The Nachi piston pump crankcase is lubricated with splash oil. A skeleton oil seal is installed at the connection between the crankshaft and the crosshead connecting rod and the outside of the cabinet to prevent oil leakage. The skeleton oil seal is composed of an oil seal body, a reinforcing skeleton and a self-tightening coil spring.
The inner diameter of the oil seal rubber lip is smaller than the outer diameter of the journal and the connecting rod, and an interference fit is used for installation. During the operation of the Nachi plunger pump, oil leakage often occurs, and oil leakage occurs in a short time after replacement. This not only causes an increase in the oil consumption of the Nachi plunger pump, but also causes the lubrication condition of the crankshaft bushing and the crosshead cylinder to deteriorate due to the oil level drop, which is prone to accidents of the crankshaft or crosshead cylinder.
1. Oil seal installation deflection causes oil leakage
When the oil seal is installed, the lip and the neck are fully fitted. The oil seal installation will cause the lip of the oil seal to be not perpendicular to the journal or connecting rod. Under the traction of the reinforcing skeleton, the lip will change from round to oval. The asymmetry of the lip contact surface causes the eccentric oil seal lip, and the gap increases to cause the Nachi plunger pump oil seal to leak oil.
2, the oil seal lip is too large or too small to cause oil leakage
(1) The oil seal quality is unqualified. If the oil seal lip is too large, there is a gap between the lip and the journal after installation. Although it can be fixed on the journal by the self-tightening coil spring, the lip rubber will be pulled and deformed. The contact surface between the lip and the journal is changed from a ring groove type to a single ring shape, and the contact surface becomes small, and a lubricating oil film cannot be formed between the lip and the journal. Therefore, the sealing effect of the Nachi plunger pump is deteriorated, resulting in loss of the oil seal. .
(2) If the oil seal lip is too small, the radial pressure of the journal or the connecting rod and the oil seal lip will be too large, which can enhance the sealing performance of the Nachi plunger pump oil seal, but it is difficult to seal in the oil seal and the journal ring groove type. An oil film is formed on the contact surface, and the lip rubber is dry-grinded with the journal or the connecting rod, and oil leakage occurs in a short time.
(3) Oil leakage caused by self-tightening coil spring
The self-tightening coil spring is installed outside the oil seal lip to play the role of correcting the lip and adjusting the radial pressure. After the Nachi plunger pump is operated, the temperature inside the crankcase rises. Due to the different rubber and journal materials of the lip, the deformation after heat rise is different. The gap between the lip seal and the journal increases, and the spring force is required to be restrained. The gap between the oil seal lip and the journal, if the spring falls off, the radial pressure of the oil seal lip to the journal can not be maintained, so that the gap between the oil seal and the journal increases, causing oil seal leakage in a short time after starting the Nachi plunger pump. .
(4) Self-tightening coil spring is too tight to cause oil leakage
If the self-tightening coil spring is too tight, the radial pressure of the lip of the Nachi plunger pump is too large, so that the lubricating oil can not enter the contact surface of the lip and the journal to form a continuous oil film, which will produce dry grinding, and a short time lip The mouth is severely worn, causing oil leakage.
3, the surface of the journal or connecting rod has a low surface finish, resulting in oil leakage
(1) Due to scratches or corrosion holes on the surface of the journal or connecting rod, the wear of the oil seal lip will be aggravated during the operation, and a gap is formed between the corrosion hole and the oil seal lip, causing oil leakage.
(2) Oil leakage due to excessive radial runout of the journal or connecting rod
The rubber seal rubber lip has an interference fit with the journal or the connecting rod. If the radial runout of the crankshaft is too large, during the high-speed rotation, the oil seal lip deformation cannot be synchronized with the journal's runout, which will result in the lip. A gap is formed between the journal and the journal, and the eccentric wear of the lip is aggravated to cause leakage. The Nachi piston pump connecting rod is reciprocating, and the oil seal is also a reciprocating wear. The wear degree is more than the wear of the shaft neck position, and the degree of leakage is more serious.
4, the oil contains impurities to cause oil leakage
Nachi plunger pump is equipped with a bearing bush between the crankshaft and the connecting rod. The grinding debris generated by the bearing wear will enter the gap between the oil sealing lip and the journal with the lubricating oil, and the lip contact surface will be generated as the journal rotates. Scraping, both the oil seal lip rubber and the journal, make the oil seal seal invalid.
5, the cross head pin copper sleeve wear causes the connecting rod oil seal to leak oil
The crosshead is the main component of the crankshaft linkage, connecting the crankshaft and the plunger rod. The crosshead pin bushing is made of copper to avoid wear on the crosshead pin and the connecting rod. If the crosshead pin sleeve is worn, the connecting rod will deviate from the axis during the reciprocating process, so that a gap is formed between the oil seal lip and the connecting rod, and the wear of the oil seal of the Nachi plunger pump is also aggravated, causing the oil seal to leak oil.