JP2019060368A - Hermetically sealed structure - Google Patents

Abstract

To provide a hermetically sealed structure which has low friction and exerts stable seal performance.SOLUTION: A groove side surface 30 of a low pressure side L of a seal concave groove 3 has a shape inclined toward the inside of the groove. A resin ring 4 mounted inside there has a low pressure side gradient surface 8 coming into abutting contact with the slope-like groove side surface 30 of the seal concave groove 3.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a sealing structure, and more particularly to a low friction moving sealing structure.

In a continuously variable transmission (CVT) of an automobile, an automatic transmission (AT) and the like, a resin ring is used as a fluid-sealed structure, and characteristics such as low leak, low abrasion and low torque are required.
For example, conventionally, a resin ring 40 having a rectangular cross-sectional shape as shown in FIG. 6 is embedded in a seal groove 41 having a rectangular cross-sectional shape, and the first member 46 and the first member 46 that perform relative rotation R ₄₆ or linear movement N ₄₆ are Sealing structures have been used to seal the gap 42 between the two members 47.
In recent years, there has been a demand for reduction in fuel consumption of automobiles as a countermeasure against environmental problems, and a reduction in sliding (friction) resistance is strongly demanded also for a sealing structure composed of the resin ring 40 and the seal groove 41.
In FIG. 6 showing the conventional example, the sliding (friction) resistance can be reduced as the contact width W ₁ ′ of the resin ring 40 with respect to the second member 47 is set smaller.
That is, since the pressure receiving area of the bottom surface 40A of the resin ring 40 is reduced if the width dimension (axial dimension) of the resin ring 40 having a rectangular cross section is reduced, the pressing force K against the second member 47 is the contact width The smaller FIG. 6 (B) of W ₁ ′ is smaller than FIG. 6 (A).

However, if the contact width W ₁ ′ is reduced as shown in FIG. 6B, the posture of the resin ring 40 in the seal groove 41 becomes unstable, which may cause a fluid leak. This becomes remarkable as the diameter of the whole resin ring 40 becomes large. In FIG. 5 described later, in the case of the resin ring 40 of W ₁ ′ = 1.1 mm, the posture became unstable during the test, the fluid leaked a lot, and the frictional resistance could not be measured.
Therefore, conventionally, there has been proposed a resin ring (seal ring) having a stable posture, less fluid leakage and small sliding resistance and in which complicated notches, small holes and small convex portions are formed ( Patent Document 1).

International Publication No. 2014/196403

Although the resin ring described in Patent Document 1 has an advantage that the posture in the seal groove is stable and the sliding resistance is small, the resin ring has a complicated notch, a small hole, and a small convex portion, so that the stress is stressed. There is a risk that fatigue damage may occur due to concentration, and it can be said that there is concern in terms of failure or life of the internal sealing structure such as CVT or AT of the automobile.
Therefore, the present invention can set the contact width small, can suppress the sliding (friction) resistance sufficiently low, moreover, the sealed structure having a stable posture, less occurrence of fluid leakage, and excellent durability. The purpose is to provide

  Therefore, in the present invention, in a sealing structure provided with a seal groove and a resin ring embedded in the seal groove; the groove side surface on the low pressure side of the seal groove is inclined toward the inside of the groove The resin ring has a low pressure side sloped surface which is parallel to the groove side surface and in contact with the groove side surface in a pressure receiving state.

  According to the present invention, as a simple cross section having no complicated notch, small hole and small convex portion in the resin ring, there is no possibility of occurrence of fatigue failure, excellent in durability and reliability, and sliding. The dynamic (friction) resistance is stably kept low enough, the posture in the seal groove is stable, the fluid does not easily leak, and the sealing performance is excellent.

It is principal part sectional drawing which showed embodiment of this invention with an effect | action, Comprising: (A) is a figure which shows the case where contact width is small, (B), when the contact width is large. It is an expanded principal part sectional view for explanation of pressure distribution in the case of a large contact width, and operation. It is an expanded principal part sectional view for explanation of pressure distribution in the case of small contact width, and operation. It is a figure for demonstrating the resin ring in which cross-sectional shape and a dimension differ in order to obtain | require the value of the thrust K by FEM analysis. It is a graph which took pressure P on the horizontal axis, and took friction resistance Y on the vertical axis, and is a graph which compared the present invention and a conventional example. It is principal part sectional drawing for operation | movement explanatory which showed two types of conventional examples from which a dimension and a shape differ for comparison, Comprising: (A) shows a case where a contact width is small, when a contact width is large.

