Park Pawl Sensor Assembly for Transmission Engagement Verification
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Solution Overview
Problem
Conventional park pawl mechanisms in automatic transmissions are prone to errors, as they only monitor the actuation of the park pawl linkage upstream and not the actual engagement with the output gear, compromising safety by potentially allowing vehicle movement before failure is detected.
Innovation Solution
A park pawl engagement and sensor assembly that includes two sensors: one to monitor the actuation of the park pawl linkage and another to ensure actual engagement with the output gear, providing real-time monitoring without relying on sensing the output gear's rotation, thus ensuring safety by confirming engagement before vehicle movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single sensor monitors the actuation of the park pawl linkage upstream, then the device complexity is reduced, but the reliability of preventing vehicle movement is compromised because actual engagement cannot be confirmed
Solution Approach 1:
The patent combines multiple sensor functions into a single integrated sensor assembly that monitors both linkage actuation and park pawl engagement simultaneously. This merging approach maintains high reliability through comprehensive monitoring while reducing device complexity by replacing what would otherwise be multiple separate sensors and assemblies with one unified component.
Solution Approach 2:
The sensor assembly performs multiple monitoring functions through a single device: it detects both the actuation of the park pawl linkage and the actual engagement of the park pawl with the output gear. This multi-functionality ensures comprehensive safety monitoring without proportionally increasing device complexity, as one assembly accomplishes what would traditionally require separate monitoring systems.
2Reliability
If multiple sensors are used to monitor both linkage actuation and actual engagement, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The patent integrates multiple sensing capabilities into a single sensor assembly located at the output gear. This assembly simultaneously monitors linkage actuation and park pawl engagement, achieving high reliability through comprehensive monitoring while avoiding the complexity of multiple separate sensor installations throughout the transmission system.
Solution Approach 2:
The sensor assembly acts as an intermediary monitoring point at the output gear that indirectly detects both linkage actuation and park pawl engagement through the gear's rotational state. This intermediary approach provides reliable dual-function monitoring without requiring direct access to or installation on both the linkage and park pawl components, thereby reducing overall system complexity.
3Reliability
If the output gear rotation is sensed to confirm engagement, then the reliability is improved, but the measurement precision is reduced because it only detects rotation after failure has occurred
Solution Approach 1:
The sensor assembly performs preliminary monitoring of the output gear rotation to detect park pawl engagement before any potential failure or vehicle movement can occur. By continuously monitoring gear rotation and comparing it against expected engagement patterns, the system identifies engagement status proactively, enabling preventive action rather than reactive detection after failure.
Solution Approach 2:
The sensor assembly provides continuous feedback on the output gear rotation status to the control system, enabling real-time verification of park pawl engagement. This feedback mechanism allows the system to confirm proper engagement before allowing vehicle operation, thereby maintaining high measurement precision and reliability by detecting engagement status rather than merely responding to failure conditions.
Data Source
AI summary
A park pawl assembly for use in a vehicle with an automatic transmission, including: a park pawl member comprising a raised tooth structure disposed at an end thereof, wherein the raised tooth structure is configured to selectively engage a corresponding recessed structure of an output gear, thereby selectively preventing rotation of the output gear; a linkage physically contacting the end of the park pawl member and configured to selectively bias the raised tooth structure of the park pawl member into the recessed structure of the output gear; a control arm physically coupled to the linkage and configured to selectively actuate the linkage; a first sensor component coupled to and configured to sense actuation of one or more of the linkage and the control arm; and a second sensor component coupled to and configured to sense actuation of the park pawl member.