Hydrostatic Work Vehicle Control for Implement Speed and Travel Stability
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Solution Overview
Problem
Conventional work vehicles equipped with hydrostatic transmissions require operators to simultaneously manage the accelerator pedal, work implement lever, and inching pedal, making it difficult to seamlessly operate the work implement and travel.
Innovation Solution
A work vehicle system that includes sensors and a controller to determine target input horsepower and engine rotational speed based on the operation of the accelerator and work implement, allowing for independent adjustment of work implement speed and vehicle travel performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the operator increases engine speed by depressing the accelerator pedal to increase work implement speed, then the discharge flow rate of the work implement pump increases, but the input horsepower to the hydrostatic transmission also increases causing the work vehicle to accelerate unintentionally
Solution Approach 1:
The control unit acts as an intermediary that receives the accelerator operation signal and automatically adjusts the traveling pump displacement to compensate for changes in traveling speed caused by work implement operations. This mediator function prevents the need for the operator to manually coordinate multiple controls while maintaining both work implement speed and vehicle travel stability.
Solution Approach 2:
The control system merges the control functions of the accelerator pedal into a single input that simultaneously manages both work implement speed and vehicle travel. By integrating these control functions, the system eliminates the need for separate control operations, reducing operational complexity while achieving both speed control objectives.
2Ease of operation
If the operator uses the inching pedal to reduce the displacement of the traveling pump to prevent acceleration, then the work vehicle acceleration is reduced, but the operator must simultaneously manage multiple controls
Solution Approach 1:
The system extracts the travel control function from the inching pedal and integrates it into the accelerator control system. By removing the need for separate inching pedal operation and incorporating travel control into the accelerator signal processing, the system reduces the number of controls the operator must manage simultaneously while maintaining precise travel control.
3Adaptability or versatility
If the operator simultaneously operates the work implement lever, accelerator pedal, and inching pedal to control both work implement movement and vehicle travel, then both functions can be controlled, but the operation becomes difficult and complex
Solution Approach 1:
The accelerator pedal is given universal control capability, serving both its traditional function of controlling engine speed for work implement operation and the additional function of controlling vehicle travel speed. This multi-functionality eliminates the need for separate controls while maintaining full operational capability for both work implement and vehicle movement.
Solution Approach 2:
The control unit continuously monitors the accelerator operation signal and automatically adjusts the traveling pump displacement in real-time to maintain appropriate vehicle speed while the work implement is operating. This feedback mechanism ensures that both work implement and vehicle travel are properly controlled without requiring complex manual coordination.
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
Facilitates easier operation of the work implement and vehicle travel by allowing operators to adjust speeds and traction forces without needing to operate multiple controls simultaneously.
Implementation Method 1
The hydrostatic transmission includes a traveling pump, a traveling motor, and a hydraulic circuit connecting the traveling pump and the traveling motor. The traveling pump is driven by the engine and discharges hydraulic fluid. The hydraulic fluid discharged from the traveling pump is supplied to the traveling motor via the hydraulic circuit.
Implementation Method 2
The work implement pump is driven by the engine. The work implement is driven by the hydraulic fluid discharged from the work implement pump.
Data Source
AI summary
A work vehicle includes an engine, a hydrostatic transmission, a work implement pump driven by the engine, a work implement driven by hydraulic fluid discharged from the work implement pump, an accelerator, a first sensor configured to output a signal indicative of an operation amount of the accelerator, a work implement operating member, a second sensor configured to output a signal indicative of an operation amount of the work implement operating member, and a controller. The controller is configured to receive signals from the first sensor and the second sensor, determine a target input horsepower input to the hydrostatic transmission from the operation amount of the accelerator, and determine a target rotational speed of the engine from the target input horsepower and the operation amount of the work implement operating member.