JP2019094939A - Sealing structure - Google Patents

Abstract

To provide a sealing structure capable of reducing rotational torque without depending on a direction in which a seal ring is mounted.SOLUTION: A sealing structure is configured such that when pressure difference occurs across both sides through a seal ring 300 in an annular clearance, the seal ring 300 closely contacts with a side wall surface of a low pressure side (L) in an annular groove 110, and slides on an inner peripheral surface of a shaft hole of a housing 200, to seal the annular clearance. The sealing structure is characterized in that the largest portion of an outer diameter in the seal ring 300 is constituted by a columnar surface, and a region containing a portion, where an outer peripheral surface of the seal ring 300 slides, of an inner peripheral surface of the shaft hole is constituted by an inclination surface whose diameter becomes larger from the low pressure side (L) toward a high pressure side (H).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sealing structure that seals an annular gap between a relatively rotating shaft and a housing.

  In Automatic Transmission (AT) and Continuously Variable Transmission (CVT) for automobiles, a seal ring is provided to seal an annular gap between the relatively rotating shaft and the housing in order to hold the hydraulic pressure. . In such a seal ring, in order to reduce fuel consumption, it is required to reduce the rotational torque (sliding torque at the time of rotation) in the seal ring. A sealing structure according to the conventional example will be described with reference to FIG. FIG. 8 is a schematic cross-sectional view of a sealing structure according to Conventional Example 1. In FIG. 8, the right side in the drawing is the high pressure side (H), and the left side in the drawing is the low pressure side (L).

  The seal ring 600 according to Conventional Example 1 is mounted in an annular groove 110 provided on the outer periphery of the shaft 100. The seal ring 600 is in close contact with the inner peripheral surface of the shaft hole of the housing 500 into which the shaft 100 is inserted, and is slidably in contact with the low pressure side (L) side wall surface of the annular groove 110. , And an annular gap between the shaft 100 and the shaft hole of the housing 500.

  In the seal ring 600 according to this conventional example, annular notches 610 are respectively provided on the inner peripheral surface side of both side surfaces. That is, in the seal ring 600, the shape of the cross section cut along a plane including the central axis is T-shaped.

  In the case of the seal ring 600 configured as described above, fluid pressure acts from both sides at the portion where the notch portion 610 is provided. Therefore, these fluid pressures are offset. Therefore, the sliding resistance by the seal ring 600 with respect to the side wall surface of the annular groove 110 does not affect the portion where the notch portion 610 is provided. In other words, the sliding resistance of seal ring 600 against the side wall surface of annular groove 110 is the fluid pressure acting on the portion of side surface of seal ring 600 on the high pressure side (H) where notch 610 is not provided. Depends only on. Therefore, the sliding resistance can be reduced as the radial width of the portion where the notch portion 610 is not provided is narrowed. The arrows in the figure indicate the state of fluid pressure acting on the seal ring 600.

  However, in order to ensure that the seal ring 600 slides on the side wall surface of the annular groove 110, the radial width of the portion of the side surface of the seal ring 600 where the notch 610 is not provided is set. The width of the annular gap between the shaft 100 and the shaft hole of the housing 500 should be wider than the width of the tolerance of each member. When the shaft 100 is eccentric with respect to the housing 500, the eccentricity must also be considered. Therefore, depending on the use environment, there is a limit to narrowing the radial width of the portion of the side surface of seal ring 600 where notch 610 is not provided, and rotational torque can not be sufficiently reduced. There is.

  Therefore, a technique is also known in which the outer peripheral surface of the seal ring is caused to slide relative to the inner peripheral surface of the shaft hole of the housing, and the rotational torque is reduced. Such a prior art will be described with reference to FIG. FIG. 9 is a schematic cross-sectional view of a sealing structure according to Conventional Example 2. In FIG. 9, the right side in the drawing is the high pressure side (H), and the left side in the drawing is the low pressure side (L).

