What are the most common seals in hydraulic cylinder?

What are the most common seals for hydraulic cylinder? Hydraulic transmission depends on the change of sealing element volume to transfer motion, and the performance of sealing element directly affects the performance and efficiency of hydraulic transmission. Therefore, good performance of sealing element is required in hydraulic sealing element. As the executive sealing element of the hydraulic system, the sealing performance of the hydraulic cylinder directly affects the working performance and efficiency of the hydraulic cylinder. Therefore, the sealing element selected by the hydraulic cylinder should have good sealing performance under certain working pressure, so that the leakage is not significantly increased due to the pressure increase. Sealing elements should also be simple in structure, low friction, long life. The sealing parts of hydraulic sealing cylinder include sealing of fixed parts (such as sealing parts between cylinder body and end cover) and sealing of moving parts (such as piston sealing parts and cylinder body sealing parts, piston rod sealing parts and end cover sealing parts, etc.). The commonly used sealing method of the hydraulic cylinder in the hydraulic seals has the gap seal and the seal element to seal. Let's take a look at some of the most common seals on hydraulic cylinders. I. working principle and structural features of clearance seals: clearance seals are guaranteed by small matching gaps between relative moving parts. There are several annular grooves (generally 0.5mmx0.5mm) on the piston. On the one hand, it can reduce the contact area between piston and hydraulic cylinder wall. On the other hand, the uniform distribution of oil pressure in the groove makes the piston in the center position, reduces the friction between the piston and the hydraulic cylinder wall caused by side pressure caused by poor precision of parts, and can reduce leakage. However, the method of gap seal has low friction resistance, poor sealing performance and high machining accuracy. Therefore, it is only suitable for small size, low pressure and high speed of movement (working environment, medium). The clearance between the piston and the hydraulic cylinder wall is usually 0.02-0.05mm. 2. Working principle and structure characteristics of sealing ring: sealing ring is the most widely used sealing method in hydraulic transmission system. The sealing ring is made of oil resistant rubber sealing material, nylon sealing material and other sealing materials. The section of the ring is usually made of o type sealing ring, y type sealing ring, v type sealing ring or special type sealing ring. Take the case of o-type sealing ring with section as O type. O-ring is one of the sealing elements with circular cross section shape. It is simple in structure, easy in manufacture, reliable in seal and low in friction. Therefore, it is widely used, which can be used for both the sealing of fixed parts and the sealing of moving parts. In order to ensure the sealing performance, the parting surface (where the flight force is generated) should be selected at a position of 45 degrees, which is inclined to the axis. The working principle and structure characteristics of Y type sealing ring: the section of Y type sealing ring presents Y type, its structure has wide applicability and good sealing effect, and it is often used for sealing between piston and hydraulic cylinder, piston rod and hydraulic cylinder end cover. Generally, the y-type sealing ring can be directly put into the groove for use, but it should be fixed by the supporting sealing ring when the pressure changes greatly and the movement speed is high (working environment, medium). The working principle and structure characteristics of v-type sealing ring are different in shape, it is made up of supporting sealing ring, sealing ring and pressing ring. V ring contact surface large, reliable sealing, but friction resistance, mainly in the moving speed of the hydraulic cylinder. Under the action of pressure oil, the lip of Y type sealing ring and V type sealing ring is open and attached to the sealing surface. The greater the oil pressure, the better the sealing performance. Therefore, attention should be paid to the installation direction when using, so that it can be opened under the action of pressure oil.

The above: Japan NACHI hydraulic oil pump