Swing Hydraulic Motor Pressure Control Under Engine Horsepower Limits
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hydraulic actuators in rotational systems, such as swing hydraulic motors, continue to accelerate if the torque is kept constant and no external force is applied, leading to increased flow requirements over time, which can result in sudden decreases in torque and discomfort to the operator, or underutilization of engine power if pressure is kept low to avoid maximum output.
Innovation Solution
A work machine with a controller that calculates a target pressure for the hydraulic actuator based on speed deviation, limits the target pressure to prevent exceeding horsepower limits, and adjusts the pressure using a regulator and bleed-off valve to maintain appropriate torque and acceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the target pressure of the hydraulic pump is suddenly decreased when it reaches the vicinity of the engine's maximum output, then the output of the hydraulic pump does not exceed the maximum output of the engine, but the torque of the swing hydraulic motor sharply decreases causing discomfort to the operator
Solution Approach 1:
The controller performs preliminary action by calculating and limiting the target pressure in advance based on predicted future flow rates, rather than reactively adjusting pressure when engine output is reached. This predictive approach prevents sudden torque changes by preparing the pressure limitation before the engine's maximum output is actually reached, ensuring smooth operation while preventing power overload.
2Ease of operation
If the target pressure of the hydraulic pump is kept low in advance, then the engine's output is not fully utilized, but the torque remains stable and does not cause discomfort to the operator
Solution Approach 1:
The system dynamically adjusts the target pressure based on real-time operating conditions and predicted future demands. Rather than maintaining a statically low pressure, the controller continuously calculates the optimal target pressure that fully utilizes engine output when appropriate while preventing discomfort. This dynamic adjustment allows the system to adapt to changing load conditions and maximize power utilization without compromising operator comfort.
3Speed
If the discharge flow rate of the hydraulic pump is increased to meet the increasing flow requirements of the accelerating swing hydraulic motor, then the motor acceleration is maintained, but the engine's maximum output is exceeded
Solution Approach 1:
The controller implements feedback control by continuously monitoring the actual flow rate of the swing hydraulic motor and comparing it with the predicted future flow rate requirements. Based on this feedback, the controller adjusts the target pressure of the hydraulic pump to ensure that the engine's maximum output is not exceeded while still meeting the motor's acceleration demands. This closed-loop control enables the system to balance power constraints with performance requirements.
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
The system allows for smooth and stable operation of the swing hydraulic motor within power limitations, reducing operator discomfort and optimizing engine utilization by anticipating future horsepower needs.
Implementation Method 1
a hydraulic pump that discharges pressure oil
Implementation Method 2
a swing hydraulic motor that swing-drives the swing body by supply of the pressure oil from the hydraulic pump
Implementation Method 3
a regulator that adjusts a discharge flow rate of the hydraulic pump, and a bleed-off valve that releases the pressure oil discharged from the hydraulic pump to the hydraulic oil tank
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The work machine includes a pressure adjustment device capable of adjusting the driving pressure of the swing hydraulic motor and a controller for controlling the pressure adjustment device. The controller calculates the target pressure of the swing hydraulic motor based on the speed deviation between the target speed of the swing hydraulic motor calculated based on the operation signal of the operating device and the actual driving speed detected by the speed sensor. Then, the controller limits the target pressure of the calculation result so that the estimated input horsepower to the swing hydraulic motor does not exceed the limit value when it is assumed that the driving pressure of the swing hydraulic motor reaches the target pressure after a predetermined time, and controls the pressure adjustment device based on the limited target pressure.