Hybrid Drive Motor Torque Control for Parking Noise Reduction
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Solution Overview
Problem
Hybrid vehicles experience abnormal grating sounds due to variations in engine torque when the parking mechanism is activated, primarily caused by inaccuracies in drive motor torque generation and backlash between the clawed pole and parking gear.
Innovation Solution
A drive control system that includes a drive motor target torque calculation processing device and a drive motor target torque restriction processing device to restrict variations in drive motor target torque when the parking mechanism is in operation, controlling the generator revolution number to meet engine target conditions and parallelizing engine and generator torque, while also calculating torque correction values to reduce vibrations and angular acceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the drive motor torque is controlled based on sensor output during engine start/stop operations, then the engine revolution number can be adjusted to meet starting conditions, but noise and grating sounds occur due to torque variations affecting the parking mechanism
Solution Approach 1:
The control device detects when the parking mechanism is engaged and proactively restricts torque variations before they can cause grating sounds. By anticipating the harmful effect and applying counter-measures in advance, the system prevents noise during engine start/stop operations while maintaining reliable engine starting capability.
Solution Approach 2:
The control system dynamically adjusts the drive motor torque based on real-time detection of parking mechanism state. When the parking mechanism is detected as engaged, the system switches to a restricted torque control mode that limits variation magnitude, thereby adapting the torque control strategy to the current operational context and preventing harmful vibrations.
2Object-affected harmful factors
If the drive motor torque variation is restricted when the parking mechanism is engaged, then grating sounds are prevented, but the responsiveness of engine start/stop operations may be reduced
Solution Approach 1:
The control device applies partial restriction to torque variations rather than complete elimination. By setting appropriate upper and lower limit values that partially constrain torque changes, the system achieves sufficient noise reduction while preserving enough torque responsiveness to maintain acceptable engine start/stop performance.
Solution Approach 2:
The control system changes the torque control parameters dynamically based on parking mechanism state. When parking is engaged, the system transitions from normal torque control with higher responsiveness to restricted torque control with reduced variation limits, thereby adjusting the parameter set to balance noise reduction and operational responsiveness.
3Object-affected harmful factors
If the upper and lower limit values for drive motor torque are set to restrict torque variation, then the grating sound between clawed pole and parking gear is reduced, but the ability to generate sufficient drive motor torque may be compromised
Solution Approach 1:
The control device applies localized quality control by implementing torque restrictions specifically during the critical phase when the parking mechanism is engaged and engine start/stop operations occur. The upper and lower limit values are set to provide sufficient restriction during this local condition while allowing full torque capability to be available when the parking mechanism is disengaged, thereby achieving noise reduction without compromising overall torque availability.
Data Source
AI summary
A drive control system for an electric vehicle and a method of drive control of the electric vehicle. The drive control system for the electric vehicle includes a drive motor target torque calculation processing device for calculating a drive motor target torque representing a target torque of a drive motor; and a drive motor target torque restriction processing device that judges whether or not a parking mechanism is in operation and, if the parking mechanism is in operation, restricts variations in the drive motor target torque.