Powertrain Torque Control for Vehicle Hop Resonance Damping
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Solution Overview
Problem
Power-induced hop resonances in vehicle traction control systems, caused by interactions between tire, road, and suspension, lead to increased vehicle noise, vibration, and harshness (NVH) and durability concerns, especially on surfaces with varying friction coefficients like asphalt with standing water, which existing systems struggle to mitigate effectively without costly fast-acting components.
Innovation Solution
The method involves adjusting wheel torque based on the amplitude and direction of band-pass filtered driven wheel speed to dampen vibrations, using engine-based torque adjustments and processing signals to detect and control hop levels, allowing for effective reduction of power-induced hop without requiring wheel braking torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If counter-phase torque is applied to control power-induced hop, then hop resonance is reduced, but system complexity and cost increase due to requirement of fast hop detecting device and fast-acting actuating components
Solution Approach 1:
The patent changes the control parameters by using wheel acceleration (derivative of wheel speed) as the control input instead of direct hop detection. The traction control system modifies engine torque based on wheel acceleration magnitude and direction, which indirectly controls hop resonance without requiring fast hop detecting devices. This parameter transformation simplifies the system while maintaining effectiveness.
Solution Approach 2:
The patent introduces wheel acceleration as an intermediary variable that mediates between the hop resonance phenomenon and the torque control action. Instead of directly detecting and responding to hop resonance, the system uses wheel acceleration (which is naturally available from wheel speed sensing) as an intermediate indicator to trigger appropriate torque adjustments, thereby avoiding the need for specialized fast detecting hardware.
2Object-affected harmful factors
If wheel braking torque is used to control hop, then hop resonance is reduced, but manufacturing cost increases
Solution Approach 1:
The patent enables the existing engine torque system to serve the additional function of hop control. By utilizing the engine's natural torque response characteristics and controlling it through wheel acceleration feedback, the system makes the existing powertrain self-sufficient for hop mitigation, eliminating the need for additional braking components and reducing manufacturing costs.
Solution Approach 2:
The patent makes the engine torque system multi-functional by having it perform both its primary function of providing driving torque and its secondary function of controlling hop resonance. The same engine torque actuator that controls vehicle acceleration is also used to dampen hop oscillations, thereby avoiding the need for separate dedicated hop control actuators and reducing overall system cost.
3Speed
If traction control system excites hop by in-phase powertrain torque response to oscillating wheel acceleration, then torque control responsiveness is improved, but vehicle noise, vibration, and harshness increase
Solution Approach 1:
The patent inverts the conventional approach by using out-of-phase torque response instead of in-phase response. When wheel acceleration indicates hop oscillation, the system applies torque adjustments that are opposite in phase to the oscillation, thereby damping rather than exciting the resonance. This inverted control strategy reduces NVH while maintaining responsiveness.
Solution Approach 2:
The patent implements feedback control by continuously monitoring wheel acceleration and using it to modulate engine torque. The feedback loop measures wheel acceleration, determines whether it represents hop oscillation, and adjusts torque accordingly to dampen the oscillation, thereby reducing vehicle noise, vibration, and harshness while maintaining control effectiveness.
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 reduces wheel torque adjustments as hop levels increase, encouraging wheel speed to return to a desired slip level, thereby preventing the excitation of hop by the powertrain control system, thus minimizing NVH and durability issues.
Implementation Method 1
adjusting wheel torque in response to an amplitude of a band-pass filtered driven wheel speed
Implementation Method 2
the friction coefficient (μ) and surface torque capacity may change significantly with respect to wheel slip and suspension loading
Implementation Method 3
control of wheel slip on certain road surfaces may interact with natural frequencies in the driveline or suspension, which may be referred to as power induced 'hop'
Implementation Method 4
This cyclical interaction may excite the normally insignificant suspension vibration or hop resonance
Data Source
AI summary
A method for controlling a powertrain of a vehicle with wheels during a traction control event is provided. The method comprises adjusting wheel torque in response to an amplitude of a band-pass filtered driven wheel speed and a direction of acceleration of driven wheels.