JPS63163072A - Shaft seal device - Google Patents

Abstract

PURPOSE:To form an adequate clearance between seal surfaces in the time of assembly and starting, by forming a core metal of a seal member by a shape memory alloy. CONSTITUTION:In the case of close seal devices S2, S3 formed so as to be mounted respectively to both end parts in the axial direction of a ball bearing 1, a core metal 12 of one seal device S3 is formed using a shape memory alloy of one-way type as the material. This core metal 12, providing a plurality of notches in the radial direction, forms many protruding pieces 14 in the diametric direction. An internal diametric end part 14a of said protruding piece 14 most approaches a seal surface 9A of an inner ring 9 in a high temperature phase similarly as in the past. On the contrary in a low temperature phase, the end part 14a is processed being flexed in the non-seal direction toward the outside so as to be opened and detached from the seal surface 9A of the inner ring 9. Accordingly, a lip 3A is set with no interference with the inner ring 9 in a low temperature. in the time of assembly, while reset to a proper seal position in the time of high temperature.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a shaft sealing device, and in particular to a shaft sealing device that utilizes the shape memory effect of a shape memory alloy and is extremely easy to install.
It is also a shaft sealing device that can reduce starting torque.

[Conventional technology]

There have been various types of shaft sealing devices such as bearing seals and oil seals. For example, the one shown in FIG. 8 is a type of bearing seal, and the sealing devices i&s1. It is S2.

This sealing device has an annular core 2 made of a thin plate of cold rolled steel plate (SPCG) and a sealing member 3 made of a rubber elastic body.
are integrally fixed together by vulcanization molding.

When assembling the ball bearing 1, in the raceway groove 5 of the outer ring 4,
Balls 7 held by retainer 6 are inserted.

Next, sealing devices Sl and S2 are press-fitted inside the axially protruding ring portions 8 at both ends of the outer ring 4. Thereafter, the inner ring 9 is pushed in from the axial direction, and the balls 7 are seated in the raceway groove 1°0. As a result, the lip 3A of the sealing member 3 of the sealing device S1 comes into sliding contact with the sealing surface 9A of the inner ring 9, and the sealing device S2
The lip 3B of the sealing member 3 is the end face sealing surface 9 of the inner ring 9.
Slide into contact with B. In this way, the inside of the bearing mechanism can be completely isolated from the outside.

In addition, in the case of an oil seal (not shown), it is inserted between the rotating or reciprocating shaft and the housing.
The fixed side of the seal member is brought into close contact with the seal portion of the housing, and the lip side of the seal member is brought into sliding contact with the shaft,
Prevent foreign objects from entering.

[Problem that the invention seeks to solve]

However, in general, in the conventional shaft sealing device described above, when the shaft sealing device is installed, it is necessary to ensure sealing pressure by bringing the sealing member 3 into close contact with the sealing portion, and the size is designed to take into account the tightening margin for this. There is. For this reason, the following problems have arisen, for example, when the sealing device is installed or when the shaft is operated.

That is, when the inner ring 9 of the bearing 1 is pushed in from the axial direction and installed, the lip 3A of the sealing device S1 touches the inner ring sealing surface 9.
It may be reversed on A as shown in FIG. 8(b).

Alternatively, when press-fitting and assembling the sealing devices Sl, S2 into the outer ring side, the outer peripheral portion of the elastic sealing member 3 may be chewed or deformed by the edge portion of the outer ring 4.

Furthermore, even if the sealing member 3 is not damaged or deformed, static friction changes to dynamic friction during startup when the shaft is driven, so -i requires a larger torque than during steady operation. In addition to this, the contact resistance of the elastic member of the sealing device is added, further increasing the starting torque.

This invention was made by focusing on such conventional problems, and by forming an appropriate clearance between the sealing surface and the sealing surface during assembly and startup, the assembly can be prevented from deformation and deformation during assembly. The object of the present invention is to provide a sealing device that can prevent galling, lip reversal, etc., and can also reduce starting torque.

