associated with the throttle, the ends of the coil being connected to brushes 115 adapted tb engage conducting segments 114 on a disc on the throttle spindle 3. The heater warms the fuel as it passes to the nozzle through a passage 65 formed in a depending cylindrical extension 53 of the bowl 52. The passage 65 opens into a circumferential groove 78 in a member 77 and the groove is connected by a radial passage with a central bore 79 the opening of which is controlled by an adjustable needle valve 81 which is mounted in a quick threaded sleeve 83 provided with a handle 87 whereby it may be temporarily lowered to flush the nozzle for cleaning purposes. The member 77 has a conical top which engages with small clearance an upper member 72 similarly formed with a circumferential groove and radial passages opening into the central channel, these conduits supplying the nozzle through passages 66, with any light vapours evolved from the fuel. Further opening of the throttle cuts out the heater 110. The air carburetted by the heavy fuel passes to the vaporizer which comprises tubes 101, through which the exhaust gases pass, mounted between endplates 102 secured in a casing 100, the combustible mixture passing around the tubes and being maintained in close contact therewith by a heat-retaining baffle 107 having apertures only slightly larger than the tubes 101. The baffle may be slid along the tubes to facilitate cleaning.