  The seal ring 700 according to Conventional Example 2 is mounted in an annular groove 110 provided on the outer periphery of the shaft 100. The seal ring 700 is in close contact with the side wall surface on the low pressure side (L) of the annular groove 110 and slidably contacts the inner peripheral surface of the shaft hole of the housing 500 into which the shaft 100 is inserted. , And an annular gap between the shaft 100 and the shaft hole of the housing 500.

  The seal ring 700 according to Conventional Example 2 is provided with a tapered surface 710 on the high pressure side (H) and on the outer peripheral surface side. In the seal ring 700, fluid pressure acts from both the outer peripheral surface side and the inner peripheral surface side at the portion where the tapered surface 710 is provided. Therefore, these fluid pressures are offset. Therefore, the portion provided with the tapered surface 710 does not affect the sliding resistance of the seal ring 700 against the inner peripheral surface of the axial hole of the housing 500. That is, the sliding resistance due to seal ring 700 against the inner circumferential surface of the axial hole of housing 500 acts on the range in the axial direction on the inner circumferential surface of seal ring 700 where taper surface 710 is not provided. It depends only on the fluid pressure. Therefore, the sliding resistance can be reduced as the range is narrowed. The arrows in the figure indicate the state of the fluid pressure acting on the seal ring 700.

  In the case of the seal ring 700 according to the conventional example 2, the problem as in the case of the seal ring 600 according to the conventional example 1 does not occur. However, in the case of the seal ring 700 according to the conventional example 2, when mounting the seal ring 700 in the annular groove 110, it is necessary to mount so that the tapered surface 710 faces the high pressure side (H). If the tapered surface 710 is attached to the annular groove 110 so as to face the low pressure side (L), the effect of offsetting the fluid pressure can not be obtained, so the rotational torque can not be reduced. In addition, the side surface of the low pressure side (L) of the seal ring 700 may slide against the side wall surface of the annular groove 110. Therefore, some means must be provided to prevent the tapered surface 710 of the seal ring 700 from being attached to the annular groove 110 toward the low pressure side (L).

Patent No. 5598000 gazette

  An object of the present invention is to provide a sealing structure capable of reducing rotational torque without depending on the mounting direction of the seal ring.

  The present invention adopts the following means in order to solve the above problems.

The sealing structure of the present invention is
A housing having an axial hole;
A shaft which is inserted into the shaft hole and rotates relative to the housing;
A resin mounted in an annular groove provided on the outer periphery of the shaft, which seals the annular gap between the shaft and the housing, and holds the fluid pressure of the sealing target area configured to change the fluid pressure With a seal ring made of
Equipped with
In the annular gap, when a differential pressure is generated on both sides via the seal ring, the seal ring closely contacts the side wall surface on the low pressure side of the annular groove, and slides on the inner circumferential surface of the shaft hole A sealing structure in which the annular gap is sealed by
The largest outside diameter portion of the seal ring is formed of a cylindrical surface, and
A region including a portion of the inner peripheral surface of the shaft hole on which the outer peripheral surface of the seal ring slides is characterized by an inclined surface whose diameter increases from the low pressure side to the high pressure side.

  According to the present invention, the largest portion of the outer diameter in the seal ring is formed of a cylindrical surface, and the region including the portion of the inner peripheral surface of the axial hole where the outer peripheral surface of the seal ring slides is the low pressure side to the high pressure side. It is comprised by the inclined surface which diameter-expands toward. Therefore, in the state where the differential pressure is generated, the low pressure side end portion of the seal ring with the largest outer diameter and the inner peripheral surface (inclined surface) of the shaft hole are in a state of linear contact. As a result, the fluid pressure acting from both the outer peripheral surface side and the inner peripheral surface side with respect to the seal ring is canceled in the region on the higher pressure side than the line contact portion. Thereby, the rotational torque can be reduced without depending on the mounting direction of the seal ring.

  The seal ring may be symmetrical with respect to a center of a width in a central axial direction of the seal ring.

