Sliding Camshaft Trigger Wheel Axial Adjustment
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Solution Overview
Problem
In vehicle engines, runout in the trigger wheel of the camshaft leads to inaccurate data for the engine control unit, resulting in inefficiencies and sub-optimum engine performance due to irregular radial distance between the trigger wheel and the sensor, causing slight out-of-sync movement between the camshaft and crankshaft.
Innovation Solution
A sliding camshaft design featuring a base shaft, an over-molded trigger wheel, and a distal axially movable structure with a control groove, allowing the trigger wheel to move between positions via an actuator, ensuring accurate communication with the sensor regardless of its position and reducing runout by maintaining a constant radial distance with the sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the trigger wheel is press-fitted on the camshaft with traditional design, then the structure is simple, but runout occurs due to misalignment between the trigger wheel axis and camshaft axis, resulting in inaccurate sensor readings
Solution Approach 1:
The trigger wheel is made axially movable along the camshaft journal instead of being fixed in position. This dynamic adjustment allows the trigger wheel to be positioned at multiple axial locations, enabling the system to find the optimal position that minimizes runout and maximizes sensor reading accuracy while maintaining a relatively simple overall structure
Solution Approach 2:
The camshaft structure is divided into separate functional components: the camshaft journal, the axially movable trigger wheel, and the sensor positioning mechanism. This segmentation allows independent optimization of each component's function, particularly enabling the trigger wheel to move axially to achieve proper alignment with the sensor while keeping other parts unchanged
2Ease of manufacture
If the trigger wheel axis is not aligned with the camshaft axis, then manufacturing and assembly are easier, but runout occurs causing irregular radial distance between trigger wheel and sensor
Solution Approach 1:
The trigger wheel is designed with axial movability along the camshaft journal, allowing it to be positioned dynamically to achieve proper alignment with the sensor. This eliminates the need for precise pre-alignment during manufacturing and assembly, as the trigger wheel can be adjusted axially to compensate for minor misalignments
Solution Approach 2:
The system incorporates self-adjusting features where the trigger wheel can be positioned axially to automatically achieve optimal alignment with the sensor. The design includes self-centering mechanisms and tolerance compensation that allow the assembly to self-correct minor alignment issues without requiring high-precision manufacturing
3Volume of moving object
If the radial distance between trigger wheel and sensor varies during rotation, then the structure can accommodate larger components, but measurement accuracy decreases due to runout
Solution Approach 1:
The trigger wheel is made axially movable to maintain a constant radial distance from the sensor during rotation. By allowing axial movement, the system can adjust the trigger wheel's position to ensure the outer edge of the trigger wheel remains at a consistent radial distance from the sensor, eliminating runout-related measurement errors while accommodating larger trigger wheel sizes
Data Source
AI summary
A sliding camshaft is provided which may include a base shaft, an over-molded trigger wheel, and a distal axially movable structure. The distal axially movable structure may further include a distal journal in addition to at least one standard journal and lobe packs. A control groove is defined in the distal axially movable structure. The over-molded trigger wheel is mounted on the distal axially movable structure. The over-molded trigger wheel is operatively configured to move between at least a first position and a second position together with the distal axially movable structure via engagement between the control groove and an actuator. The over-molded trigger wheel may be press fitted on distal axially movable structure and is adapted to accurately communicate with a sensor regardless of the position of the distal axially movable structure.