Views: 268 Author: Site Editor Publish Time: 2021-05-19 Origin: Site
The control method of variable pumps in automatic transmission hydraulic system are divided into power control, full power control, and cross power control.
Each of the two hydraulic pumps in the variable hydraulic power transmission system has an independent constant power regulator, and the flow of each hydraulic pump is only affected by the load pressure of the circuit where the hydraulic pump is located. The sub-power system simply combines two constant-power hydraulic pumps, and each hydraulic pump absorbs up to 50% of the diesel engine's rated power. And only when each hydraulic pump is working within the rated power and maximum power can the full power be used. Since the load pressure in each circuit is generally not equal, the output flow of the hydraulic pump is not equal. The advantage of this hydraulic transmission system is that the flow of the two hydraulic pumps can be individually changed according to the load of their respective circuits, and the adaptability to the load is better than that of a full-power system. The disadvantage is that each hydraulic pump can only absorb 50% of the power of the diesel engine, and when one of the hydraulic pumps is working under the starting pressure, the other hydraulic pump cannot absorb the spare power of the diesel engine. The power is not fully utilized, which limits the working capacity of the excavator. Therefore, this system is basically eliminated on large and medium-sized excavators abroad.
In the full power variable system, there are two forms of power adjustment of the hydraulic pump in hydraulic power transmission system. One is that the two hydraulic pumps share a power regulator, and half of the sum of the working pressures of the two hydraulic pumps is applied to the regulator through the pressure balancer to realize the common variable of the two pumps. The other is two hydraulic pumps equipped with a regulator, and the two regulators are hydraulically linked. The pressure oil of the two hydraulic pumps is respectively passed into the annular cavity of the pump regulator and the small end cavity of the other hydraulic pump regulator to achieve hydraulic linkage. The area of the cavity is equal to the area of the circular cavity, and the pressure of each hydraulic pump has the same pushing effect on the regulator, so that the swash angle of the two hydraulic pumps are equal, and the output flow is equal. The two specifications can be executed at the same time. Institutions maintain a synchronized relationship. There are three advantages. First, it can make full use of diesel engine power under certain conditions. Second, each of the two hydraulic pumps can absorb the full power of the diesel engine, which improves the working capacity of the working device. Third, the structure is simple. Due to the above characteristics, the full-power variable pump hydraulic system has been widely used in excavators.
In principle, the cross power control is a full power adjustment in hydraulic mechanical transmission system. The difference from the full power control is that the displacement of the two hydraulic pumps can be different. Through the cross-connection configuration, the working pressures of the two hydraulic pumps interact with each other's regulator, and the output flow of each hydraulic pump is not only related to its own outlet pressure, but also related to the outlet pressure of the other hydraulic pump. If one hydraulic pump does not work or works with less than 50% of the total drive power, the second hydraulic pump automatically uses the remaining power, and in extreme cases can reach 100% of the total drive power. Cross power control not only has the ability to adjust the output of the hydraulic pump according to the load of each hydraulic pump, but also makes full use of the power of the diesel engine. At present, the cross power control does not work alone, but is combined with other control methods to limit the sum of the power of the double pumps.
Variable pumps are used in hydrostatic drive systems. Jazzy Industrial is a professional manufacturer of hydraulic components such as hydraulic hose fitting, hydraulic adapter, hydraulic quick release coupling, and hydraulic ball valve.
