JPH0590050U - Bidirectional rotating gas seal - Google Patents

Abstract

(57) [Abstract] [Purpose] A bidirectional rotary gas seal capable of maintaining stable sliding performance is provided by providing a dam portion on the outer peripheral portion of a dynamic pressure generating groove provided on a sliding surface and extending in the radial direction. To do. [Structure] In a bidirectional rotary gas seal in which a plurality of dynamic pressure generating grooves 11 extending in the radial direction for obtaining a levitation force are provided in the circumferential direction between sliding surfaces 31, 51, the dynamic pressure generating groove 11
It is characterized in that the dam portion 9 is provided on the outer diameter side and the notch 10 for gas entrainment is provided at the outer end portion of the sliding surface 31.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a gas seal used for a shaft seal device for a rotary shaft, and more particularly to a bidirectional rotation type gas seal.

[0002]

[Prior Art]

 A conventional gas seal of this type has a structure as shown in FIG. 4, for example. That is, of the fixed-side sliding member 100 and the rotating-side sliding member 101, the sliding surface 101A of the rotating-side sliding member 101 is provided with a dynamic pressure generation groove 102 for obtaining a levitation force between the sliding surfaces. Has been.

The fixed-side sliding member 100 is supported by a spring 103, and is normally floated by entraining the gas G between the sliding surfaces 100A and 101A. A gap h of about 1 to 10 μm is formed between the moving members 101, and sealing is performed while allowing a slight leak.

[0004]

[Problems to be solved by the device]

 4B to 4E show spiral grooves 102A and radial direction grooves 102B as the dynamic pressure generating grooves 102. In the spiral groove 102A, the gas G flows into the inner circumference by rotation to generate a levitation force, but in the radial groove 102B, since the groove width is wide and the outer diameter side is open, the levitation force is generated. At the same time, the centrifugal force also causes the discharge of gas G. Especially under high-speed and low-pressure conditions, the centrifugal force is large and the gas pushing force is weak, so the levitation force is weak and stable sliding performance cannot be expected.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and its purpose is to provide an outer peripheral portion of a dynamic pressure generating groove provided in a sliding surface and extending in a radial direction. The purpose of the present invention is to provide a bidirectional rotating gas seal that can maintain stable sliding performance by providing a dam portion.

[0006]

[Means for Solving the Problems]

 In order to achieve the above object, in the present invention, the sliding surface of the fixed-side sliding member or the rotating-side sliding member is extended in the radial direction to obtain a levitation force between the sliding surfaces during rotation. In a bidirectional rotary gas seal having a plurality of dynamic pressure generating grooves in the circumferential direction, a dam portion is provided on the outer diameter side of the dynamic pressure generating groove, and the sliding surface outer end portion having the dynamic pressure generating groove is further provided. It is characterized in that a notch for gas entrainment is provided.

[0007]

[Action]

 In the gas seal having the above structure, even if centrifugal force is applied during rotation, the outer diameter of the gas caught between the sliding surfaces can be changed by the dam portion provided on the outer diameter side of the dynamic pressure generating groove. Leakage to the side can be prevented.

Further, although the dam portion prevents the gas from being entrained between the sliding surfaces during rotation, the gas is entrained by the notch provided at the outer end of the sliding surface, and the gas is generated in the dynamic pressure generating groove. Supplied.

[0009]

【Example】

 The present invention will be described below based on the illustrated embodiment.

FIG. 1 shows the overall structure of the gas seal. That is, reference numeral 1 denotes the entire seal, which is roughly composed of a rotary side sliding member 3 fixed to the rotary shaft 2 and a fixed side sliding member 5 mounted to the housing 4. The rotation-side sliding member 3 is arranged on the gas G side, which is a sealing target, and the gas G is configured to leak from the outer peripheral side of the sliding surface to the inner peripheral side.

The rotating-side sliding member 3 is fixed in the axial direction and the rotating direction with respect to the rotating shaft 2 via the holding member 6, and is disposed between the holding member 6 and the back surface of the rotating-side sliding member 3. An O-ring 7 for sealing is attached to the.

On the other hand, the fixed-side sliding member 5 is fixed in the rotating direction and movably in the axial direction, and is pressed against the rotating-side sliding member 3 by the spring force of the spring 8.

The facing surfaces of the rotary side sliding member 3 and the fixed side sliding member 5 are flat surfaces that are orthogonal to the axial direction, and constitute sliding surfaces 31 and 51 that rotate and slide with respect to each other. The gas G is sealed between the sliding surfaces 31 and 51. The sliding surface of either the rotating-side sliding member 3 or the fixed-side sliding member 5, that is, the sliding surface 31 of the rotating-side sliding member 3 in this embodiment, extends in the radial direction for generating dynamic pressure during rotation. A plurality of dynamic pressure generating grooves 11 are provided in the circumferential direction.

The dynamic pressure generating groove 11 extends from the outer diameter side of the rotation side sliding member 3 toward the inner diameter side to a midway position thereof, and the inner diameter side region of the sliding surface 31 is a groove-free groove. There is no area 32. Therefore, while the rotating shaft 2 is stopped, the gas G is sealed in the grooveless region 32 in close contact with the sliding surface 51 of the fixed-side sliding member 5 without a gap, and the gas G is caught in the dynamic pressure generating groove 11 during rotation. As a result, dynamic pressure is generated and buoyancy is exerted between the sliding surfaces 31 and 51.

