Lock-up Clutch Control for Transmission Lubrication
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Solution Overview
Problem
The existing lubricating oil supply system in construction machines is insufficient when the lock-up clutch is maintained at a low speed range, leading to potential transmission damage due to inadequate lubrication, especially when the vehicle is traveling uphill with a heavy load, and this issue is exacerbated by the need to balance fuel efficiency with sufficient oil supply.
Innovation Solution
A lubricating oil supply control device that includes a clutch-state determining section, a lubricating oil amount detecting section, and a lock-up clutch controlling section, which detects the vehicle speed, engine speed, and the duration of low speeds to ensure sufficient oil supply by switching the lock-up clutch to a decoupled state when insufficient lubrication is detected, thereby increasing engine speed and oil pump discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the lock-up clutch is maintained in a coupled state at low vehicle speed to improve fuel efficiency, then fuel consumption is reduced, but the lubricating oil supply to the transmission becomes insufficient
Solution Approach 1:
The lock-up clutch control is made dynamic by continuously monitoring vehicle speed and automatically switching between coupled and decoupled states based on real-time operating conditions. This dynamic control allows the system to optimize fuel efficiency at appropriate speeds while preventing lubrication insufficiency when speed drops below safe thresholds
Solution Approach 2:
The system implements feedback control by detecting vehicle speed and using this information to determine the appropriate lock-up clutch state. The control unit receives speed feedback and automatically adjusts the clutch state to maintain both fuel efficiency and sufficient lubrication, resolving the contradiction between these two requirements
2Reliability
If the pump capacity is enlarged to ensure sufficient lubricating oil supply at low engine speed, then oil supply is sufficient, but pump loss increases and fuel consumption rises
Solution Approach 1:
Instead of always providing excessive oil supply capacity, the system applies partial action by using a standard-capacity pump and only increasing oil flow when necessary through lock-up clutch decoupling. This avoids the continuous energy loss of an oversized pump while ensuring sufficient lubrication when needed
Data Source
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AI summary
A control device is produced for enabling a locked-up state at a low speed range and preventing thereby-caused insufficiency in the lubricating oil supply amount to a transmission. The control device controls the lubricating oil supply amount to a transmission in a construction machine including a torque converter with a lock-up clutch. The control device includes a clutch state determining section, a lubricating oil amount detecting section and a lock-up clutch controlling section. The clutch state determining section determines whether or not the lock-up clutch (7) is being coupled. The lubricating oil amount detecting section detects whether or not the lubricating oil supply amount to the transmission (2) is short of a preliminarily set supply amount. The lock-up clutch controlling section decouples the lock-up clutch (7) when the lock-up clutch (7) is being coupled and the lubricating oil supply amount is short of the preliminarily set supply amount.