Design of hydraulic system of the hottest YWB230 s

Design of the hydraulic system of YWB230 stabilized soil mixer

Abstract: This paper briefly introduces the basic composition and design method of the hydraulic system of YWB230 stabilized soil mixer, and briefly analyzes the characteristics of the system

key words: mixer walking pump working device rotor motor, steering gear, lifting cylinder

4, introduction to yvvb230 mixer without vibration in the environment

YWB230 full hydraulic stabilized soil mixer designed and produced by our factory is a wheeled self-propelled stabilized soil mixer that can effectively extend the endurance mileage of electric vehicles. It is mainly used for on-site mixing of stabilized soil in the base course and base course of highways, urban roads, squares, wharves and other projects; It is also applicable to the construction of rural and low-grade roads. It can mix grade I and II soil and stable materials (such as lime, cement cinder ash, waste steel slag). It is allowed to add stones with a particle size of less than 40mm into the mixing materials; It can also mix grade III and IV soil or stable materials

the working requirements of the mixer are: when walking, the rotor descends, and the rotor motor performs reverse rotation mixing operation. When stopping, the rotor lifts, the rotor motor stops, and the steering is free when walking: these actions are all hydraulic control, that is, hydraulic control of walking, steering, mixing operation, rotor lifting and lowering, and tailgate opening and closing

2 principle design and characteristics of hydraulic system

according to the requirements of mixer operation and referring to foreign advanced models, a hydraulic system including four main parts is designed. See Figure 1 for the schematic diagram of hydraulic system

2.1 traveling system

the traveling speed of the mixer during operation has a certain relationship with the rotating speed of the mixing rotor. Fast traveling speed requires fast rotating speed of the rotor. At the same time, the rotor reverse mixing operation also requires large traction. This machine adopts two sets of independent hydraulic drive systems: walking and working rotors. At the same time, a pressure limiter (POR) connecting the high-pressure oil circuit of the rotor system is added to the control valve of the walking pump. When the load increases to the set value, the pressure limiter controls the flow of the walking pump to gradually decrease, and the walking speed will gradually decrease; When the load decreases, the flow of the travel pump will increase and the travel speed will increase until the original set speed is restored. This characteristic of the system enables the mixer to overcome the overload by automatically reducing the walking speed, and automatically return to the original walking speed after the overload disappears. During this period, there is no need for driver intervention, which reduces the driver's operation intensity and improves the work efficiency. The automatic control ability of walking speed enables the mixer to adapt to different mixing conditions. In the case of overload, reduce the walking speed, that is, reduce the walking power, so as to ensure that the mixing power increases the strain at a certain point of an elastic element ε It is directly proportional to the force on the elastic element, which is the automatic matching of the whole machine power. After actual measurement, it is found that there is a relationship between the displacement of the walking pump and the displacement of the working pump, as shown in Figure 2. The relationship between the displacement of the walking pump and the displacement of the working pump without por is shown in Figure 3

in addition, the forward and backward of the mixer are controlled by the forward and reverse oil supply of the walking plunger pump. The travel speed is controlled by the manual valve to change the displacement of the pump by controlling the inclination of the swashplate of the travel pump, so as to change the speed of the travel speed. Two safety valves are installed on the motor circuit, which can prevent the working pressure of the circuit from overload when the mixer moves forward and backward, that is, overflow when the pressure exceeds 34mpa. A three position three-way hydraulic spool valve is also installed on the motor circuit. Under the pressure difference of the high and low pressure pipeline, the pressure oil control spool valve is connected to the oil return tank. The function of slide valve is to replace the hot oil system; Flush the motor and pump circuit, acting as the flushing circuit; The minimum pressure of the control system is 1.4mpa

the advantage of this design is that with the progress of science and technology:

(1) when encountering hard soil during mixing, the working pressure increases, this signal is transmitted to the por input port, and the displacement of the walking pump decreases, so that the total power is controlled within a certain range

