The function of the inner and outer skeletons of the hydraulic oil filter element

Outer Skeleton - External Protection
The Outer Skeleton is located on the outermost layer of the filter element and comes into direct contact with the hydraulic fluid being filtered. It primarily performs three core functions:

1. Resisting external pressure.
When hydraulic fluid enters the filter element, it creates impact. The Outer Skeleton resists this pressure, preventing the filter media within from bulging, deforming, or even breaking.

2. Protecting the filter media.
When installing or removing the filter element, the Outer Skeleton prevents the fragile filter material (such as filter paper) from rubbing against the outer shell, minimizing physical damage.

3. Assisting in oil flow distribution.
Some Outer Skeleton are designed with uniform openings to guide the hydraulic fluid smoothly and evenly into the filter media, preventing localized excessive oil flow that could affect filtration accuracy.

Inner Skeleton - Internal Support
The Inner Skeleton is located on the inside of the filter element and comes into contact with the clean, filtered fluid. It also serves an irreplaceable purpose:

1. Preventing the media from collapsing.
When pressure is applied outside the filter element and low pressure is applied inside, the filter media can be "sucked" inward. The Inner Skeleton provides support from within, maintaining the hollow structure of the filter element and ensuring smooth outflow of clean oil.

2. Ensures unobstructed oil flow.
The Inner Skeleton itself is a hollow structure with holes, providing a stable outflow path for filtered oil, preventing oil from stagnating inside the filter element and ensuring the flow requirements of the hydraulic system.

3. Enhances the overall rigidity of the filter element.
The inner and outer skeleton work together to maintain the shape of the entire filter element, making it less susceptible to distortion due to vibration or pressure fluctuations even during long-term use, thereby extending its service life.

The Logic of the Inner and Outer Skeleton - Neither is Indispensable
The inner and outer skeleton work in tandem. Missing either one will affect filter element performance:

1. Without the outer skeleton, the filter media will be crushed by external oil pressure, allowing impurities to enter the system.

2. Without the inner skeleton, the filter media will be flattened, preventing clean oil from flowing out, resulting in insufficient oil supply to the system.