Hydraulic motor and hydraulic pump of the same point
1. from the principle, hydraulic motors and hydraulic pumps are reversible, if driven by an electric motor, the output is pressure energy (pressure and flow) which is a hydraulic pump; if the input pressure oil, the output is mechanical energy (torque and speed), it becomes a hydraulic motor.
2. From the structural point of view, the two are similar.
3. Hydraulic motors and pumps have the same basic structural elements - a closed and cyclically variable volume and a corresponding oil distribution mechanism. Hydraulic motors and hydraulic pumps are the principle of operation is the use of sealing changes in the working volume of oil suction and discharge. For hydraulic pumps, the working volume increases when the oil suction, the working volume decreases when the discharge of high-pressure oil. For hydraulic motors, the working volume increases into the high-pressure oil, the working volume decreases when the discharge of low-pressure oil.
Differences between hydraulic motors and hydraulic pumps
1. hydraulic pump is the motor's mechanical energy into hydraulic energy conversion device, the output flow and pressure, hope that the volumetric efficiency; hydraulic motor is the liquid pressure energy into mechanical energy conversion device, the output torque and speed, hope that the mechanical efficiency is high. Therefore, the hydraulic pump is an energy device, while the hydraulic motor is an executive element.
2. Hydraulic motor output shaft steering must be able to positive and negative rotation, so its structure is symmetrical; and some hydraulic pumps (such as gear pumps, vane pumps, etc.) steering has a clear regulation, can only be unidirectional rotation, can not change the direction of choice.
3. hydraulic motor in addition to the inlet and outlet, there is a separate leakage of oil; hydraulic pumps generally only inlet and outlet (except axial piston pumps), the leakage of oil with the inlet.
4. Hydraulic motor volumetric efficiency is lower than the hydraulic pump.
5. Usually the working speed of the hydraulic pump is relatively high, while the hydraulic motor output speed is low. 6.
6. In addition, gear pumps have large suction ports and small discharge ports, while gear hydraulic motors have the same size suction and discharge ports.
7. The number of teeth of gear motor is more than the number of teeth of gear pump.
8. The blade of vane pump shall be installed obliquely, while the blade of vane motor is installed radially; the blade of vane motor relies on the swallow spring at the root to press on the surface of the stator, while the blade of vane pump relies on the pressure oil and centrifugal force at the root to press on the surface of the stator. From the working principle, hydraulic motors and hydraulic pumps are relying on the sealing of the working chamber volume changes and work, but because of the two use different purposes, there are many differences in structure, generally can not be directly reversed universal.
Hydraulic pump classification by structure: piston pumps, gear pumps, vane pumps three categories.
According to whether the displacement is adjustable: quantitative pumps, variable pumps.
According to the direction of oil discharge: unidirectional pumps, bidirectional pumps.
According to the pressure level: low pressure, medium pressure, high pressure, ultra-high pressure pump.
Gear pumps: smaller volume, simpler structure, less stringent requirements for oil cleanliness, cheaper; but the pump shaft is subject to unbalanced force, serious wear and tear, leakage is larger.
Gear pumps are widely used in mining equipment, metallurgical equipment, construction machinery, engineering machinery, agricultural and forestry machinery and other industries.
Vane pump: divided into double-acting vane pump and single-acting vane pump. This pump flow uniformity, smooth operation, low noise, for pressure and volumetric efficiency than gear pumps, the structure is more complex than gear pumps. Lifting and transportation vehicles, construction machinery in the hydraulic system of the choice of high-pressure vane pumps.
Piston pump: high volumetric efficiency, small leakage, can work under high pressure, mostly used in high-power hydraulic systems; but the structure is complex, materials and processing precision requirements, expensive, high oil cleanliness requirements. Bicycle diesel engine commonly used piston pumps to transport high-pressure fuel.
Classification of hydraulic motor
According to the structure form: gear type, vane type and plunger type several main forms.
According to the speed, torque range: high-speed motor and low-speed motor. Gear hydraulic motor structure is simple, inexpensive, commonly used in high speed, low torque and movement smoothness requirements are not high occasions. Such as drive grinding machine, fan, etc.. Vane hydraulic motor small moment of inertia, sensitive action, low volumetric efficiency, soft mechanical characteristics, suitable for more than medium speed, torque is not large, the requirements of starting, frequent change of direction occasions. Axial piston motor high volumetric efficiency, a wide range of adjustment, and low-speed stability.
