Motor Grader Lock-Up Clutch Control for Stall Prevention
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Solution Overview
Problem
Motor graders face engine stall issues during low-speed operations, which can degrade operator control feeling and are not effectively addressed by existing technologies, particularly when the lock-up clutch is disengaged to prevent stalls.
Innovation Solution
A motor grader system that includes an engine, torque converter with a lock-up clutch, and a control unit that maintains the lock-up clutch in an engaged state until the engine revolution reaches a predetermined lock-up release revolution lower than low idle, then disengages it to prevent engine stalls without compromising operator control feeling, and optionally includes a damper to manage vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lock-up clutch is disengaged to prevent engine stall, then engine reliability is improved, but operator speed control feeling deteriorates
Solution Approach 1:
The patent introduces a new parameter - lock-up release revolution - which is lower than the traditional low idle revolution. By changing the threshold parameter for lock-up clutch disengagement from low idle revolution to lock-up release revolution, the system can maintain clutch engagement at very low speeds (preserving operator control feeling) while automatically disengaging when the engine approaches stall conditions (preventing engine stall). This parameter change resolves the contradiction by enabling differentiated control based on actual engine state.
2Ease of operation
If the lock-up clutch is kept engaged during low speed travel, then operator speed control feeling is maintained, but engine stall risk increases
Solution Approach 1:
The patent implements a feedback control mechanism where the control unit continuously monitors engine revolution and automatically adjusts the lock-up clutch state based on real-time engine performance. When engine revolution approaches the lock-up release revolution threshold, the system provides feedback to disengage the clutch, preventing stall. This closed-loop feedback resolves the contradiction by dynamically balancing clutch engagement benefits against engine stall risks based on actual operating conditions.
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
The system allows motor graders to operate at low speeds without engine stalls and maintains operator control feeling, while preventing vehicle body vibrations by strategically managing the lock-up clutch state and engine revolutions.
Implementation Method 1
a torque converter configured to transmit driving force from the engine
Implementation Method 2
the torque converter further includes a damper configured to inhibit vibration of the engine
Data Source
AI summary
A motor grader includes an engine, a torque converter, a drive wheel, an engine revolution detector, and a control unit. The torque converter, including a lock-up clutch, transmits driving force from the engine. The drive wheel is rotationally driven by the driving force from the engine. The engine revolution detector detects engine revolution. When the lock-up clutch is engaged, the control unit is configured to: maintain the engaged state of the lock-up clutch when the engine revolution is greater than a predetermined lock-up release revolution lower than a low idle revolution; and switch the lock-up clutch into a disengaged state when the engine revolution is less than or equal to the predetermined lock-up release revolution.