US1763127A - Piston ring - Google Patents

Description

June 10, 1930; G. BEER 1,763,127

PISTON RING Filed Sept. 12, 1929 Patented June 1930 GEOBG BEER, F WIESBADEN', GERMANY PISTON RING Application filed September 12, 1929, Serial This invention for which I have filed applications in Germany May 17 1926, and August 10, 1928, relates to piston-rings and consists in an improved construction which may a be used to advantage in connection with piston-rings consisting of two concentrically adj acent ring-members.

The general object of my invention is to improve the contact between the piston-ring and the front and rear surfaces of the pistongroove which serves for the reception of the piston-ring and to prevent carbonized constituents of the fuel from depositing in the joint of the piston-ring, that is in the space intermediate the butt-ends of the piston-ring. It is important to attain the best possible tightening between the piston-ring and the cylinder-wall on the one hand and the piston on the other hand and to prevent motion of the piston-ring withinthe piston-groove. It

is furthermore desirable to maintain this tightening after some longer use of the engine, that is after the pistons, the cylinderwallsas well as the piston-rings have worn off to a smaller or greater extent. I

Among other things the wear of the front and rear surfaces of the piston-groove, that is those surfaces of said groove which extend from the periphery towards the center of the piston, is a great disadvantage and in such case there will be an excessive axial play of the piston within the piston-groove and in consequence thereof the piston-ring will Wobble within the piston-groove during operation of the engine. With piston-rings of known construction in this case an excessive quantity of fuel will be caused to pass into the explosion space of the cylinder in that deadcenter position of the piston which is Inter- 40 mediate the suction and the compression stroke. This is due to the fact that the piston-ring during motion of the piston will al-' ways be pressed only against the one of the radially directed surfaces of the pistongroove which surface is positioned oppositely to the temporary direction of motion of the piston. During passage of the piston through the dead-center point there will be a change of the direction 'of motion of the piston and by reason of this the piston-ring No. 392,160, and in Germany ma 17, 1926.

at this moment will be out of contact with both radially directed surfaces of the pistongroove. In consequence thereof at this momentthe vacuum in the cylinder will cause fuel to be drawn-in through the interstice which is present in the front and in the rear of the piston-ring. This condition will again arise when the piston-ring is in its other deadcenter position the only rdifference being that gases will discharge through said interstices 60 at the moment when explosioncommences.

In order to avoid these disadvantages it had already been proposed to use a resilient inner piston-ring having a conical outer surface contacting witha likewise conical inner surface of an outer piston-ring in order to cause this compound piston-ring due to the pressure exerted between said conical surfaces to be kept in proper contact with both the axially directed surfaces of the pistongroove. This arrangement however, is con-' nccted with the drawback that the usual radial thickness of the piston-ring will not be sufiicient to use a proper angle of inclination for said conical surfaces and jamming be- 7 tween the two ring-members along said conical surfaces will be the result. The rings in this case will easily stick to each other and fail to serve the desired purpose, viz: to fully fill out the piston-groove and to avoid play of the piston-ring in the piston-groove, especially during reversal of the motion of the piston.

A further drawback, especially in case of piston-rings with overlapping ends which form a stepped joint consists therein that 'carbonized substances of the fuel may easily deposit and collect in the cut or joint of the piston-ring. This is qilite especially the case with unevenly worn-off cylinders. In this case said substances will be kept jammed inthe joint of the piston-ring during passage of the latter past the less worn-ofi' parts of thecylinder. As a consequence of this, the

piston-ring will expand and exert a heavy pressure against the wall of the cylinder. Frequentlyin this case also the butt-ends of the piston-ring will be torn-off, and in addition to this heavy friction will arise between the piston-ring and the wall of the 10 cylinder, said friction exerting an unfavorable effect upon the operation of the engine. With the known two-part piston-rings having conical contact surfaces between the two parts as above mentioned, even with a most favorable angle of inclination of said contactsurfaces in case of such heavy friction the piston ring would not remain in contact with the front and rear surface of the pistongroove because in this case large axial forces are exerted which would fully counteract the resiliency of the piston-ring.

On account of the fact that a resilient inher ring is provided according to my invention at its outer periphery with. a plurality of small oblique surfaces which press against similar oblique surfaces on the inner periphery of the outer ring there will be the possibility of providing the required angle of obliquity between the contact surfaces of both rings, without, however, exceeding the usual radial thickness of the piston-rings. My present invention further avoids the disadvantage that the front and rear surfaces of the ring are composed of a weaker and of a stronger part. Furthermore by my present invention the injurious effect of depositing carbonized constituents of the fuel will be most successfully avoided by cutting off the butt-ends of the piston-rings obliquely with respect to the tangential direction so that the cut or joint provided between said butt-ends will form an interstice which enlarges either towards the outside or towards the inside. By so constructing the butt-ends of the piston-ring the carbonized constituents of the fuel which enter into the cut or joint will be forced either towards the outside or towards the inside away from the oblique cut during compression of the piston-ring.

