Vehicle Powertrain Controller Torque Direction Management
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Solution Overview
Problem
Torque reversal in vehicle torque transfer assemblies leads to noise and jerk experienced by drivers and passengers due to backlash in gear meshes and driveline components, particularly during transitions between engine overrun and acceleration states.
Innovation Solution
A controller for a motor vehicle powertrain that continuously applies torque to each group of wheels in a predetermined direction relative to the vehicle's longitudinal axis, ensuring that the net torque corresponds to a predetermined demand value, thereby minimizing lash crossing and reducing noise, vibration, and harshness (NVH) by maintaining consistent torque direction during acceleration, deceleration, and constant speed operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If torque reversal occurs in torque transfer assemblies during transitions between engine overrun and acceleration states, then the vehicle can respond to driver input, but noise and jerk are generated due to backlash in gear meshes and driveline components
Solution Approach 1:
The controller applies a preliminary counteracting torque in the opposite direction before the actual torque reversal occurs. When the system detects a transition from engine overrun to acceleration, it first applies a torque in the reverse direction to take up backlash in the gear meshes, then transitions to the required drive torque. This preliminary action prevents the harmful noise and jerk that would otherwise occur when backlash is crossed during torque reversal.
2Object-generated harmful factors
If high precision torque transfer components are used to minimize backlash, then noise and jerk are reduced, but manufacturing cost and device complexity increase
Solution Approach 1:
The invention replaces the need for high-precision mechanical torque transfer components with an electronic control system. Instead of relying on mechanically precise gear meshes and driveline components to minimize backlash, the system uses a controller that detects torque reversal conditions and applies compensating torques electronically. This substitution allows the use of standard, less complex mechanical components while achieving the same noise and jerk reduction效果.
3Object-generated harmful factors
If torque is continuously applied in the same direction to prevent lash crossing, then noise and jerk are reduced, but the ability to meet varying torque demand efficiently is compromised
Solution Approach 1:
The controller implements periodic torque application in the form of controlled oscillations around the required mean torque value. During transitions, it applies torque in alternating directions at a frequency that prevents backlash crossing while maintaining the average torque at the desired level. This periodic action ensures continuous engagement of gear meshes without excessive wear and maintains torque delivery efficiency by keeping the system in a state of controlled motion.
Solution Approach 2:
The system dynamically changes torque parameters by adjusting the magnitude and direction of applied torque based on operating conditions. During engine overrun to acceleration transitions, it temporarily increases torque in the reverse direction to take up backlash, then transitions to the required drive torque. This parameter change allows the system to maintain efficient torque delivery while preventing lash crossing and reducing noise and jerk.
Data Source
AI summary
A controller for a motor vehicle powertrain, the controller being configured to control the amount of torque generated by each of a plurality of drive torque sources, each drive torque source being coupled via a respective torque transfer arrangement to a respective group of one or more wheels, the controller being configured to cause a first of the drive torque sources, during acceleration, deceleration and substantially constant speed operation, substantially continually to apply a drive torque to a first group of one or more wheels to which the first drive torque source is coupled acting in a first direction relative to a longitudinal axis of the vehicle and causes a second of the drive torque sources, during acceleration, deceleration and substantially constant speed operation, substantially continually to apply a drive torque to a second group of one or more wheels to which the second drive torque source is coupled, the direction of drive torque applied to the second group being in a second direction opposite the first such that a net drive torque applied to the first and second group in combination corresponds substantially to a predetermined drive torque demand value, the predetermined torque demand value being determined at least in part by reference to a torque demand signal received by the controller.