Switchable Pulley Decoupler for Rapid Engine Restart
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Solution Overview
Problem
Vehicles with belt starter generators face challenges in restarting the internal combustion engine quickly and comfortably from a stationary air-conditioning operation due to the inability to mechanically separate the belt drive from the crankshaft, leading to increased interior temperature and CO2 emissions, especially when magnetic couplings are used, as they cannot be combined with a belt pulley decoupler.
Innovation Solution
A switchable pulley decoupler system with a positive locking element allows for quick restarts by using a friction-locked or positive-locking connection, and by reversing the direction of the electric machine's rotation during stationary air-conditioning, minimizing the time required to brake ancillary units and reducing torque-related stress on the belt pulley.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a friction-locked clutch is used for impulse start, then the combustion engine can be started directly from stationary air-conditioning, but a combination with a belt pulley decoupler is not possible due to space constraints
Solution Approach 1:
The patent combines the friction-locked clutch and belt pulley decoupler into a single integrated unit. The friction clutch is positioned inside the decoupler housing, allowing both functions (friction engagement for impulse start and mechanical decoupling for stationary air-conditioning) to coexist in the available space. This merging resolves the contradiction by eliminating the need for separate components while maintaining both restart capability and stationary cooling function.
2Temperature
If the belt drive is mechanically separated from the crankshaft to enable stationary air-conditioning, then the interior temperature can be maintained during stop phases, but the ancillary units must be braked before coupling back to the combustion engine, increasing restart time
Solution Approach 1:
The electric machine is used to brake the ancillary units before they are coupled back to the crankshaft. This preliminary braking action reduces the speed difference between the stationary crankshaft and the rotating ancillary units, minimizing the braking time required during restart. By performing this speed equalization in advance using the electric machine's regenerative braking capability, the overall restart time is reduced while maintaining the ability to provide stationary air-conditioning.
3Adaptability or versatility
If magnetic couplings are used for ancillary units, then the operating point of crankshaft separation can be represented, but a combination with a belt pulley decoupler is not possible
Solution Approach 1:
The friction-locked clutch acts as an intermediary mechanism that enables the belt pulley decoupler to represent the crankshaft separation operating point. Instead of using magnetic couplings directly, the friction clutch provides a mechanical means of engagement and disengagement that is compatible with the decoupler's ramp system. This intermediary friction connection allows the mechanical decoupler to achieve the same operating point representation while maintaining compatibility with the belt drive system.
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 approach enables a comfortable and rapid restart of the internal combustion engine while minimizing the time required for the restart process and reducing the stress on the belt pulley, thereby improving both the comfort and efficiency of the restart process.
Implementation Method 1
the e-machine has the greatest motor torque at 0 speed. You can take advantage of this for a quick restart by operating the ancillary units or the electric machine in stationary air conditioning mode in the opposite direction of normal operation
Implementation Method 2
Frictionally working clutches (e.g. magnetic clutches) basically meet this requirement, since the existing speed difference is compensated for by slip and the combustion engine can therefore be started immediately (pulse start)
Data Source
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AI summary
The invention relates to a vehicle, comprising an internal combustion engine, a belt-driven starter generator, and an auxiliary power take-off for auxiliary units, which auxiliary output can be decoupled. At least an air-conditioning compressor and an electric machine usable as a motor and a generator as a belt-driven starter generator are provided as auxiliary units in the auxiliary power take-off. The vehicle is characterized in that the auxiliary power take-off is decoupled and coupled by means of a form-closed coupling, in particular a switchable ratchet freewheel, and that standstill air conditioning is occurs during the standstill of the internal combustion engine in short stop phases by rotating the auxiliary units backwards and the internal combustion engine is started after the stop phase by reversing the direction of rotation of the electric machine.