A hydraulic motor that is one of the actuators of the hydraulic system is a hydraulic device that rotates the components of the drive unit. So how do you choose a hydraulic motor and what are the precautions during installation and use?
How to choose the hydraulic motor?
The four technical indicators commonly used in hydraulic motors are as follows:
1, traffic
- (1)The hydraulic oil is injected into the hydraulic motor. The injected hydraulic oil is measured by the “flow rate”, which is the volume of hydraulic oil injected into the motor for one minute, and the unit is “L/min”.
- (2)After the hydraulic oil is injected into the motor, it will flow out. Otherwise, the hydraulic oil will accumulate in the motor, which is to cause an explosion. In theory, the flow rate of the hydraulic oil injected into the motor and the flow from the hydraulic motor are equal.
- (3) flow rate and motor output shaft speed are related, they are proportional relationship, then we get another invisible parameter of the motor called displacement, that is, the hydraulic pressure injected or discharged when the motor rotates one revolution Oil volume in units of "ml/r".
- (4)The size of the hydraulic motor is measured by displacement, so the size of the motor refers to the displacement.
- (5) The flow rate of the hydraulic motor can be measured by the flow meter. Almost every hydraulic system is equipped with a flow meter to monitor the flow changes of the hydraulic system at any time.
How to choose the hydraulic motor? 6 precautions must be known during installation and use
2, pressure
- (1) After the hydraulic oil is injected, the motor should be driven to rotate, so the hydraulic oil needs a certain pressure, that is, a force is required to drive the hydraulic motor to rotate. This driving force is pressure. Their unit is not “N” but “MPa”. This is a pressure unit, but in hydraulic pressure the pressure is usually called pressure.
- (2) The hydraulic motor pressure is determined by the load and is not generated by the motor.
- (3) The rated pressure of the motor is the allowable pressure value when the motor is running continuously.
- (4) The pressure is measured by a pressure gauge. The range of the pressure gauge is selected according to the maximum pressure of the hydraulic system. It is better to reserve a few pressure gauge interfaces when designing the hydraulic system so as to monitor the pressure change of the system at any time.
3, the speed
- 1 The speed of the hydraulic motor is a parameter to measure the rotation speed of the motor output shaft, which is generally determined by the customer according to the operating speed of the equipment.
- 2 The classification of hydraulic motors is defined by the speed, divided into high-speed motors and low-speed motors. High-speed motors are generally more than 500 rpm, and low-speed motors are rpm below 500 rpm.
- 3 Hydraulic motors generally have a minimum stable speed. Below this value, the motor will crawl.
4, torque
- 1 The output shaft of the motor is to drive the mechanical parts to rotate. Therefore, the motor must have a certain driving force to drive the mechanical parts. What is the parameter to measure the driving force of the motor? "Torque", the unit "Nm" Is the force acting on a force arm of a certain length.
- 2 The amount of torque of the motor is determined by the load. How much torque is required to drive the load, how much torque the motor will provide. If the torque required by the load is too large, the motor will have a fixed load, and then the motor will come. Said to be overloaded.
- 3 Torque measurement is measured with a torque meter.
For a hydraulic motor, the energy generated by the hydraulic oil injected into the hydraulic motor and the energy generated by the output shaft of the motor are theoretically equal. This is the energy conservation of the motor, that is, the power input and output of the motor are equal. It can be expressed by the following formula: P hydraulic oil = P output shaft.
a, hydraulic oil power = flow X pressure
b, output shaft power = torque X angular velocity
c, flow X pressure = torque X angular velocity
After calculation, the flow X pressure = torque X2πX speed
As can be seen from the above formula, as long as any three parameters are known, the size of the other parameter can be obtained. The selection of the motor is calculated by this formula.
6 precautions must be paid attention to during motor installation and use
Precautions when installing hydraulic motor
As one of the actuators of the hydraulic system, the hydraulic motor is particularly important in practical use. But what should you pay attention to during the installation process? The drive shaft of the hydraulic motor must be concentric or flexible with other mechanical connections. For more information, please refer to the following steps:
1. The bearing of the hydraulic motor is subject to the radial force. For motors that cannot bear the radial force, the transmission parts such as the pulley should not be directly mounted on the main shaft.
The drive sprocket is driven by a hydraulic motor and the passive sprocket drives the conveyor belt roller. According to the user's report, the motor often leaked oil, and the seal was replaced after less than 3 months. What causes the oil leakage? The hydraulic motor drives the pulley through the chain drive. Because the chain drive also generates radial force, the oil seal is deformed by the radial force, resulting in oil leakage.
2, hydraulic motor chain drive
- (1)The motor leakage pipe should be unblocked. Generally, the back pressure is not connected. When the leakage pipe is too long or the back pressure is required due to some need, the size should not exceed the value allowed by the low pressure seal.
- (2) The external leakage oil should ensure that the motor casing is filled with oil to prevent all the oil in the casing from flowing back to the tank when the machine is stopped.
- (3) For motors with long downtime, they cannot be directly loaded with full load, and should be used after a period of operation.
3. The frame of the motor must have sufficient rigidity.
- (1) The bracket and the base of the motor must be rigid enough to withstand the reaction force of the motor when outputting torque.
- (2) Insufficient rigidity of the frame of the mounting motor will cause vibration or deformation, and even an accident will occur, and the concentricity of the connection between the driver and the motor shaft cannot be guaranteed to be within 0.1 mm.
4. Hydraulic motor and gearbox should not be used together.
- (1) One of the characteristics of the hydraulic transmission is that the power-to-weight ratio is large, and in general, the hydraulic motor circuit itself can perform the usual speed regulation and shifting functions.
- (2) If the hydraulic motor is used together with the gearbox, the hydraulic control is lost, and the volume and cost of the device are significantly increased.
5. The drain port of the hydraulic motor should be returned to the tank separately.
- (1) Although from the general concept, all the oil return pressure is not high, but the return oil in many hydraulic systems still has a certain pressure, and the hydraulic motor's drain chamber is not allowed to have pressure.
- (2) The inside of the drain port of the hydraulic motor is connected to the housing cavity. The shaft seal of the motor shaft only acts as a seal and is not resistant to pressure. If this port is connected with other oil return lines, it will easily cause damage to the motor shaft seal, resulting in oil leakage. Therefore, it is not allowed to connect the drain port of the hydraulic motor and other oil return lines.
6, the hydraulic motor should not enter the air
- (1) In the initial operation of the hydraulic system, it is inevitable that air will be contained in the piping of the system.
- (2) An important part of system commissioning is to exhaust the air in the system, which is especially important for hydraulic motors.
- (3) The hydraulic medium has a process in the motor that suddenly changes from high pressure to low pressure, and the process frequency is high, averaging about 10 times per revolution.
- (4) When the hydraulic oil entering the motor contains air, it will locally cause cavitation at the sudden change of pressure, causing the motor to be damaged quickly.
The above hydraulic motor technology you have mastered, you will know no matter which brand, as long as the technical requirements work needs to be achieved, the hydraulic motor is the same.