Who invented the piano accordian?

Answer 1

The accordion is one of several European inventions of the early 19th century that used free reeds driven by a bellows; notable among them were:
The Aeoline, by German Bernhard Eschenbach (and his cousin, Caspar Schlimbach), 1810. It was a piano with an added aeoline register. Similar instruments were the Aeoline Harmonika and Physharmonika. Aeoline and Aura were first without bellows or keyboard.

Answer 2

The piano-accordion was probably invented in France around the mid-nineteenth century. The first patent of an accordion with a piano keyboard was made by Philippe Joseph Bouton of Paris in 1852. In 1880, piano-accordions with sixty-four bass and chord buttons for the left-hand were built by Tessio Jovani in Stradella, Italy. In 1890 a deluxe piano-accordion was built by Mariano Dallape and Company, also in Stradella, which featured a right-hand keyboard of three octaves and 112 left-hand buttons.

But few instruments found their way across the Atlantic ocean to the United States. The "accordeon" which Americans knew was the one- to three-row diatonic button accordion, which was sold by the Sears Roebuck Company through their mail-order catalog.