Hydraulic vane motors are a common type of hydraulic motor. Because of its high efficiency, smooth operation, and strong reliability, it is widely used in many industrial machinery and equipment. This article will show you the components and working principles of hydraulic vane motors, and will also teach you how to choose the most suitable hydraulic vane motor for your needs. Whether you are an engineer or a purchasing specialist who wants to learn about hydraulic components, you will find useful information here.
What is a Hydraulic Vane Motor
A hydraulic vane motor is a hydraulic motor that drives the rotation of vanes by applying pressure to a fluid.
Components of Hydraulic Vane Motors
To understand how the hydraulic vane motors work, you should understand their components and the function of each component. A hydraulic vane motor consists of a housing, end caps, vanes, rotor, and shaft. The function of each component is as follows:
Housing
The housing is the basic structure of hydraulic vane motors. Its main function is to contain the hydraulic fluid and protect other components inside the motor. Its size also determines parameters such as the motor’s displacement and rotational speed.
Rotor
The rotor is the key component of hydraulic vane motors. Its interior features radial grooves that can accommodate blades and springs.
Blade
The blades are typically installed together with the springs in the radial slots of the rotor. It can press against the housing and the rotor, forming a sealed chamber with the inner wall of the casing.
End Cap
End caps are typically used together with seals. It is equipped with oil holes and oil passages. When in use, it ensures the smooth flow of hydraulic fluid without leakage, and when not in use, it provides a sealing function.
Axis
The shaft is an important component of hydraulic vane motors. It is usually connected to the rotor. It can support the rotation of the rotor and also transmit the torque of the rotor.
How does a Hydraulic Vane Motor Work?
After knowing the components of a hydraulic vane motor, you can then learn about its working principle. In this section, I will gradually explain the internal mechanisms and the details of hydraulic vane motors.
Fluid Entry
First, the hydraulic pump draws fluid from the tank and pumps it to the entrance of the hydraulic motor. The hydraulic pump applies pressure to the fluid.
Leaves Unfolding
After entering the motor, the fluid applies a radial force on the blades and pushes them forward. At the same time, the springs in the groove apply an axial force to the blades, pushing them outwards and keeping them tightly against the inner wall of the housing.
Forming a Chamber
Because the blades always remain in close contact with the inner wall of the casing as they extend outwards, a sealed chamber is formed between two adjacent blades, the rotor, and the inner wall of the casing.
Create a Pressure Differential
Because the rotor is eccentrically mounted relative to the housing, meaning its center and the center of the housing are not at the same location, the distance between the rotor and the inner wall of the casing will change when the rotor rotates. The volume of the chamber also increases on the inlet side and decreases on the outlet side, thus generating a pressure differential.
Generate Torque
Because the size and pressure of the intake chamber are higher than those of the exhaust chamber, a net force is generated between the blades. This force drives the rotor to rotate.
Rotor Rotation and Blade Sliding
Because the blades need to slide continuously during the rotation of the rotor, although the blades must be in close contact with the inner wall of the casing, the friction cannot be too great, otherwise it will cause wear on the blades. Therefore, radial grooves are usually provided on the side where the blade contacts the inner wall of the casing to balance hydraulic pressure.
Fluid Discharge
After the fluid passes through the inlet and chamber and completes its function of driving the blades, it is expelled through the outlet of the casing as the chamber contracts, and then enters the fluid storage container.
Endlessly Repeating
The above describes the complete process of one full rotation of the rotor. Of course, the hydraulic vane pump continuously draws fluid during operation and delivers it to the motor, providing the power for its continuous operation. During this process, the centrifugal force generated by the rotating rotor makes the blades press more tightly against the inner wall of the casing, and the chamber will have better sealing performance. The reduced inertia of the rotor also decreases the force required to rotate it, further reducing energy consumption.
Technical Parameters and Purchasing Advice for Hydraulic Vane Motors
The performance characteristics of a hydraulic vane motor determine its behavior during operation. So if you want to buy a suitable hydraulic vane motor, you should understand its performance characteristics so that you can make an informed decision when buying. Below, I will explain the technical parameters of hydraulic vane motors and teach you how to select the right hydraulic vane motor.
Displacement Per Revolution
Displacement per revolution refers to the volume of fluid required to rotate the output shaft by one revolution, and its unit is cm³/rev. Its typical range is 20 to 500 cm³/rev. If you need to rotate a heavy load, you should choose a high-power motor. If the load you need to rotate is relatively light, then you can choose a motor with a smaller displacement. It’s important to note that for hydraulic vane motors, the larger the displacement, the slower the rotational speed.
