Pure water hydraulic drive system of lifting platform

[0012] as attached figure 1 As shown, the pure water hydraulic drive system of the lifting platform of the present invention includes: filter 1, plunger pump 2, frequency conversion motor 3, overflow valve 4, first two-position two-way reversing valve 5, one-way valve 6, first Proportional valve 7, accumulator 8, second two-position two-way reversing valve 9, hydraulic control check valve 10, second proportional valve 11, three-position four-way reversing valve 12, hydraulic cylinder 13, water tank 14.

[0013] Among them, the variable frequency motor 3 is connected with the plunger pump 2 to drive the plunger pump 2 to work, and the water inlet T of the filter 1 1 Connected with the water tank 14, the water outlet P of the filter 1 1 With the suction port T of the plunger pump 2 2 Connected, outlet P of plunger pump 2 2 Inlet P with overflow valve 4 3 , the water inlet P of the first two-position two-way reversing valve 5 4 , Water inlet P of check valve 6 5 , the control water port K of the hydraulic control check valve 10 1 Connected, outlet T of overflow valve 4 3 , Outlet A of the first two-position two-way reversing valve 5 1 Connected with the water tank 14, the water outlet P of the one-way valve 6 3 With the water inlet P of the first proportional valve 7 7 , water port P of accumulator 8 8 , the water inlet P of the second two-position two-way reversing valve 9 9 Connected, outlet A of the second two-position two-way reversing valve 9 2 With the water inlet P of the hydraulic control check valve 10 10 Connected, the water outlet P of the hydraulic control check valve 10 11 Connected with the water tank 14, the water outlet A of the first proportional valve 7 3 With the water inlet P of the three-position four-way reversing valve 12 13 Connected, the first working water port A of the three-position four-way reversing valve 12 5 It communicates with the rodless cavity of the hydraulic cylinder 13, and the second working water port B of the three-position four-way reversing valve 12 1 In a blocked state, the water return port T of the three-position four-way reversing valve 12 4 With the water inlet P of the second proportional valve 11 12 connected, the water outlet A of the second proportional valve 11 4 It communicates with the water tank 14, and the hydraulic cylinder has a rod cavity that directly communicates with the water tank 14. .

[0014] Working process of the present invention is as follows:

[0015] In the initial state, the first two-position two-way reversing valve 5, the first proportional valve 7, the second two-position two-way reversing valve 9, the second proportional valve 11, and the three-position four-way reversing valve 12 are all powered off state, the hydraulic cylinder 13 is in a locked state, and the lifting platform is still at this moment. The pumping station system is powered on and starts to work. The pumping station system adopts the power source mode of single pump + frequency conversion speed regulation + overflow valve for water supply. At the same time, in order to improve the filtration accuracy and reduce system failures, filter is added at the pump suction port. First, the frequency conversion motor 3 starts to drive the plunger pump 2 to work, and the high-pressure water output by the plunger pump enters the interior of the accumulator through the one-way valve 6 to complete the flushing process of the accumulator. When the accumulator needs to be unloaded, the motor pump stops working, and the first two-position two-way reversing valve 5 is energized to complete the control of the water port K by the hydraulic control check valve 10 1 Here, the second two-position two-way reversing valve 9 is energized to work, and the high-pressure water in the accumulator flows back to the water tank through the second two-position two-way reversing valve 9 and the hydraulic control check valve 10 in turn. , to complete the unloading work of the accumulator.

[0016] Platform rising process: The pure water hydraulic drive system starts to work. The system uses a three-position four-way reversing valve and a normally closed proportional valve in the pure water hydraulic pressure to accurately control the movement speed of the piston rod of the hydraulic cylinder. The first proportional valve 7 and the left electromagnet of the three-position four-way reversing valve 12 are energized, and the high-pressure water output by the plunger pump passes through the one-way valve 6, the first proportional valve 7, and the three-position four-way reversing valve 12 to enter the hydraulic pressure. The rodless chamber of the hydraulic cylinder pushes the piston to move upward, and the water in the rod chamber of the hydraulic cylinder directly flows back to the water tank. The upward speed of the platform is adjusted through the first proportional valve 7 to meet the system design requirements.

[0017] The platform descending process: the platform descends by its own weight, the second proportional valve 11 and the right solenoid of the three-position four-way reversing valve 12 are energized, and the high-pressure water in the rodless chamber of the hydraulic cylinder begins to unload, and the three-position four-way reversing Valve 12, two second proportional valves 11 flow back to the water tank, and the piston descends under the action of gravity. The variation law and final speed of the descending speed of the piston are adjusted by the second proportional valve 11, which can ensure that the platform moves smoothly in the process of descending.