US1664817A - Scavenging internal-combustion engine - Google Patents

Description

E. HEW??? SCAVENG-ING INTERNAL COMBUSTION BNGINE'I Filed April 5. i936 Patented Apr. 3, 1928.

- UNITED STATES 1,664,817 PATENT orrlcs.

ERNST HERKT, OF KIEL, GERMANY, ASSIGNOR TO FRIED. KRUPP GEBKANI-A WERFT AKTIENGESELLSGHAIT, OF KIEL-GAABDEN, GERMANY.

SCAVENGING INTERNAL-COMBUSTION ENGINE.

Application filed April 3,

The invention relates to two stroke cycle double-acting internal combustion engines which are scavenged by means of ports. In scaven ing such engines difiiculties arise especizfily on the lower (piston rod) side oi the cylinder, as here the piston rod forms an obstacle for a continuous course of the scavenging air current due to its unfavorable circular cross section.

The simplest and most satisfying scavenging effect would be attained with such engines by the adaption of the well-known socalled cross scavenging method, as illustrated in Fig. 1, with which method the scavenging air entering on one side of the cylinder A throu h admission ports C is directed into para lcl with the cylinder wall by a bafilelate I) provided on the piston and after aving struck the piston rod, leaves the'cylinder through exhaust ports D diametrally opposite to said admission ports C, as with this method the scavenging current strikes the piston rod" but once, viz, at w. This method, however, suffers from some drawbacks, in particular due to the bafile plate I) which necessarily must be arranged on the end face of the piston and is undesired by certain reasons, and due to the forced double rectangular deflection of the so entering and escaping scavenging current, so

that this method recently has been abandoned and the so-called reverse method, likewise well-known, has been adopted. With this method the scaven 'ng air passes the piston end 'face in a close current, flows along the opposite cylinder wall up to the c linder cover and returns on the entrance side where it esca es through exhaust ports which are situate on this side nearer to the o cylinder coventhan the admission ports. This scavenging method is illustrated in Figs. 2 and 3 as adapted to the iston' rod side of the cylinder. This me od, however, shows from the first the drawback of the 46 scavengin current striking the iston rod on two p aces, viz, at a: and y, ig. 2. It has been proposed, therefore, in order to attain in some measure, at least on the piston end face, a shockless passage 50 ing current, to so direct the admission rts, see Fig. 3, that the scavenging air wi 1 not strike the piston rod directly and the branch currents unite again on the opposite side and ascend and so on. This measure, however,

of the scaveng said 1926, Serial No. 99,510, and in Germany April 3, 1925.

is likewise not capable of securing a continuous and eddilcss course of the scavenging current. For, as clearly will be 'seen from Fig. 3, the branch currents entering the cylinder through the groui of ports 0', meet the branch currents intro uced through the group of ports 0 under a rather large angle, this causing disturbing eddies to arise behind the piston rod. Furthermore, this scavel'iging method has the drawback of the entering and escaping scavenging currents closely passing each other in counter-current on the admission and exhaust ports. In consequence thereof violent eddies will arise on this lace too, causing the admitted fresh scavenging air to be immediately withdrawn again from the cylinder, a'loss in scavenging air thus being unavoidable.

Now my invention has for its object to create a scavenging means, in particular adapted to be used on the piston rod side of two stroke cycle double-acting internal combustion engines, by means of which the above-mentioned drawbacks are obviated and the scavenging air current must pass the piston rod but once, as in the cross-scavenging method shown 1n Fig. 1.

An embodiment of: the subject-matter of my invention is illustrated by way of example in the drawing which accompanies and forms part of this specification.

In this drawing:

Figs. 1 and 2, are vertical sections in diagrammatic form of 2 forms of piston and cylinder arrangement according to the prior art.

Fig. 3 is a cross section of line 3-3, of

Fig 2.

ig. 4 is a fragmentary lon tion through the working cy internal combustion engine, Fig. 5 is the cross section on itudinal secmder of an line 5-5 of 1g. 6 is the cross section on hne 6-6 of Fii 5.

denotes the working cylinder of a two stroke cycle double-acting internal combustion engine and B the piston reciprocating therein and having an end face I) tapering towards the piston rod E. I provide a group of admission ports 0 on both sides of cylinder A and a group of exhaust ports D. ports C, D being situated on a common level. Both said groups of ports are inclined in the direction of the angle ofthe tapered piston end face I), see Fig. tfthe exhaust ports D penetrating the cylinder -wall in radial direction, see Fig. 5, while the admission ports C are arranged so as to cause the branch currents entering therethrough to arrive behind the piston rod.

By the described arrangement and direc- "tion of the admission and exhaust ports C,

D in combination with the described shape of the piston end face 6 I attain that the branch currents entering through the admission ports C are guided, after having passed.

these ports, by the tapered piston end face 6 within the cylinder up in the manner shown in Fig. 4, and unite, without any formation of eddies, so as to "form a closed scavenging current which rises along the cylinder Fwall, branches near the cylinder cover so as toembrace the piston rod, thereupon is guided downwardly in a closedcondition along the oppositecylinder wall and finally is deflected by said tapered piston end face 6 so as to continuously escape tln'oughthe exhaust ports I). I- attain in this manner that the scavenging air entirely obviates the obstacle formed by thev piston rod and meets it but once, viz, on the cylinder cover, as in the wcll-knmvnscavenging method illustrated in Fig. 1. I further attain thatthe scavenging air is guided satisfactorily and continuously during the whole scavenging period and leaves the cylinder in a quietly flowing current, all portions of the cylinder being met by the scavenging air. Of course the generatrix of the tapered end face 6 of the piston might be formed by a suitable curve the curvature of which, however, must subside in a continuous course into the line of inclination ofthe admission and exhaust ports.

I claim:

Two'cycle internal combustion engine of the Diesel type, comprising a cylinder, a piston Working therein having a piston rod penetrating the cylinder room and an end face tapering towards the piston rod, piston controlled inlet ports arranged at both sides of the cylinder and outlet ports arranged at one side of the cylinder between the inlet ports and at the same level with the inlet ports, said inlet ports being inclined sothat theincoming scavenging air flows tangent the tapered end face of the piston on both sides and strikes the cylinder wall opposite to the outlet ports, the two flows of the scavenging air uniting and being directed along said wall to the cylinder head crossing the piston rod and flowing to the outlet ports, said outlet ports being inclined at the same angle as the tapered fa ce of the piston rod.

The foregoing specification signed. at Hamburg, Germany, this twenty-fifth day .of February, 1926.

ERNST HERKT.

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