  Thereby, the mounting direction of the seal ring is irrelevant to the sealing property.

  The above-described configurations may be combined and used as much as possible.

  As described above, according to the present invention, the rotational torque can be reduced without depending on the mounting direction of the seal ring.

FIG. 1 is a schematic cross-sectional view of a sealing structure according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of a shaft and a housing according to an embodiment of the present invention. FIG. 3 is a side view of a seal ring according to an embodiment of the present invention. FIG. 4 is a partially enlarged view of the side view of the seal ring according to the embodiment of the present invention. FIG. 5 is a partially enlarged view of the side view of the seal ring according to the embodiment of the present invention. FIG. 6 is a partially enlarged view of the seal ring according to the embodiment of the present invention as viewed from the outer peripheral surface side. FIG. 7 is a partially enlarged view of the seal ring according to the embodiment of the present invention as viewed from the inner peripheral surface side. FIG. 8 is a schematic cross-sectional view of a sealing structure according to Conventional Example 1. FIG. 9 is a schematic cross-sectional view of a sealing structure according to Conventional Example 2.

  Hereinafter, with reference to the drawings, modes for carrying out the present invention will be exemplarily described in detail based on examples. However, the dimensions, materials, shapes, relative positions, etc. of the components described in this embodiment are not intended to limit the scope of the present invention to them unless otherwise specified. . The seal ring according to the present embodiment is used for sealing an annular gap between a relatively rotating shaft and a housing in a transmission such as an AT or CVT for an automobile to hold an oil pressure. It is used. Further, in the following description, the "high pressure side" means a side which is high when a differential pressure is generated on both sides of the seal ring, and the "low pressure side" is a differential pressure generated on both sides of the seal ring. Mean the side where the pressure is low.

(Example)
A sealing structure according to an embodiment of the present invention will be described with reference to FIGS. 1 to 7. FIG. 1 is a schematic cross-sectional view of a sealing structure according to an embodiment of the present invention, and is a cross-sectional view in which a seal ring and the like are cut along a plane including a central axis of a shaft and a seal ring. FIG. 2 is a schematic cross-sectional view of a shaft and a housing according to an embodiment of the present invention, and is a cross-sectional view of the shaft and the housing at a portion where the seal ring is mounted. FIG. 3 is a side view (a schematic side view) of a seal ring according to an embodiment of the present invention. FIG. 4 is a partially enlarged view of a side view of a seal ring according to an embodiment of the present invention, and is an enlarged view of a circled portion in FIG. FIG. 5 is a partially enlarged view of the side view of the seal ring according to the embodiment of the present invention, and is an enlarged view of the circled part in FIG. 3 as viewed from the opposite side. FIG. 6 is a partially enlarged view of the seal ring according to the embodiment of the present invention as viewed from the outer peripheral surface side, and is an enlarged view of the encircled portion in FIG. 3 as viewed from the outer peripheral surface side. FIG. 7 is a partially enlarged view of the seal ring according to the embodiment of the present invention as viewed from the inner peripheral surface side, and is an enlarged view of the encircled portion in FIG. 3 as viewed from the inner peripheral surface.

<Schematic Configuration of Sealed Structure>
In the sealing structure according to the present embodiment, a housing 200 having a shaft hole, a shaft 100 which is inserted into the shaft hole and rotates relative to the housing 200, and an annular gap between the shaft 100 and the housing 200 is sealed. And a seal ring 300 made of resin. The seal ring 300 according to the present embodiment is mounted in an annular groove 110 provided on the outer periphery of the shaft 100, and seals an annular gap between the shaft 100 and the inner peripheral surface of the shaft hole provided in the housing 200. . Thereby, the seal ring 300 holds the fluid pressure of the sealing target area configured to change the fluid pressure (in the present embodiment, the hydraulic pressure). Here, in the present embodiment, the fluid pressure in the region on the right side in FIG. 1 is configured to change, and the seal ring 300 plays a role of holding the fluid pressure in the sealing target region on the right side in the diagram. There is. When the engine of the automobile is stopped, the fluid pressure in the region to be sealed is low and unloaded, and when the engine is applied, the fluid pressure in the region to be sealed becomes high. Therefore, when the engine is applied and a differential pressure is generated on both sides of the seal ring 300, the right side in FIG. 1 is the high pressure side (H) and the left side in FIG. 1 is the low pressure side (L).

