庞明

摘 要：随着油耗法规的日益严格，48VMicroBAS微混技术成为众多车企选择的低成本实现节油降排的主流技术。本文针对某48V微混车辆钥匙起动过程出现的严重起动敲击问题，进行了基于整车的振动与噪声测试试验，识别出敲击源为48V前端轮系双向张紧器，通过对比敲击剧烈的钥匙起动工况与无敲击异响的自动起动工况，识别起动敲击的产生机理，并在此基础上提出了48V双向张紧器减振降噪优化方案。实车起动验证试验表明：减振降噪结构优化后，钥匙起动过程中48V双向张紧器敲击加速度降低75%，敲击声音显著改善，有效提高了該微混车辆的起动NVH性能。

关键词：48V微混 NVH 前端轮系 钥匙起动 自动起动

Optimized Design of 48V Front-end Wheel Train of Micro-hybrid Vehicle for Start-percussion Control

Pang Ming

Abstract：48V MicroBAS technology is widely accepted by more and more automotive OEMs because it could effectively improve emission and reduce fuel economy with relative low cost. A severe key on start knocking issue of a 48V MicroBAS vehicle is deeply studied in this paper. Vehicle level noise and vibration test is conducted for sound source localization. By comparing the NVH performance between key on start condition which has noticeable knocking noise and auto start condition with no knocking at all， the root cause of the MicroBAS pulley tensioner knocking issue is revealed， and the noise and vibration reduction optimization design was proposed. Vehicle test shows that， the NVH optimization design could reduce 75% of knocking vibration of MicroBAS pulley tensioner during key on start event， and could greatly improve start knocking noise.

Key words：48V MicroBAS， NVH， front-end accessory system， key on start， auto start

1 前言

基于48V技术的微混技术，是当前主流的低成本实现混动，降低油耗和排放的前瞻技术[1]，可以在对原有动力总成改造较小的情况下实现微混，达到降低油耗与排放的效果[2，3]。48V微混系统在发动机原有12V电池的基础上，增加了48V电池与电机。加速过程中，48V电机可以为发动机提供助力，辅助发动机动力输出更加平顺，提高车辆动力性与燃油经济性;滑行过程中48V电机可以实现制动能量回收，进一步达到降低油耗的目的。

微混系统的核心部件48V电机，除具备传统12V电机发电功能外，还具有自动启停（Auto Start）[4]、加速助力（boost）与制动能量回收（regen）的功能，即既可以在起动及加速工况下对发动机曲轴提供驱动力，又可以作为曲轴负载提供车内用电并在车辆滑行过程中实现制动能量回收（regen）。……