Transmission Shifter Actuator Assembly With Compact Multi-Stage Gearing
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Solution Overview
Problem
In vehicles with shift-by-wire systems, the loss of electrical power disrupts the ability to control transmission gear shifts, and the compact nature of the shift control unit's location limits the use of larger components or connecting members between the shift control unit and the transmission.
Innovation Solution
A gear shift actuator assembly featuring an electrically operated drive member with a drivetrain that includes multiple stages of gears providing torque increase and direction change, allowing for a compact design that can be used in confined spaces and enabling gear shifts even without electrical power, using a combination of spur, bevel, face, crown, or hypoid gears.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a shift-by-wire system is used to eliminate cables and mechanical linkages, then device complexity and vehicle weight are reduced, but the system becomes vulnerable to electrical power loss and requires additional safety mechanisms
Solution Approach 1:
A mechanical cable connects the shift control unit to the transmission shift mechanism, serving as a backup intermediary that enables gear shifting when electrical power is lost. The cable acts as a fail-safe mechanism that bridges the control unit and transmission mechanically, ensuring operational reliability during electrical failures.
2Volume of moving object
If the shift control unit is located in a confined space adjacent to the transmission, then ease of installation and compact vehicle layout are improved, but the ability to accommodate larger motors and drivetrain components is reduced
Solution Approach 1:
The drivetrain is divided into multiple gear stages (first portion, second portion, third portion) that can be arranged in a compact configuration. Each gear stage provides incremental torque multiplication, allowing the total torque output to reach 150:1 or 300:1 while keeping individual gear sizes manageable and the overall assembly compact enough for confined spaces.
Solution Approach 2:
The drivetrain uses multiple gear stages arranged in series, exploiting the dimensional aspect of torque multiplication through gear ratios. By stacking gear reductions across multiple stages rather than using a single large gear, the system achieves high torque output in a compact volume suitable for confined installation spaces.
3Power
If a high torque output is required from the motor to overcome transmission resistance, then gear shift reliability is improved, but the motor size and system cost increase
Solution Approach 1:
The drivetrain is segmented into multiple gear reduction stages that collectively provide torque multiplication of 150:1 to 300:1. This segmentation allows a small, cost-effective motor to generate sufficient torque through cumulative gear reductions rather than requiring a single large, expensive motor.
Solution Approach 2:
The multi-stage drivetrain acts as a mechanical intermediary between the small motor and the transmission shift mechanism. The drivetrain components (gears, shafts, bearings) serve as intermediaries that amplify the motor's limited torque output to the high levels needed for reliable gear shifting.
4Weight of moving object
If a compact actuator assembly is used to fit confined spaces, then vehicle weight and fuel efficiency are maintained, but the available space for drivetrain components is limited
Solution Approach 1:
The drivetrain is divided into three portions with multiple gear stages arranged compactly. This segmentation enables efficient space utilization where each gear stage contributes to torque multiplication while maintaining a compact overall footprint suitable for weight-sensitive applications.
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 actuator assembly provides a significant torque increase, allowing a smaller and less expensive motor to be used while ensuring reliable gear shifts, and its compact design fits within confined spaces, maintaining vehicle weight reduction and fuel efficiency.
Implementation Method 1
an electric motor having a drive shaft driven by the motor for rotation about a first axis
Implementation Method 2
The drivetrain may include a plurality of gears that provide a mechanical advantage that amplifies the torque of the motor
Implementation Method 3
The drive gear may be rotated about a first axis and a first gear may be meshed with and driven by the drive gear for rotation about a second axis offset from and parallel to the first axis
Data Source
AI summary
In at least some implementations, a gear shift actuator assembly to cause gear changes in a vehicle transmission includes an electrically operated drive member, a drivetrain driven by the drive member and having a plurality of gears arranged in a plurality of stages to provide a torque increase and a direction change within the drivetrain and an output driven by the drivetrain for rotation to cause a gear change in the vehicle transmission. In some implementations, the torque increase from the motor to the output is between 150:1 and 300:1.