JPH017851Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a non-contact seal, which is effective when supplying oil-free high-pressure gas or vacuum pressure to a high-speed rotating body, and has a small structure with less leakage of high-pressure gas and vacuum pressure. The purpose is to provide a non-contact seal that can be used.

As a conventional example, a case will be described in which vacuum pressure is supplied to a high-speed rotating body. Usually, a labyrinth seal, which is a type of non-contact seal, is used for such applications. A conventional example is shown in FIGS. 1 and 2. Reference numeral 1 denotes a shaft having a flange 2. Although not shown, this shaft 1 is supported by a bearing on the body and rotated by a motor or the like. 3 is a groove 4 formed concentrically, and a groove 5 formed radially from the center of rotation.
... and a hole 6 that communicates these grooves 4 and 5,
This is a vacuum chuck fixed to the flange 2 with bolts (not shown) or the like. 7 is a hub fixed to the vacuum chuck 3 with bolts 8. The bolt 8 has a hexagonal hole 9 and a through hole 10 for tightening the bolt. 11 is a radial ball bearing, an outer ring 12 is press-fitted into the hub 7, and a seal retainer 14 is press-fitted into the inner ring 13. Reference numeral 15 denotes a sealing member, which is attached to the outer ring 1 of the radial ball bearing 11.
After pressing 2 and press-fitting into the hub 7, set screw 27
It is fixed to the seal retainer 14 by. This sealing member 15 has a convex portion 16 and a concave portion 17 of the hub 7.
The labyrinth seal portion 23 is formed by this. 18
is a lever having an air circulation hole 19, and is rotatably supported by a shaft 20 fixed to the machine body (not shown) in the directions of arrows A and B in FIG. A rubber lining 28 is provided to improve the quality. 21 is lever 18
This is a tube that connects the vacuum source and a vacuum source (not shown). 2
Reference numeral 2 denotes a workpiece whose center portion is positioned by the outer periphery of the hub 7 and placed on the vacuum chuck 3.
Of course, when attaching and detaching the workpiece 22 to and from the vacuum chuck 3, the vacuum pressure is turned off and the lever 18 is rotated in the direction of arrow A in FIG.

When vacuum pressure is applied in FIG. 1, air is exhausted through the path shown by arrow C, and the workpiece 2
2 is suctioned and fixed to the vacuum chuck 3. In addition, the external air flows through the path shown by arrow D in FIG.
It flows into the interior 26 through the gap 25 between the inner ring 13 and the inner ring 13 . The amount of inflow is determined by the shapes and gaps of the convex portions 16 and recesses 17 that make up the labyrinth seal portion 23, and when the inflow amount is large, the vacuum pressure in the interior 26 becomes weak and the workpiece 22 is pressed with a sufficiently strong force. It becomes impossible to adsorb. In that case, a vacuum source with high exhaust capacity is required. After the workpiece 22 is attracted to the vacuum chuck 3, when the shaft 1 is rotated by a motor or the like, the seal retainer 14 is supported by the radial ball bearing 11, and the lever 18 is pulled by the vacuum pressure inside the inside 26, and the rubber lining 28 is pressed against the seal retainer 14, and since the rubber lining 28 has a large friction coefficient, the rubber lining 28 and the seal retainer 14
will not cause any slippage. In some cases, the lever 18 may be biased by a spring or the like to press the rubber lining 28 against the seal retainer 14. In the conventional example described above, the labyrinth seal part 23 is configured separately from the radial ball bearing 11, so it is not possible to increase the mounting accuracy of the labyrinth seal part 23. Therefore, the seal gap is usually about 0.1 to 0.05 mm at the smallest. However, there was a large leakage of vacuum pressure, resulting in low efficiency. In addition, in order to increase efficiency, it is necessary to overlap several constriction sections and expansion sections, making it impossible to construct a compact structure. In addition, in order to strengthen the internal vacuum pressure in a seal with a large pressure leak, a vacuum source such as a vacuum pump with high exhaust capacity is required, which is disadvantageous in terms of cost. Also, if the radial ball bearing 11 is used in a state with large leakage,
The leakage loss of the grease in the shield 24 increases, and a large amount of external dust also enters between the inner ring 13, outer ring 12, and balls 29, and the life of the radial ball bearing 11 is significantly shortened, requiring frequent replacement. The need arose.

