The structure of A4VG series axial piston pump

A4VG series Swash plate type axial piston pump is a high-pressure, closed, swash plate axial piston pump, nominal pressure 400 bar, peak pressure 450 bar.
In addition to conventional piston cylinder plunger pumps and other main components, it also integrates a charge pump, fill the oil pressure relief valve, charge check valve, two high pressure relief valve, a pressure cut-off valve and variable institutions.
 
Displacement Controls
HD: hydraulic control variable, and control of stress-related
HW: hydraulic control, manual servo
Operating direction of the pump is proportional to the displacement of the control handle a or b to angle
DA: hydraulic control, and speed-related
DG: hydraulic control, direct control
EZ: two electric control, with switching solenoid
EP: Electrical control with proportional solenoid
Pump displacement with proportional solenoid (a and b) of the current was proportional.
Pressure shut-off valve
Maximum operating pressure limited system, when the swash plate back in its role, no longer export oil, reduce the relief valve opening time. Generally about 100ms work.
 
Pressure shut-off valve function: pressure shut-off valve consists of a shuttle valve and a relief valve outside the control of the composition, pressure cut off is actually a pressure regulator, when the pressure reaches the set value of the system pressure, the valve can pump Displacement is adjusted to near zero (only maintain the system leak small displacement). Pressure shut-off valve at the pump fast variable, preventing the high-pressure relief valve to open, thereby preventing the emergence of high-pressure systems often overflow, reducing system heat. Therefore necessary to set the pressure high pressure relief valve set pressure higher than the pressure cutoff value. Peak pressure and maximum system pressure occurs rapidly oscillating pump swash plate is determined by the high pressure relief valve.
 
A port is a high pressure pump state, since the upper part of the shuttle valve spool pressure lower than the lower pressure, the shuttle valve spigot B closed, the shuttle valve open spigot A high pressure oil from the mouth into the spool pusher A lower when A When the inlet pressure reaches the set value, the spool pusher in the role of high-pressure oil to push the relief valve spool, fill the oil pressure passage and pump housing passage communicates the control pressure variable cylinder unloading, to achieve pressure cut-off ʱ??


Way valve

Pump high pressure relief and charge check valve mounted on the pump as a whole, its structure diagram is shown below. Its main components have security hydraulic lever pilot valve spring, the pilot valve spool, the return spring, the relief valve spool and so on. The way valve has two functions, namely pressure overflow and check up the oil.

Used for relief

Maximum pressure peak limit system, open a short time, usually around 20ms to open overflow.
 
When the system is not the same as the pressure reaches the set value, the pilot valve spool can not overcome the spring force of the upward movement, the A and B pressure chamber pressure chamber, A chamber cavity area larger than B, the relief valve spool closed, the system does not overflow flow; When the system pressure reaches the set value, the pilot valve spool under high pressure, the upward movement against the spring force and the pressure chamber through the pilot valve A pressure relief valve body, and because the throttle chamber B core throttle the role of the B chamber pressure is greater than A chamber, relief valve spool is turned up, the system overflow.

Charge for one-way valve
Select the charge direction, one-way check valve in the relief work to the low pressure side fill oil.