JP2963159B2 - Oil seal for bidirectional rotation and molding method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention has a resin sealing element whose free edge bends toward a fluid storage chamber, and the sealing element is fixed in an axial direction with respect to a rotating shaft. The present invention relates to a bidirectional rotation oil seal that contacts in width and can effectively exert a sealing function in any rotation direction.

(Prior art) When a resin, particularly a fluororesin such as an ethylene tetrafluoride resin, is used as a seal element, an oil seal made of wear-resistant, excellent in heat resistance and chemical resistance can be provided.
Since the rigidity is higher than that of rubber, the sliding surface is smooth or the seal function is reduced in a simple plain type.

For this reason, as a device for improving the sealing function than before, for example, an annular spring is mounted on the sealing element to increase the sealing pressure, or an equidistant concentric annular groove is provided on the sliding surface side of the sealing element. I have.

However, in any case, it cannot be said that leakage of the fluid can be sufficiently sealed.

In the case of a one-way rotation oil seal, a spiral-shaped groove can be formed to further improve the sealing function.However, when this is used for a two-way rotation shaft, fluid leakage is promoted during reverse rotation. become.

(Object of the Invention) It is an object of the present invention to further improve the sealing function of a bidirectional rotating oil seal made of a high heat and chemical resistance.

(Technical Means for Achieving the Object) In order to achieve the above object, the present invention has a resin sealing element having a free edge bent toward the fluid storage chamber,
In a two-way rotary oil seal in which the seal element is in contact with the rotary shaft 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. The annular grooves are arranged at unequal intervals so that the distance between the annular grooves gradually decreases from the free edge side to the fixed edge side.

Further, in order to further improve the wear resistance, heat resistance and chemical resistance, a fluorine-based resin such as a tetrafluoroethylene resin is used as the resin sealing element.

As a method of forming the seal element, three or more concentric annular grooves having different diameters around the center of the seal element are formed on one side surface of a flat resin seal element, and the interval between the annular grooves is set at the center. The diameter of each annular groove is set so as to gradually decrease from the side toward the radially outward side, and the seal element is bent (has a bending process) toward the side where the annular groove is not formed.

(Embodiment) FIG. 1 shows a state in which an oil seal according to the present invention is mounted on a housing. An oil seal 10 is fitted in a housing 2 such as a case 4, and the oil seal 10 has a cross section on the outer peripheral side. An outer annular metal fitting 5 having an L-shape is provided. A holding metal fitting 6, a seal element 8 and a rubber gasket 7 are arranged on the inner peripheral side of the annular metallic fitting 5 in this order from the fluid storage chamber R side. It is clamped between 5a and swaged portion 5b. The fluid storage chamber R stores engine oil L and the like as a fluid.

The seal element 8 is made of a fluororesin, for example, an ethylene tetrafluoride 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 fitting 6 and the rubber gasket 7, the inner peripheral free end bends toward the fluid storage chamber R, and the sliding surface 8a extends in the axial direction. It is in pressure contact with the outer peripheral surface of the rotating shaft 1 with a constant width.

On the sliding surface 8a of the seal element 8, three or more, for example, six annular grooves are provided at uneven intervals in the axial direction during mounting.
T1 to T6 are formed.

FIG. 4 is an enlarged sectional view of a free edge side portion (sliding surface portion) of the seal element 8. Each of the annular grooves T1... T6 has an acute triangular cross section and a radially outward portion. As it goes, the side opposite to the fluid storage chamber R, for example, the outside S
It is inclined to come to the side. Spacing between each annular groove T1… T6
A2... A6 are separated by a predetermined length (for example, 0, 4 mm, or 0 mm) from the free edge side (the fluid storage chamber R side) to the outside S side.
(Each 0.3 mm) The intervals are set to be unequal so that they gradually become narrower. Also, the interval between the annular groove T1 on the most free edge side and the free edge T0
A1 corresponds to the change in the interval between the annular grooves, and the annular grooves T1 and T2
Is set to be longer by the above-mentioned predetermined length than the interval between.
That is, A1>A2>A3>A4>A5> A6.

Next, the process of forming the oil seal will be described. FIG. 3 shows the seal element 8 in a flat plate state before being bent, and a slit-shaped annular groove T1... T6 is formed on one side of the flat plate element 8 serving as a sliding surface by cutting. ing.

