JPH0241391Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention relates to a seal structure for guide rollers that support the endless track belt of construction machines such as hydraulic excavators, and is also applicable to seal structures for bulldozers, muddy water pumps, etc. It is possible.

[Conventional technology]

To explain a conventional example of a shaft sealing device provided on a guide roller 2 used in the undercarriage of a tracked vehicle 1 shown in FIG. 8, as shown in FIGS. 9 and 10, A roller 2 on the movable side is rotatably mounted on a shaft 3 fixed to the vehicle body by a bearing 4, and a roller 2 on the movable side is fixed on the end side of the shaft 3 with a pin or the like and is mounted opposite to the roller 2. A shaft sealing device is constituted by the fixed collar 5, the recess 2a provided in the movable collar 2, and the floating seal mechanism 6 built in the recess 5b provided in the fixed collar 5.
The floating seal mechanism 6 includes a seat ring 8 held within the recess 2a via an O-ring 7a.
a and a seat ring 8b held within the recess 5b via an O-ring 7b, and both seat rings 8
It has a structure in which the contact surfaces of a and 8b are configured as sliding surfaces 9a and 9b. The seat ring 8b is in a floating state with respect to the shaft 3 supported by the O-ring 7b within the recess 5b of the collar 5, and is configured to be movable in the axial direction by interference, twisting, etc. of the O-ring 7b. and the other seat ring 8a
is supported by the O-ring 7a within the concave portion 2a of the roller 2 and floats on the shaft 3, and can move in the axial direction due to the interference, torsion, etc. of the O-ring 7a, and is rotated together with the roller 2. The torque from the roller 2 is transmitted to the seat ring 8a via the O-ring 7a, and the same rotational speed as the roller 2 is applied to the seat ring 8a.

In addition, the recess 2a of the roller 2 and the recess 5 of the collar 5
The O-ring receiving surface at b is symmetrical with a slope K, and the sliding surfaces 9a, 9 of the seat rings 8a, 8b are
b are in contact with each other with sliding surface pressure at an intermediate position between the recesses 2a and 5b, and are relatively rotatable. , 8b, and has a sealing function to prevent dirt, muddy water, etc. from entering into the roller 2 from the outside. . In addition, O-rings 7a, 7b
The contact surfaces of the roller 2 and the sloped surface K of the collar 5 act as a seal for the fixed portion in addition to the rotating seal surfaces on the sliding surfaces 9a and 9b.

[Problem that the invention attempts to solve]

In the conventional shaft sealing device as described above, both the seat rings 8a and 8b are brought into contact with each other mainly by the interference of the O-rings 7a and 7b, and the sliding surfaces 9a and 9b have an appropriate sealing surface pressure. However, since the O-ring is made of rubber, as shown in Fig. 11, if the O-ring is held for a long time, the load due to the interference, that is, the compressive load W, will decrease, and the load (or surface pressure) required for the seal will decrease over a certain period of time. below, the sealing performance deteriorates,
This causes problems such as leakage of lubricating oil and intrusion of sewage.

[Means for solving problems]

In order for the O-ring that maintains the seal surface pressure to always apply the load (surface pressure) necessary for sealing to the seat ring, in addition to the elastic force of the O-ring, the O-ring has a built-in spring system such as a coil spring or a leaf spring. It is integrally molded to add O-ring elastic force + spring force to the seal ring.

Unlike rubber, the spring force does not change over time and provides stable sealing surface pressure. Note that the spring system is arranged inside the O-ring, and the outer periphery of the O-ring has a mechanism in which a rubber portion necessary for a fixed seal remains.

[Effect]

By incorporating a spring system in the O-ring that does not change its load over time, it always maintains the surface pressure necessary for a sliding seal, and the rubber on the outer periphery of the O-ring provides a fixed seal, ensuring a stable seal. Get performance.

〔Example〕

FIGS. 1 and 2 show typical embodiments of the floating seal mechanism of the present invention and the double O-ring used in the seal mechanism. Since the overall structure of the shaft sealing device is the same as that explained with reference to FIGS. 8 to 10, the overall description of the shaft sealing device will be omitted, and the structure of the O-ring will be explained.

As shown in Figure 2, the conventional O made of rubber
A steel hollow ring 10 in which a tube with a thin wall thickness and high elastic modulus is processed into a ring shape inside the ring.
is integrally molded and manufactured. The hollow ring 10 is shaped so that a rubber coating layer 11 having an appropriate thickness t remains on its outer periphery. The combination of the rubber portion 11 and the hollow ring 10 is referred to as a double O-ring 12. A structure incorporating a double O-ring 12 as a floating seal 6 is shown in FIG.

Further, as shown in FIGS. 3 to 6, a continuous leaf spring 13 with a U-shaped cross section or an intermittent leaf spring 1
4 and a double O-ring 12 incorporating a coil spring 15 can also be formed.

[Effect of idea]

By constructing a floating seal mechanism using a double O-ring that has a spring system such as a hollow steel ring inside the rubber O-ring, the surface pressure that presses the seat ring can be reduced as shown in Figure 7. The compressive load W to be maintained is the elastic force W ₁ of the rubber + the built-in steel spring system W ₂ , and the seal surface pressure increases, and the compressive load of the steel spring system does not change over time. By designing the spring force to be greater than the minimum load required for sealing, the sealing performance can be stabilized for a long time.

Furthermore, since there is a rubber coating layer around the steel spring system, it can also be fixedly sealed in the same way as in the past.

[Brief explanation of the drawing]

Fig. 1 is an axial sectional view of an embodiment of the floating seal mechanism of the present invention, Fig. 2 is an axial sectional view of the double O-ring of Fig. 1 before assembly, and Fig. 3 is an axial sectional view of the double O-ring of another type. Axial cross-sectional view of O-ring, Figures 4 and 5
The figures are sectional views taken along line A-A in Fig. 3 of different types of double O-rings, Fig. 6 is an axial sectional view of other types of double O-rings, and Fig. 7 is a sectional view of the double O-rings of different types. It is a load characteristic diagram of a ring. Fig. 8 is a side view showing a general tracked vehicle, Fig. 9 is a sectional view of a shaft sealing device attached to a conventional roller, and Fig. 10 is an enlarged sectional view of the floating seal mechanism part of Fig. 9. , FIG. 11 is a load characteristic diagram of an O-ring in a conventional floating seal mechanism. 2...Roller, 5...Color, 8a, 8b...
Seat ring, 9a, 9b...Sliding surface, 10...
Steel hollow ring, 11...Rubber, 12...Double O
ring.

Claims (1)

[Scope of utility model registration request] In a floating seal mechanism consisting of a pair of seals that are held via an O-ring by both adjacent holding members on a movable side and a fixed side and have sliding surfaces that engage with each other, the O-ring is placed in the center. Double O with built-in spring system such as steel hollow ring
A floating seal mechanism characterized in that the O-ring is a ring and reduces changes over time in the compressive load applied to the seat ring.