US1960597A - Cylinder of two-stroke internal combustion engines - Google Patents

Description

May 29, c SCHAER v 1,960,597 CYLINDER 0F TWO-STROKE INTERNAL COMBUSTION ENGINE Filed Ja.:n..5, 1952 2 Sheets-Sheet 1 v wmmw m V Fw- W /JW -rru RN 5% May 29,1934. HA'ER I 1,960,597

CYLINDER OF TWO-STROKE INTERNAL COMBUSTION ENGINE Filed Jan. 5. 1932 2 Sheets-Sheet 2 I N\/ENTE] 35 and Patented May 29, '1934 oYLiNnE'It or TWO-STROKE INTERNAL COMBUSTION ENGINES Charles Schaer, Langenthal, Switzerland; as-

signor to the firm of 'Sulzer Frres Societe Anonyme, Winterthur, Switzerland Application January 5, 1932, Serial No. 584,807

In Switzerland January 7, 1931 Claims.

This invention relates to cylinders of twostroke internal combustion engines of the kind having admission and" exhaust ports controlled by the piston, the admission ports being arranged 5 in the cylinder wall substantially opposite to the exhaust ports.

It has hitherto been proposed to provide a two stroke internalcombustion engine cylinder with elongated admission ports extending in a spiral direction in the cylinder wall, the admission was sages leading to these ports being so inclined that the gases i. e. air issue from each port into the cylinder on a path which, when projected on to the cylinder wall, is substantially parallel to the 5 length of the port.

According to 'the present invention the admission passages which terminate in the spirally arranged elongated ports are so inclined that the air enters the cylinder through each port along a path which, when projected on to the cylinder wall, lies ina direction substantially at right angles to the length of the port.

Two constructions of cylinder according to the.

Figure 2 shows a development of the admission 30 ports shown in Figure 1,

Figure 3 is a section on the line III-III of Figure 2,

Figure 4 is a view similar to Figure 2 of a modified arrangement of the admission ports,

Figure 5 illustrates the invention as applied to a double-acting two-stroke engine.

In the construction illustrated in Figure 1 the combustion chamber 1 is'bounded by the cylinder head 2, piston 3 and liner 4, the cylinder casing 5 being connected at one side to an air receiver 6 and at the other side to an exhaust pipe 7. The air receiver 6 communicates with admission passages 8 in the cylinder wall through an inter- 5 mediate chamber 9, non-return valves 10 being arranged as shown between the chambers 6 and 9. In accordance with the present invention the admission passages 8 terminate in elongated ports in the cylinder wall as shown, thelength or each port extending in a spiral direction while'the walls 11 boimding each of the passages 8 are so inclined that the air enters the cylinder through ,the corresponding port along a path which, when projected on to the cylinder wall, lies at right 5 anglesto the length of the port; Thus the main body of the air will enter the cylinder through each admission port in a path whose projection on the cylinder corresponds to the vector R (Figure 2) which can be resolved .into a vertical component X and a tangential component Y.

In Figures 2 and 3 the admission ports are arranged in two sets, one set on each side of a central dividing wall 14. Each port in one set extends in a spiral direction which is at a substantial angle to that of the ports in the other set, whilst in addition the walls 11 bounding each passage are inclined at an angle a (preferably between 30 and 45) with a plane tangential to the cylinder. The angle of inclination of the passages are similar for each set of ports on either side of the dividing wall 14 but the'passages in one set are inclined at an angle to the passages in the other set. Exhaust ports 14, formed by dividing walls 13 arranged in the usual manner, are disposed in the cylinder wall substantially opposite to the admission ports. 1 The walls 11 are preferably stream-lined as shown in Figure 3, the central wall 14 serving as a guide for the piston rmgs.