The slit-shaped annular grooves T1 to T6 reach a depth of approximately half the thickness of the seal element, and are inclined so as to become outward as they approach the fluid storage chamber. The inclination angle θ with respect to a plane perpendicular to the axial direction is, for example, 45 °. Each annular groove T1 ... T6 is formed concentrically with the center of the seal element as the center, and the free end edge T0 and the innermost annular groove
The difference D1-D0 (2A1) in diameter from T1 and the difference in diameter (2A2 ... 2A6) between the adjacent annular grooves T1 ... T6 are divided by a predetermined length from the inside to the outside. (Each 0, 4 mm, or 0.3 mm, for example) are unequally spaced so as to be sequentially shorter. That is, A1>A2>A3>A4>A5> A6.

In this way, concentric slit-shaped annular grooves T1 with different diameters…
As shown in FIG. 2, the cut T6 is pressed from the side where the annular groove is formed by the tapered shank 11, and is curved to the fluid storage chamber side.

Next, the oil seal to which the present invention is applied, the conventional plain type, the spring mounted type, the equally-spaced annular groove type as shown in FIG. 6 and the annular groove interval are widened radially outward as shown in FIG. 7 shows data obtained by performing a comparative experiment under the same conditions with an inverted unequally 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: Shaft center (7) Oil temperature: 120 ゜ (8) Shaft eccentricity: 0.1mm TIR or less (9) Mounting eccentricity: 0.1mm TIR or less (10) Shaft rotation speed: 6000rpm (11) Rotation cycle: 20 hours Operation, pause for 4 hours (B) Specific dimension example 1 of the embodiment of the present invention in FIG. 3 (1) Thickness of seal element: 1.1 mm (2) Number of annular grooves: 6 (3) Angle θ of annular grooves: 45 ゜ (4) Depth of cut of annular groove: axial depth 0.6mm (5) Diameter of free edge T0 and diameter of each annular groove T1 ... T6 in Fig. 3 D0: φ50.0, D1: φ52. 8, D2: φ55.2, D3: φ57.2, D4: φ58.8, D5: φ60.0, D6: φ60.8 (6) Distance between free edge T0 and annular groove T1 and between annular grooves 2A1: 2.8, 2A2: 2.4, 2A3: 2.0, 2A4: 1.6, 2A5: 1.2, 2A6: 0.8, i.e. difference in diameter It is less by 0.4mm.

(C) Specific dimension example 2 of the embodiment of the present invention in FIG. 3 (1) Thickness of seal element: 1.1 mm (2) Number of annular grooves: 6 (3) Angle θ of annular grooves: 45 ° (4) Cutting depth of annular groove: axial depth 0.6mm (5) Diameter of free edge T0 and each annular groove T1 to T6 D0: φ50.0, D1: φ52.4, D2: φ54.5, D3: φ56 .3, D4: φ57.8, D5: φ59.0, D6: φ59.9 (6) Distance between free edge T0 and annular groove T1 and between annular grooves 2A1: 2.4, 2A2: 2.1, 2A3: 1.8 , 2A4: 1.5, 2A3: 1.2, 2A4: 0.9, that is, the diameter difference is reduced by 0.3 mm.

(D) Example of dimensions of the equally spaced annular grooved seal element 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) ) Cut depth of annular groove: axial depth 0.6mm (5) Diameter of free edge T0 and each annular groove T1-T6 D0: φ50.0, D1: φ52.0, D3: φ54.0, D4: φ56.0, D5: φ58.0, D6: φ60.0 D7: φ62.0 (6) Distance between free edge T0 and annular groove T1 and between annular grooves Difference in diameter 2A1, 2A2, 2A3, 2A4, 2A5 And 2A6 are all 2mm
And

(E) Example of dimensions of reverse unequal spacing type seal element in FIG. 8 (1) Seal element thickness: 1.1 mm (2) Number of annular grooves: 6 (3) Angle of annular grooves θ: 45 ° ( 4) Cut depth of annular groove: axial depth 0.6mm (5) Diameter of free edge T0 and each annular groove T1 to T6 D0: φ50.0, D1: φ50.8, D2: φ52.0, D3 : φ53.6, D4: φ55.6, D5: φ58.0, D6: φ60.8 (6) Spacing between free edge T0 and annular groove T1 and between annular grooves 2A1: 0.8, 2A2: 1.2, 2A3 : 1.6, 2A4: 2.0, 2A5: 2.4, 2A6: 2.8, that is, the diameter difference is increased by 0.4 mm.

