Engine Starting Method Using Reverse Crankshaft Rotation
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Solution Overview
Problem
Existing methods for starting internal combustion engines equipped with integrated starter-generators require high torque, leading to increased size and cost, and struggle with precise crankshaft positioning.
Innovation Solution
A method that uses an electromechanical device to rotate the crankshaft in a controlled manner, reducing torque requirements by rotating the crankshaft in the direction opposite to the engine's rotation to reach the reverse compression region, allowing for engine start without precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the crankshaft is rotated to a specific predetermined position using a controlling device, then the engine can be started with proper timing, but the cost of the controlling device increases
Solution Approach 1:
The method uses the engine's own compression pressure to automatically position the piston at TDC during reverse rotation, eliminating the need for external sensing and control devices. The engine system itself provides the positioning function through its mechanical characteristics during the compression stroke.
Solution Approach 2:
The patent replaces complex electronic sensing and control systems with a purely mechanical approach. By rotating the crankshaft in reverse and utilizing the compression pressure buildup, the system naturally achieves TDC positioning without electronic intervention, substituting mechanical phenomena for electronic control.
2Reliability
If high torque is applied to overcome forward compression pressure, then the engine can be started, but the size and cost of the integrated starter-generator increases
Solution Approach 1:
The patent inverts the traditional starting approach by rotating the crankshaft in reverse direction first. This allows the compression pressure to build up and assist the forward rotation, converting the harmful compression resistance into a helpful force that reduces the torque demand on the starter-generator.
Solution Approach 2:
The method changes the rotational direction parameter of the crankshaft during the starting process. By temporarily rotating in reverse and then transitioning to forward rotation, the system exploits the compression stroke to reduce the torque parameter required for engine starting, allowing for a smaller starter-generator design.
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 method enables efficient engine starting with reduced torque, minimizing the size and cost of the integrated starter-generator and eliminating the need for precise crankshaft positioning.
Implementation Method 1
rotating the crankshaft in a direction opposite to the direction of rotation (reverse direction) of the engine by means of the electromechanical device coupled to the crankshaft by a fourth predefined angle so that the piston reaches the region of reverse compression
Data Source
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AI summary
The present invention describes a method of starting an internal combustion engine. The method includes the steps of; receiving an engine start command; rotating the crankshaft from an initial position in forward direction; following a path A (208) or a path B (214) to rotate crankshaft in reverse direction so that the piston reaches the region of reverse compression; and rotating the crankshaft in forward direction to start the engine. The path A is followed when the crankshaft is rotated by a first predefined angle (206) before a predefined rotational time. While the path B is followed when the crankshaft is rotated for a predefined rotational time (212). Also described is a method of starting an internal combustion engine which includes a path C (614) or a path D (618).).