Double-wheel vibratory roller hydraulic system is the core of the working device, its stability and reliability has always been the design of the key and difficult. Vibration and hydraulic system to start and stop, stop the vibration process is a process of acceleration and deceleration, if the start-up, stop vibration speed too fast, will cause start-up, vibration acceleration is too large, the vibration of the hydraulic system to produce a very large impact load, resulting in The reliability of the system components is deteriorated and the service life is shortened. Machine in the process of vibration, the inertial force will drag the engine, making the engine speed instantaneous increase, and thus the engine reliability and service life disadvantage. Therefore, in the design of vibratory roller hydraulic system, we must consider the impact of start-up and stop vibration on the quality of compaction and the impact of impact load on the reliability of the machine.
Improve the lack of vibration before the hydraulic system
In the dynamic test of the vibrating hydraulic system of a double-roller vibrating roller of the Company, we found that the starting time was only 0.9 s during the start-up process, and the maximum working pressure of the vibration hydraulic system was about 34 MPa, The system vibration pump and vibration motor rated working pressure 23 MPa. In the process of vibration, the vibration motor continues to rotate due to inertia, the pipeline produces negative pressure, vibration hydraulic system there is the phenomenon of suction.
This type of double drum vibratory roller hydraulic system shown in Figure 1. It is mainly composed of vibration pump (not shown), start-up solenoid valve, logic combination valve and vibration motor. When the pressure oil from the P port to enter, by the opening and closing of the solenoid valve to open and close to achieve start or stop vibration. As the start-up solenoid valve action time is very short, resulting in vibration system response speed, the system impact is very large.
When the start-up, the start-up solenoid valve power, vibration pump pressure oil from the P port to enter. Because the vibration resistance at the vibrating motor is much smaller than that of the start-up solenoid valve and the logic combination valve, a large amount of the pressure oil passes through the vibration motor under the action of the vibration pump, so that the vibration system can start and start immediately. When the vibration is stopped, the start-up solenoid valve is de-energized, because the logic combination valve opening pressure is greater than the opening pressure of the start-up solenoid valve, so the pressure pump produces the pressure oil is not through the logic combination valve (also known as the cone valve) But through the solenoid valve back to the T port. At this time, the flow rate of the vibrating solenoid valve is very small, the throttle phenomenon is very obvious, the system is very hot.