JPH088344Y2 - Pressure-resistant sealing device for crankshaft supporting bearing of two-cycle engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a pressure-resistant sealing device for a bearing for supporting a crankshaft of a two-cycle engine, and more particularly to a sealing device using a fluororesin for suppressing wear.

<Prior art> As a sealing device, generally, an annular core metal is covered with an elastic body such as rubber, and an inner peripheral portion of the elastic body is in contact with an inner ring of a rolling bearing or an outer peripheral surface of a shaft or the like. It has a structure with. By the way, it has been considered to coat the seal lip with a fluororesin in order to suppress the wear of the contact portion of the seal lip with respect to the shaft (for example, US Pat. No. 4504067 and US Pat. No. 4132421).
reference).

As a sealing device using this kind of fluororesin, the inventors of the present invention are considering a structure as shown in FIG. The sealing device of the illustrated example includes a cored bar ring 1 having an L-shaped cross section, and rubber attached to one side surface of the disk-shaped part 2 along the radial direction of the cored bar ring 1 so as to cover the outer peripheral edge part. And an outer periphery of the seal lip 5, and a seal lip 5 which is continuously provided on an inner peripheral portion of the elastic body 3 and is in sliding contact with an outer peripheral surface portion of an inner member 4 such as an inner ring or a shaft of a rolling bearing. The garter spring 6 is fitted to the portion to forcibly press the seal lip 5 against the outer peripheral surface of the inner member 4, and the fluororesin 7 is attached to the seal lip 5 at a position described later.

This sealing device is fixed by being elastically fitted to the inner peripheral surface portion of the outer member 8 such as the outer ring of the rolling bearing via the elastic body of the outer peripheral edge portion of the cored bar ring 1.

The fluororesin 7 is applied from the slope of the seal lip 5 on the side of the core bar 1 to the inner surface of the thin portion 9 of the core ring 1. However, the fluororesin 7 is the core metal ring 1
The seal lip 5 is not adhered to the inner surface of the thin wall portion 9 and is swingable around the portion indicated by A in FIG. The reason why the seal lip 5 can be swung in this way is to prevent the seal lip 5 from becoming rigid by the hard fluororesin 7 and to have some flexibility.

<Problems to be Solved by the Invention> When the above sealing device is used, for example, in the crankshaft supporting portion of a two-cycle engine, the pressure in the spaces on both sides of the sealing device alternately increases and decreases, so that the seal lip 5 is It will swing greatly together with the fluororesin 7. In particular, when the seal lip 5 is tilted to the left side of the drawing, in the case of the conventional structure, the seal lip 5 and the fluororesin 7 are pulled from the position of the swing fulcrum A to the side separated from the cored bar ring 1. Therefore, the tensile stress concentrates on the portion of the swing fulcrum A, and a crack is generated there, or if severe, it is broken.

As shown in FIG. 6, holes 7a are made in the circumference of a portion of the fluororesin 7 along the thin portion 9 of the core metal ring 1, and the elastic body 3 is attached to the core metal ring through the holes 7a. It has been considered that the movement of the seal lip 5 and the fluororesin 7 is restrained by adhering it to the thin portion 9 of No. 1, but this is still insufficient.

The present invention was created in view of such circumstances,
It is an object of the present invention to prevent cracks and tears in the swing fulcrum portion of the seal lip even when used in a harsh environment in which the pressure in the space on both sides of the sealing device is alternately increased and decreased.

<Means for Solving the Problem> In order to achieve such an object, the present invention has the following configuration.

The sealing device of the present invention includes a cored bar ring, an elastic body, a seal lip, and a fluororesin. The cored bar ring is formed in a circumferential groove of a circumferential step portion provided on a shoulder portion of an inner peripheral surface of a bearing outer ring. , The elastic body is attached to the inner surface of the bearing in the cored bar ring, and the seal lip is formed in a substantially triangular cross section. It is provided so as to be continuous with the elastic body and is provided so as to project inward in the radial direction from the inner circumference of the core metal ring. It is characterized in that it is adhered to the surface along the radial direction.

