JPS6213872A - Shaft sealing device - Google Patents

Abstract

PURPOSE:To prevent leakage of sealing fluid effectively, in a sealing device for a rotary shaft or a reciprocal shaft, by providing a space around the movable shaft and encapsulating sealing fluid which has not affinity with the fluid to be sealed in said space. CONSTITUTION:The shaft sealing device is comprising the oil seal rings 3-5 placed between a rotary shaft 1 and a housing 2 and sealing fluid Q filled in the groove P formed in the innercircumferential face of the housing 2 between the oil seal rings 4, 5. The oil seal ring 3 will contact against the fluid R to seal at the frontmost stage. While the oil seal rings 4, 5 will hermetically seal the fluid Q in the groove P from the opposite sides in axial direction. The sealing fluid Q is not compatible with the fluid R to be sealed and silicon oil or fluoro-oil is employed for such fluid R as mineral lubricant.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a shaft sealing device for sealing around a rotating shaft or a reciprocating shaft.

[Technical background of the invention and its problems]

When an oil seal or the like is used as a shaft sealing device, oil leakage is likely to occur if the pressure of the fluid to be sealed temporarily increases or if shaft vibration occurs. For example, in a system such as a Stirling engine where the permissible leakage amount of fluid to be sealed is small, such oil leakage causes a decrease in the performance of the entire system.

In addition, in a reciprocating wheel seal device, a liquid film of several molecular layers moves in and out of the shaft seal while remaining attached to the shaft to lubricate and seal the shaft circumferential surface. In some cases, a large amount of oil evaporates from the fluid film between the time it leaves the seal and the time it enters the seal, and this evaporation amount ends up becoming a leakage amount.

[Purpose of the invention]

The present invention has been made based on such conventional drawbacks, and an object of the present invention is to provide a shaft seal device that can effectively prevent leakage of seal fluid and suppress the deterioration in system performance caused by this. .

[Summary of the invention]

The present invention provides a shaft seal device that is provided between a fixed element and a movable shaft to prevent leakage of a fluid to be sealed along the movable shaft, in which a space is provided around the axis of the movable shaft, and the space is filled with the space. It is characterized in that a sealing fluid that is incompatible with, or difficult to get along with, the fluid to be sealed is sealed.

〔Effect of the invention〕

According to the present invention, since the area around the movable shaft is filled with a sealing fluid that is difficult to mix with the fluid to be sealed, the fluid to be sealed is almost completely sealed by the presence of this sealing fluid. Leakage of the fluid to be sealed can be effectively prevented. Therefore, according to the present invention, it is possible to prevent the performance of the system from deteriorating.

[Embodiments of the Invention] Details of the present invention will be described below based on illustrated embodiments.

In the figure, reference numeral 1 denotes a rotating shaft rotatably supported inside a hole provided in a housing 2. As shown in FIG. A fluid R to be sealed, such as lubricating oil for the crankshaft, is sealed in the space on the left side of the rotating shaft 1 in the figure, and leakage of the fluid R to be sealed in the right side space directly affects the performance of the system. The photographic composition is arranged to give an effect.

The shaft seal device according to this embodiment includes three oil seal rings 3 interposed between the rotating shaft 1 and the housing 2.
．． 4.5, and a sealing fluid Q filled in a circumferentially extending groove P formed between the oil seal rings 4 and 5 on the inner peripheral surface of the housing 2. The oil seal ring 3 is in contact with the fluid R to be sealed,
This fluid R is sealed at the earliest stage. Also,
The oil seal rings 4 and 5 seal the sealing fluid Q filled inside the groove P from both sides in the axial direction. Further, the sealing fluid Q is incompatible with the fluid R to be sealed, that is, it is difficult to get along with it. For example, when the fluid R to be sealed is a mineral lubricating oil, silicone oil, fluorine oil, etc. is used.

In the shaft sealing device having such a configuration, for example, suppose that the pressure of the fluid R to be sealed increases and the fluid R leaks into the annular space between the oil seal rings 3 and 4.

This leaked fluid R moves in the axial direction of the rotating shaft 1 and reaches the oil seal ring 4, and tries to enter the inside of the sealing fluid Q via this oil seal ring 4, but the fluid Q Since it is difficult to mix with fluid R, intrusion into fluid Q is effectively prevented. In this case, it is possible that some sealing fluid Q may leak from the oil seal ring 5, but by choosing a sealing fluid Q that will not affect the system even if some leakage occurs, it will directly affect the operation of the system. It will no longer have any impact. Further, if the pressure of the sealing fluid Q is set to be higher than the pressure of the fluid R to be sealed to some extent, a practically sufficient sealing performance can be obtained even if the oil seal ring 3 is omitted.

The present invention is also applicable to a reciprocating shaft seal in which the rotating shaft 1 shown in the figure is used as a reciprocating wheel.

Particularly when the ambient temperature is high, in order to eliminate leakage due to evaporation of a liquid film that flows in and out of the seal while remaining attached to the shaft, a fluid with a low vapor pressure may be used as the sealing fluid Q. For example, if the fluid R to be sealed is water, the space between the oil seal rings 3 and 4 will be filled with water vapor, but if the sealing fluid Q is a low vapor pressure lubricating oil, for example, for a vacuum pump, Water vapor is blocked by the oil seal ring 4, and only a very small amount of vapor of the lubricating oil for the vacuum pump leaks into the space on the right side of the oil seal ring 4 in the figure. In this case, if the distance between the oil seals 3 and 4 is longer than the stroke of the axial movement, the fluid film of the fluid R to be sealed will not reach the oil seal ring 4, so that the fluid Q and the fluid R can be directly connected. There is no contact. Therefore, a decrease in the concentration of the fluid Q can be prevented.

[Brief explanation of the drawing]

The figure is a sectional view of a shaft seal device according to an embodiment of the present invention. 1... Rotating shaft, 2... Flange, 3.4.5...
Oil seal ring, P...Groove, Q...Sealing fluid, R...Fluid to be sealed.

Claims (3)

[Claims] (1) In a shaft seal device that is provided between a fixed element and a movable shaft and prevents the fluid to be sealed from leaking along the movable shaft, the fluid to be sealed is prevented from leaking around the axis of the movable shaft. A shaft seal device characterized by having a space filled with a compatible sealing fluid. (2) The shaft seal device according to claim 1, wherein the sealing fluid is a fluid with low vapor pressure. (3) The shaft sealing device according to claim 1, wherein the fluid to be sealed is a mineral fluid, and the sealing fluid is silicone oil or fluorine oil.