The admission ports are so arranged that when the piston moves outwards on its expansion stroke, before beginning to uncover the exhaust ports 12, the piston begins to uncover the admission ports, whereupon the contents of the cylinder expand into the intermediate chamber 9, the non-retum valves 10 preventing the gases from passing into the receiver 6. As soon as the piston uncovers the exhaust ports 12 the cylinder contents will escape through the exhaust pipe 7 whereupon scavenging of the cylinder will commence, air flowing from the receiver 6 through the inclined admission passages 8. The scavenging air then enters the cylinder through each of the elongated ports as 'above described, and the air flowing from any port adjacent to the central wall 14 will be deflected by the tangential speed component Y of the air flowing through the port 'or ports more remote from the central wall 14, the internal curvature of the cylinder serving to guide the air flowing from those ports which are remote from the central wall. In this way the scavenging air will be directed upwards against the inner surface of the cylinder above the admission ports, i. e, on that side of the cylinder opposite to the exhaust ports, the air from both sets of admission ports then flowing towards the cylinder head substantially as shown by the arrows 15 in Figure 1. The upward current of air 2 will tend to prevent that entering through the ports adjacent to the central wall 14 from passing 110 diametrically across the cylinder and escaping through the exhaust ports without taking part in the scavenging operation.

By arranging the admission ports and passages as shown in Figure4 in which all the ports extend in similar spiral directions and the inclination of all the walls of the passages leading to the ports issimilar, the air will be caused to flow around the inner surface of the cylinder and to rotate about the cylinder axis on its way towards the cylinder head.

The invention may be applied with advantage to double-acting two-stroke engines as illustrated in Figure 5, since in engines of this type the overall height is necessarily restricted with a consequent restriction of the dimensions of the scavenging air ports, which may make it a matter of some difliculty to obtain effective scavenging of all parts of the cylinder. By providing ports in accordance with'the invention however this diificulty is overcome even when the dead centre of the piston lies in the radial plane be- 'tween the two halves of the cylinder.

It will be seen that with a cylinder having admission ports arranged in accordance with the present invention that part of the combustion chamber above the admission ports is swept by an upward current of fresh air flowing at high speed, i

and that the escape of scavenging air directly across the cylinder to the exhaust ports is reduced to a minimum.

The constructions above described are given by way of example only and details may be modified without departing from the spirit of the invention. For example the spiral directions in which the admission ports extend and the inclination of the passages leading to these ports may be .lar.

air at a pressure difl'erent from that of the air supplied to the remaining ports:

I claim: a

1. In a cylinder for two-stroke internal combustion engines the combination with the piston of admission and exhaust ports controlled by the piston, the admission ports being arranged in the cylinder wall substantially opposite to the exhaust ports and a series of admission passages terminating in elongated ports in. the cylinder wall, the length of eachport extending in a spiral direction in the cylinder wall, the passages being so inclined that the air enters the cylinder through each port along a path which, when projected on to the cylinder wall, lies in a direction substantially at right angles to the length of the port.

2. In a cylinder as claimed in claim 1 the arrangement, that at least some of the ports and the passages leading thereto are inclined in a direction different from that in which others are directed so that the air enters the cylinder from some of the ports along paths each or which, when projected on to the cylinder wall, lies at a substantial angle to the paths of the air enter- 100 ing the cylinder from the other ports.

3. Ina cylinder as claimed in claim 1 the arrangement, that all the ports extend in similar spiral directions and the inclination of all the walls of the passages leading to the ports is simi- 105 4. In a cylinder as claimed in claim 1 the arrangement, that the walls of the passage leading to each admission port from an angle of between 30, and 45 with a plane tangential to the cylinder.

5. A two-stroke internal combustion engine cylinder, having admission ports and passages leading thereto as claimed in claim 1, in which there is also, an air supply conduit or chamber communicating with the admission ports, and one or more non-return valves for controlling the flow of air between the chamber and the admission ports, the latter being so arranged that they begin to be uncovered by the piston before same begins to uncover the exhaust ports.

CHARLES SCHAER.

Images