Work Vehicle Cooling Fan Speed Control via Lock-Up Clutch State
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Solution Overview
Problem
Existing work vehicle cooling systems set a uniform upper limit for cooling fan rotational speed based on engine speed, leading to excessive cooling ability and inefficient fuel usage, as they do not account for the actual heat balance and operational conditions of the vehicle.
Innovation Solution
A controller adjusts the upper limit of the cooling fan's target rotational speed based on the state of the lock-up clutch and transmission gear, reducing the fan's speed when the lock-up clutch is engaged to prevent excessive cooling and enhance fuel economy, while maintaining adequate cooling when the clutch is released.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the upper limit of fan target rotational speed is set high to ensure adequate cooling ability in all circumstances, then cooling reliability is improved, but fuel economy deteriorates due to excessive cooling when not needed
Solution Approach 1:
The upper limit of fan target rotational speed is dynamically adjusted based on the lock-up clutch state. When the lock-up clutch is engaged, the upper limit is set to a lower value (first upper limit value). When the lock-up clutch is released, the upper limit is set to a higher value (second upper limit value). This dynamic adjustment ensures adequate cooling when needed while reducing energy consumption when the clutch is engaged and less cooling is required.
Solution Approach 2:
The control system changes the parameter of fan rotational speed upper limit based on the operational state of the lock-up clutch. By detecting whether the clutch is engaged or released, the system selects different upper limit values, thereby optimizing the balance between cooling performance and energy efficiency under different operating conditions.
2Device complexity
If the upper limit of fan target rotational speed is uniformly determined based on engine rotational speed, then control simplicity is improved, but cooling efficiency deteriorates due to inability to adapt to actual heat balance conditions
Solution Approach 1:
The control system incorporates feedback from the lock-up clutch state sensor to adjust the fan rotational speed upper limit. This feedback mechanism allows the system to adapt to actual operating conditions and heat balance requirements, improving cooling efficiency without significantly increasing control complexity. The controller continuously monitors the clutch state and adjusts the fan speed limit accordingly.
Solution Approach 2:
The fan speed upper limit transitions from a static uniform value to a dynamic value that changes based on clutch state. This dynamic control enables the system to adapt to varying heat balance conditions, reducing energy loss while maintaining adequate cooling performance across different operating scenarios.
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 approach prevents excessive cooling ability and enhances fuel economy by optimizing the cooling fan's rotational speed according to the vehicle's operational conditions, ensuring efficient energy use and maintaining favorable heat balance.
Implementation Method 1
The cooling device has a cooling fan and a hydraulic motor. The hydraulic motor is driven by hydraulic pressure supplied from a hydraulic pump, and the cooling fan is thereby rotated.
Data Source
AI summary
A controller of a work vehicle sets the upper limit of a fan target rotational speed in accordance with an engine rotational speed. The controller reduces an upper limit of the fan target rotational speed further when a lock-up clutch is in an engaged state than when the lock-up clutch is in a released state.