[Means for solving problems]

The present invention achieves the above object by integrally molding and fixing a sealing member made of an elastic body to an annular mandrel to maintain a sealed state between the sealing member and a mating sealing surface. In the sealing device, the mandrel is a shaft sealing device in which at least a portion of the mandrel is made of a shape memory alloy that memorizes a seal shape in a high temperature phase and is formed into a non-seal shape in a low temperature phase.

[Effect]

In the sealing device of this invention, the mandrel made of a shape memory alloy is pre-memorized in a high temperature annealing state so that when heated, it assumes the regular shape of the mandrel necessary to maintain an appropriate interference. be. That is, it is held in its regular shape and heat-treated at a predetermined aging temperature (above the phase transformation temperature) and aging time to memorize the shape at that high temperature. On the other hand, concentric metal is plastically worked in a low-temperature state to deform it into a light contact state where the interference is almost zero, or a non-contact state where the interference is negative and there is a gap between the metal and the sealing surface. .

This works as follows.

(1) When the sealing device is assembled, the shape memory alloy that constitutes the core metal is in a low temperature phase state. Therefore, there is no interference between the lip portion or fixing portion of the sealing member and the sealing surface, so that the sealing member can be mounted with sufficient clearance. therefore,
No inversion of the lip, galling or deformation of the fixed part, etc. will occur. When the core metal is reheated to the aging temperature after the installation is completed, it will be heated to a high temperature and will recover to the normal shape of the metal core stored in advance.

If the core is made of shape memory alloy only and no bias spring is used, the above change is irreversible.
After that, even if the temperature drops, the regular shape is maintained as it is,
Acts as a normal sealing device.

(2) If the mandrel is a combination of a shape memory alloy and a bias spring, the mandrel reversibly deforms between the high temperature sum shape and the low temperature phase shape depending on the temperature. Therefore, when the drive shaft is not operating, the mandrel is in a low-temperature shape and the sealing member is in non-contact or light contact. When the drive shaft starts up and continues to operate, the temperature rises, the core metal becomes hot, and the seal member has sufficient tightness. In this way, the seal resistance during startup is reduced to zero and the startup torque is reduced.

[Examples] Examples of the present invention will be described below with reference to the drawings.

Note that the same reference numerals are given to parts that are the same as or corresponding to the conventional ones.

FIG. 1 is a partial vertical sectional view of the main parts showing a first embodiment of the present invention.

In this embodiment, the present invention is applied to a ball bearing. The sealing devices s'2 are installed at both ends of the ball bearing 1 in the axial direction. In S3, the mandrel 12 of one of the sealing devices S3 is made of a unidirectional shape memory alloy.

FIG. 2 shows the planar shape of the mandrel 12, in which a plurality of radial notches 13 are provided to form a large number of radially protruding pieces 14. And each of these protruding pieces 14
The inner diameter end portion 14a is different between the high-temperature phase and the low-temperature phase. That is, in the high temperature phase, the sealing surface 9 of the inner ring 9
Directly in the radial direction to bring it closest to A (Fig. 1b)
) and memorize its shape. On the other hand, in the low-temperature phase, the inner ring 9 is bent outward in the non-sealing direction (FIG. 1a) and plastically worked to separate it from the sealing surface 9A of the inner ring 9.

Next, the operation of the sealing device S3 formed in this way will be explained.

When assembling the ball bearing 1, the sealing device S3 is press-fitted and mounted inside the axially protruding ring portion 8 at one end of the outer ring 4, as in the conventional case.

At this time, the mandrel 12 of the sealing device S3 is in a low-temperature non-sealing shape, and the tip lip portion 3A of the sealing member 3 is retracted outward from its normal position.

