Both hydraulic pumps and hydraulic motors are energy conversion components in a hydraulic transmission system. What is the difference between the two? How to differentiate? Where are they applied?

Similarities between hydraulic motors and hydraulic pumps

1. In 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 pressure oil is input, 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. The hydraulic motor and the hydraulic pump have the same basic structural elements-a closed but cyclically variable volume and corresponding oil distribution mechanism. The working principle of hydraulic motors and hydraulic pumps is to use the change of the seal working volume to suck and discharge oil.

For hydraulic pumps, oil is sucked when the working volume increases, and high-pressure oil is discharged when the working volume decreases. For hydraulic motors, high-pressure oil enters when the working volume increases, and low-pressure oil is discharged when the working volume decreases.

The difference between hydraulic motors and hydraulic pumps

1. A hydraulic pump is a conversion device that converts the mechanical energy of a motor into hydraulic energy. It outputs flow and pressure and hopes to have a high volumetric efficiency; a hydraulic motor is a conversion device that converts the pressure energy of a liquid into mechanical energy, and outputs torque and speed. efficient. Therefore, the hydraulic pump is the energy device, and the hydraulic motor is the actuator.

2. The steering of the output shaft of the hydraulic motor must be able to rotate forward and reverse, so its structure is symmetrical; and some hydraulic pumps (such as gear pumps, vane pumps, etc.) have clear regulations for steering, which can only be rotated in one direction, not at will Change the selection direction.

3. In addition to the oil inlet and outlet ports, hydraulic motors have separate oil leakage ports; hydraulic pumps generally only have oil inlet and outlet ports (except for axial piston pumps), and the leaking oil is connected to the oil inlet port.
4. The volumetric efficiency of hydraulic motors is lower than that of hydraulic pumps.

5. Generally, the working speed of hydraulic pumps is relatively high, while the output speed of hydraulic motors is relatively low.

6. In addition, the oil suction port of the gear pump is large and the oil discharge port is small, while the oil suction and discharge ports of the gear hydraulic motor are the same size.

7. The gear motor has more teeth than the gear pump.

8. The vane of the vane pump must be installed obliquely, while the vane of the vane motor is installed radially; the vane of the vane motor relies on the root spring to make it pressed against the surface of the stator, while the vane of the vane pump relies on the pressure of the root Oil and centrifugal force are pressed against the surface of the stator.

In terms of working principle, both hydraulic motors and hydraulic pumps rely on changes in the volume of the sealed working chamber. However, due to the different purposes of use, there are many differences in structure, and generally they cannot be used directly and inversely.
Hydraulic pump classification

According to the structure: plunger pump, gear pump, vane pump three categories.

According to whether the displacement can be adjusted, it can be divided into quantitative pump and variable pump.

According to the direction of oil discharge: one-way pump, two-way pump.

According to the pressure level: low pressure, medium pressure, medium high pressure, ultra high pressure pump.

Gear pump: small in size, simple in structure, less demanding on oil cleanliness, and cheaper in price; but the pump shaft is subject to unbalanced force, severe wear and large leakage.

Gear pumps are widely used in mining equipment, metallurgical equipment, construction machinery, construction machinery, agricultural and forestry machinery and other industries.
Hydraulic motor classification

According to the structure, there are several main types: gear type, vane type and plunger type.

According to speed and torque range: high-speed motor and low-speed motor.

Geared hydraulic motors are simple in structure and low in price. They are often used in occasions where high speed, low torque and smooth motion are not required. Such as driving grinders, fans, etc.

The vane-type hydraulic motor has small moment of inertia, sensitive action, low volumetric efficiency, and soft mechanical characteristics. It is suitable for occasions above medium speed, low torque, and frequent starting and frequent commutation.

Axial plunger motor has high volumetric efficiency, large adjustment range, good low-speed stability, poor impact resistance, and high-pressure system with high common language requirements.