JPH0483978A - Oil seal for two-way rotation and molding method thereof - Google Patents

Abstract

PURPOSE:To further improve a sealing function by arranging three or more annular grooves at unequal intervals such that a distance between the adjoining annular grooves is gradually decreased from the free edge side of a seal element toward the fixed edge side thereof. CONSTITUTION:A seal element 8 is formed of fluorine resin and three or more, for example, six annular grooves T1-T6 are axially formed in a slide surface 8a at unequal intervals during mounting. The annular grooves are formed at unequal intervals such that distances A2...A6 between adjoining annular grooves T1...T6 are gradually decreased by a given length at each interval from the freed edge side toward the external part S side. A press work is applied from the side where the annular groove is formed by means of a taper shank 11, and a curve toward the fluid containing chamber side is formed. This constitution reliably prevents leakage of fluid and further improves low wear resistance, heat resistance, and chemical resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention has a resin sealing element whose free end side bends toward a fluid storage chamber, and the sealing element has an axially constant position with respect to a rotating shaft. The present invention relates to an oil seal for bidirectional rotation that is in contact with the width thereof and can effectively exhibit a sealing function in either direction of rotation.

(Prior art) When a resin, especially a fluorine-based resin such as tetrafluorinated ethylene resin, is used as the seal element, an oil seal with excellent wear resistance, heat resistance, and chemical resistance can be provided, but it is less effective than rubber. Due to its high rigidity, the sealing function will be degraded if the sliding surface is smooth or if it is just a plain type.

For this reason, as a way to improve the sealing function compared to before,
For example, an annular spring is attached to the seal element to increase the sealing pressure, or concentric annular grooves are formed at equal intervals on the sliding surface of the seal element.

However, none of these can be said to be able to sufficiently seal fluid leakage.

In the case of an oil seal for unidirectional rotation, the sealing function can be further improved by forming a thinly wound groove, but if this is used for a bidirectional rotation shaft, fluid leakage will be promoted during reverse rotation. It turns out.

(Objective of the Invention) An object of the present invention is to further improve the sealing function of a crude oil seal for bidirectional rotation with high heat resistance and chemical resistance.

(Technical Means for Achieving the Object) In order to achieve the above object, the present invention has a resin sealing element whose free end side bends toward the fluid storage chamber, and the sealing element is arranged with respect to the rotating shaft. In oil seals for bidirectional rotation that are in contact with each other at a constant width in the axial direction, three or more concentric annular grooves centered on the seal center are formed on the sliding surface side of the seal element, running from the free end edge of the seal element to the fixed end edge. Accordingly, the annular grooves are arranged at irregular intervals so that the distance between the annular grooves becomes gradually smaller.

Further, in order to further improve wear resistance, heat resistance, and chemical resistance, a fluororesin such as tetrafluoroethylene resin is used as the resin seal element.

As a method of molding two seal elements on the top, three or more concentric annular grooves with different diameters are formed around the center of the seal element on one side of a flat resin seal element, and the interval between the annular grooves is The diameter of each annular groove is set so that it becomes gradually smaller from the center side toward the outer side in the radial direction, and the seal element is bent (beveled) toward the side where the annular groove is not formed.

(Example) Fig. 1 shows the state in which the oil seal according to the present invention is installed in the housing, and the oil seal 10 is fitted in the /X housing 2 of the case 4, etc.
0 is equipped with an outer annular metal fitting 5 having a rectangular cross-section on the outer circumferential side,
A presser metal fitting 6, a seal element 8, and a rubber gasket 7 are arranged on the inner peripheral side of the annular metal fitting 5 in this order from the fluid storage chamber R side, and are held between the flange portion 5a and the caulking portion 5b of the outer peripheral annular metal fitting 5. There is. The fluid storage chamber R stores engine oil L and the like as fluid.