A piston-ring constructed according to my present invention is shown in the accompanying drawing of which Fig. 1 is a perspective view. partly in cross-section, showing a piston-ring composed of two parts, one of said parts being shown broken away, Fig. 2 an enlarged cross-section through the ring shown in Fig. 1, when placed in the pistongroove in contact with the cylinder, said piston and said cylinder being also shown broken away, Fig. 3 an axial view of a pistonring with a gas-tight closure at the butt-ends, Fig. 4 a perspective view of the butt-ends of a piston-ring, Fig. 5 a perspective view of the butt-ends of a piston-ring having a stepped closure and a cut formed by oblique surfaces of X-shaped conformation, and Fig. (i a similar view of theends of a piston-ring having a stepped closure with V-shaped cutaway surfaces.

Referring now more particularly to the drawing, Figs. 1 and 2 show a compound piston-ring composed of an outer ring-member 1' provided around its interior periphery with ribs 3 and an inner ring-member (3 provided with similar ribs 4 around its outer periphery, said ribs 4 extending into the interstices intermediate said ribs 6 and vice versa. The one end of the outer ring 1, as shown at 7, is formed by a cut-off surface which is directed obliquely to a direction tangential to the ring. A like obliquity 7 in opposite direction is provided at the other end of the ring.

Fig. 2 shows the interstices which are provided intermediate the ribs on either ringmcmber of the compound piston-ring, said interstices being not shown in Fig. 1. These interstices are produced by staggering or displacing the ribs 4 relatively to the ribs somewhat in axial direction so that the ribs on the one i'ingwill not exactly fit into the interstices or depressions between the ribs on the other ring. The piston which is shown broken away in Fig. 2 is provided with a groove into which both ring-members of the piston-ring are placed in such a manner that the inner ring-member 6 contacts with the upper radial surface 5 of the groove, while the outer ring-member 1 contacts with the under radial surface 8 of said groove. The cylinder is likewise shown in contact with the outer ring 1.

In Fig. 3 a joint of a piston-ring is shown having oblique butt- ends 7 and 10 of V-shaped conformation forming a. gas-tight closure. According to Fig. 4 the butt-ends of the ring are likewise designated with the numerals 7 and 10, the same as in Fig. 3. The overlapping parts of the ends of the ring are in contact with each other along a surface which forms a quarter of a full circular or cylindrical surface. In Figs. 5 and 6 a ring with butt-ends of a different conformation is shown and designated with the same numerals 7 and 10. According to Fig. 5 these butt-ends are of the conformation of an X, while according to Fig. 6 the butt-ends are of theconformation of a V. Moreover. in both Figures 5 and 6 the end-parts ot the rings are constructed to form an ordinal-v stepped joint. The butt-ends may also he arranged in the form of a K, one of the surfaces of said butt-ends being positioned radially and the other being broken and directed obliquely to the tangential direction of the piston-ring.

It will also be possible to place two inner rings together with one outer ring or also two outer rings together with one inner ring into the piston-groove, and to provide said rings at their outer and inner contact surfaces with ribs as had above been described. Furthermore, either only the outer member or also both the outer and the inner members may be provided with oblique buttonds. Also in case two rings are used which are designed to act in the manner of a stuffing box, the inner ring is constructed as the tightening nieniber proper. while the outer ring serves as the actuating member for tinstufling box and for this purpose is'made resilient in inward direction.

v The mode of operation of a piston-ring constructed according to my invention will now be as follows: In case of two-part rings which are provided at the outer surface of the inner part and the inner surfaceof the outer part with ribs alternating with depressions in such a manner that the ribs on one part engage with the depressions on the other part and vice versa, a pressure will be exerted in axial direction by the resiliency of the interior ring,-this pressure being due to the fact that the ribs and depressions of the one ring are staggered or displaced with respect to the ribs and depressions of the-other ring.

This axial ressure will cause. both parts of the ring to e pressed away from each other in opposite directions and axially to the piston and will firmly contact with the front and rear surface of the pistonroove. This effect evidently is due to the a orementioned staggering or, displacing of the ribs and depressions of one ring with respect to the ribs or depressions of the other ring. Apparently, if only a single oblique surface isproof the inner member and the inner periphery of the outer member having alternatin circumferential annular ribs and grooves t ereon, the ribs on one of said members-being displaced from the to of the member by distances greater than t e displacement of the grooves on the other member from the top of the member, so as to increase the combined axial width'of the members. I

3. A piston ring, comprising inner and outer concentric ring members, the outer pevided at the contact between the two parts of the piston-ring, as known, this may eventually produce to a certain extent an axial displacement of the two rings which, however, will not be suflicient to attain a tight fit of the rings with the front and rear surface of the plston-groove.

The obliquity of the surfaces at the 'oint of the piston-ring will have the effect t at the carbonized constituents of the fuel which may have collected between said surfaces are pressed towards the outside or towards the inside, if the piston-rim is being widened out, such as is especial y. the case with worn-off cylinders. In like manner, the carbonized constituents will be caused to be pressed out of the joint during compression of the piston-ring. By reason of this obliquity, therefore, jamming of c rbonized particles of the fuel within the joint of the piston-ring will be effectively prevented which is the case with rings having endjsurfaces which are positioned radially with respect to the piston and cylinder.

I claim:

1. A piston ring, com rising inner and ,puter concentric ring mem ers, the outer periphery of the inner member and the inner periphery of the outer member having alternating circumferential annular ribs and grooves thereon, the ribs on one of said members being axially offset with respect to the grooves on the other of said members so as to increase the combined axial width of the members when the ring is assembled between a piston and a cylinder.

2. A piston ring, comprising inner and outer concentric ring members of substantially equal thickness, the outer periphery

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