Engine Unit Rotor Position Detection for Crankshaft Acceleration
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Solution Overview
Problem
Existing engine units face challenges in improving early-start ability while maintaining vehicle mountability, as increasing starter motor output power requires larger components, which complicates integration into vehicles.
Innovation Solution
The engine unit incorporates a rotor position detection system with dual signal variations from the forward and rearward ends of detection object parts to precisely control current flow in stator windings, allowing for earlier and more accurate crankshaft rotation acceleration without increasing starter motor power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the output power of the starter motor is increased to improve early-start ability, then the crankshaft rotation acceleration is improved, but the device complexity and vehicle mountability deteriorate due to larger component size
Solution Approach 1:
The patent changes the control parameters of the starter motor by implementing dual-edge detection of detection object parts (detecting both forward end and rearward end signals). This allows precise control of current flow timing in the stator windings, optimizing the motor's torque output without increasing physical size. The parameter change in detection timing enables improved crankshaft acceleration while maintaining compact dimensions suitable for vehicle mounting.
Solution Approach 2:
The patent replaces mechanical power increase (larger motor components) with electromagnetic control optimization. By using precise electrical signal detection and control of current flow timing in stator windings, the system achieves better acceleration performance through optimized electromagnetic field generation rather than through increased mechanical size or power capacity.
2Speed
If the cycle of current variation in stator windings is shortened to accelerate crankshaft rotation, then early-start ability is improved, but rotor followability deteriorates causing rotation failure
Solution Approach 1:
The patent implements feedback control by detecting the position of detection object parts on the rotor using dual-edge detection. The control device uses the detected forward end and rearward end signals to determine rotor position and adjust current flow timing accordingly. This feedback mechanism ensures that even with shortened current cycles, the rotor remains synchronized with the stator magnetic field, preventing rotation failure while achieving faster acceleration.
Solution Approach 2:
The patent dynamically adjusts the control strategy based on rotor position. By detecting both forward and rearward ends of detection object parts, the system can adapt current flow timing to match the rotor's rotational state at different phases. This dynamic control allows the system to maintain reliability during rapid acceleration by ensuring the rotor continuously follows the rotating magnetic field.
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 enhances early-start ability by improving rotor followability and detecting desynchronization early, thus accelerating crankshaft rotation while maintaining compact vehicle integration.
Implementation Method 1
As the detection object parts move along with rotation of the rotor, a magnetic state changes so that an electrical signal flowing in the detection-purpose winding varies.
Implementation Method 2
The rotor position detection device includes a detection-purpose winding. As the detection object parts move along with rotation of the rotor, a magnetic state changes so that an electrical signal flowing in the detection-purpose winding varies.
Implementation Method 3
The control device firstly performs on/off-operation of switching parts at predefined timings. As a result of the on/off-operation of the switching parts, a current flowing in the stator windings varies. The control device then performs on/off-operation of the switching parts at timings that are based on a variation in the electrical signal flowing in the detection-purpose winding. Thus, the control device is able to accelerate forward rotation of the crankshaft.
Data Source
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AI summary
An engine unit having its early-start ability further improved with suppression of deterioration in mountability to vehicle. The engine unit includes a four-stroke engine body, a starter motor, a plurality of detection object parts, a rotor position detection device having a detection-purpose winding, and an inverter having a plurality of switching parts. A control device: shifts from a start control mode for performing on/off-operation of the plurality of switching parts at predefined timings to start forward rotation of the crankshaft, to an acceleration control mode for performing on/off-operation of the plurality of switching parts at timings based on an electrical signal flowing in the detection-purpose winding to accelerate forward rotation of the crankshaft; and in time periods during which the start control mode and the acceleration control mode are performed, causes rotation of the rotor to follow a variation in a current flowing in the multi-phase stator windings by controlling on/off-operation of the plurality of switching parts based on both a timing of a variation corresponding to the forward end of the detection object part and a timing of a variation corresponding to the rearward end of the detection object part among variations in the electrical signal flowing in the detection-purpose winding.