Shift Cam Mechanism for Smooth Gear Synchronization
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Solution Overview
Problem
Conventional vehicular multi-speed transmissions with multiple clutches face difficulties in smooth gear shifting due to synchronization issues between gear ratio switching units and gears, requiring substantial force for connection, which is challenging with existing shift mechanisms that cannot apply large torque to shift cams.
Innovation Solution
A shift mechanism with a configuration that includes a shift cam and follower cam mechanism, allowing for seamless power transfer between odd-numbered and even-numbered gears using friction drive clutches, enabling smooth gear shifting by selectively engaging and disengaging clutches to synchronize gear connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dog mechanism is used to connect gear ratio switching units and gears, then gear connection reliability is improved, but synchronization difficulties require substantial connection force that existing shift mechanisms cannot provide
Solution Approach 1:
The shift mechanism applies preliminary torque to the shift cam before the actual gear connection occurs. This preliminary action prepares the synchronization by pre-positioning the gear ratio switching unit and reducing the synchronization error, so that when the dog mechanism engages, the required connection force is significantly reduced and the engagement is more reliable.
Solution Approach 2:
The shift cam acts as an intermediary mechanism between the shift fork and the gear ratio switching unit. By applying torque through the shift cam and follower cam mechanism, the system mediates the connection process, allowing controlled synchronization and reducing the impact force required for dog mechanism engagement.
2Reliability
If substantial force is applied to synchronize gear ratio switching units and gears, then connection reliability is improved, but existing shift mechanisms cannot apply large torque to shift cams
Solution Approach 1:
The follower cam mechanism serves as an intermediary that amplifies and transmits torque to the shift cam. This mechanism enables the shift mechanism to apply large torque to the shift cam by using the follower cam to convert the motion and force from the actuator into effective torque on the shift cam, thereby achieving reliable synchronization without requiring the actuator itself to generate extremely high torque.
Solution Approach 2:
The cam profiles (shift cam and follower cam) utilize curved surfaces to transform rotational or linear motion into the desired reciprocating motion with variable force characteristics. The curved cam surfaces allow the mechanism to apply torque progressively and smoothly, enabling large torque application during critical synchronization phases while maintaining control.
3Ease of operation
If gear ratio switching units and gears are connected with precise synchronization, then smooth gear shifting is achieved, but synchronization issues cause connection difficulties in conventional transmissions
Solution Approach 1:
The follower cam mechanism provides a form of mechanical feedback by maintaining continuous contact with the shift cam. This contact allows the system to sense and adjust for synchronization errors in real-time during the shifting process, ensuring that the gear ratio switching unit and gear are properly aligned before engagement, thereby achieving smooth gear shifting even with normal manufacturing tolerances.
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 dependable gear connection and smooth shifting by applying the necessary torque through the shift cam and follower cam mechanism, improving the connection between gear ratio switching units and gears, thus enhancing the overall gear shifting process.
Implementation Method 1
friction drive clutches
Implementation Method 2
shift cam and follower cam mechanism
Data Source
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AI summary
A shift mechanism, within a transmission and adjacent to shift forks (143-144), that moves the shift forks (143-144) connected to a gear of the transmission and changes a gear position of the transmission, comprises a rotatable shift cam (14) that has, on an outer peripheral surface, cam grooves (14a-14d) to which the shift forks (143-144) are connected, the shift forks (143-144) being configured to be moved upon rotation of the shift cam (14); and a cam phase holding means (801, 813, 814, 145, 791, 792, 793, 794, 795, 796) configured to hold the shift cam (14) at one of a plurality of rotation angles. The cam phase holding means comprises a first rotating member (801) comprising a projecting section (813) and a concave section (814); a groove section (145) on the outer peripheral surface of the shift cam (14); a plurality of springs (791, 792); a plurality of moving members (793, 794), wherein each moving member (793, 794) abuts against one end of one spring (791, 792); and a plurality of balls (795, 796), wherein each ball is biased towards at least one of the first rotating member (801) and the shift cam (14) by one spring of the plurality of springs (791, 792) via one moving member of the plurality of moving members (793, 794). The shift mechanism further comprises a second rotating member (803) configured so as to be able to rotate in forward and reverse directions from a reference position, and to rotate the shift cam (14); a transferring means, comprising a first transferring member (807) and a third rotating member (805), configured to rotate in response to a motor rotation, to rotate in one of the forward and reverse directions from the reference position, and to transfer the rotation to the second rotating member (803) thereby rotating the second rotating member (803); a regulating member (804) configured to hinder, while the transferring means (805) is rotating in one direction in response to the motor rotation, the rotation of the second rotating member (803) until a predetermined rotation angle is reached, and to allow the rotation of the second rotating member (803) at or above the predetermined rotation angle; a biasing member (808) configured to increase a bias following an increase in a rotation angle of the third rotating member (805) in the one direction; and an accumulated torque releasing means (804, 805) configured to release, when the rotation angle of the third rotating member (805) reaches the predetermined rotation angle, the bias accumulated in the biasing member (808) and thus causing rotation of the second rotating member (803) in response to the rotation of the transferring means, wherein the second rotating member (803) rotates due to the bias released from the biasing member (808), thereby rotating the first rotating member (801) and the shift cam (14) rotates due to the rotation of the first rotating member (801).