<Sealing ring>
The seal ring 300 according to the present embodiment will be described with reference to FIGS. 1 and 3 to 7. As a specific example of the material used for the seal ring 300 which concerns on a present Example, polyetheretherketone (PEEK), polyphenylene sulfide (PPS), a polytetrafluoroethylene (PTFE) etc. can be mentioned. The seal ring 300 according to the present embodiment has a rectangular cross-sectional shape cut at a plane including the central axis (see FIG. 1). Therefore, the largest portion of the outer diameter in the seal ring 300 (corresponding to the entire outer peripheral surface in the case of the present embodiment) is formed of a cylindrical surface. In addition, seal ring 300 is symmetrical with respect to the center of the width in the direction of the central axis.

  In the seal ring 300 according to the present embodiment, the outer diameter of the seal ring 300 in the inner peripheral surface of the shaft hole in the housing 200 does not slide when the external force is not applied (the fluid pressure is not applied). It is designed to be smaller than the inner diameter of the moving part.

  Further, in the seal ring 300 according to the present embodiment, a joint portion 310 is provided at one place in the circumferential direction. That is, the seal ring 300 according to the present embodiment has a configuration in which the abutment portion 310 is formed for an annular member having a rectangular cross section. However, this is only an explanation of the shape, and it does not necessarily mean that the processing for forming the abutment 310 is performed using an annular member having a rectangular cross section as a material. Of course, after forming the annular member having a rectangular cross section, the joint portion 310 can be obtained by cutting, but depending on the resin material, one having the joint portion 310 can be molded, and the manufacturing method is particularly limited. It is not a thing.

The abutment section 310 adopts a so-called special step cut provided with a step-like mating surface (cut surface) when viewed from any of the outer peripheral surface side and both side wall surfaces. Thus, in the seal ring 300, the first fitting convex portion 311X and the first fitting recess 312X are provided on the outer peripheral side on one side via the mating surface, and the first outer peripheral side on the other side is the first A second fitting recess 312Y in which the fitting protrusion 311X is fitted and a second fitting protrusion 311Y in which the first fitting recess 312X is fitted are provided. The end surface 313X on the inner peripheral surface side on one side and the end surface 313Y on the inner peripheral side on the other side face each other via the mating surface. As the special step cut is a well-known technology, its detailed description is omitted, but it has the property of maintaining stable sealing performance even if the circumferential length of the seal ring 300 changes due to thermal expansion and contraction. In addition, about "a joint surface (cutting surface)", not only when obtained by cutting, but also when obtained by shaping | molding is included.

  However, the gap section is not limited to the above special step cut, and various known techniques can be adopted. For example, a straight cut, a bias cut, a step cut or the like may be employed. Since these are publicly known techniques, the detailed description thereof will be omitted, but the straight cut is a structure which is cut straight in the radial direction. Also, the bias cut is a structure that is cut obliquely to the radial direction. In addition, the step cut is cut in a step shape as viewed from the outer peripheral surface and the inner peripheral surface, and linearly cut as viewed from both side surfaces, or cut into a step shape as viewed from both side surfaces. It is a structure cut | disconnected linearly when it sees from an inner peripheral surface. These cut structures may be formed by molding in addition to the case where they are formed by cutting literally. Moreover, it is also possible to set it as an endless (endless) seal ring, without providing an abutment.

