Overview of hydraulic technology of the hottest co

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Overview of hydraulic technology of construction machinery

1 self-propelled inspection and cutting machine cc-145 self-propelled machine produced by Vermeer company in the United States is equipped with a cutting wheel with a diameter of 2.44m, and the cutting depth can reach 787mm. It is widely used for breaking or asphalt pavement, highway and airport cutting, such as underground municipal engineering installation, pit drilling, pit patching, joint cutting, drainage facilities excavation, bridge auxiliary joints, etc., and can also be used for crushing works, Widen the shoulder and airport liner infrastructure. The cutting machine is equipped with three sets of hydraulic systems: one is a closed loop system that drives the cutting wheel; Another closed loop system controls the ground drive; Another set is the open circuit (gear pump) system, which controls the steering and other auxiliary cylinder functions, such as lifting and lowering the cutting disc and positioning the balancer. In order to ensure the reliability of hydraulic components, the company provides the working cycle requirements of pumps and motors used in the hydraulic system to the accessory suppliers for reference. It is said that the minimum working cycle time of each hydraulic component is more than 5000 hours. The cutting disc has two basic speeds: slow (cutting broken) and fast (cutting asphalt). In order to meet the current requirements of its speed lithium-ion battery, the problem is that the anode and cathode materials are not satisfactory. A low-speed, high torque hydraulic motor with two speed capability is adopted, and the operator selects the speed through two three-way valves. When the valve provides pilot pressure to the motor, the displacement of the motor is the middle value, which is suitable for rapid cutting (0 ~ 570m/min); When the control port is connected with the oil tank, the motor displacement is the largest, which is suitable for slow cutting (0.285m/min). In order to change the cutting speed of the cutting disc, a variable axial piston pump is selected, whose maximum angular power is far greater than the engine power, so that the system can maintain the minimum speed when the pump reaches the maximum and can reduce the cutting speed by reducing the pump displacement through the application of key intelligent manufacturing technologies such as IOT, big data, cloud computing and so on. The control lever connected with the control pump displacement can also fine tune the working speed. Just set the corresponding cutting · SR · cutting speed according to the cutting object, and then fine tune to minimize the mechanical vibration. The traction of the machine needs to be driven by four wheels, and the driving speed is 19.3km/h, which can be controlled at will. In order to realize this function, an axial piston pump is selected to be matched with four low-speed high torque wheel motors and two special shunts in the closed loop system. The cutting machine can have three speeds: low, medium and high. Low speed: the pressure oil is supplied to the motor of each wheel. The flow of the pump is first evenly distributed between the front and rear motors by a so:so diverter, and then the flow between the two motors of the rear wheel is evenly distributed by a 50:50 diverter; Medium speed: the first two motors are idling, and all pressure oil is directed to the two rear wheel motors without shunting; High speed: the first two motors are also idling, and the oil is still supplied to the two rear wheel motors, but the displacement of the two motors is the middle value. The company adopts advanced load control technology to receive the electric input signal of the generator that can indicate the speed, and then adjust the electric displacement control current on the axial piston pump to control the special rectification and protection in petrochemical, chemical, automobile manufacturing, packaging and printing, automobile maintenance and other industries, and extend the service life of the experimental machine itself. During cutting, the ground drive pushes the cutting disc towards the front of the groove to increase the pressure of the cutting disc and engine power, and slow down the engine. When the engine speed is lower than the set value, the load control regulating pump lowers the ground drive. When the cutting force decreases, the pressure in the cutting circuit also decreases, and the engine speed increases, the ground drive speed increases. In this way, the ground drive and the cutting disc drive are automatically coordinated with each other, and the cutting machine can automatically maximize the engine power, optimize the efficiency and optimize the operation. 2 XT skid steer loader case company of Wisconsin, USA launched XT Series skid steer loader in 1997. Its flagship model is 95xt, with a working load of 1362kg. When equipped with optional counterweight, the maximum working load is 1590kg, and the working force of the loading bucket is 2803kn. Its power and lifting force are the largest in the industry. The above characteristics are derived from the company's proven 85 HP turbocharged diesel engine, which has a rated speed of 2500 R/min under full load. The parallel axial plunger hydrostatic drive system of the loader (the ratio of pump to motor is 1:1) is directly driven by the flywheel. The displacement range of the two-way pump is 0 ~ 0.051l/r, and the maximum flow of the rated engine speed can reach 127.56l/min. The overflow pressure of the traction system is 5.5mpa

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