JPH0440044Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a float-type segment seal that performs a shaft sealing function with a minute clearance interposed between it and the outer peripheral surface of a rotating body.

[Conventional technology]

A shaft sealing device that arranges a non-rotating annular body on the outer peripheral surface of a rotating body (such as a rotating shaft or a sleeve attached to the rotating shaft) and performs shaft sealing with the annular body slightly floating from the outer peripheral surface of the rotating body. One type of seal is the float type segment seal.

5 and 6 schematically show an example of this float type segment seal, in which an annular accommodating portion 102 formed on the inner periphery of the housing 101 is shown.
The inside is divided into a plurality of segments 103' in the inner circumferential direction, and the divided parts 104 are hermetically joined to each other, and the extension spring 1 on the outer circumference is divided into a plurality of segments 103'.
An annular body 103 bound in the circumferential direction at 05 is accommodated. This annular body 103 is connected to the low pressure space B by a compression spring 106 whose one end is supported by an end plate 107 on the inner periphery of the housing 101.
The one end surface 103b is pressed toward the housing 1.
It is in close contact with the end surface 101a of 01, and the inner peripheral surface 10
3a connects to the rotating body 10 through a minute clearance C.
It faces the outer circumferential surface 108a of No.8. 110 is
A pin that engages with a hole 111 formed in one end surface 103b of the annular body 103 to prevent rotation of the annular body 103.
is implanted in.

[The problem that the idea attempts to solve]

The above-mentioned segment seal performs shaft sealing in a state where the annular body 103 is slightly floating from the outer circumferential surface 108a of the rotating rotary body 108 due to the dynamic pressure of the fluid. A clearance C between the body 108 and the outer peripheral surface 108a is formed by making the inner diameter of the annular body 103 slightly larger than the outer diameter of the rotating body 108. From the viewpoint of improving sealing performance, it is desirable that the radial width C ₁ of this clearance C is made as small as possible.

However, due to limitations in machining accuracy of the inner circumferential surface 103a of the annular body 103 and the outer circumferential surface 108a of the rotating body 108, the radial width of the clearance C is
It was extremely difficult to set C ₁ to a minute value. In addition, increasing the axial width _C2 of the clearance C is also effective in improving sealing performance, but
In this case, there were problems in that the mounting space for the seal became large and the vibration of the rotating body 108 increased.

The present invention was developed in view of the above-mentioned problems, and its purpose is to utilize the initial wear due to the sliding of the inner circumferential surface of the annular body to improve rotation between the inner circumferential surface and rotation of the annular body. The purpose is to form a clearance interposed between the outer circumferential surfaces of the body with an extremely small radial width to improve sealing performance.

[Means to solve the problem]

The float type segment seal according to this invention is
A non-rotating annular body that is circumferentially divided into a plurality of segments and bound together in the circumferential direction with an extension spring is housed in an annular housing formed on the inner periphery of the housing. In a float type segment seal in which one end surface is in close contact with the end surface of the housing and the inner circumferential surface of the annular body faces the outer circumferential surface of the rotating body through a minute clearance, the radius of curvature of the inner circumferential surface of each segment is The diameter is slightly smaller than the radius of the outer circumferential surface of the rotating body, and the inner circumferential surface of each segment disappears when the inner circumferential surface of each segment becomes a cylindrical surface concentric with the outer circumferential surface of the rotating body due to wear. It is characterized by the formation of a slight gap.

[Effect]

According to the float type segment seal of the present invention, at the beginning of use, a slight gap is formed between the divided parts of the annular body, and each segment constituting the annular body is moved radially inward by the tension of the extension spring. The inner peripheral surface of each segment, whose radius of curvature is slightly smaller than the radius of the outer peripheral surface of the rotating body, is tightened so as to reduce the gap in the circumferential direction. It contacts the outer peripheral surface of the rotating body at both end portions. As a result, the inner circumferential surface of each segment undergoes rapid initial wear from both end portions in the circumferential direction, and due to the tension of the extension spring, each segment is displaced radially inward to follow the wear. , the gap between the divided portions decreases. When the initial wear progresses until the inner circumferential surface of each segment becomes a cylindrical surface concentric with the outer circumferential surface of the rotating body, the gap between the divided parts disappears and each segment becomes in close contact with each other in the circumferential direction. Therefore, after that, the wear hardly occurs, and an extremely small clearance is formed between the inner peripheral surface and the outer peripheral surface of the rotating body due to the wear.

〔Example〕

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The float type segment seal of the present invention will be described below with reference to illustrated embodiments.

In the embodiment shown in FIG. 1, 1 is a housing, and a seal ring 3 as an annular body is accommodated in an annular accommodating portion 2 formed on the inner periphery of the housing. This seal ring 3 is made of a sliding material such as carbon, and is divided into a plurality of segments 3' in the circumferential direction, and bound together in the circumferential direction with an extension spring 4 wound around the outer circumferential surface of the seal ring 3. Further, due to the pressing force of a compression spring (not shown), one end surface 3b is brought into close contact with the end surface of the housing 1 surrounding the accommodation portion 2, similar to the conventional one shown in FIG. Further, an engagement hole 5 is provided in the one end surface 3b of each segment 3'.
A pin 6 protruding from the end surface of the housing 1 is loosely fitted into the engagement hole 5 to prevent the seal ring 3 from rotating.

