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What is an oil seal, the basic characteristics and uses of oil seals

 

What is an oil seal

The oil seal is a sealing element used to seal the rotating shaft in mechanical equipment, and the cavity is basically stationary, so the oil seal is also called the rotary shaft lip seal.

Oil seals are used to prevent oil from leaking from the gaps in the machine, and oil seals are used to prevent water and chemicals from leaking into the friction part of the machine, as well as dust and soil sand from the outside

The sealing state of the oil seal, first, is a static seal between the outer edge of the oil seal and the cavity, and at the same time ensures the reliable positioning of the outer edge of the oil seal between the cavities. The second is the sealing state between the oil seal lip and the shaft, when the shaft rotates, it is a dynamic seal, and when the shaft is stationary, it is a static seal. The combined effect of various influencing factors and their interaction have a great impact on the sealing performance and service life of oil seals.

 

The main use of oil seals

It is used for sealing engine crankshafts and camshafts

Sealing of transmission systems (e.g. gearboxes, wheel hubs, axles, differentials) for cars, motorcycles and commercial vehicles

Seals of transmission systems of agricultural machinery and construction machinery such as forklifts, excavators, etc

Sealing of gearboxes for industrial use

Sealing of hydraulic components (pumps, motors).

Sealing of washing machines for daily use

It is widely used in mechanical engineering and equipment processing industries

 

The main characteristics of oil seals

The outer part of the oil seal is cylindrical to ensure the static sealing of the cavity - the rubber outer edge of the inner metal skeleton is adopted; The outer edge of the exposed metal skeleton is mostly polished and plated with an anti-corrosion coating.

Spring-loaded sealing lips ensure sealing reliability for dynamic and static sealing of shafts. As a result of long-term development research, the lip structure of the oil seal has been improved to excellent performance, which in turn improves seal reliability over a wider load range

The addition of dust lips, or in special cases, multiple dust lips prevents the ingress of external contaminants and dust

 

Hydrogen-cooled turbine generators must be sealed with sealing oil to ensure that hydrogen does not leak inside the generator and prevent air and moisture from entering the generator. The sealing oil system of the steam turbine generator adopts the double-flow ring sealing tile structure, which has good sealing effect and wide adjustment range, and is a very mature product. However, if the structure is not well understood, improper operation may also cause oil ingress accidents inside the generator. Especially in the case of no pressure inside the generator, the oil level of the sealed oil tank is not easy to control, and the seal oil is easy to enter the inside of the generator along the axial direction. Oil inlet inside the generator is a vicious accident and should be taken seriously. The following is an introduction to the generator sealing oil system, the reasons for the internal oil intake of the generator and the preventive measures.

 

Introduction to the sealing oil system

The sealing oil system adopts double flow ring sealing pads. Since the rotor shaft of the hydrogen-cooled generator must pass through the end cap of the generator, this part becomes the key to the sealing of the hydrogen internal coolant generator. The sealing oil is divided into two oil circuits, airside and hydrogen side, and the oil is supplied to two annular oil distribution grooves on the shaft sealing pad, and the oil flows out along the axial direction of the shaft through the gap between the inner diameter of the sealing pad and the rotating shaft. If the oil pressure in these two oil circuits is exactly equal at the sealing pad, the oil will not flow in the gap between the two oil distribution tanks, and usually as long as the sealing oil pressure is always higher than the gas pressure in the machine, hydrogen can be prevented from sealing the oil system of the power generator.