S.,
Ahh this sounds so familiar. Like I wrote it! My son is now 3 and we still fight at nap time. Since he is my only one and I am a SAHM sometimes I lay down with him in my room with Noggin on and no sound. I ask him to sing mommy to sleep, telling him I need a nap. Being that your son is not yet 2 it is a little harder because their understanding level is a little less. Just a little warning, when my son turned to all hell broke loose. Sorry just how it is!! Naptimes were such a blessing, god I miss those easy days when he would lay down and go to sleep.
The only thing I can recommend is on days when he wont take a nap and starts getting mean around 5:30 is what I used to do. My son had the same trouble so around 5 we would have relax time. When he was still taking a bottle I would mix up something he really liked, strawberry milk was a favorite, then I would turn on a good movie or favorite cartoon and let him curl up with a blanket and pillow on the floor of the living room. He wouldn 't go to sleep but we could then make it to bed time without me having a nervous breakdown.
Wish I could help more, just know that you are not alone. Lots of kids have done this and their mommy's know how you feel!!
Good luck and take care of yourself
T.