ATV Reverse Gear Protection via Dynamic Speed Limiting
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Solution Overview
Problem
High-torque all-terrain vehicle (ATV) engines experience gear misalignment and breakage during reverse operation due to flexing drive shafts under heavy loads, particularly when transitioning from low to high traction surfaces or when stuck, as existing rev limiters fail to manage power effectively.
Innovation Solution
A reverse system for ATVs that engages four-wheel-drive mode when the override switch is activated, allowing higher engine speeds and balancing load distribution across the drive shaft to prevent gear misalignment, using a reverse actuator, engine speed limiter, and override switch connected to a two-/four-wheel-drive selector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rev limiter is used to control engine speed during reverse operation, then gear breakage is prevented under normal conditions, but the system cannot provide sufficient power when the ATV is stuck or needs to back up a steep ramp
Solution Approach 1:
The patent implements a dynamic rev limiter system that automatically adjusts the engine speed limit based on drive mode. In two-wheel-drive reverse mode, the rev limiter maintains a lower speed threshold to protect gears. When four-wheel-drive reverse mode is engaged, the system dynamically raises the speed threshold, allowing higher engine speeds and power output without causing gear breakage, thus resolving the contradiction between reliability and power.
Solution Approach 2:
The system changes the operational parameters of the rev limiter based on the selected drive mode. The predetermined engine speed threshold is modified according to whether two-wheel-drive or four-wheel-drive reverse operation is active, enabling the system to provide appropriate power levels while maintaining gear protection under each specific operating condition.
2Reliability
If the drive shaft is made more rigid to prevent flexing under heavy reverse loads, then gear misalignment is reduced, but the system adds excessive weight and cost
Solution Approach 1:
The patent replaces the mechanical solution of reinforcing the drive shaft with a control system solution. Instead of adding physical strength through heavier materials or additional bearings, the system uses electronic control to monitor and regulate engine speed based on drive mode, preventing the conditions that cause shaft flexing and gear misalignment without any mechanical modifications to the shaft itself.
Solution Approach 2:
The system prevents gear misalignment by changing the operational parameters (engine speed limits) rather than the physical parameters (shaft rigidity). By controlling the engine speed to appropriate levels based on drive mode, the system eliminates excessive flexing forces without requiring a heavier, more rigid drive shaft.
3Power
If the engine speed limit is increased to allow higher power output, then the ATV can overcome stuck conditions, but the drive shaft flexes more and gear teeth misalign and break
Solution Approach 1:
The patent implements a dynamic speed limiting system that adapts the engine speed threshold based on the selected drive mode. During two-wheel-drive reverse operation, a lower speed limit protects the gear system. When four-wheel-drive reverse mode is activated, the system dynamically increases the speed limit, allowing higher power output while the four-wheel-drive configuration provides balanced load distribution that prevents shaft flexing and gear misalignment.
Solution Approach 2:
The control system acts as an intermediary between the driver's power demands and the mechanical gear system. By monitoring the drive mode selection and automatically adjusting the rev limiter threshold accordingly, the system mediates between the need for high power output and the need to protect the gear system, allowing high speeds only when the four-wheel-drive configuration provides adequate mechanical protection.
Data Source
AI summary
A reverse system for an all-terrain vehicle (ATV) having an engine and an engine drive shaft, a reverse activator, an engine speed limiter, and an override switch. The reverse activator is coupled to the drive shaft. The reverse activator activates operation of the ATV in a reverse direction. The engine speed limiter limits engine speed to below a predetermined level while the reverse activation switch is engaged. The override switch allows engine speeds above the predetermined level only when the transmission is in four-wheel-drive. The method of carrying out the invention is also disclosed.