Fault Analysis and Application Case Introduction of Quantitative Plunger Pump

Quantitative piston pump is an important device in hydraulic systems that utilizes the volume changes formed by the piston and pump wall during the reciprocating motion of the pump cylinder, and repeatedly sucks in and discharges liquid to increase pressure. According to the arrangement direction of the plunger pump, it can be divided into two categories: axial plunger pump and radial plunger pump. Compared to plunger pumps, gear pumps, vane pumps, and plunger pumps, the volumetric efficiency is higher, reaching 0.92~0.98, with a higher rated working pressure of up to 35MPa, high output speed, and a large power to mass ratio. All hydraulic pumps have. The output flow rate of the plunger pump is small in pressure pulsation, stable, and easy to change displacement, which can be made into various types of variable displacement pumps. Due to the comprehensive performance of plunger pumps, they are widely used in high-pressure, high flow and flow adjustment situations, such as engineering machinery, aerospace, and weapon equipment. However, the plunger pump has a complex structure, high cost, and high cleanliness requirements for use. It also has requirements for the self suction capacity, usage, and maintenance of the oil.

Axial piston pump is a hydraulic pump that evenly arranges the number of pistons in a porous outer cylinder body at an angle parallel or inclined to the centerline of the piston shaft and cylinder body axis. It can be divided into valve disc and valve disc types according to the different valve discs. According to the characteristics of valve distribution piston pumps with different transmission modes and structures, they can be divided into inclined plate and inclined shaft types. Taking the inclined plate axial piston pump as an example.

The structure of the swash plate axial piston pump and the working principle of the pump swash plate are fixed with the valve plate, and the motor drives the transmission shaft, cylinder body, and plunger to rotate together. When the plunger spring is at the rear end, the ball head of the plunger always maintains close contact with the surface of the swash plate, and the inner plunger, along with the hole wall and valve plate inside the plunger, forms a sealing chamber. When the transmission shaft is in the direction of rotation, it begins to move to the right under the constraint of the inclined plate located at the top of the piston, thereby reducing winding. Oil is discharged into the system from the valve plate pressure oil, achieving the oil pressure process; The lower end of the plunger on the surface of the swash plate gradually cools down, and the oil is absorbed by the cylinder under atmospheric pressure.

Working principle of axial piston pump: When the axial piston pump is working, its main performance is that the flow rate of its main performance gradually decreases until it exceeds the lower limit of use; Or suddenly malfunction and stop working. The occurrence of this phenomenon is caused by the following reasons: bearing and transmission shaft biting and sticking damage; The gap between the plug holes increases; The ball head is worn and the plunger is stuck; Poor sealing at the outlet of the one-way valve, internal leakage, and fracture of the spring plunger.

This is mainly due to the following reasons, taking Q * PCY14-1B constant power variable piston pump as an example. Pump, belonging to the field of swash plate axial piston pump, is caused by contact friction between the transmission shaft and bearings, and damage caused by bearing temperature rise; The column jack is caused by long-term movement of the plunger, which leads to increased clearance and high/low pressure oil manipulation, resulting in leakage and reduced flow rate; The contact between the punch and the ball bearing, due to their small area and slow cooling, indicates oxidation and wear. Due to frictional heat, the flow rate of the pump decreases. The term does not replace hydraulic oil, does not clean the oil tank in a timely manner, or due to the failure of coarse and fine filters, the plunger is often sticky debris; Due to poor quality of high-pressure oil or oil, the sealing of the valve and the skeleton oil seal inside the valve disc opening is affected.

The service life and daily maintenance of pumps, the quantity and quality of hydraulic oil, and the cleaning of oil