<Housing shaft hole>
In particular, with reference to FIGS. 1 and 2, the axial bore of the housing 200 will be described in more detail. A region including a portion where the outer peripheral surface of the seal ring 300 slides in the inner peripheral surface of the shaft hole of the housing 200 according to the present embodiment has an inclination in which the diameter increases from the low pressure side (L) to the high pressure side (H) It is constituted by the face 210. In the present embodiment, “the region including the portion where the outer peripheral surface of the seal ring 300 slides on the inner peripheral surface of the shaft hole of the housing 200” includes the entire region facing the annular groove 110 of the shaft 100. . The inner circumferential surface of the shaft hole of the housing 200 according to the present embodiment is a large diameter portion (cylindrical surface) with a small diameter portion (small diameter portion formed by a cylindrical surface) on the low pressure side (L) and a high diameter side (L) The large diameter portion to be configured is connected by the inclined surface 210 described above. Moreover, the inclined surface 210 which concerns on a present Example is comprised by the taper surface. The inclination angle α of the inclined surface 210 with respect to the central axis of the shaft hole (which coincides with the central axis of the shaft 100) is preferably set in the range of 0.05 ° or more and 0.4 ° or less. That is, the taper angle of the inclined surface 210 is desirably set in the range of 0.1 ° or more and 0.8 ° or less.

  However, the inclined surface is not limited to the tapered surface, and it is also possible to adopt an inclined surface in which the cross-sectional shape cut by a surface including the central axis of the axial hole is a curved line.

<Mechanism when using sealed structure>
In particular, referring to FIG. 1, the mechanism in use of the sealing structure will be described. As described above, in the seal ring 300 according to the present embodiment, the outer diameter in the state where no external force is applied is greater than the inner diameter of the portion of the inner peripheral surface of the shaft hole in the housing 200 where the seal ring 300 slides. It is designed to be small. Therefore, in the unloaded state, the outer peripheral surface of the seal ring 300 can be separated from the inner peripheral surface (portion of the inclined surface 210) of the axial hole of the housing 200. In addition, the side surface of the seal ring 300 (the side surface on the low pressure side (L) when a pressure difference is generated) may be separated from the side wall surface of the annular groove 110.

When the engine is applied and differential pressure is generated, the fluid pressure from the high pressure side (H) brings the seal ring 300 into close contact with the side wall surface of the annular groove 110 on the low pressure side (L). Further, seal ring 300 is expanded in diameter by receiving fluid pressure from the inner peripheral surface side, and the outer peripheral surface of seal ring 300 is in contact with the inner peripheral surface of the axial hole of housing 200. Here, while the outer peripheral surface of seal ring 300 is formed of a cylindrical surface, a portion of the inner peripheral surface of the shaft hole of housing 200 where the outer peripheral surface of seal ring 300 contacts is inclined as described above. It is constituted by the face 210. Therefore, in the outer peripheral surface of the seal ring 300, the end portion of the low pressure side (L) is in contact with the inclined surface 210 in a state of line contact or the like. A portion indicated by X in FIG. 1 is a portion where the outer peripheral surface of the seal ring 300 is in contact with the inclined surface 210.

  According to the sealing structure configured as described above, the fluid pressure acts on the range of the high pressure side (H) of the outer peripheral surface of the seal ring 300 than the portion in contact with the inclined surface 210. In addition, fluid pressure acts on the entire inner peripheral surface of the seal ring 300. Therefore, the fluid pressure acting from both the outer peripheral surface side and the inner peripheral surface side with respect to the seal ring 300 is canceled in the region of the high pressure side (H) than the region of the line contact (the region shown by X in FIG. 1). Be done. Also, fluid pressure acts on the entire side surface of the high pressure side (H) of the seal ring 300, and fluid pressure does not act on the side surface of the low pressure side (L). The arrows in FIG. 1 indicate the state of the fluid pressure acting on the seal ring 300.

  As described above, the fluid pressure acting from the high pressure side (H) to the low pressure side (L) with respect to the seal ring 300 is sufficiently larger than the fluid pressure acting from the inner peripheral surface side to the outer peripheral surface side of the seal ring 300. Therefore, while the shaft 100 and the housing 200 are relatively rotated, the side surface of the seal ring 300 is in close contact with the side wall surface of the annular groove 110 (side wall surface on the low pressure side (L)) The sliding contact between the outer circumferential surface 300 and the inclined surface 210 is maintained. From the above, the annular gap between the shaft 100 and the housing 200 is sealed.

