Dual-Input Gearbox Switching to Prevent Backdriving
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Solution Overview
Problem
Existing transmissions, particularly in military and electric vehicle applications, face challenges in quickly and safely switching between manual and motorized inputs to prevent backdriving and ensure operator safety, with a need for a dual bidirectional input single bidirectional output transmission that allows independent or simultaneous torque transmission with different gear ratios and seamless switching.
Innovation Solution
A dual bidirectional input single bidirectional output gearbox with a constant mesh gear train design, eliminating sliding splines and synchronizers, utilizing a clutch or brake to switch between inputs, and incorporating a planetary gear set to combine torques, prioritizing one input and preventing backdriving through a reverse locking clutch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a manual input and motorized input are used in a drive unit, then the operator can control the drive unit through multiple inputs, but the manual input may not quickly disengage from the output such that when the motorized input is used, the manual input is also actuated compromising safety
Solution Approach 1:
A clutch mechanism is introduced as an intermediary between the manual input and the output shaft. The clutch selectively engages or disengages the manual input from the output, allowing the motorized input to operate independently without the manual input being actuated. This mediator component enables safe switching between input modes while maintaining the versatility of multiple input options.
2Adaptability or versatility
If sliding splines or synchronizers are used to switch between operational modes, then the transmission can change gear ratios, but the reliability decreases due to wear and potential failure of these components
Solution Approach 1:
The patent extracts and eliminates the sliding splines and synchronizers from the transmission system. Instead of using these wear-prone components for gear ratio changes, the design employs a constant mesh gear train where gears are permanently engaged. Gear ratio switching is achieved through alternative means that do not require sliding contact, thereby removing the source of wear and improving component durability and overall reliability.
Solution Approach 2:
Rather than using sliding splines to engage and disengage gears (the conventional approach), the patent inverts the approach by keeping all gears constantly engaged in mesh. The gear ratio changes are achieved by selectively blocking or unblocking specific gear paths using more reliable mechanisms such as brakes or one-way clutches, reversing the conventional engagement/disengagement paradigm.
3Adaptability or versatility
If dog clutches are used for switching between inputs, then the transmission can change modes, but the complexity and potential for harmful factors increases
Solution Approach 1:
The patent replaces the mechanical dog clutch system with a brake-based system for input switching. Instead of using dog clutches that engage through impact and generate noise and wear, the design uses brakes to selectively lock or unlock the manual input shaft. This substitution eliminates the harmful impact forces and noise associated with dog clutch engagement while maintaining the ability to switch between input modes.
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 provides high reliability, seamless switching, and safety by preventing backdriving, allowing independent or simultaneous torque transmission with different gear ratios, enhancing operator safety and ease of use in military and electric vehicle applications.
Implementation Method 1
the gear train may be a constant mesh system which eliminates sliding splines, dog clutches or synchronizers
Implementation Method 2
By use of a clutch or brake, the power or torque transmitted from a first bidirectional torque input to the common bidirectional output using a second bidirectional input as a fixed rotation reference
Implementation Method 3
The disclosure may also include a planetary gear set load combiner to cause both bidirectional torque inputs to transmit torque or power to the common torque output simultaneously
Data Source
AI summary
A method of operating a dual bidirectional input to single bidirectional output transmission is disclosed. The method includes providing said transmission. The method includes activating a computer controller capable of receiving torque data signals from a first bidirectional torque input, a second bidirectional torque input, and a single bidirectional torque output. The method includes determining torque input from said first and second bidirectional torque input, and determining whether to transmit torque to said single bidirectional torque output. In cases where it is so determined, the method involves transmitting torque to said single bidirectional torque output.