Work Vehicle Drive Control Engine Stall Prevention
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Solution Overview
Problem
Existing drive control systems for working vehicles with emission control compliant engines struggle to prevent engine stall during sudden changes in load, particularly during forward/reverse switching operations, leading to potential engine stalling and increased fuel consumption.
Innovation Solution
A drive control system that includes a controller with engine load factor detection, forward/reverse command, accelerator pedal stroke detection, and vehicle speed detection, which adjusts the target engine speed by adding an engine stall-preventing increment when forward/reverse switching occurs, ensuring engine torque exceeds load torque and minimizing fuel consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the target engine speed is increased to prevent engine stall during forward/reverse switching, then engine stall prevention is improved, but fuel consumption increases
Solution Approach 1:
The patent applies dynamics by making the target engine speed adjustable based on operating conditions. The ECU dynamically changes the target engine speed from a basic idle speed to a higher speed during forward/reverse switching operations, allowing the system to adapt to varying load conditions without permanently increasing fuel consumption.
Solution Approach 2:
The patent changes the parameter of target engine speed based on detected operating conditions. When forward/reverse switching is detected, the ECU modifies the target engine speed parameter from the basic idle speed to a higher value, thereby increasing engine torque output only when necessary to prevent stall during transient load conditions.
2Reliability
If the target engine speed is equally increased for all load conditions, then engine stall prevention is improved, but fuel consumption increases unnecessarily
Solution Approach 1:
The system dynamically adjusts the target engine speed based on real-time detection of forward/reverse switching operations. By making the speed increase conditional rather than constant, the system maintains reliability during critical transitions while avoiding unnecessary energy loss during normal operating conditions.
Solution Approach 2:
The ECU detects forward/rereverse switching operations in advance and proactively increases the target engine speed before engine stall can occur. This preliminary action allows the engine to maintain adequate torque reserves during anticipated high-load transitions without continuously operating at higher speeds.
3Object-generated harmful factors
If the engine operates at low idle speed for emission control, then emission control compliance is improved, but engine stall liability increases
Solution Approach 1:
The patent implements dynamic target engine speed control that operates at low idle speed during normal conditions to comply with emission control requirements, then temporarily increases the target speed during forward/reverse switching operations to prevent engine stall. This dynamic adjustment allows the system to meet both emission compliance and reliability requirements.
Solution Approach 2:
The ECU applies preliminary anti-action by detecting forward/reverse switching operations and proactively increasing the target engine speed before the engine load becomes excessive. This prevents engine stall from occurring in the first place, allowing the engine to maintain low idle speed for emission compliance while still protecting against stall during transient conditions.
Data Source
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AI summary
To provide a drive control system for a working vehicle, which can prevent engine stall with certainty even when a large load suddenly acts on a vehicle-mounted engine and which is also excellent in environment friendly performance. When a vehicle speed of a wheel loader (1) is determined to be not higher than a reference value (Yes) in step S4 and a forward/reverse command means (40) is determined to have been switchingly operated (Yes) in step S5, the routine advances to step S6 where an increment ΔN of engine speed according to an engine load factor is determined. In step S7, the increment ΔN of engine speed is then added to a target engine speed Na corresponding to a depression stroke of an accelerator pedal (38), the thus-determined Na=Na+ΔN is set as a new target engine speed Na, and a target engine speed command i1 is sent to an engine controller (37).