GB2263327A

GB2263327A - Side rails for oil ring assemblies

Info

Publication number: GB2263327A
Application number: GB9304998A
Authority: GB
Inventors: Makoto Shiono
Original assignee: Riken Corp
Current assignee: Riken Corp
Priority date: 1989-10-27
Filing date: 1990-09-21
Publication date: 1993-07-21
Anticipated expiration: 2010-09-21
Also published as: GB2263327B; GB9304998D0; JPH0367759U

Abstract

A compound oil ring assembly comprises side rails 1 and a spacer expander 2. An inner circumference of each side rail 1 that contacts a shoulder 3 of the spacer expander 2 is formed to have corrugations 5', 6' inclined to be generally parallel to a tangent line 5, 6 to a profile of the shoulder 3 of the spacer expander 2 at the point of contact 4 of the side rail 1, thus hindering relative rotation between the side rails 1 and the spacer expander 2 and preventing the gaps in the upper and lower side rails coming into alignment. <IMAGE>

Description

TITLE SIDE RAILS F#OR OIL RING ASSEMBLIES DESCRIPTION: BACKGROUND OF THE INVENTION This invention relates to a compound steel oil ring assembly and, more particularly to improvements in a compound steel oil ring assembly having a spacer expander and side rails disposed above and below the spacer expander and brought into pressured contact with the inner wall of the cylinder of an internal combustion engine by the spacer expander.

In a conventional compound oil ring assembly, a situation arises in which the side rails disposed above and below the spacer expander undergo rotational motion in the circumferential direction during operation of an internal combustion engine, as a result of which the openings in the upper and lower side rails become aligned one above the other. In such case, a thick lubricating oil film formed by the gaps in the openings of the side rails is left on the cylinder wall in the form of streaks, and the oil is carried into the combustion chamber of the internal combustion engine. Such oil is consumed wastefully.

In order to solve this problem, the applicant has previously proposed a compound steel oil ring assembly having side rails, the inner circumferential surfaces of which are formed to have fine corrugations extending in the axial direction (see Japanese Utility Model Application Laid-Open No. 1-78769).

SUMMARY OF THE INVENTION The invention provides a compound oil ring assembly comprising side rails and a spacer expander, characterized in that an inner circumferential surface of each side rail that contacts a shoulder of said spacer expander is formed to have corrugations inclined to be generally parallel to a tangent line to a profile of the shoulder of said spacer expander at the point of contact of the side rail.

According to the invention, the corrugations on the inner circumferential surface of the side rail are formed to extend in the inclined direction of the profile line of the spacer expander shoulder portion. Consequently, the edge portion of the spacer expander shoulder is fitted between the corrugations on the inner circumferential surface of the side rail to prevent circumferential motion of the side rail relative to the spacer expander.

Since relative rotational motion of the upper and lower side rails with respect to the spacer expander is prevented, the openings in the two side rails are prevented from overlapping during operation. As a result, wasteful consumption of lubricating oil is eliminated Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a sectional view illustrating a compound steel oil ring assembly; Figure 2 is a partial front view of a spacer expander; Figure 3 is a partial perspective view of a side rail; and Figure 4 is a diagram showing part of a side rail seen from an inner circumferential side, in which (A) and (B) are views showing different examples.

DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention illustrated in the drawings will now be described.

Figure 1 illustrates a compound steel oil ring assembly having a spacer expander 2 and two side rails 1 disposed above and below the spacer expander 2. The spacer expander 2 has a shoulder 3 which is contacted by the inner circumferential surface of each side rail 1 at a contact point 4. Owing to the pressure applied to each side rail 1 by the corresponding shoulder 3 of the spacer expander 2, the side rails 1 are brought into contact with the inner wall of a cylinder of an internal combustion engine.

Figure 2 is a front view of the spacer expander 2. The profile of the shoulder 3 of spacer expander 2 defines a circular arc. In Figure 2, the side rails 1 are indicated by two-dot chain lines. It will be noted that each side rail 1 and shoulder portion 3 of the spacer expander contact at contact points 4, at which tangent lines 5,6 extend with respect to the profile of the shoulder portion 3 of the spacer expander 2.

Figure 3 is a partial perspective view illustrating a side rail. Here the inner circumferential surface of side rail 1 is formed to have fine corrugations 5' and 6' extending in parallel to the tangent lines 5 and 6 to the profile of the shoulder portion 3 of spacer expander 2 (Figure 2). Relative movement between the side rail 1 and the spacer expander 2 in the circumferential direction is checked since the corrugations 5' or 6' of side rail 1 abut against the edge of shoulder 3 of the spacer expander 2.

Figure 4(A) is a diagram showing part of a side rail seen from an inner circumferential surface thereof. Here the corrugations 5' and 6' are formed parallel to the tangent lines 5,6 of Figure 2. As shown in Figure 4(b), corrugations 5" and 6" of side rail 1 may be formed only at the contact points 4 between the side rail 1 and the shoulder portion 3 of spacer expander 2 shown in Figure 2. The corrugations 5",6" provide effects similar to those of the corrugations 5',6'.

Thus according to the present invention, movement of the side rail relative to the spacer expander in the circumferential direction can be checked in a reliable fashion. As a result, overlapping of the openings of upper and lower side rails is prevented, thereby making it possible to prevent wasteful consumption of lubricating oil.

Claims

CLAIMS:

1. A compound oil ring assembly comprising side rails and a spacer expander, characterized in that an inner circumferential surface of each side rail that contacts a shoulder of said spacer expander is formed to have corrugations inclined to be generally parallel to a tangent line to a profile of the shoulder of said spacer expander at the point of contact of the side rail.

2. An oil ring assembly according to claim 1, wherein said corrugations are arranged in mutually spaced pairs, each pair being in the form of a cross.

3. An oil ring assembly according to claim 1 or claim, 2 wherein said corrugations comprise intermittent lines.

4. An oil ring assembly substantially as described herein with reference to Figures 1 to 3 and 4(A) or Figures 1, 2 and 4(B).

4. An oil ring assembly substantially as described herein with reference to Figures 1 to 3 and M(A) or Figures 1, 2 and 4(B).

Amendments to the claims have been filed as follows 1. A compound oil ring assembly comprising side rails disposed on a spacer expander, characterized in that an inner circumferential surface of each side rail contacts a shoulder of the spacer expander, the shoulder having a generally arcuate profile when viewed along a radius of the side rail, and wherein the inner circumferential surface of the side rail has corrugations inclined to the plane of the side rail so as to be generally parallel to a tangent line to the profile of the shoulder of the spacer expander at the point of contact of the side rail.

2. An oil ring assembly according to claim 1, wherein said corrugations are arranged in pairs, each pair being in the form of a cross and spaced from neighbouring pairs.