(2) the machine works smoothly in the mixing process

(3) reduce the labor intensity of operators

2.2 working device

the working device circuit adopts a closed circuit composed of two working pumps, two rotor motors and valve blocks. The two motors drive the mixing rotor to work at the same time. Since the pressure oil output by the two working pumps cannot be exactly the same, the output high-pressure oil of the two pumps is first combined in the manifold block and then divided into two circuits, so as to balance the power required by the motors at both ends. The working pump used here is set as one-way oil supply to meet the requirements of one-way reverse mixing of rotor motor. The motor is a low-speed axial motor with high torque. It has high starting efficiency, large starting torque and stable operation

an accumulator and a check valve are installed in the low-pressure area of the circuit, which can make the system always full of oil, reduce the pressure fluctuation of the circuit and reduce vibration. And when the oil pump stops supplying oil, it replenishes oil into the motor oil circuit due to the existence of moment of inertia

2.3 hydraulic steering

the steering return circuit is composed of duplex gear pump, one-way stable diverter valve, hydraulic steering gear, steering hydraulic cylinder and other components

the oil output by the gear pump reaches the one-way stable shunt valve, which divides into three oil circuits: one is the stable flow oil circuit to the steering gear; One way into the multi-channel directional valve; The other way is overflow oil way. Since the oil flow to the steering gear is stable, this can ensure that the steering system can meet the steering performance requirements of the main engine when the oil supply of the hydraulic pump and the system load change

the steering gear bzzl-200 is a follow-up valve, which operates the steering wheel to drive the steering gear valve core to turn an angle. The pressure oil enters the rotary valve, enters the feedback motor from the rotary valve, and finally enters the steering cylinder. When the pressure passes, the feedback motor rotates and drives the valve seat to rotate until the rotary valve is in the middle

2.4 hydraulic control

this system is used to operate the lifting cylinder to drive the mixing rotor to lift and lower, and operate the tailgate hydraulic cylinder to drive the tailgate to open and close. The action is completed by the multi-channel directional valve. A two-way hydraulic lock is installed on the lifting circuit. When the multi-way valve is in the middle position, no matter where the working device is, the hydraulic lock can lock the hydraulic cylinder to ensure that the mixing depth remains unchanged

here, discuss the difference between the return port of the overflow valve and the front and back of the one-way throttle valve when the working rotor descends

as shown in Figure 4, the one-way throttle valve of this circuit plays the role of oil return throttling, which can reduce the falling speed of the working rotor and reduce the impact. According to the design requirements, when the hydraulic cylinder descends, it is required that there is less oil into the small chamber to reduce the speed. In this way, part of the pressure oil will overflow from the overflow valve. If the return oil of the overflow valve is connected to the P section, due to the throttling loss, the pressure P section is higher than P at this time, causing P2 to rise with the increase of back pressure, which will increase the power loss and heat the system. Therefore, it is best to connect the return oil of the overflow valve at P, which will reduce power loss and heating, improve system performance and reduce the occurrence of faults

3 selection of components and oil

in the hydraulic system of the mixer, not only slide valves but also cartridge valves are used. Both slide valves and cartridge valves are installed with valve blocks, which makes the whole hydraulic system compact, easy to maintain, reduces leakage, and improves the reliability of the hydraulic system

in the selection of hydraulic components, we pay attention to the performance of components and product brands, such as the axial piston pump of Sauer company and the seals of Parker company, so as to improve the reliability of the whole machine. In the design of hydraulic system, the selection of working medium is also very important. It has a direct impact on prolonging the service life of components, improving the reliability of the system and saving energy. Considering the use requirements of the mixer, hm-n68 anti-wear hydraulic oil is selected. And a cooler is set in the circuit to prevent the oil temperature from being too high, so as to prolong the service life of the oil

the practical application shows that the hydraulic system meets the performance requirements of the whole machine and works reliably. It has been put into mass production and has been highly praised by users. (end)