Excavator Hydraulic Pump Control for Variable Negative Feedback
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Solution Overview
Problem
The existing negative control hydraulic system in shovels has a fixed correspondence between the hydraulic pump discharge amount and control pressure, leading to situations where either excessive or insufficient hydraulic oil is discharged, lacking flexibility in control.
Innovation Solution
A shovel with a negative control hydraulic system that includes a controller to adjust the discharge quantity of the hydraulic pump based on operation details, using a swash plate variable displacement hydraulic pump and a control valve unit to dynamically control the flow of hydraulic oil, allowing for flexible control of the discharge amount.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed correspondence between hydraulic pump discharge amount and control pressure is used, then the system structure is simple, but the control flexibility is insufficient leading to excessive or insufficient hydraulic oil discharge
Solution Approach 1:
The patent applies dynamics by making the discharge amount of the hydraulic pump variable rather than fixed. The controller dynamically adjusts the discharge amount based on real-time control pressure feedback, allowing the system to adapt to different operating conditions. This resolves the contradiction by enabling control flexibility through dynamic adjustment while maintaining a relatively simple overall system structure.
Solution Approach 2:
The patent implements a feedback control mechanism where the controller monitors the control pressure and adjusts the hydraulic pump's discharge amount accordingly. When control pressure increases, the controller reduces discharge amount, and when control pressure decreases, the controller increases discharge amount. This feedback loop provides the necessary control flexibility without requiring complex system architecture.
2Reliability
If the hydraulic pump discharges excessive hydraulic oil, then sufficient hydraulic oil is available for actuators, but energy is wasted through unnecessary discharge
Solution Approach 1:
The feedback control mechanism monitors control pressure and adjusts pump discharge accordingly. When actuators require hydraulic oil, control pressure decreases, triggering the controller to increase pump discharge, ensuring sufficient supply. When actuators don't require oil, control pressure increases, and the controller reduces discharge, preventing energy waste. This resolves the contradiction between reliability and energy efficiency.
Solution Approach 2:
The system changes the discharge parameter of the hydraulic pump dynamically based on control pressure conditions. By adjusting this key parameter in response to system needs, the patent ensures sufficient hydraulic oil supply when needed while minimizing discharge and energy consumption when not needed, resolving the contradiction between supply reliability and energy efficiency.
3Loss of energy
If the hydraulic pump discharges insufficient hydraulic oil, then energy consumption is reduced, but the actuators cannot operate properly
Solution Approach 1:
The feedback control system detects when control pressure decreases, indicating that actuators require hydraulic oil. In response, the controller immediately increases the pump's discharge amount to ensure proper actuator operation. This feedback mechanism guarantees that energy consumption is optimized without compromising actuator functionality, resolving the contradiction between energy efficiency and operational reliability.
4Productivity
If a variable discharge control system is implemented, then control flexibility and energy efficiency improve, but the control system complexity increases
Solution Approach 1:
The patent uses a feedback control mechanism that, while adding some control complexity, maintains operational simplicity through automatic adjustment. The controller automatically monitors control pressure and adjusts pump discharge without requiring complex manual intervention or sophisticated control algorithms. This feedback-based approach achieves high operational efficiency with minimal increase in actual system complexity.
Solution Approach 2:
The system implements self-service control where the controller automatically adjusts pump discharge based on real-time control pressure conditions without external intervention. This self-regulating capability improves operational efficiency while minimizing the complexity burden, as the system manages its own optimization without requiring complex external control infrastructure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration ensures that necessary hydraulic oil is supplied to actuators while minimizing unnecessary discharge, optimizing energy consumption and operational efficiency by adjusting the control characteristic of the negative control according to the operating conditions.
Implementation Method 1
a hydraulic pump configured to be driven by the engine
Implementation Method 2
using a swash plate variable displacement hydraulic pump
Data Source
AI summary
A shovel includes a lower traveling structure, an upper swing structure mounted on the lower traveling structure, an engine mounted on the upper swing structure, a hydraulic pump configured to be driven by the engine, a hydraulic actuator, an operating device configured to operate the hydraulic actuator, and a hardware processor configured to control the discharge quantity of the hydraulic pump through negative control and change a control characteristic of the negative control according to the details of an operation on the operating device.