Shovel Engine Stall Prevention via Predictive Hydraulic Load Control
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Solution Overview
Problem
Hydraulic shovels with turbocharged engines face challenges in maintaining engine output when sudden hydraulic loads increase, as the existing output control apparatuses struggle to swiftly respond to external forces like excavation reaction forces, leading to potential engine stall due to insufficient supercharging pressure.
Innovation Solution
A shovel system with a controller that proactively increases the load on the internal combustion engine via the hydraulic pump before a hydraulic load increases, using a swash-plate variable displacement hydraulic pump and a turbocharger to maintain constant engine rotational speed and supercharging pressure, thereby preventing engine stall.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine maintains constant rotational speed with existing output control apparatus, then the engine operates stably, but the supercharging pressure increases slowly when hydraulic load increases, causing engine stall
Solution Approach 1:
The controller increases the discharge amount of the hydraulic pump before the hydraulic actuator actually requires the hydraulic oil, based on predictive judgment of upcoming work. This preliminary action builds up supercharging pressure in advance, so when the hydraulic load increases, the engine can maintain constant rotational speed without stall.
2Power
If the engine increases output by increasing supercharging pressure in response to hydraulic load, then the engine maintains rotational speed, but the response is delayed causing temporary engine stall
Solution Approach 1:
The system performs preliminary action by increasing pump discharge amount before the hydraulic load actually increases. The controller judges based on operation lever position and other parameters that work is about to start, and preemptively increases hydraulic pump output, thereby building supercharging pressure in advance and eliminating the time delay in engine response.
3Use of energy by moving object
If the hydraulic pump maintains constant discharge amount, then the system operates efficiently, but it cannot swiftly respond to sudden increases in hydraulic load
Solution Approach 1:
The hydraulic pump operates dynamically with variable discharge amount rather than constant discharge. The controller adjusts the pump discharge amount based on real-time conditions including operation lever position, current hydraulic pressure, and predictive judgment of upcoming work, allowing the system to be efficient during idle periods and highly responsive when work is required.
Solution Approach 2:
The system incorporates feedback mechanisms where the controller continuously monitors operation lever position, hydraulic pressure, and pump discharge amount. This feedback loop enables the controller to adjust the pump discharge amount appropriately, increasing it before work starts and maintaining efficiency during idle operation, thus resolving the contradiction between efficiency and responsiveness.
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 solution ensures consistent engine output and prevents engine stall by preemptively increasing supercharging pressure and maintaining engine rotational speed even under sudden hydraulic loads, enhancing the shovel's operational reliability and efficiency.
Implementation Method 1
The turbocharger increases the output of the engine by performing supercharging by delivering, to the intake system of the engine, a pressure obtained by rotating a turbine using the engine's exhaust gas.
Implementation Method 2
a hydraulic pump connected to the internal combustion engine, and a controller configured to control horsepower absorbed by the hydraulic pump
Data Source
AI summary
A shovel includes a lower-part traveling body, an upper-part turning body mounted on the lower-part traveling body, a hydraulic actuator mounted on the upper-part turning body, an internal combustion engine disposed in the upper-part turning body, provided with a supercharger, and configured to be controlled at a constant rotational speed, a hydraulic pump connected to the internal combustion engine, and a controller configured to control horsepower absorbed by the hydraulic pump. The controller is configured to increase a load on the internal combustion engine with the hydraulic pump before a load on the hydraulic actuator increases.