To fire a component event, the syntax is a bit different from an application event, and uses the name identifier to identify the event:
var compEvent = component.getEvent("sampleComponentEvent");// Optional: set some data for the event (also known as event shape)// A parameter's name must match the name attribute// of one of the event's <aura:attribute> tags// compEvent.setParams({"myParam" : myValue });compEvent.fire();