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The Vivinus Patent Piston Ring.

4th November 1915
Page 10
Page 10, 4th November 1915 — The Vivinus Patent Piston Ring.
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Which of the following most accurately describes the problem?

Details of a New Invention which has already been Mentioned Briefly in "The Commercial Motor."

In August last we intimated in our columns that a distinguished Belgian engineer of great experience had, during his present sojourn in this country, perfeeted an entirely new form of piston ring, and, although we were not then at liberty, owing to the restrictions imposed during the completion of patent formalities, to divulge particulars of the invention, we were enabled to put a number of interested people into touch with the inventor there and then.

We have now been afforded permission to illustrateand describe the new idea without restriction.

The drawings reproduced herewith will convey to many of our readers the principle which has been adopted by the inventor, who, by the way, is Monsieur Vivinus, a name well-known in connection with engine and chassis design in the Belgian factory which he owned previous to the German occupation. Piston-ring design has, in so far as its application to the smaller types of internal-combustion engines is concerned, remained at a standstill whilst so many other features of the motor have been improved and transformed out of knowledge. The eccentric split east-iron ring has held its own almost. unchallenged for many years past. This type of construction has also, of course, been found sufficient for many larger steam, gas and oil engines, although many patent devices have been adopted in connection with bigger prime-mover units and those in which the pressures have been exceptional.

It will be seen that M. Vivinus has adopted a design of which perhaps the principal advantage is the considera,ble saving in weight effected not only in connection with the rinft, but with that part of the casting which houses it. Two rings only a,re used for each piston, and these are made of phosphor-bronze. The two are superimposed, with their cuts opposed. The relative positions of the cuts are retained by slight indentations in the rings. The Cross section of the rings themselves is clearly shown in the illnstra,tion accompanying the present notes. The shqpe is of such a nature that it is obvious that the gas leaking up to the rings will press them jointly outwards on to the cylinder walls as well as into their own housings. It is claimed by the inventor that "the contact surface is small and the friction on the cylinder walls is reduced to a minimum." It is to be remembered, of course, in this connection, that. the amnen+ of friction is not dependent on area in contact. M. Vivinus has at his disnosal data which go to sunnort his claims as compared with the ordinal, cylindrical ring these claims include saying of weight, cheapness of produc

B36 tion, better gas-tightness, higher efficiency, and freedom from breakage.

It is an interesting development, and we shall watch with care the results which may be achieved by any engine builders who decide to experiment with it. It would appear, however, in the absence of our own practical experience, that, quite apart from how the pressure Abetween cylinder wall and piston ring, is secured, to preventeleakage, the tightness of the ring must be the same, whether it be of the ordinary cylindrical or the new Vivinus cross section. That implies that the net frictional loss must he the same, so that if the areas in contact be reduced, it is difficult to sec how greater wear is to be avoided, owing to the higher incidence of pressure per square inch as betweentring and wall.

Obviously two sets of rings cannot be employed on any one cylinder, as no pressure would be available to operate the lower pair. If one pair of Vivinus rings be found sufficiently gas-tight for one piston, why should not one nair of equally tight cylindrical rifles be found equally satisfactory.

There may be a small increase of efficiency in the case of the Vivinus device, on account of the lessening of pressure between rings and cylinder walls at all times other than the explosion stroke. It is questionable, however, if, mechanically, the rings could respond to the changes with suffi_eient delicacy.

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