Shift-by-wire transmission with manual park release mechanism
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Solution Overview
Problem
Existing shift-by-wire gear shift control systems in vehicles lose functionality when electrical power is lost, leading to inability to control transmission shifting, and there is a risk of the vehicle rolling away when parked.
Innovation Solution
A gear shift control system with first and second drive members, a drivetrain, and a retainer that allows manual operation or use of stored energy to shift gears even without electrical power, utilizing a planetary gear set and a drive gear that can be manually rotated to shift the transmission into or out of park gear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a shift-by-wire system is used to eliminate mechanical cable coupling, then ease of operation and control precision are improved, but reliability deteriorates when electrical power is lost
Solution Approach 1:
The system is divided into two independent drive members: a first drive member (electric motor) for normal operation and a second drive member (manual or spring-operated) for power failure operation. This segmentation allows each component to be optimized for its specific function while ensuring system reliability across different operating conditions.
Solution Approach 2:
The system changes its operational parameters based on power availability. During normal operation, the electric motor provides precise electronic control. During power failure, the system switches to mechanical operation via the second drive member, fundamentally changing how the shift mechanism is actuated while maintaining functionality.
2Device complexity
If a single electric motor is used for shift control, then device complexity is reduced, but reliability deteriorates when the motor fails or loses power
Solution Approach 1:
The drive mechanism is segmented into two independent drive members with distinct functions. The first drive member (electric motor) handles normal operation, while the second drive member (manual crank or spring mechanism) handles power failure scenarios. This segmentation increases redundancy without requiring a completely complex dual-system design.
Solution Approach 2:
The second drive member acts as a pre-prepared backup system that is already in place and ready to operate immediately upon power failure. This beforehand cushioning ensures that the system can continue functioning without interruption or damage, even when the primary electric drive fails.
3Ease of operation
If the transmission remains in drive position during power failure, then ease of operation is maintained, but harmful factors increase due to risk of unintended vehicle movement
Solution Approach 1:
The system automatically performs the action of shifting to park position as a preliminary response to power failure detection. This preliminary action prevents the harmful effect of unintended vehicle movement before it can occur, while the second drive member remains available if manual intervention is needed.
Solution Approach 2:
The power failure condition, which could lead to harmful unintended movement, is converted into a beneficial automatic safety feature. The loss of electrical power automatically triggers the shift to park position through the disengagement of the electromagnetic actuator, turning a potentially harmful situation into a safety mechanism.
4Reliability
If a mechanical cable coupling is used instead of shift-by-wire, then reliability during power failure is improved, but ease of operation and control precision deteriorate
Solution Approach 1:
The system segments the control mechanism into an electromagnetic actuator for normal operation (providing easy electronic control) and a mechanical cable connection for power failure operation (providing reliability). This allows the system to enjoy the benefits of both approaches in their respective operating conditions.
Solution Approach 2:
The shift control system is designed with multi-functionality to handle both normal and power failure conditions. The electromagnetic actuator provides precise electronic control during normal operation, while the mechanical cable connection provides reliable direct mechanical actuation during power failure, making the system universally capable across different operating scenarios.
Data Source
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Figure 2
Figure 3~5
AI summary
At least some implementations of a gear shift control system include first and second drive members, a drivetrain selectively driven by the first and second drive members and a retainer. The drivetrain includes a first input driven by the first drive member, a second input and an output coupled to and selectively driven by both the first input and the second input. The second drive member is coupled to the second input to drive the output through the second input during a second mode of operation to cause a transmission gear shift. The retainer is selectively coupled to the second input and movable between first and second positions to permit movement of the second input during the second mode of operation and prevent such movement during a first mode of operation.