Automatic Stop System Slope Restart Logic
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Solution Overview
Problem
The existing automatic stop/restart systems for internal combustion engines with hydraulic transmissions and parking mechanisms face issues such as belt slippage and reduced hydraulic pressure when shifting from a parking range to a drive range on slopes, leading to potential damage and decreased fuel economy due to the abrupt release of load on pulleys in idle reduction mode.
Innovation Solution
An automatic stop/restart system that includes a shift position detector, inclination angle detector, and brake operating state detector, controlled by a restart controller to determine if the vehicle's inclination angle is greater than or equal to a predetermined value, allowing the engine to restart and maintain hydraulic pressure, thus preventing belt slippage and optimizing fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine is automatically stopped in idle reduction mode, then fuel economy is improved, but hydraulic pressure drops causing belt slippage risk when shifting from parking range
Solution Approach 1:
The system performs preliminary detection of the parking range shift position while the engine is still running, and proactively restarts the engine before the shift operation is completed. This preliminary action ensures hydraulic pressure is restored before the load is transferred to the transmission, preventing belt slippage while maintaining fuel economy benefits during normal operation.
Solution Approach 2:
The control unit acts as an intermediary between the shift position detector and the engine restart system. It monitors shift position signals and mediates the timing of engine restart based on detected parking range engagement, coordinating the hydraulic pressure restoration with the transmission load transfer to prevent belt slippage.
2Reliability
If the engine is restarted when shift lever is in P range on slope, then hydraulic pressure is maintained, but accidental restart may occur
Solution Approach 1:
The system applies different restart policies based on the local condition of shift lever position. When the shift lever is detected in the P range, the system locally modifies the restart logic to require additional confirmation (shift lever moving to D range) before restarting the engine, while maintaining normal restart functionality for other shift positions.
3Reliability
If a motor-driven oil pump is used to maintain hydraulic pressure in idle reduction mode, then belt slippage is prevented, but costs increase and fuel economy deteriorates
Solution Approach 1:
The system extracts and eliminates the need for a motor-driven oil pump by utilizing the existing engine-driven hydraulic system. By strategically restarting the engine based on shift position detection, the system maintains hydraulic pressure through the natural engine operation rather than requiring an additional energy-consuming pump mechanism.
Data Source
AI summary
A vehicle equipped with an automatic stop/restart system for an internal combustion engine includes a hydraulic continuously variable transmission and a parking mechanism. The continuously variable transmission changes power of the internal combustion engine using hydraulic pressure boosted by rotational driving force of the internal combustion engine. The parking mechanism holds the vehicle stationary by locking, with a locking member, the rotation of a power transmitting member between the internal combustion engine and driving wheels when a shift position is in a parking range. In an automatic stop state of the internal combustion engine, when the shift position is in the parking range and brakes are turned off, an electronic control unit executes restart if an inclination angle of the vehicle is greater than or equal to a predetermined value, and maintains the automatic stop state if the inclination angle is smaller than the predetermined value.