JPH0225973Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement of a sealing device related to shaft sealing technology.

[Conventional technology]

Conventionally, as a type of shaft seal device, a sealing member made of fluororesin and a holding ring made of metal have been used, and the proximal end of the sealing member extending approximately in the radial direction is supported by the holding ring, and the distal end lip portion is supported by the holding ring. 2. Description of the Related Art A sealing device that closely slides on a sliding member is known. When this type of sealing device is attached to the sealed part of various devices, for example, when the retaining ring is fitted to the inner periphery of the shaft hole of the device housing, the inner lip of the sealing member is attached to the shaft that is the mating sliding member. When inserted, the lip part is elastically bent and deformed in the axial direction, and the inner circumferential surface of the lip portion and the shaft circumferential surface directly and closely slide, and are exposed to lubricating oil or the like filled in the device shaft hole. The sealing fluid will be sealed. Some types of sealing devices have a threaded groove formed on the inner circumferential surface of the inner circumferential lip portion. This threaded groove serves as a seal so as to push back liquid that has entered the close sliding portion due to the threaded pumping action caused by the rotation of the shaft.

[Problem that the invention attempts to solve]

In a sealing device equipped with the above-mentioned thread groove, its sealing ability increases as the cross-sectional area of the thread groove increases, but on the other hand, if the cross-sectional area of the thread groove is increased too much, when the shaft stops, the sealing ability increases due to the increase in the cross-sectional area of the thread groove. There is a problem of liquid leakage, and sealing devices equipped with this fluororesin seal member, regardless of whether it has a thread groove, have a higher Young's modulus of the material than ordinary rubber materials. Because of the hardness, the lip could not sufficiently follow the eccentricity of the shaft, causing liquid leakage.

In view of the above points, the sealing device of the present invention is intended to prevent leakage during operation and rest, and to improve the ability to follow shaft eccentricity, based on the formation of the thread groove.

[Means for solving problems]

In order to achieve the above object, the sealing device of the present invention bends the inner peripheral lip part of the fluororesin seal member whose outer peripheral part is supported by the retaining ring in one direction in the axial direction,
In a sealing device in which the inner circumferential surface of the inner circumferential lip portion closely slides on the circumferential surface of a mating sliding member such as a shaft, the bending between the inner circumferential lip portion and the outer circumferential portion from the tip of the inner circumferential lip portion. A thread groove is formed throughout the inner peripheral lip portion, and the cross-sectional area of the thread groove becomes gradually smaller toward the tip of the inner circumferential lip portion and gradually increases toward the bent portion.

[Effect]

In the sealing device of the present invention having the above configuration, the thread groove performs a pumping action as the shaft rotates, as in the prior art, but in particular, the cross-sectional area is made smaller toward the tip of the inner circumferential lip. The cross-sectional area of the wetted opening is extremely narrow compared to conventional thread grooves, which provides good leakage protection during rest, while the cross-sectional area of the thread groove gradually increases toward the bend. This provides good screw action and ability to follow shaft eccentricity during operation.

〔Example〕

An embodiment of the sealing device of the present invention will be described below with reference to the drawings.

In FIG. 1, radial portions 3,
4, a proximal outer peripheral portion 6 of an annular seal member 5 made of fluororesin (for example, PTFE) is held between them.
As shown in FIG. 2, this sealing member 5 is formed into a disk shape with a shaft hole 7, and when press-fitted onto the shaft a, an inner peripheral lip portion 8 is elastically bent and deformed in the axial direction. The inner circumferential surface 9 serves as a sealing sliding surface for the circumferential surface of the shaft a, and the cross-sectional area gradually decreases from the tip to the bent portion 10, and the cross-sectional area decreases toward the bent portion 10. A single thread groove 11 is formed in which the diameter gradually increases.

The above-mentioned sealing device is designed to seal a liquid b to be sealed such as lubricating oil in the upper part of the figure with the tip of the seal member 5 facing, and to prevent the liquid b from leaking to the atmosphere side c.
The pressing force of the inner circumferential lip portion 8 on the circumferential surface of axis a and the axis a
The sealing effect is achieved by the screw pump action of the screw groove 11 accompanying the rotation of the shaft. While this reduces the leakage of liquid b through the thread groove 11 when stopped, since the cross-sectional area of the thread groove 11 near the bent portion 10 is enlarged, the pumping action is improved and the bending portion 10 is By reducing the substantial thickness, it becomes possible to make the portion easier to bend and deform, thereby improving the ability to follow eccentricity of the axis a.

[Effect of idea]

As explained above, the sealing device of the present invention forms a thread groove from the tip of the inner lip to the bent part between the inner lip and the outer circumference, and
The cross-sectional area of the thread groove, which was uniform in the conventional technology, is made smaller toward the tip of the inner circumferential lip portion and larger toward the bent portion. The practical effects of the present invention are extremely large, as it has made it possible to achieve both good leakage prevention and improved ability to follow shaft eccentricity all at once.

[Brief explanation of the drawing]

FIG. 1 is a half-cut sectional view showing a sealing device according to an embodiment of the present invention in a state of being extrapolated onto a shaft, and FIG. 2 is a half-cut sectional view of a sealing member. 1, 2... Retaining ring, 5... Seal member, 8...
Inner circumferential lip portion, 9... Inner circumferential surface, 10... Bent portion,
11...Screw groove.

Claims (1)

[Scope of utility model registration request] The inner circumferential lip portion 8 of the fluororesin seal member 5 whose outer circumferential portion 6 is supported by the retaining rings 1 and 2 is bent in one direction in the axial direction, and the inner circumferential surface 9 of the inner circumferential lip portion 8 is aligned with the axis a.
In a sealing device that closely slides on the circumferential surface of a mating sliding member, a thread groove 11 is formed from the tip of the inner circumferential lip portion 8 to the bent portion 10 between the inner circumferential lip portion 8 and the outer circumferential portion 6. A sealing device characterized in that the cross-sectional area of the thread groove 11 gradually decreases toward the tip of the inner peripheral lip portion 8 and gradually increases toward the bent portion 10.