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Views: 0 Author: Site Editor Publish Time: 2024-12-06 Origin: Site
The hydraulic motor is an executive element of the hydraulic system, which converts the liquid pressure energy provided by the hydraulic pump into the mechanical energy (torque and speed) of its output shaft. Liquids are the medium through which force and motion are transmitted.
Hydraulic motors, also known as oil motors, are mainly used in injection molding machinery, ships, lifting machines, engineering machinery, construction machinery, coal mining machinery, mining machinery, metallurgical machinery, Marine machinery, petrochemical industry, port machinery and so on.
Hydraulic motors, also known as oil motors, are mainly used in injection molding machinery, ships, lifting machines, engineering machinery, construction machinery, coal mining machinery, mining machinery, metallurgical machinery, Marine machinery, petrochemical industry, port machinery, etc.
High-speed motor gear motor has the advantages of small size, light weight, simple structure, good process, insensitive to oil pollution, impact resistance and small inertia. Disadvantages include large torque pulsation, low efficiency, small starting torque (only 60% - 70% of rated torque) and low speed stability.
From the point of view of energy conversion, hydraulic pump and hydraulic motor are reversible hydraulic components, and the input of working liquid to any hydraulic pump can make it become a hydraulic motor condition; On the contrary, when the main shaft of the hydraulic motor is driven by the external torque, it can also be changed into the hydraulic pump condition. Because they have the same basic structural elements - a closed and periodic volume and the corresponding oil distribution mechanism. However, due to the different working conditions of hydraulic motors and hydraulic pumps, their performance requirements are not the same, so there are still many differences between the same type of hydraulic motors and hydraulic pumps. First of all, the hydraulic motor should be able to be positive and reverse, so it requires its internal structure to be symmetrical; The speed range of the hydraulic motor needs to be large enough, especially its minimum stable speed has certain requirements. Therefore, it usually uses rolling bearings or static plain bearings; Secondly, because the hydraulic motor works under the input pressure oil condition, it does not need to have the self-priming ability, but it needs a certain initial sealing to provide the necessary starting torque. Because of these differences, the hydraulic motor and the hydraulic pump are relatively similar in structure, but they cannot work reversibly.
Due to the action of pressure oil, the force imbalance causes the rotor to produce torque. The output torque of the vane hydraulic motor is related to the pressure difference between the displacement of the hydraulic motor and the inlet and outlet of the hydraulic motor, and its speed is determined by the flow of the input hydraulic motor. Since hydraulic motors generally require positive and negative rotation, the blades of vane hydraulic motors should be placed radially. In order to make the blade root always have pressure oil, a check valve should be set on the path that the return and pressure oil cavities pass into the blade root. In order to ensure that the vane hydraulic motor can start normally after the pressure oil is passed, the top of the blade must be in close contact with the inner surface of the stator to ensure a good seal, so the pre-loaded spring should be set at the blade root. The vane type hydraulic motor has the advantages of small volume, small moment of inertia and sensitive action, and can be applied to the occasions with high commutation frequency. However, the leakage is large and it is unstable at low speed. Therefore, vane hydraulic motors are generally used for occasions with high speed, small
torque and sensitive action requirements.
The working principle of the radial plunger hydraulic motor is that when the pressure oil enters the bottom of the plunger inside the cylinder block through the window of the fixed oil distribution shaft 4, the plunger extends outward and tightly holds the inner wall of the stator, because the stator and the cylinder block have an eccentricity. At the contact between the plunger and the stator, the reaction force of the stator on the plunger is. The force can be divided into two components. When the oil pressure acting on the bottom of the plunger is p, the plunger diameter is d, and the Angle between the force and is X, the force produces a torque on the cylinder block, making the cylinder block rotate. The cylinder block then outputs torque and speed outward through a drive shaft connected to the end face. In the case of torque generated by a plunger analyzed above, because there are several plungers acting in the oil pressure area, the torque generated on these plungers all causes the cylinder block to rotate and output torque. Radial piston hydraulic motor is mostly used for low speed and large
The working principle diagram of the single acting connecting rod type radial piston motor is shown in the connecting rod motor diagram, the shaft distribution hydraulic motor diagram, and the assembly animation of the Pentagon radial motor, whose appearance is like a five-pointed star. The motor is composed of a shell , a crankshaft , a distribution shaft , a connecting rod , a plunger , and a eccentric wheel . Advantages: Simple structure, reliable work. Disadvantages: large volume, large weight, torque pulsation, low speed stability is poor.
