BACKGROUND OF THE INVENTION

The invention relates to a piston ring device applicable in piston reciprocating machines, mainly in internal combustion engines.

It is well-known that the role of the piston ring device in piston reciprocating machines, e.g. piston pumps, compressors, working hydraulic or pneumatic cylinders or internal combustion engines is to seal the gap between the piston making reciprocating motion (stroke) in the cylinder and the cylinder wall. The better is the sealing, the lower is the loss of medium in the cylinder space.

PRIOR ART

The piston rings used in internal combustion engines fit into ring grooves machined in the outer mantle of the piston. According to their role, they are compression rings or oil retaining rings (scraper rings) .

The presently used piston ring devices are made - without exception - as a single split circular ring, mostly of grey cast iron, or alloyed casting. The cross sectional profile of this self-tensioning compression ring is generally flat quadrangle, its outer cylindrical mantle tightly rests on the cylinder wall but its inner cylinder mantle is arranged at a radial gap from the cylindrical wall of the ring groove. The known compression ring generally has 0.02 - 0.03 mm axial gap in the ring groove.

SUBSTITUTE SHEET

The known oil retaining piston rings are made similarly as a single, split rectangular circular ring provided with oil retaining holes or ducts in their middle part [see e.g. Pattantyus: Gepesz es Villamos Mernδkδk Kezikόnyve (Manual for electrical and mechanical engineers) , Mfϊszaki Kδnyv- kiadό, Budapest, Hungary, 1962 vol.4., p.304-307)].

According to the experiences acquired in the practice, the main problem of the traditional and presently still widely used piston ring devices is the dimensional changes due to thermal expansion, causing jamming, comsequently stuck pistons mainly at higher temperatures. Further problem is that owing to the reciprocating motion of the piston, the piston rings become "knockout", thus their sealing will be more and more inefficient. This involves partly increased gas loss and partly the lubricating oil flowing into the combustion chamber. The latter one causes excessive oil consumption and increases the environment polluting exhaust gas emission. In the wake of their joint effect, the engine's efficiency deteriorates, while its fuel consump¬ tion and the environment pollution considerably increase, hence it will shortly be in need of complete renewal of the engine at a high cost.

ESSENCE OF THE INVENTION

The present invention is aimed at elimination of above shorcomings, i.e. at the realization of an improved piston ring device ensuring better sealing between the piston and cylinder for a much longer life than the known solutions.

The solve the problem, the piston ring device described in the introductory part was used as starting point, machined as a split circular ring which when built in, sits by way of self-tensioning in the piston's ring groove and tightly fits the cylinder wall.

The piston ring device according to the invention was further developed by dividing the piston ring device (en¬ gaged with the same piston's ring groove), i.e. it consists of at least two separate, self-tensioning split ring elements. When built in, they are in connection locked and loaded by force directly through their tapered surfaces, or in given case indirectly with the insertion of additional split ring or other packing piece (shim) , where each of the tapered surfaces of the ring elements in radial section has an inclined straight or curved constituent, and the ring elements axially form a tight fit with the ring groove.

In a preferred embodiment of the invention the piston ring device consists of two split ring elements only built in by turning their tapered polished surfaces of the same size opposite each other, and where the gap - created by splitt¬ ing the ring elements arranged preferably on the top in the ring groove - is smaller in dismounted state than the one arranged underneath in the ring groove. This further simpli¬ fies the manufacture and building in.

According to the invention such embodiment is also feasible, where the piston ring device consists of two V-shaped split ring elements, and a third central split ring element load¬ ing these elements ourwardly with the surfaces tapered on both sides, where the outer cylindrical mantle of the two external ring elements tightly fit the cylinder wall, and their end-faces rest on the front walls of the ring groove. This way, the self-tensioning mantle pressure of the piston ring device can be adjusted even more safely to the value at discretion.

But a further embodiment is also feasible according to the invention, where the piston ring device has a triangular central split ring element the outer cylinder mantle of which tigtly fits the cylinder wall, while its upper and lower tapered surfaces coact with the tapered surfaces of

the second and third ring elements by forcing the external ring element radially ourward, furthermore, the end-faces of the second and third ring elements rest on the upper and lower front walls of the ring groove.

