A New Petrol-Electric System.
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Particulars of "L'Auto Mixte" Vehicles Constructed by Messrs. Pieper of Liege.]
Members of the Press were on Friday, the 23rd ultimo, invited to make an inspection of a new bus chassis, manufactured at the works of Messrs. Pieper, of Liege, which is being put on the market by Messrs. Johnston and Phillips,
of Charlton, Kent. This particular make of chassis has been named " L'Auto Mixte," and, after a thorough inspection of the whole system, we are able to state that many practical and novel points have been incorporated in the construction of this new commercial vehicle. The motive power is derived from a petrol engine in conjunction with an electrk motor. Transmission is by an electric clutch, and cardan shaft to the back axle, which carries the differential gearing. No gear box is used for the different speeds. The petrol engine and the motor are placed in the fore-part of the frame. This electric motor is of special design and construction, and is situated directly at the back of the engine, and its armature is carried on an extension of the crankshaft. The usual objectionable characteristic of a petrol engine, viz., the necessity of turning a crank when starting up, is obviated by the utilisation of a set of accumulators, which, when connected up with the motor, give the power necessary for the first few revolutions, and in this way the initial movement of the vehicle is made without any of the shocks or jars so frequently obtained in the heavy petrol vehicles at present on the streets.
The engine has four cylinders of 'comm. stroke and bore, and mechanically-operated valves ure
employed. Ignition is by make-and-break contact, producing -a spark of varying intensity in the cylinders. The spark is varied by increasing or diminishing the self-induction of a coil, and its temperature is higher in proportion as the piston speed is greater and demands a more rapid ignition of the mixture. Cooling is on the thermo-syphon principle, with a radiator, behind which is fitted a fan. The carburetter supplies the engine with a constant mixture, and this is admitted and controlled by an electro-magnetic regulator. The revolutions of the engine are limited by the dynamo (or motor), which it drives. The crown of the electro-magnetic dutch is bolted to the extension of the crankshaft behind the dynamo, and acts as a fly-wheel.
The dynamo (or motor) is of the four-pole type with series drum winding and shunt excitation ; it has auxiliary commutator poles with series winding. The use of the auxiliary poles allows of a variation of between 400 and r,600 revolutions per minute; the same speed as that of the petrol engine which drives it. The variation in speed is obtained by a controller, which is also used for the electric brake and the reverse speed. The latter is purely electric, and the engine is not used at all.
The battery of accumulators consists of 24 cells connected in series, and specially designed to supply heavy currents without deteriorating. It gives out approximately so volts, and the various parts, including the clutch, brakes, and lighting, are designed to work at this voltage. The battery drives the vehicle only when starting, or when the engine speed falls below a predetermined point. The carburetter is a Longuernare of the usual pattern with a float feed, but the mixture admission valve is controlled automatically by the action of a soft iron cone suspended to a spring, and placed in a solenoid with two windings. The tension of the spring is so regulated that when the accumulators are fully charged the dynamo neither produces nor absorbs current, and the petrol engine develops just the necessary power to drive the vehicle at the normal speed. The clutch consists of an iron disc, the surfaces of which are face to face with two crowns, also of iron. One of these is moveable, and keyed to the end of the dynamo shaft, whilst the other is fitted to the framework of the chassis. Each of the crowns has a magnetising coil through which an electric current can be made to pass. The central iron plate is drawn into contact either with the crown on the dynamo shaft (forming the clutch), or with the one placed in the frame (making the brake), according to the position of a small controller. In the course of a recent report Mr. W. Worby Beaumont,
M.I.C.E., M.I.M.E., M.I.E.E., says The trial runs in Belgium were made with the road's in very bad condition, and offering, a rolling resistance of, as I estimate, from 6o1b. to651b. per ton as compared with from 441b. per ton with roads in good and average condition. The runs on the first day were from Liege to Tillf and Esneux—a run which included a long hill with some steep stretches—and on the second day from Liege to Oise, near the Holland frontier, on worse roads but less hilly." Mr_ Beaumont, in continuation, remarks that :—" I made a further trial run of a fourseated car from London to Reigate, up the long Reigate Hill as a test of the sustaining power of the buffer battery. After carefully considering the design, construction, and the results of all these trial runs, I am of opinion that the Pieper system is one of great importance for all kinds of road motor vehicles."
The whole design of the chassis is interesting, and any vehicle which will run efficiently without the necessity for the usual gear box, ought to be welcomed by the omnibus engineer and proprietors alike. The designer and makers have been able to secure a simple transmission, and, cornpared with an ordinary chassis of the same power, thisvehicle is approximately the same weight.
L'Auto Mixte was shown at the last French Salon, where it attracted much attention, Its elasticity, quiet running, and general efficiency have been satisfactorily demonstrated tinder varied conditions.