JP2008038979A - Wire for piston ring - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wire for a piston ring which prevents uneven abrasion from being generated in an outer circumferential edge part of a ring groove with the maximum load acting via a piston ring in an expansion stroke of an internal combustion engine. <P>SOLUTION: In this wire for the piston ring as a raw material for the piston ring 4 attached to the ring groove 6 in an outer circumference of a piston 5, a portion abutting on an outer circumferential edge angled part of the ring groove 6 of the wire is cut out to be formed into a substantially trapezoidal cross-sectional shape 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a piston ring wire as a material for a piston ring mounted in a ring groove on the outer periphery of a piston, and more particularly to a piston ring wire suitable for a piston ring of an internal combustion engine.

  Normally, a piston of an internal combustion engine has a configuration in which a ring groove is formed on the outer periphery of the piston and a piston ring is attached to the ring groove in order to keep the combustion chamber airtight and prevent oil from entering the combustion chamber. ing.

  In general, as the above-described piston ring, a compression ring that mainly plays the role of maintaining airtightness and an oil ring that peels off excess oil on the cylinder wall surface are used.

  A high combustion pressure acts on the upper surface of the piston ring, particularly the compression ring, during the expansion stroke of the internal combustion engine. At this time, the load due to the combustion pressure acts on the upper surface of the piston ring evenly distributed over almost the entire surface. The combustion ring presses the piston ring against the lower surface of the ring groove, that is, the surface of the ring groove on the crankcase side.

  However, since the piston ring is mounted on the piston with its outer peripheral portion protruding from the ring groove, the surface pressure (pressure) that the lower surface of the ring groove receives from the piston ring during the above pressing is shown in the figure. 2 (b) is indicated by an arrow f, and the pressure curve thereof is almost like a quadratic curve a that becomes higher toward the opening (outer peripheral edge) of the ring groove. In this way, the ring groove is subjected to uneven surface pressure via the piston ring, and as a result, the ring groove is subject to uneven wear so that the groove width increases in the vicinity of the opening (outer peripheral edge). appear. This uneven wear of the ring groove causes rattling of the piston ring, leading to a decrease in airtightness and a mounting failure of the piston ring.

  As a countermeasure against such a problem, a piston ring as described in Patent Document 1 has been proposed.

This piston ring will be described with reference to FIG.
In FIG. 3, reference numeral 11 denotes a ring groove for mounting the compression ring formed in the piston 20, and the piston ring 14 is mounted in the ring groove 11.
The piston ring 14 has a two-layer structure in which an upper layer 17 and a lower layer 18 formed of materials having different thermal expansion rates are laminated (the thermal expansion rate of the upper layer 17 is smaller than the thermal expansion rate of the lower layer 18). Due to the difference in rate, the state of contact with the mounted ring groove is autonomously adjusted in relation to the engine load by thermally deforming into a curved section as shown in the figure according to the temperature rise accompanying the increase in engine load It can be configured. Reference numeral 21 denotes a cylinder.
JP-A-2005-351460

Since the above-described conventional piston ring has a two-layer structure in which an upper layer and a lower layer formed of materials having different thermal expansion rates are laminated, the manufacturing cost becomes expensive. In addition, this piston ring is subject to repeated thermal deformation and restoration that are deformed into a curved shape in correlation with the engine load, and thus has a problem of poor durability. In particular, in an internal combustion engine for automobiles, acceleration operation and idling operation that require a high output are repeated, and therefore, repeated repeated thermal deformation and restoration of the piston ring are performed, Issues remain in durability.
The present invention seeks to solve the above-described problems in conventional piston rings.

  By forming the cross-sectional shape of the piston ring into a shape in which the lower surface of the piston ring does not contact the vicinity of the opening (outer peripheral edge) of the ring groove during the expansion stroke of the internal combustion engine, The maximum load is applied to the opening (outer peripheral edge) of the ring groove via the piston ring during the expansion stroke of the internal combustion engine, so that the vicinity of the opening (outer peripheral edge) of the ring groove is prevented from being unevenly worn. It is characterized by the points.

  Specifically, the present invention is a piston ring wire as a material of a piston ring mounted in a ring groove on the outer periphery of the piston, and a portion of the wire that contacts the outer peripheral edge of the ring groove is substantially trapezoidal. It is formed in a cross-sectional shape.

  As described above, the present invention forms the cross-sectional shape of the piston ring so that the lower surface of the piston ring does not contact the vicinity of the opening (outer peripheral edge) of the ring groove during the expansion stroke of the internal combustion engine. As a result, during the expansion stroke of the internal combustion engine, the lower surface of the piston ring can be prevented from coming into contact with the vicinity of the outer peripheral edge of the opening of the ring groove, and uneven wear near the outer peripheral edge of the opening of the ring groove can be prevented. Is possible.

