Hydraulic system oil leakage is one of the common failures of the hydraulic transmission system, according to the oil leakage parts can be divided into two categories of oil leakage and connecting parts leakage. Since the causes of leakage is very complex, some new equipment leakage, some use more than 10 years of old equipment does not leak oil. To completely solve the problem of oil leakage, we must figure out the factors and ways of oil leakage. The following Dahlan hydraulic manufacturers through a few typical examples to analyze the causes of self-leakage and solutions.
1 Hydraulic pump oil leakage
The finished hydraulic parts do not allow oil leakage, but for various reasons, the new factory hydraulic pump in the process of debugging pump station, the oil temperature just reached 50 ℃, from the journal of the oil leakage. Analysis of oil leakage from the part, the vast majority of the leakage from the low-pressure cavity to the outside, that is, from the pressure cavity of a large number of oil seepage to the low-pressure cavity (leakage) of the oil, due to a certain amount of back pressure in the system, so that a part of the low-pressure oil leakage; there are hydraulic components of the low-pressure cavity does not allow the return of the oil, such as the shaft of the hydraulic pump to extend the parts. Various types of hydraulic pumps from the transmission shaft extension to the outside of the oil leakage is more common, especially in the gear pump journal end cap of the self-tightening rotary rubber seals. Such structure of its own oil leakage causes are:
(1) pump axial clearance exceeds the prescribed value, the pressure oil into the low-pressure area, the self-tightening rotary rubber seals open to the outside oil leakage;
(2) hydraulic pump in the system for years of use and wear, so that the axial clearance increases, and a large amount of pressure oil into the low-pressure area, the rotary sealing ring to wash away to the outside oil leakage.
(3) new processing and assembly of the hydraulic pump, due to processing and manufacturing of a component of the geometric size tolerance exceeds the specified value, or several parts of the cumulative size tolerance exceeds the specified value.
From the above reasons, to solve the journal part of the oil leakage is mainly from the prevention of axial clearance is too large to start: ① to prevent oil leakage at the shaft extension, the design of gear pumps, the installation of two self-tightening rotary rubber seals at the journal; ② long-term use of the gear pump leakage, basically due to the pipeline connection part of the seal aging, damage or deterioration and oil temperature is too high, oil viscosity is too low and other reasons, can be dealt with the cause.
2 control valve oil leakage
Control valve in the process, did not meet the design drawings of the coaxiality and chamfering requirements, which is the main cause of oil leakage.
Spool ends of the chamfer can not be customary 45 °, this chamfer is very harmful to the valve body when assembling the spool, it is easy to O-ring card injury. Divided into three cases: ① valve body hole to the O-ring groove coaxiality exceeds the specified value, O-ring in the groove, one side of the compression is very large, the other side of the compression is small, light oil leakage occurs, overdose serious, to the valve hole when the spool will be loaded with O-ring will be cut off half a circle or a circle. In the test bench to make the factory test, due to the short time, low oil temperature and no back pressure, will not find oil leakage, when used in hydraulic equipment for some time after the start of oil leakage; ② Valve body at both ends of the O-ring and the coaxiality of the main valve hole is qualified, the valve spool should be chamfered at both ends of the angle of 15 ° -20 °, if greater than the specified value, but also O-ring card breakage. ③ both are qualified, in the assembly of the valve hole, O-ring and spool not to the valve coated with lubricant (imported lubricant use of misunderstanding), to the valve body when the spool can also be cut off a piece of O-ring.
Visible from the above, to prevent the control valve leakage, should start from the processing and assembly of the two processes to ensure that the hydraulic components do not leak.
On the hydraulic system hydraulic parts leakage problem analysis
3 hydraulic cylinder oil leakage
3.1 Control of processing quality
(1) cylinder hydraulic cylinder manufacturing quality is poor, the new cylinder will appear oil leakage phenomenon, such as the processing of cylinder cylinder barrel bore (keyway) chamfering, chamfering in the processing of the bore on both sides of the keyway does not meet the provisions of the drawings and is greater than 20 °, in the assembly of cylinders, first of all, the two holes on the piston with the sealing ring card injury caused by the internal leakage of oil, and secondly, in the assembly of the guide sleeve, the outer diameter of the fixed oil seals of the O ring will be cut off a piece or Half a circle, which gives in use buried oil leakage hidden trouble. When installed in the equipment system has a certain back pressure, use for a period of time the oil temperature reaches 50-60 ℃ or more, will begin to leak from the front of the cylinder.
(2) piston rod in the piston rod front chamfer, such as the use of commonly used 45 ° chamfer, to the cylinder cylinder when the guide sleeve, will be O-shaped seals broken. And the use of 20 °, in the assembly will not cut off the O-shaped seal, which is the main measure to prevent oil leakage.
3.2 Reasonable assembly
(1) In the case of cylinder bore and piston rod chamfer are qualified, when assembling the cylinder, the front of the cylinder bore, the front of the piston rod, as well as the outer diameter of the guiding sleeve, the bore should be coated with clean lubricating oil, this method of assembling the cylinder is to overcome the seals are not an important part of the damage.
(2) Prohibit the use of a certain pressure, the piston rod and guide sleeve to the cylinder assembly method of fierce top. Prevent the movement of the guiding sleeve within the seal and the outer diameter of the fixed oil seal from damage, which is also an important way to overcome the hydraulic cylinder without oil leakage.