Utility Vehicle Auto Shift Control for Smooth Speed Range Changes
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Solution Overview
Problem
Utility vehicles face challenges with manual shifting between speed ranges, leading to jerky operations, engine bogging, and excessive stress on mechanical and hydraulic systems, as operators often default to one speed range for convenience, limiting versatility and increasing wear.
Innovation Solution
An automatic shift control system for utility vehicles, using an electronic controller to monitor drive motor speed and other conditions, automatically shifting between low and high speed ranges to optimize performance and reduce operator fatigue, mimicking smooth transitions like continuously variable transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual speed range selection is used, then the operator can control the vehicle speed, but jerky operation occurs during upshifting and downshifting
Solution Approach 1:
The control system monitors engine speed and load conditions before initiating a speed range shift, and delays the shift until appropriate conditions are met. This preliminary monitoring and conditional delay prevents jerky transitions by ensuring the engine is ready for the load change associated with shifting.
Solution Approach 2:
The system continuously monitors engine speed, load conditions, and current speed range, and uses this feedback to determine the optimal timing for upshifting and downshifting. This closed-loop control ensures shifts occur only when engine conditions support smooth transitions, eliminating jerky operation.
2Speed
If manual upshifting is performed under high engine load, then the vehicle can achieve high speed, but the engine bogs down due to excessive load
Solution Approach 1:
The control system monitors engine load conditions in real-time and uses this feedback to prevent upshifting when the engine is under excessive load. By continuously comparing current engine parameters against thresholds for safe shifting, the system avoids bogging down while still enabling high-speed operation when conditions permit.
Solution Approach 2:
The system evaluates engine load conditions before permitting an upshift, and only allows the transition when the engine has sufficient capacity to handle the increased demand. This preliminary check prevents high-load upshifting that would cause bogging, while still achieving high speeds when engine conditions are favorable.
3Speed
If manual downshifting is performed, then the vehicle can achieve high acceleration, but jerky operation and excessive engine revving occur
Solution Approach 1:
The control system monitors current speed range, vehicle speed, and engine conditions, and uses this feedback to determine the optimal timing for downshifting. This ensures downshifts occur when they will provide acceleration without causing excessive revving or jerky transitions, smoothing the deceleration process while maintaining performance.
Solution Approach 2:
The system evaluates current operating conditions before initiating a downshift, and delays the transition until conditions favor smooth deceleration. This preliminary assessment prevents premature downshifts that would cause excessive engine revving, while still achieving rapid acceleration when appropriate.
4Ease of operation
If the vehicle operates continuously in low speed range, then fine control and high tractive effort are available, but travel speed between worksites is limited
Solution Approach 1:
The control system dynamically adjusts the speed range based on real-time monitoring of vehicle speed, operator inputs, and operating conditions. This allows the vehicle to automatically transition between low and high speed ranges, providing fine control when needed while enabling high-speed travel between worksites without operator intervention.
Solution Approach 2:
The system autonomously manages speed range selection by monitoring vehicle operations and automatically shifting between ranges based on detected conditions. This self-service capability eliminates the need for manual speed range changes, allowing the vehicle to maintain precision control during work operations while automatically enabling high-speed travel when moving between worksites.
5Speed
If the vehicle operates continuously in high speed range, then rapid transport between worksites is achieved, but the machine struggles to dig or move soil effectively
Solution Approach 1:
The control system dynamically monitors operating conditions including vehicle speed, hydraulic system demands, and work operation intensity, and automatically adjusts the speed range accordingly. This enables the vehicle to operate in high speed range during transport while automatically switching to low speed range during digging or soil movement operations, maintaining versatility across different work modes.
Solution Approach 2:
The system autonomously determines the appropriate speed range based on detected work operations, automatically downshifting when digging or soil movement is detected and upshifting during transport. This self-adjusting capability ensures the vehicle maintains optimal performance for both rapid transport and effective work operations without requiring operator awareness or intervention.
6Ease of operation
If automatic shift control is implemented, then smooth transitions between speed ranges are achieved, but the control system complexity increases
Solution Approach 1:
The control system uses feedback from standard vehicle sensors (engine speed, load conditions, hydraulic pressure) that already exist in the vehicle, processing these signals through a controller to determine shift timing. This feedback-based approach achieves smooth transitions using readily available data, minimizing the need for additional complex sensing infrastructure.
Solution Approach 2:
The control system leverages existing vehicle operational data and sensor networks to autonomously manage speed range transitions, requiring minimal additional hardware beyond a controller that processes standard vehicle signals. This self-service approach to shift control achieves smooth transitions while keeping system complexity low by reusing existing vehicle systems.
Data Source
AI summary
A hydraulically driven utility vehicle, such as a wheel loader or track loader, can automatically shift between two or more operating speed ranges based on prevailing operating conditions. The default condition may be a low speed range, and the vehicle may shift into a high speed range only if an output speed of the vehicle's hydraulic drive motor exceeds a designated threshold. The designated threshold may, for example, be a designated percentage of maximum speed. The machine may automatically shift back to the lower speed range if the output speed of the hydraulic drive motor drops beneath a second designated threshold that may lower than the first designated threshold. Other operating conditions, such as commanded speed, engine load and engine speed, may also be taken into account when determining whether to auto-shift.