In case of oil retaining piston ring device, such embodi¬ ment is preferred, where the two split ring elements are identically shaped and turned opposite each other in built in state, and a prestressed elastic element e.g. an end¬ less annular coil spring is built between the opposite tapered surfaces of the ring elements. The two ring elements are axially spaced from each other, or in given case pro¬ vided with ducts to clear away the oil. This simiplifies the manufacture and building in.

BRIEF DESCRIPTION OF THE DRAWINGS:

The invention is described in detail with the aid of en¬ closed drawings presenting some embodiments of the solu¬ tion according to the invention given by way of example, in which:

Fig.l: Longitudinal section of the piston ring devic according to the invention in built in state;

Fig.2: Top view of the lower ring element of the piston ring device according to Fig.l drawn to a smaller scale;

Fig.3: Bottom view of the upper ring element of the piston ring device according to Fig.l drawn to a smaller scale;

Fig.4: Enlarged section along line IV-IV marked in Fig.2;

Fig.5: Enlarged section along line V-V marked in

Fig. 3 ;

Fig.6: Partial section of the second embodiment of the piston ring device according to the in¬ vention given by way of example, in built in state;

Fig.7: Sectional view of a further version of the solution according to Fig.6;

Fig.8: Sectional view of another embodiment according to the invention given by way of example;

Fig.9: View of the solution according to Fig.8 in dismounted state, cut out in part.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in Fig.l, a piston ring device 1 according to the invention is arranged in a ring groove 3 of a piston 2 (illustrated only in part and schematically) . The piston 2 makes reciprocating motion in a cylinder 4 of an internal combustion engine, where role of the piston ring dvice 1 is to seal the piston 2 in the cylinder 4. End-face of the piston 2 towards a combustion chamber is marked with 5, its mantle with 6, furthermore, upper and lower end plates of the ring groove 3 with 7 and 8 respectively, and its inter¬ nal cylindrical wall with 9.

The piston ring device 1 according to the invention associ¬ ated with the ring groove 3 of the piston 2 is divided, i.e. it consists of at least two separate but coacting split ring elements. In the embodiment according to Fig.l, the piston ring device 1 consists of two, an upper and a lower ring elements 10 and 11, in this case being in direct contact with each other and in connection locked and loaded by force

in built in state. The ring elements 10 and 11 are made as split self-tensioning circular rings provided with tapered surfaces 12 and 13, respectively, at their engaging parts.

The view and section of the ring elements 10 and 11 are shown better in Fig.2-5. Fig.2 and 4 present the lower ring element 11, while Fig.3 and 5 the upper ring element 10. Comparison of Fig.2 and 3 reveals, that a gap 15 formed when splitting the lower ring element 11 was selected much bigger than a gap 14 of the upper ring element 10 in order to facilitate the building in. (Position of the lower ring ele¬ ment 11 before building in is shown with dashed line in Fig.l). It is evident that the ring elements 10 and 11 are elastically deformable in the process of building in.

Comparison of Fig.4 and 5 reveals that the ring elements 10 and 11 in this case have the tapered surfaces 12 and 13 of identical cone angle 16, where the constituent in radial section is straight. However, Fig.4 and 5 present a version (marked with dashed line) , where the constituent is curved. But in given case, this constituent may be even other, convex or concave as well. The tapered surfaces 12 and 13 are polished.

The end-face of the lower ring element 11 is at a radial spacing 19 from the wall 9 of the ring groove 3 in built in state (Fig.l). As shown in Fig.l, only thermal expansion gap exists between the upper end-face of the lower ring element 11 and the upper end-plate 7 of the ring groove 3, the size of which can be about 1/100 mm.

Thus, the piston ring device 1 according to Fig.l can be used as compression ring in the internal combustion engines, the production technology and material may be the same as those used at the present time. The cone angle 19 (shown in Fig.4 and 5) may be between 10 grade to 84 grade as required by the existing utilization.

Fig.3 and 5 show that dimensions of the upper ring element

10 can be essentially the same as that of the ring element

11 discussed above. A mantle surface 20 of the ring element 10 tightly fits an inner wall 21 of the cylinder 4 (Fig.l). Furthermore, an upper end-face 22 of the ring element 10 rests on the upper end plate 7 of the ring groove 3. (The same thermal expansion gap exists between a lower end-face of the ring element 10 and the lower end plate 8 of the ring groove 3 as mentione in connection with the ring element 11) .

