Main performance parameters of hydraulic oil pump
1. Pressure
Pressure can be divided into working pressure, rated pressure and maximum pressure, etc.
①Working pressure refers to the pressure that the hydraulic pump (or motor) outputs (inputs) oil during actual work, and the working pressure is determined by the external load.
②Rated pressure refers to the maximum pressure that the hydraulic pump (or motor) can operate continuously according to the test standard under normal working conditions. Its size is limited by the life of the hydraulic pump (or motor). When the working pressure is greater than the rated pressure, it is called overload .
③ The maximum pressure refers to the maximum intermittent pressure allowed by the reliability life and leakage of the hydraulic pump (or motor), and its action time does not exceed 1% to 2% of the total working time. The pressure is determined by Relief valve setting Normally, the operating pressure of a hydraulic pump (or motor) is not equal to its rated pressure.
2. Speed
The speed (r/min) can be divided into working speed, rated speed, maximum speed and minimum stable speed.
① Working speed refers to the actual rotation speed of the hydraulic pump (or motor) during work.
②Rated speed refers to the maximum speed at which the hydraulic pump (or motor) can run continuously for a long time under the rated pressure. That is, when the speed exceeds this speed, the hydraulic pump (or motor) will cause suction Insufficient oil will generate vibration and noise, suffer cavitation damage, and reduce life.
③The maximum speed refers to the maximum speed limit that cannot be exceeded when the hydraulic pump (or motor) is not damaged abnormally.
④ The minimum stable speed refers to the minimum speed allowed for the normal operation of the motor.
The speed capability of the hydraulic oil pump (or motor) is affected by the flow rate and the mechanical load of the rotating components. It is a function of displacement and pressure. In general, when the pressure decreases or the displacement decreases, the speed capability of the hydraulic pump (or motor) improve.
Under the same pressure conditions, the speed increases with the decrease of the displacement, and it will not increase when it reaches a certain displacement between the minimum displacement (not necessarily zero displacement) and the full displacement. in the row At the highest speed, the additional load of the inertial force of the rotating components of the hydraulic pump (or motor) is extremely large, which may damage the hydraulic pump (or motor) or cause the rotation to form a limit lubrication state and aggravate wear.
Below the rated speed, the service life and transmission efficiency of the hydraulic pump (or motor) are not as sensitive to changes in speed as they are to changes in pressure. Therefore, from the perspective of improving the power utilization of the hydraulic pump (or motor) and reducing costs, the rated speed is selected as the matching Speed is suitable.
3. Displacement
Displacement refers to the volume of liquid discharged (or sucked) obtained by changing the geometry of the sealed cavity for each revolution of the hydraulic pump (or motor), ml/r.
The displacement can be changed by adjustment is called a variable pump (motor), and the displacement can not be changed is called a quantitative pump (motor).
In order to determine the hydraulic pump (motor) displacement, the concept of angular power needs to be introduced.
Angular power is a descriptive index of the limit state, it is not the power that can be obtained usually, but it effectively and comprehensively reflects the transmission capacity of the transmission device, that is, it reflects the power capacity and transformation ability of the transmission device, and the angular power is equal to The product of the maximum output torque of the transmission and the maximum speed.
When the torque is large, the speed is low, and the two cannot reach the maximum value at the same time, so the angular power is impossible to realize. However, if the hydraulic system has the angular power capability required by the special working device, the adjustment and conversion of the two parameters of torque and speed In the process, you can always find a point of maximum torque and another point of maximum speed that meets the requirements.
The hydraulic pump and hydraulic motor can be selected according to the determined hydraulic pump (or motor) pressure, speed and displacement.
4. Traffic
Flow is equal to the product of displacement and speed.
The actual flow refers to the flow at the outlet (or inlet) of the hydraulic pump (or motor) when it is working. Due to the internal leakage of the hydraulic pump (or motor), the actual flow is less than the theoretical flow. To achieve the specified speed of the motor, it is necessary to compensate Leakage, the actual input flow must be greater than the theoretical flow.
5. Efficiency
The efficiency of a hydraulic pump (or motor) is divided into volumetric efficiency and mechanical efficiency.
① Volumetric efficiency, for hydraulic pumps, refers to the ratio of actual flow to theoretical flow; for hydraulic motors, it refers to the ratio of theoretical flow to actual flow.
②Mechanical efficiency, for hydraulic pumps, refers to the ratio of theoretical torque to actual input torque; for hydraulic motors, it refers to the ratio of actual output torque to theoretical torque.
③ The total efficiency refers to the ratio of the output power of the hydraulic pump (or motor) to the input power, which is equal to the product of the volumetric efficiency and the mechanical efficiency.