Variable Pitch Gearbox Actuator for Compact High-Torque Shifting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing gearbox actuators for shift-by-wire vehicle transmissions require large dimensions to provide sufficient torque for different transmission modes, leading to bulkiness and inefficiency.
Innovation Solution
A gearbox actuator design featuring a connecting element with a control wire and shaft, incorporating a first and second shaft guide, and a toothed rack with a variable radius toothed element, which allows for variable pitch gearing and reduced overall dimensions by adjusting the gear ratio and pressure angles to optimize torque delivery across different gearshift positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If high gear ratio systems with gears of different diameters are used to provide higher torque for certain transmission modes, then the torque capability is improved, but the overall dimensions of the gearbox actuator become large and bulky
Solution Approach 1:
The patent applies variable pitch gearing where the pitch of the toothed rack varies along its length, allowing the gear ratio to change dynamically during actuator operation. This enables the system to provide high torque when needed (for certain transmission mode changes) while maintaining compact overall dimensions, as the variable pitch allows optimized force transmission without requiring large diameter gears throughout the entire mechanism
Solution Approach 2:
The invention changes the geometric parameter of the gear system by using a toothed rack with variable pitch rather than constant pitch. This parameter change allows the gear ratio to be adjusted during operation, enabling the actuator to deliver high torque for specific transmission mode changes while avoiding the need for large overall dimensions that would be required with traditional fixed high gear ratio systems
2Force
If large diameter rotating parts are used to provide required torque for changing between different transmission modes, then the torque delivery is improved, but the actuator overall dimensions are increased
Solution Approach 1:
The variable pitch toothed rack creates a dynamic gear ratio system where the effective gear ratio changes as the rack moves. This allows the actuator to use smaller rotating parts compared to traditional systems, as the variable pitch compensates for the reduced diameter by optimizing the mechanical advantage at different positions in the actuation range
Solution Approach 2:
Instead of increasing the diameter of rotating parts in the radial dimension to achieve higher torque, the invention transitions to utilizing the axial dimension of the toothed rack with variable pitch. This dimensional shift allows torque optimization without requiring large radial dimensions, thereby reducing the overall actuator size
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 design enables efficient torque delivery across various gearshift positions with reduced actuator size, allowing for a smaller motor and reduced packaging and weight, while maintaining adaptability and ease of placement.
Implementation Method 1
transforming electric energy via an electric motor into motion
Implementation Method 2
The worm gear in turn engages a third gear attached to a variable radius toothed element
Implementation Method 3
The toothed element engages a toothed end face arranged in a variable radius rotatable output lever... the toothed element and the inclined toothed rack both define a variable pitch gearing
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The gearbox actuator (100) for remotely actuating a gearbox (200) in a motor vehicle transmission comprises a connecting element (110) for connecting the gearbox actuator (100) to the gearbox (200); a motor (120) to drive a first driving gear (130) for transferring torque to the gearbox (200) through the connecting element (110); a second driven gear (140) engaging the first driving gear (130) and associated with a worm gear (150); a third driven gear (160) engaging the worm gear (150); a toothed element (170) for rotating with the third driven gear (160); and a toothed rack (180) extending along a rack extending axis (X) attached to the connecting element (110), engaging the toothed element (170), and comprising a toothed surface (181) inclined to the rack extending axis (X), and the toothed element (170) comprises a toothed curved surface (171) having a variable radius with respect to an axis of rotation (Y) of the third driven gear (160), such that the toothed rack (180) and the toothed element (170) define a variable pitch gearing.