Hereinafter, the present invention will be described in detail based on the illustrated embodiments.
As shown in FIGS. 1 to 3, the first member 1 is provided with a seal recess 3, and the resin ring 4 is in contact with the seal recess 3 via the internal minute gap 6 or in a slidable manner. The second member 2 faces in a contact manner. Reference numerals 21 and 22 indicate corresponding surfaces facing each other. In Figure 1, consists of the rotary shaft and various rotating body first member 1 is rotated R ₁ to shaft center L ₁ around, or in the opposite direction dotted arrows N ₁ and linearly reciprocating pistons such that linear movement The corresponding surface 21 (shown in FIG. 1) exhibits a circular outer circumferential surface and the corresponding surface 22 exhibits a circular inner circumferential surface.
Conversely, the second member 2 may be a rotary shaft or various rotary members, or may be a linear reciprocator, in which case the corresponding surface 21 is a circular inner peripheral surface, a corresponding surface 22. Is a circular outer peripheral surface.

  It is used to seal hydraulic fluid and the like inside automatic transmission (AT) of automobiles, or it is used to seal hydraulic fluid and the like inside continuous variable transmission (CVT).

As shown in FIGS. 1 to 4, the cross-sectional shape of the seal groove 3 is a so-called (piece) dovetail shape, and the groove opening width dimension is set smaller than the width dimension of the groove bottom surface 11. .
The groove side surface 30 of the low-pressure side L of the seal recess groove 3 is formed as an inclined shape which is inclined in the in-groove direction --- a direction approaching the groove bottom surface 11--. On the other hand, the groove side surface 31 of the high-pressure side H of the seal groove 3 is perpendicular to the groove bottom surface 11 in cross-sectional shape.
The angle θ formed between the groove side surface 30 on the low pressure side L and the groove bottom surface 11 is 30 ° to 80 °. Preferably, it is 35 ° to 70 °, and particularly preferably 40 ° to 60 °. If it is less than the lower limit value, the groove width dimension (close to the groove bottom surface 11) of the seal recessed groove 3 becomes too large, which hinders the compactification. Conversely, when the upper limit is exceeded, the low friction effect (described later) can hardly be obtained.

  The resin ring 4 has a substantially trapezoidal cross-sectional shape, and the low-pressure side sloped surface 8 in contact with the groove side surface 30 in the pressure receiving state corresponding to the inclined side surface 30 in parallel. Have. The material is PPS with filler, PTFE, PEEK or the like. Further, the overall shape of the resin ring 4 may be a closed circular ring or an annular ring having a seam (cut) at one circumferential position.

Next, for the conventional example (conventional product) (A) as shown in FIG. 4 and the inventive products (B), (C) and (D), the pressing force K at a fluid pressure of 6 MPa is determined by FEM analysis The Here, T represents a thickness dimension, and W ₁ ′ and W ₁ represent a contact width.
Conventional Example (Conventional Product) (A) and Invention Implementation Products (B) (C) (D) Each Forces the Corresponding Surfaces of the Second Members 47 and 2 to Press---Pressing Force K-- The values of were as shown in Table 1 below.

From the FEM analysis results of Table 1 above, the following can be understood.
(i) The pressing force K changes largely depending on the magnitude of the contact widths W ₁ ′ and W ₁ .
(ii) The same pressing force K can be obtained if the contact width is the same regardless of the cross-sectional shape according to the present invention or the conventional product.
(iii) The thickness dimension T does not affect the magnitude of the pressing force K.
(iv) pressing force K of the contact width W ₁ is the smallest of the embodiment sample D showed a minimum.
(v) Assuming that the coefficient of friction μ between the seal sliding surface (corresponding surface 22) of the second member 47, 2 (corresponding surface 22) and the resin rings (A), (B), (C), (D) is the same, the frictional resistance Y is , Y = μ · K. Therefore, the friction resistance Y, the embodiment sample D of the contact width W ₁ is minimum indicates the minimum value, conventional product (A) and embodied products (B) (C) shows the same value (the larger).

Regarding the above considerations (i) to (v), the fluid pressure P acting on each portion of the resin ring 4 shown in FIGS. 2 and 3 and the resin ring 4 from the first and second members 1 and 2 In the following, technical analysis and examination of the reaction force acting on and the fact that the above considerations (i) to (v) are correct will be explained.
In FIG. 2 and FIG. 3, the fluid pressures P ₁ , P ₂ and P ₃ acting on the resin ring 4 of the present invention will be described divided into three sections.

That is, the resin ring 4 is temporarily divided into the rectangular portion 12 and the triangular portion 13 by the two-dot chain line 9. The two-dot chain line 9 is a straight line that perpendicularly intersects the upper side portion 14 and the lower side portion 15 of the resin ring 4 having a trapezoidal cross section.
External force acting on the triangular portion 13, a second zone pressure P ₂ of the lower side (FIG. 2, indicated by the two-dot chain line 9 At a 3) a third zone pressure P ₃ is rectangular portion with respect to the right side 12 the pressure P ₃ which is transmitted through the reaction force F ₂₀ acting from the inclined groove side 30 in the inclined surface 8 is considered to be present.

