Shift Drum Pawl Engagement to Prevent Repulsion and Rattling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing actuating arrangements for transmissions, particularly those using shift drums and pawls, face issues with unreliable gear engagement due to pawl repulsion and rattling, leading to increased wear and potential failure in shifting processes.
Innovation Solution
An actuating arrangement with a shift drum having inclined actuating surfaces and a pivotably mounted pawl, where the pawl is pretensioned by a spring and adjusted by the shift drum to ensure reliable engagement and disengagement with shift elements, utilizing specific angular positions to control the pawl's movement and prevent unwanted engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pawl is adjusted slowly with a rapidly rotating shift element part, then the pawl can engage with the outer toothing, but the pawl strikes the tooth tip and rebounds, causing rattling and increased wear
Solution Approach 1:
The patent applies preliminary action by introducing a damping element that is pre-positioned between the pawl and the shift element part. This damping element is already in place before engagement occurs, ready to absorb冲击 energies and prevent the pawl from rebounding when it strikes the tooth tip. The damping element prepares the engagement path in advance to eliminate harmful repulsion and rattling.
Solution Approach 2:
The patent directly implements beforehand cushioning by placing a damping element (such as a rubber or elastomeric material) between the pawl and the shift element part. This cushioning element is positioned in advance to absorb the impact when the pawl engages with the outer toothing, preventing the pawl from striking the tooth tip with excessive force and thereby eliminating rebound and rattling.
2Reliability
If the pawl engagement process is extended over time to ensure proper engagement, then engagement reliability improves, but the shifting process becomes excessively long
Solution Approach 1:
The damping element is pre-positioned between the pawl and shift element part to ensure that engagement occurs smoothly and reliably in a single action. This preliminary preparation allows the pawl to engage correctly without requiring extended time for multiple attempts or adjustments, thereby maintaining reliability while minimizing shifting duration.
Solution Approach 2:
The damping element enables the pawl to rush through the engagement process quickly and reliably. By absorbing impact and preventing rebound, the damping element allows the engagement to complete in one swift motion rather than requiring prolonged adjustment periods or multiple attempts, thus reducing time loss while maintaining engagement reliability.
3Reliability
If the pawl is pretensioned by a spring to ensure engagement, then engagement reliability improves, but the risk of unwanted engagement and rattling increases
Solution Approach 1:
The damping element is positioned between the pawl and shift element part to cushion any unwanted engagement caused by spring pretension. When the pawl accidentally strikes the outer toothing due to pretension, the damping element absorbs the impact energy, preventing rebound and rattling. This allows the use of spring pretension for reliable engagement while eliminating the harmful effects of unwanted engagement.
Solution Approach 2:
The damping element converts the potentially harmful impact from unwanted engagement into a beneficial cushioning effect. Instead of allowing the spring pretension to cause damaging rebounds and rattling, the damping element absorbs this energy, transforming what would be a harmful force into a protective mechanism that reduces wear and eliminates noise while maintaining engagement reliability.
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
The solution ensures reliable and efficient gear changes by preventing pawl repulsion and rattling, reducing wear, and allowing for precise control over gear engagement, thereby improving the reliability and speed of shifting processes.
Implementation Method 1
The actuating arrangement has an actuating device which is configured to adjust the pawl out of the released position into the engaged position
Data Source
AI summary
An actuating arrangement for a transmission includes a pivotable pawl (14) and a rotatable shift drum (10). By rotating in a first rotational direction from a first into a second angular position, the shift drum (10) is configured to push the pawl (14) with the actuating surface (20) out of an engaged position into a released position and by rotating in the second rotational direction from the second into the first angular position to enable the pawl (14) to drop out of the released position into the engaged position. The actuating arrangement includes an actuating device (30) configured to adjust the pawl (14) out of the released position into the engaged position. The pawl (14) is adjusted by the actuating device (30) out of the released position into the engaged position only in a third angular position of the shift drum (10) between the first and the second angular position.