The present invention has been devised to address such conventional problems, and will be described below based on drawings showing embodiments. Incidentally, the same parts as in the conventional example are indicated by the same reference numerals, and detailed explanation thereof will be omitted. First, the first embodiment will be explained based on FIGS. 3 and 4 showing the first embodiment. The radial ball bearing 11, which has the capacity to carry radial and thrust loads, is attached to the hub 7 as before.
The lower end of the outer ring 12 is press-fitted into the hole 40 of the hub 7, and the lower end of the outer ring 12 is press-fitted and fixed to the stepped portion 41 of the hub 7 via an annular seal member 42. The sealing member 42 is formed with a sealing surface 44 that faces the lower end surface 43 of the inner ring 13 in a non-contact manner.
4 constitutes a non-contact seal portion 46. When vacuum pressure is applied to the air circulation hole 19 of the lever 18,
External air flows into the interior 26 through the path shown by arrow E in FIG. 3, that is, through the gap 25 between the shield 24 of the radial ball bearing 11 and the inner ring 13. The amount of inflow is determined by the gap G between the lower end surface 43 and the sealing surface 44 shown in FIG. When vacuum pressure is applied to the air circulation hole 19, the rubber lining 28 is pulled by the vacuum pressure and presses the inner ring 13 downward, as shown in FIG. The inner ring 13 is displaced downward due to the gap between the 12 ball raceway surfaces 47 and 48. Therefore, the amount of displacement F is managed in advance, and the lower end surface 43 of the inner ring 13 is
The seal gap G may be determined by taking into consideration the increase in displacement amount F due to runout and wear of the balls 29 and raceway surfaces 47 and 48, and the height difference H=F+G of the seal member 42 may be determined. Therefore, the only dimensions that need to be managed are F and H, and the size of the seal gap G is determined by the allowable leakage amount and the pressure difference acting on the seal part.
It can be made as small as about 10 μm, and the effective diameter of the seal, that is, in the conventional example, J in Fig. 2
Since the K dimension of the present invention can be made smaller than the dimensions, the cross-sectional area of the flow path (π×effective diameter×seal gap) becomes smaller, and leakage of vacuum pressure can be dramatically reduced. The size of the seal gap G is determined by the gas pressure difference acting on the seal portion, the allowable leakage amount, etc., but 5 to 40 μm is practically appropriate. Further, since the effective diameter of the seal is small, the runout of the inner ring 13 is not increased, and therefore there is no need to increase the seal gap to avoid contact between the seals.

Next, another embodiment of the present invention will be described. First, an embodiment for sealing high pressure gas will be described.
In the embodiment shown in FIG. 5, an annular seal member 49 is provided only at the upper end of the radial ball bearing 11, and this seal member 49 is between the upper end surface of the inner ring 13 of the radial ball bearing 11 press-fitted into the hub 7. This constitutes a non-contact seal portion 50. A nut 51 is screwed into the hub 7 and is used to press the sealing member 49 tightly against the outer ring 12. 51a is Natsu 51
This is an engagement hole with a wrench for screwing in. 52
is press-fitted into the inner ring 13 and has a nipple 53 at the upper end.
It is a cylindrical fixing member into which a nipple 53 is screwed, and is formed with a flat cut portion 54 for applying a wrench when screwing in the nipple 53. Nipple 53
When high-pressure gas is supplied to the interior 55 through the vacuum pressure, the only difference is that the inner ring 13 is displaced upward, contrary to the vacuum pressure case, and the other functions are the same as in the vacuum pressure case.

In FIG. 5, if a strong bending moment acts on the nipple 53 and one radial ball bearing 11 is unstable, two radial ball bearings 11 may be used. Radial ball bearing 1 in the configuration shown in FIG.
A configuration using two 1s is shown in FIG.

The non-contact seal of the present invention can be implemented as described above, and is disposed on the inner ring of a rolling bearing on the low pressure side of the gas pressure acting in the thrust direction, and is in close contact with the end face of the outer ring. By configuring a sealing surface that faces the end surface in a non-contact manner to seal gas, and by setting a predetermined gap between the inner ring end surface and the sealing surface of the sealing member when the gas pressure is applied, the following can be achieved. The effects described in can be obtained.

Compared to the conventional method, the number of parts that require highly accurate dimensional control during seal processing is significantly reduced, the structure is simpler and smaller, and it is possible to obtain a smaller seal gap more easily than in the conventional method at a lower cost. . By creating a small seal gap, leakage of high-pressure gas and vacuum pressure is reduced, loss of outflow of bearing grease and intrusion of dust from the outside is reduced, and the life of the bearing can be significantly extended. In addition, it is possible to reduce the capacity of the source of high-pressure gas or vacuum pressure, and it is also possible to reduce equipment costs and operating costs.

Since the end face of the inner ring, which constitutes the bearing, is used directly as the sealing surface, the runout of the sealing surface due to bearing runout is increased compared to conventional sealing surfaces that are located away from the bearing. This is very advantageous for obtaining a minute seal gap, and since the effective diameter of the sealing surface is small, the cross-sectional area of the flow path can be made smaller, which also makes it much more resistant to leaks than before. be advantageous to

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view showing a conventional example, and Figure 2 is a vertical cross-sectional view of a conventional example.
FIG. 3 is a vertical sectional view showing the first embodiment of the present invention, FIG. 4 is an enlarged view of the principal part of FIG. 3, and FIGS. FIG. 3 is a vertical cross-sectional view of a main part showing a different embodiment. 7... Hub, 11... Radial ball bearing, 12... Outer ring, 13... Inner ring, 42... Seal member, 46... Non-contact seal part, 49... Seal member, 50... Non-contact seal part.

Claims (1)

[Scope of utility model registration request] A rolling bearing is capable of carrying radial and thrust loads and has a gas passage formed inside its inner ring; A member having a sealing surface that is in close contact with an end face of an outer ring of a rolling bearing and that seals the gas by opposing the end face of the inner ring without contacting the end face of the inner ring, the member having a sealing surface that seals the gas when the gas pressure is applied to the inner ring end face and the seal. 1. A non-contact seal characterized by comprising a sealing member having a predetermined amount of clearance between the seal member and the surface.