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

In contrast, the plain type begins to leak from the early stage of operation,
After one cycle (after a 20-hour operation and a 4-hour pause), a leak of 9.97 g was detected.

In the case of the spring-mounted type, leakage started at the beginning of the operation, and 2.55 g of leakage was detected one cycle later (after a 20-hour operation and a 4-hour pause).

In the concentric circularly-spaced annular groove type shown in FIG. 6, the leakage starts at the beginning of the operation, and after one cycle (after a 20-hour operation and a 4-hour pause), 3.
A leak of 16 g was detected.

In the case of the reverse unequally-spaced annular groove type shown in FIG.
A 7 g leak was detected.

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

In the contact pressure distribution in FIG. 4, as the interval between the annular grooves becomes narrower from the fluid storage chamber R side to the outside S side, the pressure distribution in each annular groove interval increases sharply, and the entire The pressure distribution has a gradient in which the pressure increases as going to the outside S side. It is considered that the fluid from the fluid storage chamber R side is sequentially pushed back to the fluid pressure side even if it enters the seal sliding surface portion due to this pressure gradient. At the time of installation, annular groove T1
... Since the shape of T6 is an acute triangle that opens toward the fluid storage chamber as shown in FIG. 4, a wedge action occurs to increase the sealing pressure.

On the other hand, as shown in FIG. 7, in the case of the equally-spaced annular groove type, there is almost no pressure gradient and a wedge effect is generated to increase the sealing pressure, but the push-back effect by the gradient as in the present invention does not work. In the reverse unequal spacing type shown in FIG. 9, since the gradient is reversed, the oil is pushed out to the outside S side contrary to the present invention, whereby it is considered that the amount of oil leakage is large.

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

(Effect of the Invention) As described above, according to the present invention, in the oil seal for two-way rotation, three or more annular grooves centered on the seal center are formed on the sliding surface side of the seal element 8,
Since the annular grooves are arranged at unequal intervals so that the width between the annular grooves gradually decreases as going from the free edge side to the fixed edge side of the seal element, the sliding surface extends from the fluid storage chamber side to the outside side. It is thought that the contact pressure gradually increases and becomes pointed as the pressure increases, and the pressure gradient effectively pushes the fluid back to the fluid storage chamber side. As a result, leakage of fluid can be prevented more reliably.

Further, when a fluorine-based resin such as an ethylene tetrafluoride resin is used as the resin sealing element, it is possible to further improve low abrasion resistance, heat resistance and chemical resistance.

Therefore, it can be used, for example, as a bearing for various rotating members such as a crank bearing portion of a high-speed rotation diesel engine and a chemical pump.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of the seal for two-way rotation to which the present invention is applied when the housing is mounted, FIG. 2 is a longitudinal sectional view in a free state, FIG. 3 is a longitudinal sectional view showing a state before bending. 4 is a longitudinal sectional view and a contact surface pressure distribution diagram during mounting use, FIG. 5 is a partial front view, and FIGS. 6 and 8 are before and after the oil seal of the present invention is compared with the oil seal of the present invention. 7 and 9 are a longitudinal sectional view and a contact pressure distribution diagram when the oil seal of FIGS. 6 and 8 is used, respectively. 8 …… Seal element, T0 …… Free edge, T1, T2, T
3, T4, T5, T6 ... annular groove

Claims (3)

(57) [Claims] An oil seal for bidirectional rotation having a resin sealing element having a free end bent toward a fluid storage chamber and having a fixed width in an axial direction with respect to a rotating shaft. Three or more concentric annular grooves centering on the center of the seal are formed on the sliding surface side, and the annular grooves are formed so that the width between the annular grooves gradually decreases from the free edge side to the fixed edge side of the seal element. An oil seal for bidirectional rotation, which is arranged at unequal intervals. 2. The oil seal for two-way rotation according to claim 1, wherein a fluorine resin such as ethylene tetrafluoride resin is used as the resin sealing element. 3. A flat plate-shaped resin sealing element having three or more concentric annular grooves having different diameters centered on the center of the sealing element on one side surface of the sealing element, and the interval between the annular grooves is radially increased from the center side. The curved oil seal element according to claim 1, wherein the diameter of each annular groove is set so as to gradually decrease toward the outer side, and the seal element is bent toward a side where the annular groove is not formed. Oil seal molding method to be molded.