JPH0637938B2 - mechanical seal - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a mechanical seal configured to shield and seal a fluid to be sealed by a relative rotational sliding contact action of two sealed end surface members.

[Conventional technology]

In this type of mechanical seal, of course, it is preferable that the sealing end face member is made of a material having high wear resistance and lubricity, but the wear resistance (eg, abrasive wear) and lubricity (eg, Dry sliding) is an inherently contradictory characteristic, and a conventional sealed end face member that can secure both of them has not yet been proposed.

Therefore, in the conventional mechanical seal, either wear resistance or lubricity is sacrificed, or a so-called double mechanical seal or the like is provided and a lubricating means is separately provided. For example, in a double mechanical seal, in addition to the original mechanical seal, a mechanical seal, an oil seal, and other sealing mechanisms are provided.
A lubricant is enclosed between the two to ensure the lubrication performance between the sealed end face members.

[Problems to be Solved by the Invention]

However, when one of the wear resistance and the lubricity is sacrificed as in the former case, a good sealing function cannot be expected, and when the lubrication means is separately provided as in the latter case, the structure is inevitably increased in size. This complicates and prevents the weight reduction and downsizing of equipment with a mechanical seal.

The present invention eliminates such drawbacks in the conventional mechanical seal, and by devising the structure of the sealing end face member, a mechanical seal capable of securing both wear resistance and lubricity which could not be achieved in the past is provided. It is intended to be provided.

[Means for Solving the Problems]

The mechanical seal of the present invention, which has solved this problem, is particularly one in which at least one of the two sealed end face members is made of a porous new ceramic material and the pores thereof are impregnated with a lubricant.

The sealed end surface member is made of porous SiC, ZrO ₂ , Si ₃ N.
₄ , composed of a new ceramic material such as alumina,
It is preferable to use a β-type SIC sintered body having excellent strength and heat resistance.

Further, as the lubricant, microwax containing a lubricant such as fluorine oil or mineral oil is used. The microwax and the lubricating oil are appropriately selected according to the properties of the fluid to be sealed, the sealing conditions and the like. In particular, the microwax is selected such that the melting point of the lubricant can be the optimum temperature according to the sealing conditions and the like.

[Action]

Since the sealed end face member is made of a porous new ceramic material, it has excellent wear resistance, corrosion resistance, and heat resistance.

Moreover, since the pores of the sealed end face member are impregnated with the lubricant, a lubricating film is formed by the impregnated lubricant in the sliding portion without providing a lubrication means, and seizure or the like does not occur. Moreover, by using microwax mixed with lubricating oil as the lubricant, the lubrication form of the lubricant is automatically adjusted according to the sliding condition of the sealed end face member (heat generation condition due to frictional heat of sliding part). As a result, the sliding portion of the sealed end face member can be satisfactorily lubricated for a long period of time while minimizing the consumption of the lubricant.

That is, since microwax is a solid with a high melting point and liquefies at a temperature equal to or higher than the melting point, when the heat generation temperature of the sliding portion of the sealed end face member is equal to or lower than the melting point, such as at the initial stage of operation or at the time of stop. The lubricant becomes a solid state in which the outflow of the lubricating oil is blocked by the microwax, and the lubrication form of the sliding portion is so-called solid lubrication by the lubricant. However, in such a low temperature sliding condition, there is less risk of problems such as seizure, and high-level lubrication is not required. Can be performed satisfactorily,
It does not impair the sealing function of the mechanical seal.

Then, if the sliding part temperature rises due to frictional heat generated between the sealed end surface members and exceeds the melting point due to continued operation,
The microwax is liquefied and the lubricating oil is eluted, and the sliding portion is lubricated by the eluted lubricant. That is, a lubricating film made of liquid is formed on the sliding portion, and the sliding portion is liquid-lubricated. Therefore, even if the sliding portion is under a high temperature condition, the relative rotation sliding of the sealed end surface member can be smoothly performed without causing inconvenience such as seizure.

By the way, it is possible to use paraffin wax instead of microwax, but in the present invention, microwax is used for the following reasons. That is, the microwax has a larger oil content than the paraffin wax and can perform better solid lubrication. Further, since the viscosity of microwax changes remarkably with temperature rise as compared with paraffin wax, the transition from solid lubrication to liquid lubrication can be carried out quickly, and it is possible to respond appropriately to changes in the heat generation state. Furthermore, since microwax does not have a crystal transition, the volume expansion from the solid phase to the liquid phase is slower than that of paraffin wax, that is, the volume increase rate is small, which means that even in the fluid lubrication state The outflow amount does not increase more than necessary, and the consumption amount can be suppressed to the necessary minimum.