The seal element 8 is made of a fluororesin, for example, a tetrafluoroethylene resin, and has excellent wear resistance, heat resistance, and chemical resistance. The radially outer end of the seal element 8 is clamped and fixed between the presser metal fitting 6 and the rubber gasket 7, the free inner edge is bent toward the fluid storage chamber R, and the sliding surface 8a is bent in the axial direction. It is pressed against the outer circumferential surface of the rotating shaft 1 with a constant width of .

Three or more, for example, six, annular grooves T1...T6 are formed in the sliding surface 8a of the seal element 8 at unequal intervals in the axial direction when the seal element 8 is installed.

FIG. 4 shows an enlarged sectional view of the free edge side portion (sliding surface portion) of the seal element 8, and shows each annular groove TI...
T6 has an acute triangular cross-sectional shape and is inclined so that as it goes outward in the radial direction, it comes to the side opposite to the fluid storage chamber R, for example, to the outside S side. Each annular groove T1/1
・The interval A2...A6 between 16 is a predetermined length (
They are set at irregular intervals so as to become narrower (for example, by 0.4 mm or 0.3 mm). Further, the distance A1 between the annular groove T1 closest to the free edge and the free edge TO is set to be longer than the distance between the annular grooves T1 and T2 by the predetermined length, in accordance with the change in the distance between the annular grooves. There is. That is, At
>A2 >A3 >A4 >A5 >AB Next, the process of forming the oil seal will be explained. FIG. 3 shows the sealing element 8 in a flat state at the front of the curved bevel, and one side surface of the flat element 8 that becomes the sliding surface has a slit-shaped annular groove Tl...T6.
is formed.

The slit-shaped annular grooves TI...T6 extend to a depth approximately half the thickness of the sealing element, and are inclined outward toward the fluid storage chamber. The inclination angle θ with respect to a plane perpendicular to the axial direction is, for example, 456. Each of the annular grooves T1...T6 is formed concentrically around the center of the seal element, and the difference in diameter between the free edge TO and the innermost annular groove T1 is
(2AI), and each adjacent annular groove T1...1
The difference in diameter between the two (2A2...2A6) is determined by a predetermined length (for example, 0.4 m) from the inner side to the outer side.
+11 mm or 0.3 mm) are spaced unevenly so that they become shorter in sequence. That is, AI > A2 > A3 > A
4>A5>A6.

In this way, the concentric slit-shaped annular grooves T1 with different diameters
...A piece with T6 carved therein is pressed from the annular groove forming side using the tapered shank 11 as shown in Fig. 2, and is bent into a curved shape on the fluid storage chamber side.

Next, we will discuss the oil seal to which the present invention is applied, the conventional plain type, the spring-loaded type, the equally spaced annular groove type as shown in Fig. 6, and the annular groove spacing that becomes wider as it goes outward in the radial direction as shown in Fig. 8. The following is data from a comparative experiment under the same conditions with the reverse unevenly spaced annular groove type.

(A) Common conditions (1) Housing diameter: φ80H8 (2) Shaft diameter: φ60H8 (3) Shaft material: Medium carbon steel (4) Shaft hardness: HRc30~40 (5) Fluid
:Engine oil SAE 10W-30 (6) Oil level center of two shafts (7) Oil temperature: 120 @ (8) Shaft eccentricity: 0.1 mm TIR or less (9) Mounting eccentricity: 0.1 mm TIR or less (10) Shaft rotation speed: 6
000rp11 (11) rotation cycle: 20 hours operation,
4-hour break (B) Specific dimension example 1 of the embodiment of the present application in Fig. 3
(1) Thickness of seal element: 1.11 mm (2) Number of annular grooves: 6 (3) Angle θ of annular groove: 45° (4) Cutting depth of annular groove Biaxial depth 0.6 mm (5
) The diameter of the free edge TO in Fig. 3 and each annular groove T1...
T6 diameter DO: φ50.0, Dl: φ52.8, D2: φ
55.2, D3: φ57.2, D4: φ58.8,
D5: φ60.0, DO: φ60.8 (6) Spacing between free edge TO and annular groove T1 and between annular grooves 2A1: 2.8, 2A2: 2.4.2A3
:2.0, 2A4:1.6.2A5 :l, 2, 2
A6: 0.8, that is, the diameter difference is decreased by 0.4 degrees.

