In Shut Maharsham Chelek Daled Siman 111 he brings down a "shitas Ramban and shar poskim" that Tefillin you don't need l'shmo at all even by casiva.
Where is this Ramban? Who are the "shar poskim"? What other achronim have used this as a tziruf in dealing with a shailo of "l'shmo"?
(Teahuva can be found here: http://www.hebrewbooks.org/pdfpager.aspx?req=1528&st=&pgnum=129. He mentions the Ramban in the second to last paragraph of the teshuva. d'h "v'hinai")