In this way, appropriate lubrication is performed according to the heat generation state of the sliding portion, and the elution amount of the lubricant, that is, the consumption amount is suppressed to the necessary minimum. Therefore, the sliding portion can be lubricated satisfactorily for a long period of time.

〔Example〕

Hereinafter, the configuration of the present invention will be specifically described based on the embodiment shown in FIG.

In the mechanical seal shown in FIG. 1, 1 is a stationary seal ring fixedly held in a seal case 2, 3 is a rotary seal ring axially slidably held by a rotary shaft 4, and 5 is a rotary shaft 4.
A spring retainer 6 is fixed to the stationary seal ring 1, and a spring retainer 6 presses the rotary seal ring 3 against the stationary seal ring 1. Due to the relative rotational sliding contact action of the seal rings 1 and 3, the sealed portion is sealed at the sliding portion 7. The area A and the non-hermetic fluid area B can be shielded and sealed.

At least one of both sealing rings 1 and 3 is made of porous β-type Si.
It is composed of a C sintered body (pore diameter 2 to 30 μm, porosity 4 to 20%), and the pores are impregnated with a lubricant in which microwax is mixed with a lubricating oil such as fluorine oil.

In the mechanical seal having such a configuration, when the rotary shaft 4 is rotated and the heat generation temperature due to the frictional heat of the sliding portion 7 becomes equal to or higher than the melting point of the microwax, the lubricant is eluted,
A lubricating film made of an eluting lubricant is formed on the sliding portion 7 to lubricate the sliding portion 7. At this time, the lubricant is not eluted until the heat generation temperature of the sliding portion 7 reaches the melting point of the microwax, and the sliding portion 7 is solid-lubricated. When the rotating shaft 4 is stopped and the sliding portion 7 is cooled, the lubricant solidifies and its elution is prevented.

Therefore, the lubricity of the sliding portion 7 can be ensured in both liquid and air atmospheres. Moreover, the pour point of the impregnated lubricant can be freely controlled depending on the type of microwax, and a good sealing function according to the sealing conditions can be exhibited.

Further, since the β-type SiC sintered body is excellent in wear resistance, corrosion resistance, etc., it can exhibit a good sealing function even under the condition where wear resistance, corrosion resistance, etc. are required.

The present invention is not limited to the above embodiment, but can be applied to any contact type mechanical seal. Further, the porous new ceramic material and the impregnated lubricant, which are the constituent materials of the sealed end face member, are not limited to those in the above embodiment.

〔The invention's effect〕

As will be easily understood from the above description, according to the present invention, the sealed end face member is made of the porous new ceramic material impregnated with the lubricant, and the wear resistance and the lubricity which are originally contradictory characteristics are provided. Since both can be provided, it is possible to provide a mechanical seal that can exhibit a good sealing function without causing an increase in size and complexity of the structure unlike the double mechanical seal. Therefore, the mechanical seal of the present invention can be used not only under normal sealing conditions, but also for a corrosive gas stirring seal that requires corrosion resistance, a powder seal that requires wear resistance, and both air and water sealing atmospheres. It can be suitably used as a submersible pump seal in a required dry motor or a seal used under conditions where fluid lubrication cannot be performed, and is extremely practical. Further, since the lubrication form by the lubricant is automatically changed according to the heat generation condition of the sliding portion of the sealed end face member, the consumption of the lubricant is suppressed to the minimum necessary,
The sliding portion of the sealed end surface member can be satisfactorily lubricated for a long period of time. Moreover, since the melting point of the lubricant can be freely controlled by selecting the microwax,
In combination with the selection of the lubricating oil, appropriate lubrication can be performed under any sealing condition.

[Brief description of drawings]

FIG. 1 is a half sectional view showing an embodiment of a mechanical seal according to the present invention. 1 ... Stationary sealing ring (sealing end face member), 2 ... Rotating sealing ring (sealing end face member), 7 ... Sliding part.

Claims (1)

[Claims] 1. At least one of two hermetically sealed end face members that are in relative rotational sliding contact is made of a porous new ceramic material such as SiC, ZrO ₂ , Si ₃ N _4, and the pores thereof are made of microwax, fluorine oil or the like. A mechanical seal characterized by being impregnated with a lubricant containing a lubricating oil.