From Fig.l it is clearly evident, that building in the piston ring device 1 according to the invention takes place with elastic deformation of the split ring elements 10 and 11. In built in state, the self-tensioning ring elements 10 and 11 remain in direct connection locked and loaded by force through the tapered surfaces 12 and 13. As a result, the inner and lower ring element 11 tries to drive the outer and upper ring element 10 radially outward, whereby always safe ring pressure is achieved. This way, the ring element 10 will rest in sealed condition on the wall 21 of the cylinder 4 even if the piston ring device 1 has been used for a long time, because the unavoidable wear during use is automatically compensated by the piston ring device

I according to the invention through the relative movement of the self-tensioning ring elements 10 and 11 along their tapered surfaces 12 and 13.

The present invention is essentially different from the prior art in the respect too, that the ring elements 10 and

II of the piston ring device 1 with their end-faces 22 and 17 tightly fit the end plates 7 and 8 of the ring groove 3, moreover they are pressed to it (without any gap as used to be in the prior art) . This implies the advantage that the piston ring device 1 does not "float" axially in the ring groove 3, thereby its risk of "knockout" is completely eliminated. Additional advantage of the invention is that in case of cooling problems of the engine, the piston 2 does

not "get stuck", - as it may occur in the traditional piston rings - since the connection locked and loaded by force and the relative movement pissibility of the ring elements 10 and 11 along their tapered surfaces prevent this phenomenon.

Fig.6 presents a further embodiment of the piston ring device 1 according to the invention, where the upper ring element 10 and lower ring element 11 in the ring groove 3 are in indirect, i.e. coacting and connection locked and loaded by force through a centrally arranged third split ring element 23. Tapered surfaces 24 and 25 of the ring element 23 are in coaction with the tapered surfaces 12 and 13 of the ring elements 10 and 11, respectively. Thus, the ring element 23 presses the ring elements 10 and 11 radially outward and axially apart, so their mantle surfaces 18 and 20 tightly fit the wall 21 of the cylinder 4. The ring element 23 is made similarly as split ring of the same material as that of the other ring elements 10, 11.

Fig.7 shows the inverse embodiment of the piston ring de¬ vice 1 according to Fig.6. Here, the outer end-face 26 of the central ring element 23 tightly fits the wall 21 of the cylinder 4, while its tapered surfaces 24 and 25 co- act with tapered surfaces 12 and 13 of internally arranged split ring elements 10 and 11. Evidently, the ring elements 10 and 11 transmit their self-tensioning pressure addi¬ tionally loading the ring element 23 radially outward, and the ring elements 10, 11 and 23 fill out axially tightly the ring groove 3.

Finally, a further embodiment of the piston ring device 1 according to the invention given by way of example is shown in Fig.8 and 9, that can be used as oil retaining ring de¬ vice. This piston ring device l is illustrated in Fig.8 in sectional view and in built in state, while its view (partly cut out) is shown in Fig.9 in dismounted state. This oil re¬ taining piston ring device 1 consists of two ring elements

(marked also with 10 and 11 for the sake of better perspicuity) . The ring elements 10 and 11 are made as split circular rings, their tapered surfaces 12 and 13 of the same size turned opposite each other. Their splitting gaps are marked also with 14 and 15 (Fig.9).

In this case, the ring elements 10 and 11 are at axial spacing 27 from each other forming oil outlet gap at the same time. An elastic element 28 is built in between the tapered surfaces 12 and 13 of ring elements 10 and 11, forcing them axially and radially apart. This elastic element 28 in this case is mad as an endless annular pre- stressed coil spring.

Fig.8 clearly shows that external mantle surfaces 20, 18 the ring elements 10 and 11 tightly fit the wall 21 of the cylinder 4, and their pressing on is further improved by the elastic element 28. An annular oil space 29 is formed on the middle mantle surface of ring elements 10 and 11 by way of recessing in communication with the gap formed by the spacing 27.

As evident from the foregoing, the piston ring device 1 according to the invention is originally different from the traditional solutions in respect of its construction and way of functioning. Its main advantage is that at relatively low expenditure, with guaranteed long life it offers reli¬ able selaing between the piston 2 and the cylinder 4. Further essential advantage is that it prevents "knockout" of the piston ring device 1 and the piston 2 becoming "stuck", thus saving substantial expenses for the users of the engine.

In the above description and claims under the term "connec¬ tion locked and loaded by force" — a force-locking coupling or connection — is to be understood.

List of reference numbers