Further, a dam portion 9 is provided on the outer diameter side of the dynamic pressure generating groove 11 so as to prevent the gas G from escaping to the outside by the centrifugal force during rotation.

The dam portion 9 can prevent the trapped gas from escaping due to centrifugal force, and can maintain stable sliding. The position of the dam part 9 is as shown in Fig. 1 (b). Although it is located outside the outer diameter end of the fixed-side sliding member 5, it may be provided at a position facing the sliding surface 51 of the fixed-side sliding member 5 as shown in FIG. 1 (c). Good.

On the other hand, although the dam portion 9 prevents the gas G from being caught between the sliding surfaces 31 and 51 during rotation, the gas G is caught by the notch 10 provided at the outer end of the sliding surface 31. The gas G is supplied to the dynamic pressure generation groove 11.

2 and 3 show two embodiments of the dynamic pressure generating groove 11.

As shown in FIG. 2, the groove section of the dynamic pressure generating groove 11 is formed in a rectangular shape or an oval shape. The dam portion 9 is provided at the outer diameter end of the dynamic pressure generating groove 11 over the entire width of the groove, and its height is the same as the sliding surface 31. Therefore, the upper surface of the dam portion 9 is a flat surface continuous with the sliding surface 31. The height of the dam portion 9 may be lower than the sliding surface 31, and when the dam portion 9 does not face the fixed side sliding surface 51 as shown in FIG. 1 (b). May be higher than the sliding surface 31.

Further, the notches 10 are provided every two between the dynamic pressure generating grooves 11. At first, the disposition of the notches 10 is not limited to every two dispositions, and various dispositions are selected according to usage conditions. Further, the position where the notch 10 is formed is not limited to the position where the notch 10 is formed, and the notch 10 may be provided at the dam portion 9 that is provided in the notch 10.

Further, as shown in FIG. 3, a dynamic pressure generating groove 12 having a taper step shape is provided.

That is, as shown in FIG. 3 (b), the dynamic pressure generating groove 12 has a shape such that the dam portion 13 projects into the valley portion of the V-shaped groove having a large opening angle. It has taper surfaces 12A and 12B which are opposite to each other on the left and right with 13 in between.

In the case of such a taper step groove, the pressure distribution of the dynamic pressure generated between the sliding surfaces is as shown in FIG. 3 (b). At 12B, the pressure decreases and a negative pressure acts, and on the downstream tapered surface 12A beyond the dam portion 13, the wedge action of the tapered surface 12A increases the pressure and a positive buoyancy is generated. It is known that the negative pressure is small and the positive pressure is large due to the action of the dam portion 13, and the positive pressure acts on the dynamic pressure generating groove 12 as a whole to obtain a large buoyancy.

By providing the dam portion 9 in the taper step-shaped dynamic pressure generating groove 12 as described above, the positive buoyancy due to the wedge action can be further increased, and the stability can be further improved. You can

A notch 10 is formed between the dynamic pressure generating grooves 12.

[0026]

[Effect of the device]

 The present invention has the above-described structure and operation.By providing a dam portion on the outer diameter side of the dynamic pressure generation groove, the gas caught between the sliding grooves during rotation is prevented from leaking to the outer diameter side. Further, since the winding amount is increased by the notch provided between the dynamic pressure generating grooves, stable performance can be obtained even under low pressure and high speed conditions.

Further, by increasing the buoyancy between the sliding surfaces, it is possible to expand the conventional usage range.

[Brief description of drawings]

FIG. 1 (a) is a half sectional view of a gas seal according to an embodiment of the present invention, and FIG. 1 (b) shows a state in which buoyancy acts between the sliding surfaces of FIG. 1 (a). Schematic diagram, Figure (c) is the same figure (b)
FIG. 11D is a schematic perspective view of the sliding surface in the vicinity of the notch, showing another embodiment of FIG.

FIG. 2 shows one aspect of a dynamic pressure generating groove.
(a) is a plan view and (b) is a sectional view taken along line AA.

3A and 3B show another embodiment of the dynamic pressure generating groove, wherein FIG. 3A is a plan view and FIG. 3B is a sectional view taken along line BB.

FIG. 4 shows a conventional gas seal.
(a) is a half sectional view showing the overall configuration, (b) is a plan view of the spiral groove, (c) is a sectional view taken along the line CC of (b) in the same figure, and (d) is a conventional view. FIG. 6E is a plan view of the radial groove of FIG. 6E, and FIG. 6E is a sectional view taken along the line DD of FIG.

[Explanation of symbols]

 1 Gas Seal 2 Rotating Shaft 3 Rotating Side Sliding Member 31 Sliding Surface 4 Housing 5 Fixed Side Sliding Member 51 Sliding Surface 9 Dam Part 10 Notch 11, 12 Dynamic Pressure Generation Groove

Claims (1)

[Scope of utility model registration request] 1. A plurality of dynamic pressure generating grooves extending in the radial direction for circumferentially providing a levitation force between the sliding surfaces during rotation are provided on the sliding surfaces of the fixed-side sliding member or the rotating-side sliding member. In the bidirectional rotation type gas seal, a dam portion is provided on the outer diameter side of the dynamic pressure generating groove, and a notch for gas entrainment is provided at the outer end of the sliding surface on which the dynamic pressure generating groove is provided. A bidirectional rotation type gas seal characterized by.