Hydraulic Pump Pressure Control via Dead Zone Filtering
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Solution Overview
Problem
Hydraulic pressure control devices in construction machines consume unnecessary energy due to sensitive reaction to minute hydraulic pressure changes, leading to inefficient engine speed maintenance and energy wastage, especially when low hydraulic flow rates are needed.
Innovation Solution
A hydraulic pressure control device with pressure difference operation means that allows manual adjustment of the pressure difference set value, enabling the controller to optimize electric power supply to the electric motor, thereby controlling the hydraulic pump's discharge pressure relative to the load pressure, allowing for efficient power usage and energy conservation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the hydraulic pump reacts sensitively to minute changes in hydraulic pressure to maintain constant pressure difference, then pressure control precision is improved, but hunting occurs causing system instability
Solution Approach 1:
A dead zone setting unit is introduced as an intermediary component that processes the pressure difference signal before it reaches the pump control. This dead zone filter prevents minute pressure fluctuations from triggering pump response, thereby eliminating hunting while maintaining adequate pressure control. The dead zone acts as a mediator between the pressure sensor and pump controller, blocking spurious signals.
2Power
If the engine speed is constantly maintained at set speed to ensure sufficient hydraulic power, then power availability is improved, but energy is consumed needlessly during low-demand operations
Solution Approach 1:
The engine speed control is changed from a static constant-speed mode to a dynamic variable-speed mode. The engine speed is now adjusted in real-time based on actual hydraulic demand signals from the pump control system. When hydraulic demand is low, engine speed is reduced accordingly, eliminating unnecessary energy consumption while ensuring sufficient power is available when demand increases.
Solution Approach 2:
A feedback control loop is established where the actual hydraulic pressure and flow demand are continuously monitored and fed back to the engine control system. This feedback mechanism allows the engine speed to be automatically adjusted according to real-time hydraulic requirements, preventing both power deficiency and excessive energy consumption.
3Stability of the object's composition
If the pressure difference set value is fixed to ensure stable pump operation, then operational stability is improved, but adaptability to different work conditions is reduced
Solution Approach 1:
The pressure difference set value is changed from a fixed constant to a dynamically adjustable parameter. A dead zone setting unit allows operators to modify the pressure difference threshold based on specific work conditions. This dynamic adjustment capability enables the system to adapt to varying operational requirements while maintaining stable pump operation within each selected parameter range.
Solution Approach 2:
The system introduces parameter variability by allowing adjustment of the pressure difference set value and dead zone width. Different parameter combinations can be selected to optimize performance for different work conditions such as excavation, grading, or material handling, thereby achieving versatility without compromising operational stability.
Data Source
Figure 1
Figure 2
AI summary
Provided are: a hydraulic pump (32) for discharging hydraulic oil; a hydraulic actuator (39); an operating device (17) operated in order to perform actuation control; a discharge pressure sensor (37) for detecting a discharge pressure of the hydraulic oil discharged by the hydraulic pump (32); a hydraulic oil pressure sensor (38) for detecting a hydraulic oil pressure of the hydraulic actuator; an electric motor (33) for driving the hydraulic pump; an inverter (43) for supplying electric power to the electric motor (33); and a controller (40) for determining a difference between the discharge pressure detected by the discharge pressure sensor (37) and the hydraulic oil pressure detected by the hydraulic oil pressure sensor (38), and adjusting the amount of the electric power supplied to the electric motor (33) to perform control for changing the discharge pressure of the hydraulic pump (32) so that the difference reaches a specific value.