Shift-by-wire Transmission Drivetrain for Power Loss Park
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Solution Overview
Problem
In vehicles with shift-by-wire systems, the loss of electrical power prevents drivers from controlling transmission shifting, and there is no mechanism to automatically shift the transmission into park, which can lead to unintended motion.
Innovation Solution
A gear shift control system that uses a drivetrain with a planetary gear set and electric motors to enable shifting between gears, including automatically shifting into park when electrical power is lost, utilizing a locking mechanism and a return spring to facilitate this operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a shift-by-wire system is used to eliminate mechanical cable linkages, then ease of operation and modern control capabilities are improved, but reliability deteriorates because the system becomes dependent on electrical power which may be lost
Solution Approach 1:
The patent applies local quality by creating different operational modes within the drivetrain system. The electric motor provides powered shifting control under normal conditions, while the manual input mechanism provides backup capability under power loss conditions. This localized differentiation of function within the same system resolves the contradiction between modern control ease and reliability.
Solution Approach 2:
The patent implements beforehand cushioning by designing the drivetrain with a manual input mechanism that can engage when electrical power is lost. This preparatory backup system ensures that the transmission can still be shifted into park even without electrical power, cushioning against the reliability failure mode of power loss.
2Loss of energy
If electrical power is lost to the vehicle, then energy conservation is improved, but the ability to control transmission shifting deteriorates
Solution Approach 1:
The patent applies self-service by enabling the manual input mechanism to independently operate the transmission shifting function when the electric motor cannot provide power. The manual mechanism serves itself and the system without requiring external electrical energy, allowing the driver to directly control the transmission into park mode during power loss.
3Reliability
If a manual backup mechanism is added to enable shifting without power, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by designing the drivetrain with components that serve multiple functions. The output mechanism and transmission shift mechanism are used by both the electric motor-driven first input and the manual second input. This multi-functionality allows the same hardware to operate in different modes (powered and manual) without requiring completely separate systems, thereby improving reliability while limiting the increase in complexity.
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
Ensures the transmission can be safely shifted into park even without electrical power, allowing for controlled shifting when power is restored, thereby preventing unintended vehicle motion.
Implementation Method 1
The gear set is coupled to the first drive member and the output shaft, and has three intermeshed gear elements which may include a ring gear, a sun gear and at least one planet gear
Implementation Method 2
using a combination of electric motors, worm gears, and locking mechanisms to manage gear rotations
Data Source
AI summary
At least one implementation of a gear shift control system includes an output mechanism coupled to a vehicle transmission, a first drive member coupled to the output mechanism to drive the output mechanism to shift between gears of the transmission and a drivetrain. The drivetrain may include a first input driven by the drive member during a first mode of operation of the gear shift control system and an output coupled to both the first input and the output mechanism to drive the output mechanism as commanded by the drive member. During a second mode of operation of the gear shift control system a second input is coupled to the output. A second drive member is coupled to the second input to drive the output mechanism through the second input and the output during the second mode of operation to cause a transmission gear shift.