<Excellent points of the sealing structure according to the present embodiment>
According to the sealing structure of the present embodiment, the portion of the seal ring 300 having the largest outer diameter is a cylindrical surface, and the portion of the inner peripheral surface of the shaft hole of the housing 200 on which the outer peripheral surface of the seal ring 300 slides. The region including [1] is constituted by an inclined surface which expands in diameter from the low pressure side (L) to the high pressure side (H). Therefore, in the state where the differential pressure is generated, the low pressure side end portion of the seal ring 300 having the largest outer diameter and the inner peripheral surface (inclined surface 210) of the shaft hole are in a state like line contact. . As a result, fluid pressure acting on the seal ring 300 from both the outer peripheral surface side and the inner peripheral surface side is canceled in the region of the high pressure side (H) than the portion of the line contact. As a result, the rotational torque can be reduced without depending on the mounting direction of the seal ring 300. As described above, the reduction in rotational torque (sliding torque) can be achieved, whereby heat generation due to sliding can be suppressed, and the seal ring 300 according to the present embodiment can be suitably used even under high-speed and high-pressure environmental conditions. It becomes possible.

  Moreover, the seal ring 300 which concerns on a present Example is symmetrical shape with respect to the center of the width | variety of the central axis direction. Thus, the mounting direction of the seal ring 300 is irrelevant to the sealing property.

(Others)
In the said Example, the case where the seal ring was comprised by the annular member whose cross section is a rectangle was shown. However, the seal ring applied to the present invention is not limited to such a shape. For example, as in the conventional example shown in FIG. 8, a seal ring having a T-shaped cross section can also be applied. Also, other shapes of seal rings can be applied. However, the outer diameter of the seal ring is in line contact with the inclined surface 210 in the shaft hole of the housing 200, and the fluid pressure acts on the side (H) higher than the contact portion of the outer peripheral surface of the seal ring. The largest part of must be constructed with a cylindrical surface.

  Further, the seal ring applicable to the present invention is not necessarily required to be symmetrical with respect to the center of the width in the direction of the central axis. Because, if the largest part of the outer diameter in the seal ring is formed by a cylindrical surface, the low pressure end of the cylindrical surface is in line contact with the inclined surface 210 in the axial hole of the housing 200, It is because said effect can be acquired. However, in the case where the sealability is adversely affected by the change in the direction of the seal ring (for example, in the case where the cancel pressure is reduced), the present invention should not be applied.

100 axis 110 annular groove 200 housing 210 inclined surface 300 seal ring 310 joint section 311X first fitting convex section 311Y second fitting convex section 312X first fitting concave section 312Y second fitting concave section 313X, 313Y end face α inclination angle

Claims (2)

A housing having an axial hole;
A shaft which is inserted into the shaft hole and rotates relative to the housing;
A resin mounted in an annular groove provided on the outer periphery of the shaft, which seals the annular gap between the shaft and the housing, and holds the fluid pressure of the sealing target area configured to change the fluid pressure With a seal ring made of
Equipped with
In the annular gap, when a differential pressure is generated on both sides via the seal ring, the seal ring closely contacts the side wall surface on the low pressure side of the annular groove, and slides on the inner circumferential surface of the shaft hole A sealing structure in which the annular gap is sealed by
The largest outside diameter portion of the seal ring is formed of a cylindrical surface, and
A sealing structure characterized in that a region including a portion where the outer peripheral surface of the seal ring slides in the inner peripheral surface of the shaft hole is an inclined surface whose diameter increases from the low pressure side toward the high pressure side. .   The sealing structure according to claim 1, wherein the seal ring is symmetrical with respect to a center of a width in a central axial direction of the seal ring.

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