(1) Operation Overview The negative control signal pressure of the central bypass oil is operated in the following cases and controls the discharge of the pump.
1 There is no empty stop state.
2 The pilot joystick does not operate.
The hydraulic oil of the pump PL flows into the return line 9 through the centrally beside oil passage 3, channel 4 and pores 7 (in the thimble). Because the throttle of the hole is loaded. When the negative control signal pressure F1 passes through the negative circuit to the pump PL regulator, the pressure is transferred. The negative control signal controls the pump regulator to reduce the discharge of the pump P1.
The negative control overflow valve includes a thimble 2, a spring 3, and a housing. If the pressure of the channel reaches the force of the spring, the hydraulic oil segment of the central side bypass is increased, and the hydraulic oil of the passage is pushed into the oil return channel.
In the absence of load, the hydraulic oil flows through the channel, the holes and the oil return passage into the fuel tank. Thus, the pressure FL of the channel becomes maximum (Flu), since all discharge oils reduced by oil holes reduce the stroke of the pump PL, so that the tilt angle is minimized, so the emissions of the pump PL also minimize.
(2) Negative control of Hyundai excavator (with fine-tuning measurement)
With the negative control of fine-tuning measurement, if the leading control lever of the large arm is traduly operate, the pilot pressure XAB1 moves the arm-axis core to the left portion. Thus, the passage is partially opened, the central bypass tube is slightly closed, and the hydraulic oil is therefore diverted.
A portion flows through the oil hole through the channel, and the other flows into the parallel channel, the channel, and the throttle AB1. The channel flow is reduced by oil, and the pressure F of the passage is slightly lowered. When the pressure f is lowered, the emission flow of the pump P2 is increased. With the pilot control rod movement, the more traffic of the channel is turned off due to the movement of the spool, and then the flow rate of the centrally bypass tube is zero. The pressure of the passage is zero, and the amount of emissions of the pump P2 becomes larger.
Adjust the emissions of the pump through a micro-operated pilot lever to perform the precise movement of the brake.
The negative control working principle of the pump PL is also applied to the oil hole.