Hereinafter, the present invention will be specifically described with reference to embodiments shown in the drawings.
1A is a side sectional view of the piston ring wire according to the first embodiment of the present invention, and FIG. 1B is a side sectional view of the piston ring wire according to a modification of the wire of FIG. 2 (a) is a schematic diagram showing a state in which the piston ring manufactured by the wire shown in FIG. 1 (b) is mounted on the piston of the internal combustion engine, and FIG. 2 (b) is an enlarged view of the arrow A part in FIG. 2 (a). It is.

  In FIG. 1A, reference numeral 1 denotes a piston ring wire. The main portion of the wire 1 is formed in substantially the same cross-sectional shape as a normal piston ring wire. In the left side portion of Fig. 2, the portion facing the opening (outer peripheral edge) side of the ring groove 4 when the wire 1 is formed on the piston ring and mounted in the ring groove 4 (see Fig. 2 (a)) of the piston 3 However, the corner portion of the lower surface (the surface on the crankshaft side of the piston) is formed in a substantially trapezoidal shape 2. As an example, the inclination angle of the trapezoidal shape 2 is 20 °.

  In the example shown in FIG. 1B, the corner portion on the upper surface as well as the corner portion on the lower surface are formed in a trapezoidal shape 3 having substantially the same shape.

  The piston ring 4 formed of the wire shown in FIGS. 1A and 1B is used by being attached to the ring groove 6 of the piston 5 as shown in FIG. FIG. 2A shows an example in which the wire shown in FIG. 1B is mounted in the ring groove 6 of the piston 5. Reference numeral 7 denotes a cylinder.

  A high combustion pressure acts on the upper surface of the piston 5 during the expansion stroke of the internal combustion engine. Since this high combustion pressure also acts on the upper surface of the piston ring 4, as shown in FIG. 2 (a), the piston ring 4 has a lower surface of the ring groove 6, that is, a crankcase of the ring groove. Pressed against the side surface.

As shown in FIG. 2 (a), the piston ring 4 is mounted on the piston 5 with its outer peripheral portion protruding from the ring groove 6, so that the portion protruding from the ring groove 6 of the piston ring 1 is It is in a “cantilever” state with the lower corner B (outer peripheral edge of the opening of the ring groove 6) as a fulcrum.
Therefore, when the high combustion pressure acts on the piston ring 4, in the case of the conventional piston ring, the maximum load acts on the lower corner B of the ring groove 6 as shown by the arrow f in FIG. However, this is a cause of uneven wear in the lower corner B.
However, in this embodiment, as shown in FIGS. 2A and 2B, a portion facing the lower corner B of the piston ring 4, that is, a lower surface of the outer peripheral edge of the piston ring 4. Since the knurled portion has a substantially trapezoidal shape 2, the lower surface of the piston ring 4 does not come into contact with the lower corner B of the ring groove 6 during the expansion stroke of the internal combustion engine.

  Thus, the piston ring 4 formed by the wire 1 of this embodiment has a cross-sectional shape in which the lower surface of the piston ring 4 is the lower corner of the opening of the ring groove 6 during the expansion stroke of the internal combustion engine. By forming the portion B (outer peripheral edge) or a shape that does not contact the vicinity thereof, the lower corner B (outer peripheral edge) of the opening of the ring groove 6 through the piston ring 4 during the expansion stroke of the internal combustion engine ) And the vicinity thereof, it is possible to prevent the portion of the ring groove 6 from being unevenly worn. Moreover, since the piston ring 4 formed by the wire 1 of this embodiment has a simple structure as compared with the conventional piston ring shown in Patent Document 1, it is advantageous in terms of material cost and manufacturing cost. .

In the embodiment of FIG. 1B, the corner portion of the upper surface of the wire 1 is also formed in a trapezoidal shape 3 having substantially the same shape as the lower surface, and the cross section of the wire 1 is symmetrical. Is formed. This makes it possible to reduce the weight of the piston ring.
In each embodiment, the length L of the trapezoidal shapes (parts) 2 and 3 is determined by the diameter of the piston to be mounted.

(A) It is a sectional side view of the wire for piston rings concerning 1st embodiment of this invention. (B) It is a sectional side view of the wire for piston rings concerning the modification of the wire of Fig.1 (a). (A) It is a schematic diagram which shows the state which mounted | wore the piston of the internal combustion engine with the piston ring manufactured with the wire shown in FIG.1 (b). (B) is an enlarged view of arrow A part of Fig.2 (a). It is a sectional side view of the conventional piston ring.

Explanation of symbols

1: Piston ring wire 2, 3: Trapezoidal shape (part)
4: Piston ring 5: Piston 6: Ring groove 7: Cylinder

Claims (1)

  A piston ring wire as a material of a piston ring to be mounted in a ring groove on the outer periphery of the piston, and a portion of the wire that contacts the outer peripheral edge of the ring groove is formed in a substantially trapezoidal cross-sectional shape. Piston ring wire characterized by