JPH0447404Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an oil ring device provided on a piston that reciprocates within a cylinder bore of an internal combustion engine.

[Prior Art] Conventionally, as an oil ring device for a piston, a combination of a thin metal plate and two side rails has been used, as described in, for example, Japanese Utility Model Application Publication No. 56-85048. .

That is, as shown in FIGS. 1 to 3, this type of oil ring device includes a ring-shaped spacer expander 1 formed of a thin metal plate and having an inward U-shaped cross section, and two side rails 2. , 2, and press projections 3, 3 are provided on the inner peripheral edge of the spacer expander 1, and the spacer expander 1
A ring groove 5 is carved on the outer periphery of the piston 4 with the side rails 2, 2 stacked on both the upper and lower surfaces of the piston 4.
It is installed inside.

In this type of oil ring device, both end surfaces 7 and 8 of the abutment portion 6 of the spacer expander 1 are formed into planes parallel to the normal line toward the center point of the spacer expander 1. .

[Problems to be solved by the invention] However, the joint part 6 of the spacer expander 1
It is extremely difficult to process both end surfaces 7 and 8 accurately parallel to the normal line toward the center point, and there is a machining error in the parallelism of both end surfaces 7 and 8 to the normal line. , 8 make point contact at a point 11 on the outer circumferential surface 9 of the spacer expander 1, or make point contact at a point on the inner circumferential surface 10 of the spacer expander 1, as shown in FIG. Become.

When the end surfaces 7 and 8 make point contact at a point 11 on the outer circumferential surface 9 of the spacer expander 1 as in the former case, the contact point 11 is the neutral moment of inertia of the spacer expander 1 in the longitudinal direction. Since it is located outside the axis 12, when the spacer expander 1 and both side rails 2, 2 are inserted into the cylinder bore while reducing their diameters, the abutment part 6 of the spacer expander 1 is indicated by the two-dot chain line. As shown, both end surfaces 7 and 8 are deformed outward so as to come into surface contact, and when both end surfaces 7 and 8 come into contact on the inner circumferential surface 10 of the spacer expander 1 as in the latter case, the The point of contact is the neutral axis 12 of the spacer expander 1
Since the spacer expander 1 and both side rails 2 are inserted into the cylinder bore while reducing their diameters, the abutment part 6 of the spacer expander 1 is the opposite of the former case. It will deform inward.

Therefore, the pressing force of the pressing projections 3, 3 of the spacer expander 1 against the inner surface of the cylinder bore of the side rails 2, 2 becomes locally stronger or weaker, and the surface pressure of the side rails 2, 2 against the cylinder bore increases. In large areas, seizing occurs due to lack of oil, and the side rail 2,
At locations where the surface pressure of No. 2 is low, the amount of oil consumed increases due to poor scraping off of the oil.

The present invention is intended to avoid the above-mentioned problems caused by machining errors on both end surfaces at the abutting portion of the spacer expander in an oil ring device using a spacer expander and two side rails. .

[Means for Solving the Problems] Therefore, the present invention provides a method in which either one end face or both end faces of the abutting portion of the spacer expander are connected to the outer circumferential face of the spacer expander. It is formed into a chevron shape so that it makes point contact with the inner circumferential surface.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings. In the first embodiment, as shown in FIG. The end face 7 is a plane substantially parallel to the normal line toward the center point of the spacer expander 1, and the other end face 8 is formed into a mountain shape having one apex 8a.
However, the spacer expander 1 is configured to make point contact with one end surface 7 at a point between the outer circumferential surface 9 and the inner circumferential surface 10.

In the second embodiment, as shown in FIG. 6, in addition to forming the other end surface 8 of both end surfaces of the abutment portion 6 of the spacer expander 1 into a mountain shape having one apex 8a, One end surface 7 is also
It is formed into a mountain shape having one apex 7a, and the apexes 7a and 8a of both the chevron-shaped end surfaces 7 and 8 are in point contact with each other at a point between the outer circumferential surface 9 and the inner circumferential surface 10 of the spacer expander 1. It is configured as follows.

In this way, both end surfaces 7 and 8 of the abutment portion 6 of the spacer expander 1 are brought into point contact with each other at one point 7a and 8a between the outer circumferential surface 9 and the inner circumferential surface 10 of the spacer expander 1. Due to this structure, this contact point is located on the neutral axis 12 of the moment of inertia of the spacer expander 1 in the longitudinal direction, compared to when the contact point is located on the outer circumferential surface 9 or the inner circumferential surface 10 of the spacer expander 1. spacer expander 1 and its upper and lower side rails 2, 2.
When the spacer expander 1 is inserted into the cylinder bore while reducing its diameter, the amount of deformation in the inner or outer circumferential direction at the abutment part 6 of the spacer expander 1 is much smaller than in the conventional case.

In this case, the peak 7 of the chevron on both end surfaces 7 and 8
If a and 8a are located on the neutral axis 12 of the moment of inertia of area with respect to the longitudinal direction of the spacer expander 1, the amount of deformation of the abutment portion 6 in the inner or outer circumferential direction will be minimized. Moreover, it goes without saying that both end surfaces 7 and 8 may be formed into an arcuate mountain shape.

[Effects of the invention] As described above, according to the invention, one end face or both end faces of the abutting portion of the spacer expander can be formed between the outer periphery and the inner periphery of the spacer expander. By forming the spacer expander into a chevron shape so as to make point contact at the parts, it is possible to reduce the deformation of the abutting part of the spacer expander in the inner or outer circumferential direction due to machining errors on both end faces. The surface pressure exerted by the panda on the cylinder bores of both side rails becomes approximately constant over the entire circumference of the side rails, and this has the effect of reliably avoiding seizures due to lack of oil and increases in oil consumption due to poor oil scraping. have

[Brief explanation of the drawing]

FIG. 1 is a partial perspective view of the spacer expander and side rail in the oil ring device;
Fig. 2 is a sectional view when the spacer expander and side rail are attached to the piston, Fig. 3 is a plan sectional view taken from - in Fig. 2, Fig. 4 is a plan sectional view of a conventional oil ring device, and Fig. 5 is a plan sectional view of the conventional oil ring device. The figure is a plan sectional view showing the first embodiment of the present invention, and FIG. 6 is a plan sectional view showing the second embodiment of the invention. 1...Spacer expander, 2...Side rail, 3...Press projection, 4...Piston, 5...
Ring groove, 6... Joint part, 7, 8... End surface, 7
c, 8c...Apex of chevron, 9...Outer peripheral surface of spacer expander, 10...Inner peripheral surface of spacer expander.

Claims (1)

[Scope of utility model registration request] (1) A ring-shaped spacer expander made of a thin metal plate with an inward U-shaped cross section is placed in a ring groove carved on the outer periphery of the piston, and ring-shaped side rails are installed on both the upper and lower surfaces of the spacer expander. In the oil ring device, the spacer expander is fitted with a combination of the above, and a pressing protrusion against the inner circumferential surfaces of both side rails is formed on the inner circumferential edge of the spacer expander. 1. An oil ring device for a piston, characterized in that one end surface or both end surfaces are formed into a chevron shape so that the end surfaces make point contact at a portion between the outer circumferential surface and the inner circumferential surface of a spacer expander.