US-12618473-B2 - Sealing ring and sealed structure including same

US12618473B2US 12618473 B2US12618473 B2US 12618473B2US-12618473-B2

Abstract

A sealed structure includes: a shaft; a member having a hole for the shaft; and a sealing ring sealing a gap between the shaft and the member. The shaft has a circular ring groove centered around the central axis of the shaft. The bottom surface of the groove has a recess. The sealing ring has a protrusion protruding toward the central axis. The protrusion fits into the recess. When the shaft rotates, an end face X of the protrusion and an end face Y of the recess contact each other to push the sealing ring radially outward. An angle α of a straight line representing the end face X relative to the radial direction of the sealing ring and an angle δ of a straight line representing the end face Y relative to the radial direction of the shaft are both at least 45 degrees.

Inventors

Hideya Watanabe

Assignees

NOK CORPORATION

Dates

Publication Date: 20260505
Application Date: 20220408
Priority Date: 20210622

Claims (6)

1 . A sealed structure comprising: a shaft; a member having a shaft hole in which the shaft is to be inserted; and a sealing ring configured to seal a gap between an outer surface of the shaft and an inner surface of the member constituting the shaft hole, wherein: the shaft has an annular groove formed at the outer surface and having an axis line as its center, and further has one or more recesses which are provided at a bottom surface of the groove in a circumferential direction, and which are concave in a direction approaching the axis line, the sealing ring has one or more protrusions protruding from its inner circumferential surface in the direction approaching the axis line, the protrusions are identical in number to the recesses, a radius at a point of each protrusion closest to the axis line is smaller than a radius at the bottom surface of the groove in the shaft, and the sealing ring is configured so that the protrusions are accommodated in the recesses when the sealing ring is set within the groove, the sealing ring is configured so that, when the shaft is rotated, an end surface X of each protrusion in the circumferential direction and an end surface Y of each recess in the circumferential direction come into contact with each other and the end surface X of each protrusion slides along the end surface Y of each recess in a radially outward and circumferential direction to push out the sealing ring on an external diameter side, and in a cross-section in a direction perpendicular to the axis line, end surfaces X and end surfaces Y each form a straight line, and an angle a of the straight line representing each end surface X with respect to a radial direction of the sealing ring and an angle 5 of the straight line representing each end surface Y with respect to a radial direction of the shaft are between 60 degrees and 80 degrees.
2 . The sealed structure according to claim 1 , wherein: the sealing ring has an abutment portion, and in the cross-section in the direction perpendicular to the axis line, a center X c of an end surface X in the circumferential direction is present within a range of 20° to 60° with respect to the abutment portion.
3 . The sealed structure according to claim 1 , wherein: two or more protrusions and two or more recesses are present, and in the cross-section in the direction perpendicular to the axis line, the two or more protrusions and the two or more recesses are present at symmetric positions with respect to the abutment portion.
4 . A sealing ring configured to seal a gap between an outer surface of a shaft and an inner surface of a member constituting a shaft hole, the sealing ring being used in a sealed structure comprising: the shaft; and the member having the shaft hole in which the shaft is to be inserted, the shaft having an annular groove which is formed at the outer surface and has an axis line as its center, and further having one or more recesses which are provided at a bottom surface of the groove in a circumferential direction, and which are concave in a direction approaching the axis line, end surfaces Y of the recesses in the circumferential direction form a straight line, respectively, in a cross-section in a direction perpendicular to the axis line, and an angle delta of the straight line with respect to a radial direction of the shaft being between 45 degrees and 80 degrees wherein: the sealing ring has one or more protrusions protruding from its inner circumferential surface in the direction approaching the axis line, the protrusions are identical in number to the recesses, a radius at a point of each protrusion closest to the axis line is smaller than a radius at the bottom surface of the groove in the shaft, and the sealing ring is configured so that the protrusions are accommodated in the recesses when the sealing ring is set within the groove, the sealing ring is configured so that, when the shaft is rotated, an end surface Y and an end surface X of each protrusion in the circumferential direction come into contact with each other and the end surface X of each protrusion slides along the end surface Y of each recess in a radially outward and circumferential direction to push out the sealing ring on an external diameter side, and in the cross-section in the direction perpendicular to the axis line, each end surface X forms a straight line, and an angle a of the straight line with respect to a radial direction is between 60 degrees and 80 degrees.