Work Pressure
Working pressure means the pressure that the motor withstands continuously under normal/rated operating conditions, and is measured in MPa or bar. Its typical range is 7 to 14 MPa. You should be sure to check whether the pressure rating refers to the rated working pressure or the maximum working pressure when buying, and do not confuse the two. If the system’s rated operating pressure approaches or exceeds 16 MPa, you should not consider vane motors, but instead choose piston motors. This is because vane motors experience reduced lifespan and reliability at higher pressures.
Rotational Speed
Rotational speed refers to the speed at which the motor rotates per minute, and it is measured in revolutions per minute (rpm). The rotational speed of typical industrial hydraulic vane motors ranges from 100 to 2000 rpm. If your system needs frequent starting and stopping or forward and reverse rotation, then you need to care about the starting torque and whether its thermal management system is effective. Because the fluid temperature increases with higher motor speeds, it needs a cooling system. Additionally, when the motor is running, do not exceed 70–90% of the rated speed to prevent safety accidents.
Torque
Torque is the force that the motor’s output shaft can provide. and its unit is Newton-meter (N·m). The torque of the hydraulic vane motor ranges from 10 to 500 N·m. When purchasing, you should select a suitable hydraulic vane motor based on your load weight. Larger loads require higher torque to start and maintain operation. Also, you should care about the difference between starting torque and rated torque, and do not confuse the two.
Efficiency
It is mainly divided into mechanical efficiency and volumetric efficiency. Volumetric efficiency is the percentage of the actual flow rate available for doing work in a hydraulic motor compared to the theoretical flow rate. It shows the amount of internal leakage and affects the rotational speed and accuracy. Mechanical efficiency is the percentage of actual work done compared to the theoretical work done, indicating the amount of friction loss and affecting the output torque and heat generation. You should ask the seller to provide efficiency curves at different pressures and rotational speeds when buying. If your system is sensitive to accuracy or power consumption, you should choose a model with high volumetric efficiency.
FAQ
Are hydraulic vane motors only suitable for light loads?
No. Modern hydraulic vane motors employ efficient chamber structures and differential pressure designs, so they can provide considerable torque under smooth operating conditions.
Do hydraulic vane motors produce significant vibration or noise?
No. Hydraulic vane motors have a sliding vane design, so they operate more smoothly, with less fluctuation, and are more stable and quieter than many gear and piston motors.
Is internal leakage in a hydraulic vane motor always an indication of a malfunction or wear?
No. It is perfectly normal for there to be some internal leakage in a hydraulic vane motor. Authoritative data shows that the normal internal leakage rate of hydraulic vane motors is approximately 1% to 2% of the total flow rate. Some of the leakage can be used to lubricate the blades and the inner wall of the casing. Therefore, this is not a malfunction. Only excessive leakage would indicate a malfunction.
Do hydraulic vane motors require a high degree of fluid cleanliness?
Yes. Because the blades need to remain in constant contact with the inner wall of the casing, the tolerances only allow for the passage of pure liquid. If solid impurities are present, the blades will wear out quickly, and the fluid will leak rapidly.
Does a hydraulic vane motor require pre-lubrication with fluid before starting?
Yes. If the hydraulic vane motor is not lubricated with fluid before starting, the friction between the vanes and the inner wall of the casing will be very high, which can easily lead to vane wear.
Can a hydraulic vane motor reverse the direction of fluid flow?
Yes, that’s possible. Hydraulic vane motors use a symmetrical structure, so the inlet and outlet can be interchanged. If you inject the fluid from the opposite direction, the motor’s direction of rotation will also be reversed accordingly.
Final Thought
Now, maybe you have understood the working principle of hydraulic vane motors, are familiar with their key parameters, and understand the precautionary measures that need to be taken during the operation. If you can fully use it in both purchasing and usage, it will certainly perform at its best within your system.
If you are looking to equip your system with a hydraulic vane motor or are evaluating various solutions, Target Hydraulics is ready to assist you. We are a Chinese supplier of hydraulic components with 10 years of experience in manufacturing and selling hydraulic parts. Please feel free to contact us. We will help you evaluate your requirements for displacement, torque, and speed, recommend or design a hydraulic vane motor that meets your needs, provide technical support about installation and connection, and assist you in developing a maintenance plan to maximize the motor’s service life.
