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Thermo-static-electric Control for a Two ' fuel Carburetter. .
The Haddon vaporizer, as-described in. this journal in our issue of the 5th October last, incorporated an ingenious system of pneumatic control. • That .control Was Chiefly notable for the fact that the time of commencing to use paraffin as a fuel Was automatieallydetermined by the aid of -a•thermostat, which cut off the petrolSupply and turned on the larallin so Soon as the engine reached a pre-arranged temperatnre. This was undcrubtedly A desirable feature, but already, at the time of our previous de' seription it was realized that it did not go far enough, The driver had atill to be warned that in the _event of a considerable period of slow running, due to delays in .traffic or similar cause; he would be Well advised to turn, off the paraffin and rim the engine of his Vehicle for a time on the lighter-fnel. This-disability is removed by the invention DE M. Constantinesco, Which is now' made public in Patent specification 107,411. In:the-new design the-control is again everciaed by a thernicistat).but it is now effected electrically, -.instead _of ,prieu • rnatically. Two electro-magnets are to 'arranged that When both are energized petrol is cut off and paraffin is admitted to the engine_ .Further, in combination with this ikan automatic air valVe which operates to cutoff the supply of paraffin. -vapour from the engine when the latter is running slowly and with littIe suction. The principal item of interest, the thermostat, is' shoWn ir the left-hind half of' the drawing herewith The elvotri,e battery is indicated in the usual manner, and appears below the petrol float chamber. The arrangement of the circuits for the electric current may be gathered from the drawing. It will be noted•tbat thew are three terminals on the thermostat. 'The lowest of them is connected trithe battery as soon as the engine suction is sufficiento to lift the automatic air valve, Whieli wheri it lifts allows of contact being‘ made between two ,paints in this ..circuit which are otherwise .held open. Of the other two . contacts on the thermostat, that on the right is a little lower in its point of communication-with the interior of that instrument than the one on the left,
although the latter is apparently on a. level with it. That terminal on the right, which, as we have stated, is the lower of these two, is in connection with that electro-magnet which, when energized, opens the valve which controls the paraffin supply to the vaporizer. The left-hand, or top terminal, is connected to the magnet, and, when energized, closes the valve, which in a similar manner supplies petrol to the engine.
When the engine is stopped, but ready to start, '-all the electric circuits are opeli and no currentrflows. Consequently, since neither magnet is energized, the paraffin is cut off and the petrol valve is open. The engine can Atherefore be started, on a C rich mixture of petrol. Almost immediately the automatic valve opens, andadmits additional f warm air from the vaporizer, which, however, contains as yet no paraffin. As the engine warms up, the mercury in the thermostat rises; and when a predetermined tern-, perature is reached, it completes the cir cult Le the-mv'oiet on the parafllmsupply -valve,. and thus opens it. From that time on, the engine runs on, a mixture or tb.e two fuels As the temperature
furthe, increases, however, the top terminal of the thermostat enters into play, and operates to cut off the petrol supply.
The principal advantage of the arrangement will now be realized, that . if for Some cause or other the temperature of the engine is so lowered that it becomes too cool to allow the less volatile fuel to be properly vaporised, the mercury of the thermostat falls and the reverse operation to that just described takes place, namely, pet/ is, after a certain drop in temperature, admitted to the engine so that the latter runs on two fuels, and if the temperature drops still further, the paraffin is cut off altogether, so that petrol becomes the only fuel in use.
An Auxiliary Magneto for Facilitating the Starting of Large Engines.
The patent which is disclosed in speci-. fication number 107,309, by Siemens Bros. and Cu., Ltd,, of Caxton House, Westminster, is really, in the first instance, meant to apply to aeroplane engine construction. It is nevertheless of sufficient interest to justify its inclusion in these columns. It is well-known that one of the difficulties in connection with the starting of large engines is that they cannot be revolved at a speed. high enough to cause the magneto to give a spark which will ignite the mixture. Various means have been tried and' are . in use to mitigate these circumstances, all of them being more or less suitable for the purpose. in view. The special advantages claimed for the device Under consideration are, that it avoids the necessity for any considerable amount of extra wiring, that,it does not require a main magneto of special or unusual construction, that it needs no batteries, nor
any extra timing or similar gearing. .
It involves the use only of a small auxiliary magneto which may be revolved by hand. The arrangement is shown in the drawing which we publish on this page, the main magneto is represented diagrammatically by the rectangular figure, the' auxiliary one by that contained within the circle. The individual parts of the noagn.etos are represented in the usual manner on these diagrams, arid, as shown, if the auxiliary magneto be operated, a primary or low tension, cnrrent, which is all that this machine Provides, circulates from , its armature
through the interrupter, switch, the in terrupter (or contact-breaker) of the main magneto, and through earth back to the armature again. It should be noted that the interrupter of the, small magneto operates at a fairly high speed. As the engine is at the same time also
• being slowly revolved, the contactbreaker on the main magneto is opened in the usual manner when the correct instant for a spark at a plug arrives._ With the interrupter on the main magneto open, the path of the current from the small one is as follows: _From earth to the armature of this auxiliary magneto, thence through interrupter and switch to the armature of the main .component, where it excites the secondary winding 'and produces a succesSion of
sparks' at the sparking plug. .