Performance parameters of radial piston pump

创建于05.17

Performance parameters of radial piston pump

The main performance of radial piston pump includes pressure, displacement, speed, efficiency and service life. The main structural parameters include the diameter and number of plunger, swash plate angle and so on.

(1) In the radial piston pump, the pressure of valve distribution pump is higher, generally over 32Mpa, and even up to 200MPa for some products; the pressure of axial distribution pump is generally over 20MPa.

(2) The displacement of the radial piston pump mainly depends on the diameter of the plunger, the effective stroke and eccentricity of the plunger, and the number of action of each plunger in each working cycle.

The general formula for calculating the displacement of radial piston pump is as follows

V=K(π/4)d2hZ×l0-3 (mL/r)                 (5-1)

Where K -- the number of action of each plunger in each working cycle;

D -- plunger diameter, mm;

H -- effective stroke of plunger, mm;

Z -- number of plunger.

For single acting radial piston pump, because the number of action k = 1 and the effective stroke H = 2e (E is eccentricity), the displacement calculation formula is

V=(π/4)d2×2e×Z×10-3=(π/2)d2eZ×10-3 (mL/r)       (5-2)

The displacement range of radial piston pump is large, ranging from 0.5 to 5000 ml / R. the commonly used displacement varies with the product structure.

(3) For example, the speed of small displacement pump can exceed 10000r / min, the speed of medium displacement pump is 3000-5000r / min, and the speed of large specification pump can also exceed 10000r / min.

(4) The volumetric efficiency and total efficiency of the efficiency radial piston pump are related to the working conditions of the pump. Under the rated condition, the volume efficiency of valve distribution pump can reach 96% ～ 98%, and the total efficiency can reach 85% ～ 88%.

(5) The service life of the radial piston pump is very long under the correct conditions (especially when the working medium with proper viscosity is used and enough cleanliness is maintained). But generally speaking, radial piston pump is not as long as axial piston pump.

(6) Compared with gear pump, vane pump and screw pump, the flow pulsation and noise of plunger pump are larger. The flow pulsation of piston pump is the main cause of noise. Among all kinds of piston pumps, the valve distribution piston pump has the highest noise level.

The number of plunger has a great influence on the flow pulsation. According to the traditional design criteria, the number of plunger is odd, and the more the plunger, the smaller the flow pulsation. Considering the difficulty of structural arrangement, the number of plunger is generally taken as Z = 3, 5, 7, 9, and uniformly distributed along the circumference. However, because the pressure build-up and oil supply process of valve distribution piston pump are related to the rotation phase of transmission shaft, the pressure difference between inside and outside the working cylinder, and the opening and closing characteristics of valve, the above design criteria of odd number of pistons are not important for this kind of pump. For the sake of manufacturing technology and reducing bearing load, many valve distribution pumps use even number plunger.

(7) High pressure and large flow piston pump has high power density and cost performance. The power density of radial piston pump is lower than that of axial piston pump because of its larger radial dimension.

(8) The main structural parameters Z, diameter D and eccentricity e are three mutually restricted parameters, which are related to structural type, performance, strength, stiffness and workability. When the plunger number Z is determined considering the displacement, flow pulsation and structural technology of the pump, the plunger diameter D can be calculated from the plunger number and displacement. Generally, the eccentricity e can be determined as follows:

e=md (mm)                        (5-3)

Where m -- coefficient, M = 0.25-0.5, the smaller value is taken when the working pressure is high, otherwise the larger value is taken.

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