<Operation> In the present invention, the core metal ring is sandwiched between the elastic body and the fluororesin, and the seal lip, which is an extension of the elastic body, and the fluororesin are attached on the inner diameter side of the core metal ring.
When the seal lip oscillates, a part of the fluororesin adhered to the slope also oscillates. The seal lip and the fluororesin oscillate with the inner peripheral edge of the cored bar ring as the fulcrum of fulcrum. . Therefore, the swing stroke of the seal lip is smaller than that of the conventional example, and
The tensile stress when the seal lip oscillates can be received in the radial midway portion of the fluororesin, which is the fulcrum of oscillating.

In this way, since the swing stroke becomes smaller, the tensile stress that acts when the seal lip swings is smaller than in the conventional example, and the sealing device is less likely to be damaged. Moreover, since the tensile stress is made to act on the hard fluororesin, the sealing device is more difficult to break.

<Embodiment> An embodiment of the present invention will be described below in detail with reference to the drawings.

1 to 4 show an embodiment of the present invention. In the figure, 10 is a core ring, 20 is an elastic body, 30 is a seal lip, 40 is a fluororesin, and 50 is a garter spring.

In this embodiment, the configuration different from the conventional example is mainly
The core metal ring 10 is sandwiched between the elastic body 20 and the fluororesin 40.

Specifically, the cored bar ring 10 has a main body 11 whose upper half has a substantially inverted L-shaped cross section, and an inclined posture in which the main body 11 is continuously connected to the main body 11 and extends obliquely upward before mounting. It has an annular disc portion (12) which, after being attached, extends straight in a radially outward direction and has a straight posture.

The elastic body 20 extends from one side surface of the main body portion 11 (on the left side in the drawing) and one side surface of the annular disc portion 12 to the other side so as to wrap the outer peripheral edge of the annular disc portion 12 in the cored bar ring 10. Being worn over.

The seal lip 30 is integrally provided so as to be continuous with the inner peripheral portion of the elastic body 20 so as to project inward in the radial direction from the inner peripheral edge of the main body portion 11 of the cored bar ring 10, and the cross section of the upper half portion is almost the same. It is formed in a triangular shape.

The fluororesin 40 is made of a ring-shaped Teflon sheet, and is attached over one side of the seal lip 30 (right side in the figure) to the other side surface (right side in the figure) of the main body 11 of the metal core ring 10. There is. Since this fluororesin 40 has a weak adhesive strength to the metal such as the cored bar ring 10, holes 13 penetrating in the axial direction are formed in several places of the circumference of the main body 11 of the cored bar ring 10, and the elastic body is formed through the holes 13. The fluororesin 40 is attached to the core metal ring 10 by spot-bonding 20 to the fluororesin 40. The fluororesin 40 may be directly adhered to the cored bar ring 10 if the adhesive strength to the cored bar ring 10 is sufficiently ensured by roughening the surface of the fluororesin 40.

The garter spring 50 is fitted in a peripheral groove formed on the outer periphery of the seal lip 30, and is biased to forcibly press the seal lip 30 against the outer peripheral surface of the inner ring or shaft of the rolling bearing. To do.

In the case of the sealing device of this embodiment, the seal lip
When the 30 swings, the fluororesin 40 attached to it also swings.
It swings around the inner peripheral edge of the main body 11 as a fulcrum.
That is, the swing fulcrum of the seal lip 30 and the fluororesin 40 is a portion indicated by B in the figure, that is, a midway portion of the fluororesin 40 located near the inner peripheral edge of the main body portion 11 of the cored bar ring 10. . The position of this swing fulcrum is located radially inward as compared with the conventional example, and the swing stroke of the seal lip 30 is smaller than that of the conventional example.

