Hydraulic Pump Control System for Excavator Swing Acceleration
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Solution Overview
Problem
In hydraulic construction machines, abrupt operation of the lever leads to insufficient hydraulic motor revolutions, resulting in energy loss as the excess fluid returns through relief valves, limiting the flow rate and impacting initial acceleration.
Innovation Solution
A hydraulic pump control system that includes a detection sensor to calculate the required flow rate based on the operation lever's rate, compares it with a dead-zone value and flow increasing rate limit, and adjusts the discharge flow rate to prevent excessive flow, thereby reducing the initial flow supply rate and limiting the flow increasing rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the hydraulic pump supplies high flow rate at initial stage, then the swing acceleration is improved, but energy loss through relief valves increases
Solution Approach 1:
The patent applies dynamics by making the pump flow rate adjustable over time. The control unit dynamically changes the pump flow rate from a limited initial value to a higher steady-state value, optimizing performance at different time points. This resolves the contradiction by adapting the flow rate to the actual needs of the swing motor at each moment rather than maintaining a fixed high flow rate that causes energy loss.
Solution Approach 2:
The patent implements preliminary action by pre-limiting the pump flow rate at the initial stage before the swing motor reaches its operating speed. The control unit detects the swing motor speed and only limits the flow rate when the speed is below a predetermined threshold, ensuring that energy is not wasted through the relief valve during the acceleration phase while still providing sufficient flow when needed.
2Loss of energy
If the pump flow rate is limited at initial stage, then energy loss is reduced, but the operator feels reduction in initial acceleration
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the pump flow rate parameter based on the swing motor speed. The control unit increases the pump flow rate as the swing motor speed increases, ensuring that the flow rate matches the actual demand. This resolves the contradiction by changing the flow rate parameter adaptively rather than maintaining a fixed limited value, preventing operator perception of reduced acceleration while still reducing energy loss.
3Speed
If the pump supplies excess flow rate, then the hydraulic motor revolutions are sufficient, but flow rate returns through relief valve causing loss
Solution Approach 1:
The patent implements feedback by using the swing motor speed detection to control the pump flow rate. The control unit continuously monitors the swing motor speed and adjusts the pump flow rate accordingly, increasing flow rate only when the motor speed exceeds the predetermined threshold. This feedback mechanism ensures that the hydraulic motor receives sufficient flow rate to maintain revolutions while preventing excess flow that would return through the relief valve and cause loss.
Data Source
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AI summary
A hydraulic pump control system provided in a construction machine such as an excavator is provided. According to the hydraulic pump control system, a loss of a flow rate is reduced by initially supplying hydraulic fluid as much as necessary from a hydraulic pump to a hydraulic motor in order to accelerate a swing movement of an upper frame against a lower traveling structure or to make an upper swing structure swing.