用于停止开始的曲柄传感器IC

By Eric Burdette and Mike Morris
Allegro MicroSystems, LLC

停止启动功能允许汽车通过关闭发动机并以短间隔重新启动诸如交通停止时来保护燃料。此功能需要先进的传感技术以高效。本文介绍了启动停止操作和启用霍尔效应集成电路，特别是Allegro Microsystems ATS694和上一代ATS658，用于本申请。亚博棋牌游戏

Introduction

汽车配备启停功能save fuel by turning off the combustion engine when at a standstill, such as at a traffic light. The engine is restarted when the driver signals a resumption of driving, such as depressing the clutch or releasing the brake pedal. Publicized fuel economy improvements for stop-start systems are touted as up to five or ten percent. Furthermore, the reduction in fuel consumption through reduced engine idling time lessens the amount of released CO₂作为汽车制造商努力满足收紧排放标准的欧洲广泛实施的好处。

Start-Stop Operation

The start-stop concept is not a new idea; several 1980’s vehicle models were released to production with this capability. Technological improvements in the last few decades have made stop-start operation a more reliable function. Moreover, the ability of modern vehicles to accomplish a restart of the engine quickly is critical to widespread consumer acceptance of this function.

与需要并行驱动系统的混合动力相比，停止启动系统具有很大的成本效益。前者严重依赖现有的组件，只需要少数设备升级来实现燃料节省。现有的发动机控制单元（ECU）使用来自传感器的输入来动态调节发动机时序和燃料用途以优化性能。可以实现额外的ECU算法以在不需要时关闭内燃机。这需要从已经监控系统的输入，例如车轮速度，制动应用和电池状态，这是确保足够的电源来重新启动发动机并在静止时段期间维持电子设备。

为了实现发动机的重启，系统依赖于起动器发生器或较重的起动电机（以承受增加的使用）。另外，来自曲轴位置传感器的信息用于减少重启的时间仅为一秒的一部分。在典型的汽车燃烧发动机中，活性传感器用于监测曲轴上的特殊目标。为了使ECU确定绝对曲轴位置，从而提供活塞位置，传感器必须提供目标旋转的方向。即使在发动机间隙的存在下，该方向检测能力使系统能够在整个静止事件中保持同步。在不保持同步的情况下，重启事件可能需要更长时间。

传感技术

亚博棋牌游戏Allegro Microsystems，LLC提供了多种汽车级，齿槽，霍尔效应集成电路（IC），专门设计用于满足曲轴速度和用于启动系统的方向感测的要求。这些设备是在经过验证的霍尔技术之上，提供了数字非接触式的铁磁目标的感测。IC系列包括ATS658和ATS694，两者都被融合到用户友好的超模制IC中，该IC与稀土磁铁集成了霍尔效应电路。小型封装尺寸和集成磁系统可以易于组装并与各种目标齿轮和安装气隙一起使用。传感器电路与Allegro的制造设施中的后偏置磁体的组合确保了一致的设备性能，因为每个IC可以优化以匹配已知的磁路。

Although there are subtle differences between the two devices, both the ATS658 and the ATS694 contain three Hall elements used to generate two differential signals based on the magnetic stimulus produced by the rotation of the ferromagnetic target gear. The relative phase of the two signals is then used to determine the direction of target rotation. The sensor IC provides a digital voltage output signal where a short pulse is generated as the center of every target tooth passes by the device face. Two distinct output pulse widths differentiate whether the target is rotating in the forward or reverse direction. In this way, an engine control unit can determine both the speed of the target rotation, by looking at the period between consecutive pulses, and the direction of target rotation, by measuring the width of the output pulse.

这些IC内部，使用许多专利的模拟和数字信号处理技术。高级校准技术用于提供最佳信号偏移和幅度。这种校准与信号的数字跟踪相结合，可通过全方位的安装气隙和目标速度来切换精确切换。

Unique signal tracking methods are also implemented to maintain signal integrity during long periods of standstill. Digital direction detection algorithms ensure that no erroneous output pulses will be generated during target direction changes, which can occur during engine stopping events. The combination of these techniques and algorithms allows these devices to track the absolute position of a crank target throughout an engine stopping event, ensuring that the ECU knows the exact position of the crankshaft (and therefore camshaft) and enabling a rapid restart.

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