Automatic Clutch Control Using Engine Load During Braking
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Solution Overview
Problem
Existing automatic clutch systems in work machines, such as agricultural tractors, often stall the engine when driving in high gears due to reliance on vehicle speed thresholds, leading to undesirable clutch opening during braking, especially when driving downhill.
Innovation Solution
An automatic clutch system that uses a combination of brake pedal indicators, an engine load indicator, and an electrical processing circuit to control an electrically controllable clutch, opening it only when the engine load exceeds a threshold value (approximately 30% of peak load) and both brake pedals are actuated, while avoiding clutch opening at high vehicle speeds (above 20 Km/h) or when the clutch pedal is fully depressed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vehicle speed threshold is used to control automatic clutch opening, then clutch can open at low speeds to prevent engine stalling, but clutch opens inappropriately at high speeds (e.g., 9 km/h in high gear) causing engine stalling
Solution Approach 1:
The patent changes the control parameter from vehicle speed to engine load. Instead of using a fixed speed threshold (e.g., 2 km/h) that causes inappropriate clutch opening at higher speeds, the system monitors engine load and compares it against a threshold (e.g., 30% of peak load). This parameter change allows the clutch to open only when the engine is truly at risk of stalling, regardless of vehicle speed or gear position.
Solution Approach 2:
The engine load-based control system provides universal protection across all operating conditions. A single control logic based on engine load threshold works effectively whether the vehicle is moving at low speed, high speed, uphill, or downhill, eliminating the need for multiple speed thresholds for different gears or conditions.
Data Source
Figure 1
AI summary
An automatic clutch system (40) for clutching between an internal combustion (IC) engine (12) and a transmission (14) of a work machine (10) includes at least one brake pedal, at least one brake indicator (42), an electrically controllable clutch (34), and at least one electrical processing circuit (26, 28, 30). Each brake indicator (42) provides an output signal corresponding to a state of a corresponding brake pedal. The at least one electrical processing circuit (26, 28, 30) is coupled with the at least one brake indicator (42) and the electrically controllable clutch (34), and is adapted for receiving the brake indicator output signal and controlling the electrically controllable clutch (34), dependent on the brake indicator output signal. The automatic clutch system (40) is characterized by an engine load indicator (44) providing an output signal corresponding to a load state of the IC engine (12). The at least one electrical processing circuit (26, 28, 30) is adapted for receiving the engine load indicator output signal and controlling the electrically controllable clutch (34), dependent on the engine load indicator output signal.