Free-Wheeling Engine Restart via Partial Clutch Engagement
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Solution Overview
Problem
Existing methods for starting a combustion engine during free-wheeling with engine off require a high number of starts, leading to clutch wear and potential loss of lateral stability due to energy transfer from the drive wheels, and existing starter systems are either insufficient or costly.
Innovation Solution
A method and control device that control the clutch to a partially closed state to initiate engine start, then open it before synchronization with the gearbox speed, using fuel injection to synchronize the engine speed, reducing clutch wear and stability risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the combustion engine is started frequently using the clutch during free-wheeling with engine off, then fuel consumption is reduced, but clutch wear increases significantly
Solution Approach 1:
The patent extracts the engine starting function from the clutch system by introducing a dedicated starter motor. The starter motor is specifically designed to handle the high number of starts required during free-wheeling operations, while the clutch is reserved for its primary function of connecting the engine to the transmission. This separation of functions protects the clutch from excessive wear while enabling frequent engine starts for fuel savings.
Solution Approach 2:
The starter motor serves multiple functions: it can start the engine during free-wheeling with engine off, and it can also function as an additional propulsion source in hybrid operation modes. This multi-functionality justifies the added component while solving the clutch wear problem.
2Device complexity
If the combustion engine is started using the clutch by transferring torque from the drive wheels, then no upgraded starter system is needed, but lateral stability of the vehicle is affected due to braking force on drive wheels
Solution Approach 1:
The starting function is extracted from the drivetrain system and assigned to a dedicated starter motor. This eliminates the need to use the clutch for engine starting, thereby removing the source of braking force on the drive wheels that compromises lateral stability. The clutch remains dedicated to its primary function of power transmission to the wheels.
Solution Approach 2:
The starter motor acts as an intermediary device between the engine and the external environment. It provides the necessary torque to start the engine without requiring torque transfer from the drive wheels through the clutch, thus eliminating the stability-affecting braking force while still enabling engine starting.
3Reliability
If an upgraded starter system is used to handle high number of starts, then reliability of engine starting is improved, but cost increases significantly
Solution Approach 1:
The starter motor is designed to serve dual purposes: reliable engine starting during free-wheeling operations and potential hybrid propulsion assistance. This multi-functionality justifies the investment in a more robust starting system by providing additional value beyond mere engine starting.
Solution Approach 2:
The starter motor is pre-configured and positioned to immediately take over the engine starting function when needed, eliminating the need for complex control systems or sequential operations. The direct mechanical connection allows for simple, reliable operation without elaborate control mechanisms.
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
Reduces clutch wear and stability issues by minimizing energy transfer during start-up, ensuring reliable engine synchronization without the need for upgraded starter systems.
Implementation Method 1
controlling the clutch to a partially closed state so as to transfer torque from the input shaft of the gearbox to the combustion engine
Implementation Method 2
synchronising the speed of the combustion engine to the speed of the input shaft of the gearbox through control of fuel injection to the combustion engine
Data Source
Figure 1~2
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AI summary
A method, performed by a control device (100), for starting a combustion engine (2) during free-wheeling with engine off is described. The method comprises a step of controlling the clutch (9) to a partially closed state, thereby starting the combustion engine (2); a step of controlling the clutch (9) to an open state when the combustion engine (2) has started, but prior to the output shaft (8) of the combustion engine has reached a rotational speed synchronised with the rotational speed of the input shaft (10) of the gearbox; and a step of synchronising the speed of the combustion engine (2) to the speed of the input shaft (10) of the gearbox through control of fuel injection to the combustion engine (2).