(C) Specific dimension example 2 of the embodiment of the present application shown in Fig. 3 (1) Thickness of seal element: 1.1 mm (2) Number of annular grooves = 6
Book (3) Angle θ of annular groove: 45° (4) Cutting depth of annular groove Biaxial depth 0.6 mm (5
) Free edge TO and straight DO of each annular groove T1 to T6: φ5
0.0, Dl: φ52.4, D2: φ54.5
, D3: φ56.3, D4: φ57.8,
D5: φ59.0, DO: φ59.9 (6) Spacing between free edge TO and annular groove TI and between annular grooves 2Al: 2.4, 2A2: 2.1.2A3:
1.8, 2A4: l, 5.2A3: l, 2, 2
A4: Q, 9, that is, the diameter difference is reduced by 0.3 degrees.

(D) Dimension example of the equally spaced annular groove type seal element shown in Fig. 6 (1) Thickness of seal element: 1.1 mm (2) Number of annular grooves = 6 (3) Angle θ of annular groove: 45° ( 4) Cutting depth of annular groove biaxial depth 0.6+u(5
) Diameter of free edge TO and each annular groove Tl-T6 DO: φ50.0, Dl: φ52.0, D3:
φ54.0, D4: φ56.0, D5: φ58
．． 0, DO:φ60. OD7: φ62.0 (6) The diameter differences 2Al, 2A2.2A3.2A4.2A5 and 2AB between the free edge TO and the annular groove TI and between the annular grooves are all 2■.

(E) Dimension example of the seal element of the breech equidistant type shown in Fig. 8 (1) Thickness of the seal element + 1.1 mm (2) Number of annular grooves: 26 (3) Angle θ of the annular groove: 45° (4 ) Cutting depth of annular groove: Axial depth 0.6 mm (5
) Diameter of free edge TO and each annular AlT1 to T6 DO: φ50.0, DI: φ50.8, D2:
φ52.0, D3: φ53.6, D4: φ55
．． 6, D5: φ58.0° DO: φ60.8 (6) Distance between free edge TO and annular groove T1 and between annular grooves 2Al: Q, 8, 2A2: l, 2.2A3
・1.6, 2A4: 2.0.2A5: 2.4
, 2A6: 2.8, that is, the diameter difference is increased by 0.4 tnm.

(F) Results of Experiments As a result of experiments under the above conditions, no leakage occurred for 10 cycles in both the dimension examples (B) and (C) to which the present application was applied.

On the other hand, with the plain type, leakage begins from the beginning of operation, and 1
9.97g after cycle (20 hours operation, 4 hours rest)
A leak was detected.

The spring-equipped type began to leak from the beginning of operation, and a leak of 2.55 g was detected after one cycle (after 20 hours of operation and 4 hours of rest).

In the concentrically spaced annular groove type shown in Fig. 6, leakage begins at the beginning of operation, and after 1 cycle (20 hours of operation and 4 hours of rest), leakage begins to leak.
．． A leak of 16g was detected.

The breech equally spaced annular groove type shown in Fig. 8 starts leaking from the beginning of operation, and after 1 cycle (20 hours of operation and 4 hours of rest), 20
．． A leak of 0.7g was detected.

The reason why oil leakage can be effectively prevented by narrowing the annular groove interval sequentially from the fluid storage chamber side as in the present application is considered to be as follows.