The radius of curvature r ₁ of the inner peripheral surface 3a of each segment 3' is
It is set to be slightly smaller than the radius _r2 of the outer circumferential surface 8a of the rotating body 8, such as the rotating shaft or a sleeve mounted on the rotating shaft. A slight gap δ ₁ is formed between the dividing portion 7, that is, the adjacent segments 3', 3'.

According to the above configuration, at the initial stage of use, the inner circumferential surface 3a of each segment 3', which is tightened from the outer circumferential side by the extension spring 4,
The rotating body 8 only at both end portions 3a' in the circumferential direction
Since it comes into contact with the outer circumferential surface 8a of the two circumferential surfaces 3a and 8a, a crescent-shaped gap _δ2 is formed between the two circumferential surfaces 3a and 8a, and a gap _δ1 is formed in the divided portion 7. Then, as the rotating body 8 rotates,
Initial wear of the inner circumferential surface 3a of each segment 3' rapidly progresses from the end portions 3a' where the contact load is concentrated, and due to the tension of the extension spring 4, each segment 3 ' is displaced inward in the radial direction, the crescent-shaped gap δ ₂ gradually decreases, and the gap δ ₁ of the divided portion 7 also gradually decreases in the circumferential direction. In the divided portion 7, the size of the gap δ 1 is set so that when the crescent-shaped gap δ ₂ almost disappears due to the progress of the wear, the adjacent segments 3', ₃ ' are in close contact with each other. has been done. Then, since the segments 3' are brought into close contact with each other in the circumferential direction, and the seal ring 3 has a single ring shape, the initial wear hardly occurs thereafter. At this time, theoretically, the inner diameter of the seal ring 3 and the rotating body 8
However, due to the influence of vibrations caused by rotation, the radial width between the inner circumferential surface 3a of the seal ring 3 and the outer circumferential surface 8a of the rotary body 8 is actually several. This results in a throat-type seal with a minute clearance of about 10 μm.

Next, FIG. 2 is a graph showing the results of a static air leak test of the float type segment seal of the above embodiment and the conventional float type segment seal. Among these, the example type segment seal used was one in which the inner circumferential surface of the seal ring was subjected to initial wear by operating at 1800 rpm for 150 hours, and the conventional example type segment seal was A clearance of approximately 0.05 mm in radial width was used between the inner circumferential surface of the seal ring and the outer circumferential surface of the rotating body by machining in advance, and other test conditions were as follows.

Seal ring size: Inner diameter 100mm Axial width 12mm Fluid to be sealed: Air Temperature: 20℃ Pressure outside the seal: Atmospheric pressure Rotating body: Stopped state As is clear from the graph in Figure 2, the results of the above test, It was confirmed that the float type segment seal of the example suppressed the amount of air leakage to a small amount compared to the conventional float type segment seal in which a clearance was created in advance between the seal ring and the rotating body by processing.

In addition, in the above embodiment, the accommodating portion 2 of the housing 1
The annular body housed inside has a so-called 1-ring structure consisting only of a seal ring 3.
As shown in the figure, the annular body consists of a seal ring 9 and a cover ring 10 closely attached to its outer peripheral surface (both rings 9 and 10 are divided in the circumferential direction at mutually different phases), so-called 2- In the case of a ring structure, the seal ring 9 can be constructed in the same manner as the seal ring 3 shown in FIG. 1, and as shown in FIG. Also in the case of a so-called three-ring structure having a back ring 11 that faces the seal rings 9 and 10 in the axial direction and is divided in the circumferential direction, at least one of the seal ring 9 and the back ring 11 is replaced with the seal ring 3 in FIG. It can be configured in the same way as .

[Effect of idea]

As described above, according to the float type segment seal of the present invention, by utilizing the initial wear of the annular inner circumferential surface, the clearance between the inner circumferential surface and the rotating body outer circumferential surface can be formed extremely minutely and quickly. Therefore, excellent sealing performance can be achieved without increasing the mounting space in the axial direction.

[Brief explanation of drawings]

Fig. 1 is a schematic front view showing an embodiment of the float type segment seal of the present invention, Fig. 2 is a graph showing test results, and Fig. 3 is a partial sectional view showing a float type segment seal with a two-ring structure. , FIG. 4 is a partial sectional view showing a float type segment seal having a three-ring structure, FIG. 5 is a partial sectional view showing a conventional float type segment seal, and FIG. 6 is a schematic front view. 1...Housing, 2...Accommodating section, 3, 9...
Seal ring (annular body), 3'...Segment, 3
a...Inner peripheral surface, 4...Extension spring, 7...Divided portion, 8...Rotating body, 11...Buckling (annular body), _δ1 ...Gap.

Claims (1)

[Scope of utility model registration request] A non-rotating annular body that is circumferentially divided into a plurality of segments and bound together in the circumferential direction with an extension spring is housed in an annular housing formed on the inner periphery of the housing. In a float type segment seal in which one end surface is in close contact with the end surface of the housing and the inner circumferential surface of the annular body faces the outer circumferential surface of the rotating body through a minute clearance, the radius of curvature of the inner circumferential surface of each segment is The diameter is slightly smaller than the radius of the outer circumferential surface of the rotating body, and the inner circumferential surface of each segment disappears when the inner circumferential surface of each segment becomes a cylindrical surface concentric with the outer circumferential surface of the rotating body due to wear. A float-type segment seal that is characterized by the formation of a small gap.