Gearshift Unit Hollow Shaft Elastic Stop Noise Reduction
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Solution Overview
Problem
Existing gearshift units generate noise and provide an unpleasant actuation feeling when actuating the reverse gear due to the abrupt stop of the hollow shaft and potential clamping of fingers between the annular protrusion and the knob.
Innovation Solution
A gearshift unit with a spring holder featuring an elastic end stop that smoothly stops the hollow shaft at the release position, reducing noise and improving the actuation feel, using a two-part sleeve design with different materials for enhanced noise absorption and a bayonet connection for safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the hollow shaft is made of hard material to provide sufficient rigidity, then the structural strength is improved, but noise is generated when the annular protrusion strikes the knob
Solution Approach 1:
A plastic insert is introduced as an intermediary element between the hard hollow shaft and the knob. This insert absorbs the impact energy when the annular protrusion strikes the knob, preventing the generation of clicking noise while allowing the hollow shaft to maintain its hard material for structural rigidity.
Solution Approach 2:
The gearshift unit employs composite material construction by combining the hard hollow shaft with a plastic insert. This composite approach allows the system to simultaneously achieve the rigidity provided by the hard material and the noise reduction provided by the plastic material at the impact point.
2Reliability
If the hollow shaft stops abruptly at the release position, then the blocking function is achieved, but the actuation feeling becomes unpleasant
Solution Approach 1:
The plastic insert is positioned in advance within the hollow shaft to provide cushioning before the annular protrusion reaches the knob. This beforehand cushioning softens the stop at the release position, providing a pleasant actuation feeling while maintaining the reliability of the blocking function.
3Ease of operation
If the annular protrusion is pulled upwards to release the blocking, then the reverse gear can be selected, but fingers can be clamped between the protrusion and the knob
Solution Approach 1:
The plastic insert serves as a mediator between the annular protrusion and the knob, increasing the contact surface area and distributing the clamping force. This prevents finger clamping hazards while allowing the driver to pull the annular protrusion upwards to select reverse gear.
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 minimizes noise and enhances the actuation feel by using a soft plastic end stop and a two-part sleeve design, ensuring a smooth stop and reduced noise during gear shifts, while maintaining structural integrity and safety.
Implementation Method 1
a helical spring is disposed within the hollow shaft and biasing it in downward direction to a blocking position
Implementation Method 2
the material of the spring holder and the dimensions and shape of the end stop can be chosen such that the end stop elastically deforms when the hollow shaft approaches its release a position, to thereby smoothly slow down the upward movement of the hollow shaft
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The present invention is directed to a gearshift unit for a transmission of a vehicle, the gearshift unit comprising a blocking mechanism for blocking a shift lever (2) from being moved to a shifting gate including the reverse gear, said blocking mechanism comprising a hollow shaft (4) mounted to be slidable along a longitudinal direction of the shift lever, wherein an annular protrusion (42) is projecting radially from the upper end of the hollow shaft, which annular protrusion (42) may be grasped to lift the hollow shaft upwards to a release position in which the shift lever is free to be moved to the shifting gate including the reverse gear, wherein a helical spring (20) is disposed within the hollow shaft and biasing it in downward direction to a blocking position in which a stop member of the hollow shaft blocks movement of the shift lever to the shifting gate including the reverse gear, wherein a spring holder (80) fixed with respect to the shift lever supports one end of the spring (20) which acts with its opposite end on the hollow shaft (4) to urge it downwards, characterized in that the spring holder (80) is provided with an elastic end stop (82) projecting radially with respect to the shift lever axis and extending into an opening (48) of the wall of the hollow shaft, which opening (48) is arranged such that a lower edge (50) of the opening contacts the end stop (82) when the hollow shaft approaches the release position to smoothly stop movement of the hollow shaft at the release position.