Further, in this embodiment, the fluororesin 40 is not directly applied to the inner peripheral inner diameter surface of the main body portion 11 of the cored bar ring 10, but a part of the seal lip 30 is interposed therebetween. This is due to the following three reasons. First of all, first, the elastic body 20 and the seal lip 30 are attached to the core metal ring 10 and the fluororesin 40 by injection molding or the like.
When injecting the material of 30, the elastic material intervenes in the boundary gap between the main body part 11 of the core metal ring 10 and the fluororesin 40, and the core metal ring 10 and the fluororesin 40 that are difficult to adhere to each other. Helps increase the adhesive strength of. Second, the elastic body 20
In addition to the portion corresponding to the hole 13, the adhesive portion between the fluororesin 40 and the fluororesin 40 increases the adhesive area by adding a gap between the fluororesin 40 and the inner peripheral surface of the main body 11 of the cored bar ring 10. To help. Thirdly, the elastic body 20 that intervenes in the gap between the inner peripheral surface of the body 11 of the cored bar ring 10 and the fluororesin 40.
However, it serves as a cushion when the seal lip 30 and the fluororesin 40 swing and serves to reduce the tensile stress acting on the swing fulcrum.

Such a sealing device is mounted on one side of the deep groove ball bearing 60, as shown in FIG. As shown in Fig. 3 (a), this mounting procedure is performed by applying a cylindrical jig 70 to the cored bar ring 10 of the sealing device and pushing the jig 70 in the direction of the arrow. Is pushed into the depth of the peripheral step portion 62 of the outer ring 61 of the deep groove ball bearing 60. Due to this pushing operation, the annular disk portion 12 of the cored bar ring 10 of the sealing device is deformed and cuts into the circumferential groove 62a of the circumferential step portion 62 as shown in FIG. 3 (b).

The deep groove ball bearing 60 is used as a bearing for supporting the crankshaft 80, for example, as shown in FIG. In this case, the pressure in the crank chamber will be
Although it increases and decreases alternately with the exhaust process, the sealing device is supported by digging the core metal ring 10 into the outer ring 61 of the deep groove ball bearing 60, and therefore the resistance force against detachment of the sealing device becomes extremely high. And is supported in the proper posture. Further, in such a situation that the pressure is repeatedly increased and decreased, the sealing lip 30 also swings in the sealing device of the present embodiment. However, in the sealing device of this embodiment, when the seal lip 30 swings, the swing stroke of the seal lip 30 is suppressed to a smaller value than that of the conventional example by the hard fluororesin 40, so that the swing movement of the seal lip 30 is reduced. As a result, the tensile stress acting on the swing fulcrum B becomes smaller than that of the conventional example, and since the tensile stress acts on the hard fluororesin 40, the conventional problems such as cracks and tears occur. Less likely to occur.

The present invention is not limited to the above-described embodiments, and can be implemented without departing from the spirit of the present invention.

<Effect of the Invention> As described above, in the present invention, the core metal ring is sandwiched between the fluororesin, the seal lip, and the elastic body, so that the swing stroke of the seal lip is reduced by the hard fluororesin. In addition to suppressing this, the tensile stress when the seal lip swings is received near the inner peripheral edge of the core ring of fluororesin, thus avoiding the conventional physical damage such as cracks and tears. I will be able to do it.

[Brief description of drawings]

1 to 4 relate to an embodiment of the present invention. FIG. 1 is a vertical sectional view showing an upper half of a sealing device, and FIG. 2 is an upper half of a deep groove ball bearing equipped with the sealing device. FIG. 3 (a) and FIG. 3 (b) are explanatory views showing a mounting process of the sealing device,
FIG. 4 is a vertical sectional view schematically showing a crankshaft supporting portion. 5 and 6 relate to a conventional example, FIG. 5 is a vertical sectional view showing an upper half of a sealing device, and FIG. 6 is a vertical sectional view showing a main part of the sealing device. 10 ... Core ring, 20 ... Elastic body 30 ... Seal lip, 40 ... Fluororesin

Claims (1)

[Scope of utility model registration request] 1. A cored bar ring, an elastic body, a seal lip, and a fluororesin. The cored bar ring is bent in a circumferential groove of a circumferential step portion provided on a shoulder portion of an inner circumferential surface of a bearing outer ring. The elastic body is attached to the inner surface of the bearing in the cored bar ring, and the seal lip is formed to have a substantially triangular cross section. It is provided so as to extend inward in the radial direction from the inner circumference of the cored bar ring, and the fluororesin is applied from the inclined surface of the seal lip on the outer side of the bearing to the surface of the cored bar on the outer side of the bearing. A pressure-resistant sealing device for a bearing for supporting a crankshaft of a two-cycle engine, characterized in that it is attached.