Get Value from an input to fill a table

Question

I'm working in a lightning app example and i can´t get the value of an input from the controller.

When I try to get the value and insert it into a the program throws an error when calling controller.find()--->UNDEFINED. Here is the code: Component

<aura:component>
    <aura:attribute name="idCocheOut" type="Integer" />
    <aura:attribute name="nombreOut" type="String" />
    <div class="c-container">
        <lightning:input type="number" aura:id="idCoche" label="Identificador Coche" />
        <lightning:input type="text" aura:id="nombre" label="Nombre Coche" />
        <lightning:button label="Introducir coche" onclick="{!c.crearCoche}"/>
        <br/>
        <br/>
    </div>
</aura:component>   

Controller

({
   crearCoche : function(component, event) {
        var nombre = component.find('nombre').getElement().value;
        var id = component.find('idCoche').getElement().value;
        component.set("v.nombreOut",nombre);
        component.set("v.idCocheOut",id);
    }
})

Thanks!