In the contact surface pressure distribution shown in Fig. 4, as the annular groove interval becomes narrower from the fluid storage chamber R side to the outside S side, the pressure distribution within each annular groove interval increases in a pointed manner, and the overall The pressure distribution has a gradient in which the pressure increases toward the outside S side. It is thought that due to this pressure gradient, even if the fluid from the fluid storage chamber R side enters the seal sliding surface portion, it is sequentially pushed back to the fluid pressure side. Also, when installing the annular groove TI
Because the shape of T6 is an acute triangular shape that opens toward the fluid storage chamber as shown in FIG. 4, a wedge effect is generated to increase the sealing pressure.

On the other hand, in the equally spaced annular groove type shown in FIG. 7, there is almost no pressure gradient and a wedge effect occurs to increase the sealing pressure, but the push-back effect due to the gradient does not work as in the present invention.

In addition, in the breech equally spaced type shown in Figure 9, the slope is reversed, so
Contrary to the present invention, oil is pushed out to the outside S side, which is thought to cause a large amount of oil leakage.

(Another Example) The number of annular grooves is not limited to six, but may be at least three or more. It is also possible to use other fluororesins as the material for the seal element.

(Effects of the Invention) As explained above, according to the present invention, in the oil seal for bidirectional rotation, on the sliding surface side of the seal element 8,
Three or more annular grooves are formed around the center of the seal, and the annular grooves are arranged at uneven intervals so that the width between the annular grooves decreases from the free edge side to the fixed edge side of the seal element. Therefore, on the sliding surface, it is thought that the contact pressure becomes higher and more pointed as you go from the fluid storage chamber side to the outside side, and the pressure gradient effectively pushes the fluid back to the fluid storage chamber side. As shown in the results of the above experiments, fluid leakage can be more reliably prevented than with conventional oil seals of various types.

Further, when a fluorine thread resin such as tetrafluoroethylene resin is used as the resin seal element, it is possible to obtain even more excellent low friction properties, heat resistance, and chemical resistance.

Therefore, for example, the crank bearing of a high-speed diesel engine can be used as a bearing for various rotating parts such as parts, chemical pumps, etc.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a bidirectional rotary seal to which the present invention is applied when installed in a housing, FIG. 2 is a vertical cross-sectional view in a free state, and FIG. 3 is a vertical cross-sectional view showing a state before bending. Fourth
The figure is a longitudinal cross-sectional view and contact surface pressure distribution diagram when used.
FIG. 5 is a partial front view, FIGS. 6 and 8 are longitudinal cross-sectional views showing the oil seal in the experimentally compared oil seal with the present invention before bending, and FIGS. 7 and 9 are FIG. 8 is a longitudinal cross-sectional view and a contact pressure distribution diagram of the oil seals of FIGS. 6 and 8, respectively, when installed and in use. 8...Seal element, TO...Free edge, T1
, T2, T3, T4, T5, T6... Annular groove patent applicant Mitsubishi Cable Industries Co., Ltd. agent Patent attorney Tadataka Daihiru ~-1

Claims (3)

[Claims] (1) In an oil seal for bidirectional rotation, which has a resin seal element whose free edge side bends toward the fluid storage chamber side, and in which the seal element contacts the rotating shaft with a constant width in the axial direction, the sliding of the seal element Three or more concentric annular grooves centered on the seal center are formed on the surface side, and the annular grooves are arranged unequally so that the width between the annular grooves decreases sequentially from the free edge side to the fixed edge side of the seal element. An oil seal for bidirectional rotation characterized by being arranged at intervals. (2) The oil seal for bidirectional rotation according to claim 1, characterized in that the resin seal element is made of a fluororesin such as tetrafluoroethylene resin. (3) Three or more concentric annular grooves with different diameters are formed around the center of the seal element on one side of the flat resin seal element, and the intervals between the annular grooves are radially outward from the center side. The curved oil seal element according to claim 1 is formed by setting the diameter of each annular groove so that it becomes gradually smaller toward the side, and bending the seal element toward the side where the annular groove is not formed. Oil seal forming method.