Therefore, when the inner ring 9 is pushed in from the axial direction, the lip 3A of the sealing device S3 does not interfere with the inner ring 9, and therefore no reversal to the lip 3 occurs. Next, when the assembled ball bearing I is heated to a temperature higher than the transformation temperature of the shape memory alloy, the core metal 12 of the sealing device S3 recovers to the memorized shape of the high temperature phase. As a result, the lip portion 3A of the sealing member 3 in the sealing device S3 returns to its normal sealing position, and henceforth maintains its memorized shape regardless of changes in temperature. Thereby, the lip 3A of the sealing device S3 comes into sliding contact with the sealing surface 9A of the inner ring 9 while maintaining an appropriate interference margin, and it is possible to prevent foreign substances such as water and dust from entering the inside of the bearing mechanism.

FIG. 3 is a partial vertical sectional view showing the main parts of a second embodiment of the invention.

In this embodiment, the present invention is applied to a sealing device 21 such as an oil seal attached to a rotating or reciprocating drive shaft 20, and 22 is a housing.

The inner periphery of the housing 22 is provided with a groove 22A. On the other hand, the outer periphery of the cylindrical portion 23 of the sealing device 21 is provided with a protrusion 24 that engages with the groove 22A.

The mandrel 25 of the sealing device 21 is made of a unidirectional shape memory alloy, and has a cylindrical portion 25A bent into a cylindrical shape on the outer diameter side. A sealing member 26 made of a rubber elastic body is integrally fixed to the mandrel 25 by vulcanization molding.

The degree of bending of the cylindrical portion of the core metal 25 made of the shape memory alloy is different between the high temperature phase and the low temperature phase.

That is, in the high-temperature phase, it is bent at a substantially right angle, as shown in FIG. 3(b), and in the low-temperature phase, it is bent more deeply into an acute angle, as shown in FIG. 3(a). Therefore, in the low temperature phase, the protrusion 24 on the outer periphery of the seal member 26 separates from the groove 22A, which serves as a seal portion, provided in the housing 22.

On the other hand, at high temperature, the protrusion 24 approaches and engages with the groove 22A serving as a seal portion from the open state.

The shape of the high temperature phase is memorized by heat treatment at an aging temperature higher than the phase transformation temperature of the shape memory alloy forming the two-core metal 25. The shape of the low temperature phase is obtained by plastic working this at a temperature below the phase transformation temperature.

When the sealing device 21 formed in this manner is attached to the drive shaft 20, the core metal 25 is in a low temperature state.

Therefore, even if the sealing device 21 is pushed in, the outer peripheral protrusion 24 on the fixed side is retracted inward, and the housing 22
There is no risk of damage due to interference with the edge 22E. Also,
There is no problem because the lip 27 side that makes sliding contact with the drive shaft 20 flexes due to rubber elasticity and slides smoothly.

Once pushed into the predetermined position, the sealing device 21 is reheated to the aging temperature. The shape memory alloy of the mandrel 25 is heated to a high temperature and recovers to the normal shape of the mandrel, which has been memorized in advance, so that the outer circumferential protrusion 24 on the fixed side fits into the seal groove 22A of the housing 22.
It fits and performs a sealing function.

4 to 7 show a third embodiment of the invention.

In this embodiment, the starting torque of the drive shaft is reduced by reversibly changing the interference of the ball bearing sealing device depending on the temperature.

A sealing device 3 attached to the axial end of the ball bearing 1
0, the mandrel 31 is made by joining a plate 32 made of a unidirectional shape memory alloy and a spring plate 33 made of a spring material (for example, 5 pcc). In the above embodiment, when no spring material is used, substantially the same function can be expected by using a two-way shape memory alloy.

FIG. 5 shows the planar shape of the plate 32 made of the shape memory alloy, in which a large number of inner diameter projecting pieces 32B are formed by providing a plurality of radial notches 32A. Then, the inner diameter end of each protruding piece 32B is formed so as to be straight in the radial direction (see Fig. 4) so as to be closest to the sealing surface 9A of the inner ring 9 by high temperature heating, and its shape is memorized. It's a shame.

FIG. 6 shows the planar shape of the spring plate 33. The outer periphery is bent to form a shallow cylindrical flange 33A, and the inner periphery is formed with a plurality of (four in the figure) inner diameter protruding pieces 33B. It's slightly bent.