However, the resultant force of the second zone pressure P ₂ and the third zone pressure P ₃ is balanced with the reaction force F _20. In other words, the second zone pressure P ₂ is the reaction force F ₂₀ (in FIG. 2, FIG. 3) component force downward from the inclined groove side 30 is canceled. That is, the second zone pressure P ₂ is expertly is canceled by the inclined groove sides 30, increase in the pressing force against the second member 2 K (FIGS. 1 and 4 (B) (C) ( D) refer) I do not support it.
Therefore, only the first zone pressure P ₁ is, as a pressing force K with respect to the second member 2 acts. That is, the reaction force F ₀ acting from the corresponding surface 22 of the second member 2 with respect to the upper side of the virtual rectangular portion 12 becomes equal to the first area pressure P ₁ .

Thus, it was further clarified that the above considerations (i) to (v) are technically correct.
Examples those of FIG. 3, as compared with FIG. 2, the contact width W ₁ is set small, the pressing force K is reduced, in proportion to this, a small frictional resistance Y.

Next, FIG. 5 is a graph showing the fluid pressure P on the horizontal axis and the frictional resistance Y on the vertical axis. In addition, frictional resistance Y is a numerical value at the time of using two resin rings.
The test conditions are as follows.
Fluid: ATF oil
Speed: 20 mm / s
Material of each resin ring: PPS with filler
Overall outer diameter of each resin ring: 143 mm
In FIG. 5, the solid line (b) is the embodiment (B) shown in FIG. 4 (B), and the solid line (b) is a smaller contact width W ₁ of FIG. 4 (D) to 1.1 mm. It is set (see FIG. 3). The solid line (c) is the conventional product shown in FIG. 4 (A). The broken line (d) is obtained by reducing the contact width W ₁ ′ from FIG. 4 (A) to 1.1 mm (equivalent to FIG. 6 (B)).
The broken line (d) indicates that the posture in the concave groove 41 is not stable in the pressure receiving state, and the test can not be continued because of fluid leakage.

From the solid line in FIG. 5 (b), the embodiment sample of the present invention, grooves are posture regardless of the level of the pressure P is stabilized within 3, to reduce the contact width W _1, the frictional resistance Y sufficiently It can be seen that it can be mitigated. Moreover, it was also confirmed that there was little fluid leakage. Furthermore, the advantage that stick-slip does not occur easily was also confirmed.

By the way, in the present invention, since it has a so-called dovetail-shaped seal ditch, there is a case where it is difficult to mount the resin ring 4 if it is an integral groove. In such a case, the seal groove may be divided and the mounting (assembly) of the resin ring 4 may be facilitated. Alternatively, the resin ring 4 may be formed into an annular shape having a joint portion (joint).
Further, the resin ring 4 according to the present invention, the cross-sectional shape is a wedge shape, it is possible to sufficiently reduce the frictional resistance Y by reducing the contact width W _1, for a cross-sectional area greater can be secured, sealed concave The posture in the groove 3 is stable and the fluid leakage is extremely small.

According to the present invention, as described in detail above, in the sealing structure provided with the seal recess 3 and the resin ring 4 embedded in the seal recess 3, the low pressure side L of the seal recess 3 is provided. The groove side surface 30 is formed in an inclined shape which is inclined in the groove inward direction; the resin ring 4 corresponds to the groove side surface 30 in a parallel manner, and the low pressure side gradient surface 8 abuts against the groove side surface 30 in a pressure receiving state. and since it is in that configuration that includes, by setting smaller the contact width W _1, it can be suppressed sufficiently low frictional resistance Y. Moreover, always pose the resin ring 4 with the sealing grooves within 3 stably, setting small the contact width W _1, it is sufficiently large can be set the rigidity of the resin ring 4. In this way, fluid leakage is less likely to occur, durability is excellent, and stable high sealing performance is exhibited. In the prior art, it was only a static fixed sealing structure that applied so-called dovetail grooves to the seal groove, but in the present invention, the present invention is applicable to sealing of dynamic (sliding) parts. It is an invention. In particular, the sealing structure is suitable for a continuously variable transmission (CVT) of a car, an automatic transmission (AT) and the like, and can meet severe requirements such as low torque, low wear, and low leak.

3 Seal groove 4 Resin ring 8 Low pressure side gradient surface
30 Groove side L low pressure side W ₁ contact width

Claims (1)

In a sealing structure provided with a seal groove (3) and a resin ring (4) embedded in the seal groove (3),
The groove side surface (30) on the low pressure side (L) of the seal recess groove (3) is formed in an inclined shape inclining in the groove inward direction,
The resin ring (4) has a low pressure side gradient surface (8) corresponding to the groove side surface (30) in parallel and in contact with the groove side surface (30) in a pressure receiving state. Sealed structure.

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