分电器是内燃机点火系统中负责将点火线圈产生的高压按照点火顺序传给各气缸火花塞的装置。

断电器由固定在分电器转轴上的断电器凸轮、活动触点臂及固定触点组成。

分电器转轴上的断电器凸轮控制断电器的通断，凸轮的凸点数等于发动机气缸数。断电器触点的断开会使得点火线圈感应出很高的感应电动势。

分电器内部有离心点火提前调节器：一个托板固定在分电器转轴上，托板上放置一组重块，这些重块的一端松套在托板的销轴上，另一端则通过弹簧与托板相连。在发动机转速升高时，重块由于离心而绕销轴转过一定角度，带动断电器凸轮相对分电器转轴改变一定的相角，从而改变点火提前角。 此外，分电器外部还挂有真空点火提前调节器，根据进气歧管真空度来调节点火提前角。

A distributor is a device in the ignition system of an internal combustion engine that routes high voltage from the ignition coil to the spark plugs in the correct firing order. The first reliable battery operated ignition was developed by Dayton Engineering Laboratories Co. (Delco) and introduced in the 1910 Cadillac. This ignition was developed by Charles Kettering and was considered a wonder in its day. Atwater Kent invented his Unisparker ignition system about this time in competition with the Delco system.