Load Control Mechanism for Self-Propelled Working Machines
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Solution Overview
Problem
Self-propelled working machines face challenges in maintaining optimal working load, leading to increased operator burden and potential engine stall due to complex control systems and reliance on manual speed adjustments based on auditory and visual cues.
Innovation Solution
A load control mechanism that automatically adjusts travel speed by calculating the maximum working output and actual working load using a mechanical or electronic governor, allowing the electric motor to control speed and maintain appropriate load through a simple control structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual speed adjustment based on auditory and visual cues is used, then operator control flexibility is maintained, but operator burden increases and work finish quality deteriorates
Solution Approach 1:
The system enables self-service operation by automatically detecting working load through engine rotational speed monitoring and adjusting travel speed without operator intervention. The control unit automatically calculates appropriate travel speeds based on detected engine speed, eliminating the need for operators to manually adjust speeds based on auditory and visual cues, thereby reducing operator burden while maintaining consistent work finish quality
Solution Approach 2:
The system implements feedback control by continuously monitoring engine rotational speed and using this information to automatically adjust travel speed. The control unit receives feedback from the engine speed sensor and dynamically modifies the travel speed command to maintain optimal working conditions, ensuring consistent work finish quality while eliminating manual adjustment requirements
2Adaptability or versatility
If separate control actuators are used for blower and wheels, then independent control of each component is achieved, but device complexity and control complexity increase
Solution Approach 1:
The system merges the control of multiple components (blower and wheels) into a single integrated control mechanism. Instead of using separate control actuators for each component, the control unit adjusts the engine rotational speed, which simultaneously controls both the blower speed and wheel speed through the power transmission system, thereby reducing device complexity while maintaining coordinated control capability
Solution Approach 2:
The engine rotational speed control serves multiple functions simultaneously - it controls the blower operation, wheel rotation, and overall power distribution. By using the engine speed as a universal control parameter, the system achieves multi-functionality with a single control mechanism, eliminating the need for separate actuators and reducing overall system complexity
3Device complexity
If engine rotational speed is used to control both blower and travel, then control structure is simplified, but working load management becomes difficult leading to engine stall
Solution Approach 1:
The system implements feedback control by continuously monitoring engine rotational speed and using this information to automatically adjust travel speed. The control unit receives feedback from the engine speed sensor and dynamically modifies the travel speed command to maintain optimal working conditions, ensuring consistent work finish quality while eliminating manual adjustment requirements
Solution Approach 2:
The system dynamically adjusts travel speed based on real-time engine rotational speed conditions. When the engine speed drops below the predetermined threshold indicating excessive working load, the control unit automatically reduces travel speed to prevent engine stall. This dynamic adjustment mechanism maintains reliability while preserving the simplified control structure
Data Source
AI summary
A self-propelled working machine, which performs work by using power of an internal combustion engine 10 and travels by using power of an electric motor 30, includes a mechanical governor 75 for maintaining the engine at a designated engine rotational speed Nf. A load control mechanism for the working machine has a maximum working output calculator that calculates a maximum working output Qf from the designated engine rotational speed, an actual working load calculator that calculates an actual working load Qr from the designated engine rotational speed Nf and a detected actual engine rotational speed Nr, and a limit speed calculator that calculates a limit speed Vc from the maximum working output Qf and the actual working load Qr. A travel controller operates and controls the electric motor 30 by setting a travel speed V to the limit speed Vc when the actual engine rotational speed Nr is decreased to be lower than the designated engine rotational speed Nf. The travel speed of the working machine is automatically controlled so that the working load is calculated from the driving condition of the internal combustion engine to ensure the working load to be appropriate. Thus excellent finish of the working is maintained and the operator is relieved from burden.