I think it’s similar to another construction that we already know:  “voy a hacer algo”, when we say we’re going to do something.  You know how we say, “Voy a estudiar” (I’m going to study), “Va a comer allá” (he’s going to eat there) and so on.  This construction is IR+a+INFINITIVE.  

We can use a similar construction with ayudar (although with a different meaning):  AYUDAR+a+INFINITIVE.  The “a” is just a part of the overall construction of the phrase. 

 There are a number of verbs that use prepositions such as “a”, “de”, or “con” in this manner.  The topic is “verbs which require prepositions”.