Wheel Slip Management via Engine Torque Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
All-terrain vehicles equipped with centrifugal continuously variable transmissions (CVTs) face challenges in managing wheel slip during engine braking on slippery surfaces, as the unassisted CVT mechanically adjusts gear ratios, exacerbating negative torque output and leading to wheel slip issues.
Innovation Solution
A method is implemented to manage wheel slip by determining vehicle deceleration and increasing engine torque output when the sensed deceleration exceeds a threshold, using a throttle valve to adjust air supply and maintaining the increased torque until the deceleration returns below the threshold, with the option to switch between two-wheel and four-wheel drive modes to adjust torque output accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the vehicle undergoes engine braking on a slippery surface, then the engine torque output becomes negative to slow down the vehicle, but the wheels experience insufficient traction and begin to slip
Solution Approach 1:
The system detects wheel slip conditions in advance and applies counteracting torque to the slipping wheels before the slip becomes severe. The controller monitors wheel speeds and when slip is detected, it commands the engine or motor to generate positive torque to counteract the negative torque causing the slip, thereby preventing further loss of traction control
Solution Approach 2:
The system dynamically changes the engine torque parameter from negative (engine braking mode) to positive (torque application mode) when wheel slip is detected. The controller adjusts the throttle position and fuel injection to modify engine torque output, transforming the harmful negative torque into beneficial positive torque to maintain wheel traction during deceleration
2Adaptability or versatility
If a centrifugal CVT is used to automatically adjust gear ratios, then the transmission adapts to speed changes, but the negative torque output is exacerbated during engine braking, worsening wheel slip
Solution Approach 1:
The system uses feedback from wheel speed sensors and CVT position sensors to continuously monitor the vehicle's operating conditions. When engine braking causes the CVT to shift to a lower gear ratio (which increases torque multiplication and worsens wheel slip), the controller receives feedback and counteracts by applying positive engine torque to compensate for the exacerbated negative torque effect
Solution Approach 2:
The controller anticipates the harmful effect of CVT gear ratio changes during engine braking. When deceleration is detected and the CVT begins to shift to lower ratios, the system preemptively applies positive engine torque to counteract the impending increase in negative torque output, preventing wheel slip before it occurs
3Speed
If the throttle valve is closed to reduce air flow and create vacuum for engine braking, then the vehicle slows down, but the negative torque output causes wheel slip on slippery surfaces
Solution Approach 1:
The system employs periodic modulation of the throttle valve position rather than maintaining a fixed closed position. The controller opens and closes the throttle in a controlled periodic manner to generate oscillating positive torque that counteracts the continuous negative torque from engine braking, preventing wheel slip while still achieving vehicle deceleration through repeated torque applications
Solution Approach 2:
Instead of fully closing the throttle valve for maximum engine braking effect, the controller applies partial throttle closure to generate a moderate vacuum and negative torque, then supplements this with periodic partial openings to generate positive torque pulses. This partial action approach prevents the excessive negative torque that would cause wheel slip while still achieving effective deceleration
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
This approach effectively reduces wheel slip by counteracting negative torque output during engine braking, ensuring stable vehicle speed and traction, particularly on slippery surfaces, by dynamically adjusting engine torque based on deceleration and drive mode.
Implementation Method 1
A throttle valve of the engine is controlled to increase an opening position of the throttle valve
Implementation Method 2
an unassisted continuously variable transmission (CVT) operatively connecting the front wheels and the rear wheels to the engine
Data Source
AI summary
A method of managing wheel slip in a vehicle. The vehicle has a frame, an internal combustion engine, front and rear wheels operatively connected to the engine, a throttle valve for controlling a supply of air to the engine, a steering assembly operatively connected to at least the front wheels for steering the vehicle, and an unassisted continuously variable transmission (CVT) operatively connecting the front wheels and the rear wheels to the engine. The method includes: determining a sensed deceleration of the vehicle; comparing the sensed deceleration of the vehicle to a threshold deceleration; and increasing a torque output of the engine from a current engine torque output value to an increased engine torque output value when the sensed deceleration of the vehicle is greater than the threshold deceleration. A method for managing wheel slip in accordance with a drive mode of the vehicle is also disclosed.