The motor is composed of a valve shaft , a cylinder block , a plunger , a beam , a roller , a stator and an output shaft . The displacement of this motor is twice as large as that of a single-stroke motor. That's equivalent to 21 plungers. As the number of equivalent plungers increases, the output torque increases correspondingly and the torque pulsation rate decreases under the same working pressure. Sometimes this motor is made into multiple rows of plungers, the number of plungers is more, the output torque is further increased, and the torque pulsation rate is further reduced. Therefore, this motor can be made to have a large displacement and can run smoothly at a very low speed. Since the motor needs to rotate in both directions, the blade slots are arranged in a radial manner.
The plunger type high-speed hydraulic motor is generally axial.
In addition to the valve type flow distribution, other forms of axial piston pump can be used as a hydraulic motor in principle, that is, the axial piston pump and the axial piston motor are reversible. The working principle of the axial piston motor is that the oil distribution plate and the swash plate are fixed, and the motor shaft is connected with the cylinder block to rotate together. When the pressure oil enters the plunger hole of the cylinder block through the window of the oil distribution pan, the plunger extends under the action of the pressure oil and is close to the swash plate. The swash plate generates a normal reaction force p on the plunger, which can be decomposed into axial force and vertical force Q. Q is balanced with the fluid pressure on the plunger, and Q causes the plunger to generate a torque to the center of the cylinder, driving the motor shaft to rotate counterclockwise. The instantaneous total torque produced by the axial piston motor is pulsating. If the motor pressure oil input direction is changed, the motor shaft rotates in a clockwise direction. The change of swash plate inclination a, that is, the change of displacement, not only affects the torque of the motor, but also affects its speed and steering. The larger the tilt Angle of the swash plate, the larger the torque and the lower the speed.
In order to meet the requirements of positive and negative rotation, the oil inlet and outlet of the gear motor are equal, symmetrical and have a separate oil outlet, which leads the oil leakage of the bearing part out of the housing; In order to reduce the starting friction torque, using rolling bearings; In order to reduce torque ripple, the number of teeth of the gear hydraulic motor is more than the number of teeth of the pump. The gear hydraulic motor has poor dry seal, low volumetric efficiency, and the input oil pressure can not be too high and can not produce large torque. And the instantaneous speed and torque change with the position of the mesh point, so the gear hydraulic motor is only suitable for high-speed and small torque occasions. Generally used in construction machinery, agricultural machinery and mechanical equipment with low torque uniformity requirements.
Motors with a rated speed higher than 500r/min are high-speed motors. The basic forms of high-speed motors are gear type, blade type and axial plunger type. Their main characteristics are high speed, small moment of inertia, easy to start, brake, speed regulation and commutation.
Hydraulic motors with a speed lower than 500r/min are low-speed hydraulic motors. Its basic form is radial plunger type. The main characteristics of low-speed hydraulic motor are: large displacement, large volume, low speed, can be directly connected with the working mechanism, do not need the deceleration device, so that the transmission mechanism is greatly simplified, the output torque of low-speed hydraulic motor is larger, up to thousands to tens of thousands of Nm, so it is also known as low-speed high-torque hydraulic motor.
Compared with other types of motors, the blade motor has the advantages of compact structure, small profile size, low noise, long life, etc. Its inertia is smaller than the plunger motor, but the anti-pollution ability is worse than the gear motor, and the speed can not be too high, generally working below 200r/min. Because of the large leakage, the blade motor is unstable when the load changes or the speed is low.
Hydraulic motor In the late 1850s, the first low-speed high-torque hydraulic motors were developed from a fixed rotor component of the oil pump, which consisted of an internal gear ring and a matching gear or rotor. The inner tooth ring is fixed and connected with the housing, and the oil entering from the oil port drives the rotor to revolve around a central point. This slowly rotating rotor is driven by a spline shaft and output into a cycloidal hydraulic motor. After the advent of this initial cycloidal motor, after several decades of evolution, another concept of the motor began to form. The motor has a roller mounted in a built-in ring of teeth. Motors with rollers provide high starting and running torque, rollers reduce friction and thus improve efficiency, and the output shaft produces a stable output even at very low speeds. By changing the direction of the input and output flow, the motor is quickly reversed and equal value of torque is generated in both directions. Each series of motors has a variety of displacement options to meet a variety of speed and torque requirements.
