168 SCIENTIFIC AMERICAN August If), 1911
The Knight Valveless Engine By F. G. Sterling
N TH E usual autt�mobile poppet valve the poppet tests 'b eing at the same engine speed-l,200 revolu Extensive tests and experiments have been made I or mushroom valves are lifted from their seats by tions per minute. on the motor in this country, with the result that
cams and reseated by springs. In a four·cycle motor, Evidently the Daimler Company reasoned that three American firms have secured licenses. In a the valves in each cylinder are OiP ened and closed while it might be possible for a poppet valve engine few years the new motor will be as well known here once in ,two revolutions of the crank shaft. This to meet the first and second stages of the test it was as it is a:broad. intermittent movement of the valve must be pro obviously imp.ossible for such a motor to meet the The motor is not really valveless, no r is it in any duced ,by a cam and a spring mechanism. The valve final stage, i. e., to develop more power, to ,be in way akin to the two-cycle motor. Knight's invention is not closed until it is .in actual contact with its seat. better condition after continued running. After the is a mechanical or structural improvement in the Hence the valve mU8't be free to seat itself under the motor had snccess'fully withstood the test, the Daim design of the v'alve mechanism. action of the spring. Noise is produced when the ler Company was awarded the Dewar trophy and the The valve mechanisrn consists of two concentric cam strikes the valve to lift it, and also when the motor received the unqualified official indorsement sleeves sliding up ,and down between the piston and spring strikes the seat and start8 to close the valve. of the Royal Automobile Club's technical committe!), cylinder walls. Certain slots in theBe valves register This noise in itself indicates with one another at [p roper in a tendency to wear. In the tervals, producing large and usual construction ther,e is no direct openings into the 'Com way to provide for wear. Fur- bustion chamber from the ex -. thermore, neither cam nor haust and inlet ports in the spring is suitable for high cylinder. The sleeves are speed work. While the poppet operated by smll!ll connecting valves work well at low speeds, rods from a small crank shaft they are unreliable at high en or eccentric shaft running at gine speeds, and the "timing," one-half the speed of the mam or opening and closing of the shaft. valves, is uncertain. This is }<'ig. 1 shows the general ar the gravest objection to th'l rangement of the parts and poppet valve. By a radical their nomenclature. The de change in design, Charles Y. tail operations of the v'alves Knight of Chicago has produced can best be seen by a glanee at a design of valve for the four the seven diagrams comprising cycle internal combustion mo Fig. 2. In the diagrams the
tor, a design in which all th e relative positions of the inner inherent disadvantages of the and outer sleeves at various poppet valve are eliminated. pO ints in th e cycle of the For .some time !prior to 1908, motor are indicated. The Mr. Knight manufactured anrl method of reciprocating the marketed in :sm all quantities sleeves by connecting rods an automobile called the "Si from the eccentric shaft is lent Knight." The claim for shown. The eccentric shaft is silence lay in the motor. Al positively driven, by a silent though su ccessful enough, the chain, from the main .crank car, ow ing perhaps to lack cf shaft and rotates at one-half detailed refinement and the the speed of the motor. The use of the new motor, did not eccentric operating the inner appeal to the alUtomobile trade. sleeve is given a certain ad Knight, whose chief interest vance or "lead" over th at of was in the motor itself, there the outer sleeve. This lead, upon took his invention to Eng together with the rotation of land, and succeeded in inter the eccentric shaft at ha lf the esting the English Daimle:' crank shaft speed, produces Company in it. After many the cyC'le of operations. tests and further development In ·the first di.agram the pis and refinement the English ton is j-ust past its tOlp center, firm adopted it. and is starting down on its Almost immediately the en inlet stroke. The i nner sleeve gine became the subject of is at the bottom of its travel much discussion and investi and moving s,lowly Thpward, gation by British automobile the outer sleeve is about mid and technical soeieties, culmin way in its travel and is mol' ating in an exhaustive test by ing down ward rapidly. The the Royal Automobile Cluh. opening from the carburetor As a part of this test a 38 through . the inlet port into horse-power motor (4% inc]l the ,cylinder is a rapidly in bore and 5� inch stroke ) was creasing space between the run continuously for 132 hom's upper edge of the slot in the under ,a load of 54 horse-power. inner sleeve and th e lower The motor waH then placed if' edge of the sl.ot in the outer a chassis and driven for 2,001) sleeve. By the time the pis miles on the famous ton is a little more than half Bro'll: ' .of lands ,track. Next it was re Fig. 1. - Sectional view a Knight sleeve-valve motor, showing arrangement .of the parts. way down on the suctio!! turned to the testing rack and stroke th e inlet passage is run for five hours more and wide O'pen as shown in the sec developed 57 horse,p ower. Un · ond diagram of Fig. 2. The der the conditions ·of this test outer sleeve is now at the bot the load on the testing rack tom of its stroke and moving was never to be less than 1.3 very slowly, the inner sleeve times the calculated horse is gaining in speed moving power of the motor. The roa1 upward; and the inlet is closed test was to be made at a speed by the lower edge of the inner sleeve slot in passing the of not less tha I 40 miles per up hour and the final return of per edge of the outer sleeve the engine to its bench test slot, as shown in the third dia was to determine its final eon gram of Fig. 2. The inner dition. sleeve continues to move up with the piston on its com These extraordinary eondi .. Lions of the test we re insisted pression stroke, the rings in upon by the Daimler Com the head and piston tightly pany, and the final bench test sealing the eompression space, was especially desired by them. until the explosion occurs. The The reason is apparent when sleeves and piston are then in it is noted that the hors8- position shown in the fourth 1. 4. Top of 5. Exhaust opens. Exhaust open. Exhaust closes. power developed was in ex Inlet OP<'llS. Inlet open. 3. Inlet closes. 6. 7. diagram. About two-thirds of 2. compression stroke. cess of the power developed the way down on the explosion the test, ,b oth ait the start of Fig. 2.-Relative positions .of sleeves and pist.on in the .operati.on .of the Knight engine. (Continued on page 176.)
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