5 . The sealing ring according to claim 4 , wherein: the sealing ring has an abutment portion, and in the cross-section in the direction perpendicular to the axis line, a center X c of an end surface X in the circumferential direction is present within a range of 20° to 60° with respect to the abutment portion.
6 . The sealing ring according to claim 4 , wherein: two or more protrusions are present, and in the cross-section in the direction perpendicular to the axis line, the two or more protrusions are present at symmetric positions with respect to the abutment portion.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a 371 U.S. National Phase of International Application No. PCT/JP2022/017399, filed on Apr. 8, 2022, which claims priority to Japanese Patent Application No. 2021-102898, filed Jun. 22, 2021. The entire disclosures of the above applications are incorporated herein by reference. BACKGROUND Technical Field The present invention relates to a sealing ring and a sealed structure including the same. Related Art For example, in a reducer of a motor mechanism in an electric vehicle (EV), a hybrid electric vehicle (HEV) or the like, a sealed structure is used to prevent leakage of cooling oil within the reducer. Such a sealed structure has a sealing ring in it and the sealing ring is used to seal a gap between a shaft and a shaft hole in which the shaft is to be inserted. The sealing ring is accommodated within a groove formed at the outer circumferential surface of the shaft and seals the gap between the shaft and the shaft hole by contact with the inner surface of a member constituting the shaft hole, thereby preventing an object to be sealed (for example, cooling oil within the reducer) from leaking out of the shaft hole while retaining the hydraulic pressure of the cooling oil or the like in the gap between the shaft and the shaft hole. The sealing ring is usually not endless but is cut and has an abutment portion at the cut part (see, for example, JP 2016-14481 A). The hydraulic pressure of the cooling oil in the reducer of the motor mechanism in the electric vehicle (EV) or the hybrid electric vehicle (HEV) is very low or zero. That is, the hydraulic pressure applied to the sealing ring is significantly lower than the pressure (hydraulic pressure) applied to a sealing ring used to seal the operating oil in an automatic transmission (AT), a continuously variable transmission (CVT) or the like. The sealing ring used in such a low pressure environment as in a reducer or the like is usually formed using a resin material by a method such as injection molding. In a case where molding is made by, for example, the injection molding, the sealing ring is formed in a state in which the abutment portion is wide, and the molding is followed by correction (diameter reduction) to obtain a desired diameter. However, it is hard to correct the abutment portion and its vicinity. Particularly in a case where rigid resins such as PEEK (polyetheretherketone) and PPS (polyphenylene sulfide) are used as resin materials, it is harder to perform correction to obtain a desired diameter. In a case where the abutment portion and its vicinity subjected to the correction do not have a desired diameter, the sealing ring in the usage state lacks in roundness, whereby a gap is formed between the inner surface of the member constituting the shaft hole and the outer circumferential surface of the sealing ring. In a case where the sealing ring is used in the automatic transmission (AT), the continuously variable transmission (CVT) or the like, a high hydraulic pressure of the operating oil is applied to cause the sealing ring to be pressed against the inner surface of the shaft hole, whereby the gap on the outer circumferential side based on the lack of roundness of the sealing ring will disappear. However, in a case where a low hydraulic pressure or no hydraulic pressure is applied as in the reducer, the sealing ring is less likely to be pressed against the inner surface of the shaft hole, and a gap may be therefore formed on the outer circumferential side of the sealing ring. Under the circumstances, for a sealing ring used in a low pressure environment as in a reducer of a motor mechanism in an electric vehicle (EV) or a hybrid electric vehicle (HEV), a technique which is capable of suppressing occurrence of a gap between the inner surface of a shaft hole and the outer circumferential surface of the sealing ring based on the lack of roundness of the sealing ring has been required. An object of the present invention is to solve the problem as described above. Specifically, an object of the present invention is to provide a sealing ring capable of suppressing occurrence of a gap between the inner surface of a shaft hole and the outer circumferential surface of the sealing ring, and a sealed structure including the sealing ring. SUMMARY The present invention provides the following (1) to (6). (1) A sealed structure including: a shaft; a member having a shaft hole in which the shaft is to be inserted; and a sealing ring configured to seal a gap between an outer surface of the shaft and an inner surface of the member constituting the shaft hole, wherein:the shaft has an annular groove formed at the outer surface and having an axis line as its center, and further has one or more recesses which are provided at a bottom surface of the groove in a circumferential direction, and which are concave in a direction approaching the axis line,the sealing ring has one or more protrusions protr