The plate 32 is fitted to this spring plate 33, and as shown in FIG.
and 33B are brought into close contact with each other.

In this case, the elastic force of the spring plate 33 is set to be stronger than the elastic force of the plate 32 in the low temperature phase and weaker than that in the high temperature phase.

When the ball bearing 1 is used as the sealing device 30 having the core metal 31 described above, when the drive shaft is stopped or is still at a low temperature immediately after starting, it is in the state shown in FIG. 4(a).

In this state, the elastic force of the spring plate 33 is stronger than that of the plate 32 in the low temperature phase, so the mandrel 31 is bent. Therefore, the lip 3A of the sealing member 3 has the sealing surface 9 of any wheel 9.
There is no contact with A, so the starting torque of the drive shaft is extremely low.

On the other hand, when the drive shaft is operated and becomes hot, as shown in Fig. 4(b)
becomes the state of In this state, the plate 32 recovers its memorized shape in the high temperature phase, overcomes the elastic force of the spring plate 33, and becomes straight in the radial direction. As a result, the lip 3A of the sealing member 3 comes into close contact with the sealing surface 9A of the inner ring 9, and an appropriate tightening margin can be maintained. When the drive shaft stops operating and cools down due to heat dissipation, the spring plate 33 overcomes the plate 32 and bends again, so the lip 3A becomes non-contact.

In the above embodiments, a case where the present invention is applied to a ball bearing sealing device and an oil seal has been described, but it goes without saying that other types of bearings can also be applied to a ball bearing sealing device, a lip seal, etc.

〔Effect of the invention〕

As explained above, according to the present invention, in a shaft sealing device, all or a part of the mandrel has a shape that memorizes the seal shape in the high temperature phase and is formed into a non-seal shape in the low temperature phase. Since it is made of a memory alloy, an appropriate clearance is formed between it and the sealing surface during assembly and startup, which prevents deformation, galling, lip reversal, etc. during assembly, and also reduces startup torque. Effects can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a partial vertical cross-sectional view of one embodiment of the present invention;
FIG. 2 is a plan view of the mandrel shown in FIG. 1. FIG. 2 is a plan view of the mandrel shown in FIG. 1. FIG. 3 is a partial longitudinal cross-sectional view of another embodiment, in which (a) shows the state in which it is assembled, and (b) shows the state in which it is assembled. 4 to 7 show still other embodiments, and FIG. 4 is a partial vertical sectional view of the embodiment, in which (a) shows the shaft when it is stopped, and (b) shows the shaft when it is in operation. 5 and 6 are plan views of the mandrel constituent members, and FIG. 7 is an assembled view thereof. FIG. 8 is a partial longitudinal cross-sectional view showing an example of a conventional shaft sealing device, with FIG. 8(a) showing the state when the device is assembled, and FIG. 8(b) showing the state of being assembled later. SL, S2. S3, 21.30 is shaft sealing device, 2.12
, 25.31 is the core metal, 3.26. 3 is a sealing member, 32 is a plate, and 33 is a spring plate. Note that the same reference numerals in the figures represent the same or equivalent parts.

Claims (4)

[Claims] (1) In a shaft sealing device in which a sealing member made of an elastic body is integrally molded and fixed to an annular mandrel to maintain a sealed state between the sealing member and a mating sealing surface, the mandrel A shaft sealing device characterized in that at least a portion of the shaft sealing device is made of a shape memory alloy that memorizes a sealing shape in a high temperature phase and is formed into a non-sealing shape in a low temperature phase. (2) The shaft sealing device according to claim 1, wherein the inner diameter side of the annular mandrel is bent in a direction that approaches the seal portion in the high temperature phase and separates from the seal portion in the low temperature phase. (3) The shaft sealing device according to claim 1, wherein the annular mandrel is bent in a direction in which the outer diameter side approaches the sealing part in the high temperature phase and separates from the sealing part in the low temperature phase. . (4) The annular mandrel is formed by integrally combining a plate made of a unidirectional shape memory alloy and a spring plate made of a metal without shape memory. Shaft sealing device as described.