US2713851A - Crank shaft and piston assembly for internal-combustion engine - Google Patents

Description

July 26, 1955 c. o. TROUT CRANK SHAFT AND PISTON ASSEMBLY FOR INTERNAL COMBUSTION ENGINE Filed May 1, 1952 INVENTOR. CLARE/v05 o. 'r/eoz/r BYWMW CRANK SHAFT AND PISTON ASSEMBLY FOR INTERNAL-COMBUSTION ENGINE Clarence 0. Trout, Detroit, Mich. Application May 1, 1952, Serial No. 285,516

2 Claims. (Cl. 121-120) This invention relates to internal combustion engines of the opposed type having cylinders that are diametrically oppositely disposed with reference to the axis of the crank shaft.

An object of this invention is to provide a crank shaft and piston assembly for such an engine, which greatly improves the running balance and which eliminates the reciprocating out-of-balance, which inherently exists in such an opposed type of engine.

Various attempts have heretofore been made to solve the problem. The patent to Burtnett, No. 1,764,147, is indicative of the prior art. In the Burtnett disclosure, however, a two stroke cycle engine is utilized, in which only one half of the pistons employed are power pistons, the other half being employed as counterbalances and for compression purposes. It will be clearly understood therefore, that in the within disclosure all of the pistons indicated are power pistons.

In this disclosure, the applicant is not concerned with rotary out-of-balance, but is directing his attention to the elimination of out-of-balance, which results from the reciprocation of the pistons.

It has been, and now is, the general practice in the building of internal combustion engines, to utilize pistons which all have the same weight, within a very low manufacturing tolerance. I therefore propose to change such practice and to provide an opposed piston type of engine, in which the weights of the individual pistons are so varied and arranged, that in effect I have two sets of pistons, which are different in so far as weight is concerned. In my invention one half of the pistons are deliberately made heavier than the other half. The difference in weights and the disposition of the pistons along the crank shaft being such that the heavier pistons produce an unbalanced couple equal to two of the adjacent couples formed by two of the lighter pistons, and a portion of each of the heavier pistons. The pistons are arranged and weighted in accordance with the formula:

as more fully explained hereinafter. I thus retain the principal portion of all of the reciprocating out-of-balance Within the crank shaft structure, thereby reducing crank shaft bearing stresses, as well as greatly reducing the noise and vibration, and stresses throughout the whole of the engine structure.

Because of the construction and arrangement hereinabove indicated, an engine embodying my invention can be run at a much higher speed and with greatly increased efficiency, and with less noise and vibration, in as much as the principal cause of reciprocating out-ofbalance and its attending results is eliminated at or near its origin.

The foregoing and other objects and advantages of the invention will become more apparent as the description proceeds, reference being made from time to time to the accompanying drawing forming part of the within disclosure, in which drawing:

nited States Patent or any position therebetween,

"ice

Fig. l is a diagrammatic view of an internal combustion engine crank shaft and piston assembly embodying my invention. This view is taken in a plane which passes through the center of my improved engine, and for the purpose of visional clarity the heavy pistons are shaded.

Fig. 2 is similar to Fig. 1, except that the crank shaft is shown turned from the position shown in Fig. 1.

Referring now more particularly to the drawing, it will be understood that in the embodiment herein disclosed, the reference character 10 indicates a crank shaft, which is rotatable on its three main bearings or journals 11, 12, and 13. The reference characters 1, 2, 3, 4, 5, 6, 7, and 8 indicate the pistons, which are respectively connected by the connecting rods 9 to the crank shaft 10. The heavier pistons are shaded as indicated above, which said pistons are Nos. 2, 3, 6, and 7. It will be understood that the pistons reciprocate in their respective cylinders (not shown) which lie in a common plane. The reference characters 17, 18, and 19 indicate the couples and the reference characters 27, 28, 29, and 30 indicate the forces on the pistons 5, 6, 7, and 8 in Figs. 1 and 2.

In order to simplify the description of the structure, functions and results, I only make reference to that portion of the drawing between the journals or bearings 11 and 12, as the structure and function of that portion of the drawing between the journals 12 and 13 is identical.

It will be noted that the pistons 1, 2, 3, and 4 in this embodiment are equally spaced along the crank shaft 10, as indicated by the spaces 20, 21, and 22, although the pistons may be spaced along the crank shaft in any combination to suit design requirements. It will also be understood that the crank shaft 10 may be in any position without affecting the results. By the same token, the pistons may be either on top or bottom dead center with equal results. Neither the speed of rotation of the crank shaft 10 nor the materials of which the pistons are made, nor the spe cific weight of any one piston or group of pistons affect the end results as hereinafter described and illustrated in the formula. During the rotation of the crank shaft 10, and as a result of the arrangement of the four pistons 1, 2, 3, and 4, three couples 14, 15, and 16 will be developed, of which the two outer couples 14 and 16, will be in the clockwise direction (Fig. l), and the medial couple 15 will be in the counterclockwise direction (Fig. l). The couples 14, 15, and 16 are reversed in Fig. 2. In order to take full advantage of these couples and the forces 23, 24, 25, and 26 working on the pistons 1, 2, 3, and 4 in the directions indicated by the arrows, I deliberately increase the weight of the shaded pistons 2 and 3 over the weight of the pistons 1 and 4, so that their inertia forces, clue to their reciprocation, cause the medial couple 15 to exactly equal and counterbalance the couples 14 and 16, thereby effecting a substantially perfect running balance of the reciprocating parts.

Near the top dead center position the acceleration and inertia loads are somewhat higher than when the pistons are near the bottom dead center position. Consequently, with any given difference in weight between the light and heavy sets of pistons, there will be a slight out-ofbalance existing. However, my invention contemplates that the said difference be adjusted for any given engine or condition, so that the smoothest running condition possible results therefrom.

Although I have herein described an eight cylinder engine, it will be understood that the fundamentals of my invention may be practiced in a four cylinder engine or any multiple thereof.

In further explanation of the invention I submit the following formula in which D1 represents the distance between the center lines of pistons 1 and 4, or the total distance of spaces 20, 21 and 22, and D2 represents the distance between the center lines of pistons 2 and 3, or Having described my invention, what I claim and dethe space 21: sire to secure by Letters Patent is:

If: 1. In an internal combustion engine, a crank shaft hav- Wzthe Weight of each of the Pistons 1 and 4 ing not less than four power pistons equally spaced hereon, Xzthe Weight of each of the pistons 2 and 3 5 the ad acent plstons being rec1procable in opposed relat on D1:the distance between the pistons 1 and 4 with respect to the axis of the crank shaft, the two lnside Dzzthe distance between the pistons 2 and 3 pistons being heavier than the two outside pistons, whereby upon reciprocation the heavy pistons produce an unahd to have the System in balance, that is the aflti-clockbalanced couple, equivalent to two of the adjacent couples wise couple 15=the clockwise couples 14 and 16, then 10 d d b two f h li h pistolm X D2=W D1. 2. The structure of claim 1, in which the pistons are ar- Example ranged and weighted in accordance with the formula X D2:W Dl in which: W=1 pound D1=9 inches 15 W =the weight of each ou ts1de p1ston; D2:3 inches X =the weight of each inside piston;

X=unknown weight of pistons 2 and D1=the distance between the outside pistons; Applying; D2=the distance between the inside pistons. Then: XXDL'WXDI 00 References Cited in the file of this patent UNITED STATES PATENTS X=3 710,727 Wilson Oct. 7, 1902 Proof; 1,764,147 Burtnett June 14, 1930 XXD2=WXD1 2:! 2,178,246 TOWIC Oct. 31, 1939

Images