Crankshaft Starter Generator Ring Gear Position Sensing
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Solution Overview
Problem
Conventional methods for detecting the rotational position of a crankshaft starter generator's rotor relative to the stator are costly and space-intensive, requiring complex manufacturing processes and additional components that can hinder the starter engagement process.
Innovation Solution
A crankshaft starter generator design featuring a starter ring gear and a second ring gear with a distinct tooth structure, where the second ring gear serves as a sensor wheel to detect the rotational position without the need for a reference mark on the starter sprocket, and an inductive or capacitive receiving element scans both encoder tracks to determine the rotor's position relative to the stator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a cup-shaped or pot-shaped component with a sensor track is added to detect rotor position, then the rotor's rotational position can be detected, but the manufacturing complexity and production costs increase due to complex manufacturing processes such as milling, and the installation space requirement increases significantly
Solution Approach 1:
The patent combines the starter ring gear and sensor ring gear into a single integrated component on the flywheel. The starter ring gear serves dual purposes: enabling starter motor engagement and providing the sensor track for position detection. This eliminates the need for separate cup-shaped or pot-shaped components, reducing manufacturing complexity and installation space while maintaining accurate rotor position detection capability
Solution Approach 2:
The starter ring gear is designed to perform multiple functions simultaneously: it serves as the engagement gear for the starter pinion and as the sensor track for the position sensor. This multi-functionality eliminates the need for separate dedicated position detection components, reducing overall device complexity and production costs while maintaining measurement precision
2Measurement precision
If a reference mark is added to the starter ring gear for position detection, then the rotor position can be detected, but the engagement path of the starter pinion is obstructed and the starting process is impeded
Solution Approach 1:
The patent segments the ring gear into two distinct components: the starter ring gear with full circumferential teeth for uninterrupted starter pinion engagement, and a separate sensor ring gear with a reference mark for position detection. This segmentation allows each component to fulfill its specific function without interfering with the other, enabling both smooth starting operation and accurate position detection
Solution Approach 2:
The patent introduces a separate sensor ring gear as an intermediary component that provides the reference mark functionality without interfering with the starter ring gear's engagement path. The sensor ring gear acts as a mediator between the flywheel rotation and the position sensor, allowing accurate position detection while leaving the starter engagement path clear and unobstructed
3Measurement precision
If a modified starter ring gear with a reference mark is used, then the angular position can be detected, but the technical complexity of connecting the modified starter ring gear to the flywheel increases to ensure correct positioning
Solution Approach 1:
The patent segments the position detection function into a separate sensor ring gear that can be independently manufactured and positioned on the flywheel. This segmentation simplifies the assembly process by allowing the sensor ring gear to be mounted separately with its reference mark pre-aligned, avoiding the need for complex modifications to the starter ring gear and reducing assembly complexity while maintaining angular position detection accuracy
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 design reduces manufacturing complexity and space requirements while accurately determining the rotor's position, allowing for a more compact and efficient crankshaft starter generator system.
Implementation Method 1
an inductively or capacitively operating receiving element (7) which is configured to detect, by scanning, a first sensor track of the starter ring gear (5) formed by a rotating first tooth structure and a second sensor track of the second ring gear (6) formed by a rotating second tooth structure
Implementation Method 2
an inductively or capacitively operating receiving element (7) which is configured to detect, by scanning, a first sensor track of the starter ring gear (5) formed by a rotating first tooth structure
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a crankshaft starter generator comprising a stator (3), a rotor (4), a rotor carrier (2), and a starter ring gear (5) non-rotatably connected to the rotor carrier and arranged on a cylindrical surface (2a) of the rotor carrier (2). The crankshaft starter generator further comprises a second ring gear (6) non-rotatably connected to the rotor carrier and arranged axially offset from the starter ring gear on the cylindrical surface (2a) of the rotor carrier (2).