Hydraulic pump working principle analysis
The hydraulic pump uses mechanical transmission to create periodic volume changes in the sealed working chamber, converting the mechanical energy of the prime mover (electric motor/internal combustion engine) into pressure energy of the hydraulic oil.
Release Time：
2025-05-30
Hydraulic Pump Working Principle Analysis
I. Core Working Principle
Energy Conversion Mechanism
The hydraulic pump uses mechanical transmission to create periodic volume changes in the sealed working chamber, converting the mechanical energy of the prime mover (electric motor/internal combustion engine) into the pressure energy of the hydraulic oil.
Oil Suction and Pressure Process:
Oil Suction Stage: Volume increases → vacuum forms in the pump chamber → oil from the tank enters the pump chamber under atmospheric pressure.
Oil Pressure Stage: Volume decreases → oil is compressed → high-pressure oil is discharged to the system through a one-way valve.
Necessary Conditions
Periodic change in sealed volume (core characteristic).
Distribution device isolates suction and pressure oil chambers (such as one-way valve, distribution plate).
Oil tank communicates with the atmosphere (maintains suction oil pressure balance).
II. Typical Hydraulic Pump Types and Working Processes
Type Working Principle Key Structural Components
Gear Pump Gear meshing rotation → alternately increasing (suction) and decreasing (pressure) sealed chamber Driving gear, driven gear, pump body
Plunger Pump Cam/swash plate drives plunger reciprocating motion → changes the sealed volume of the cylinder Plunger assembly, cylinder, distribution plate
Vane Pump Eccentric rotor rotation → vane expansion and contraction forms a variable sealed chamber → volume change achieves oil suction and pressure Rotor, vane, stator ring
Screw Pump Multiple screw meshing rotation → spiral groove sealed chamber moves axially → low-pressure suction, high-pressure discharge Main screw, driven screw, pump casing
III. Functional Characteristics and Control Points
Flow Output Pattern
Theoretical flow rate is determined by pump speed and displacement ( Q=V×n, V is the displacement, n is the speed)
Actual flow rate needs to consider volumetric efficiency (leakage increases with pressure).
System Matching Requirements
Pressure Limit: Relies on relief valve to set peak pressure, preventing overload damage to the pump body.
Medium Cleanliness: Oil contamination easily leads to wear of the distribution device and seal failure.
IV. Application Scenarios and Selection Reference
High pressure, high flow rate: Plunger pump preferred (efficiency high >80%).
Low noise requirement: Vane pump (stable flow) or internal gear pump.
Simple and inexpensive: External gear pump (strong anti-pollution ability).
Note: As a power component of the hydraulic system, the hydraulic pump needs to work together with the actuator (hydraulic cylinder/motor), control valve and auxiliary devices to form a complete energy transmission chain.
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