Birotary Engine – Old Patents Old Birotary patents are owned by Knob Engines s.r.o. US Patent US9322274 US9322274 US Patent US9366200 US9366200 CZ Patent CZ304371 CZ304371 CZ Patent CZ304386 CZ304386 WIPO | PCT WO2013189471A1 WO2013189471A1
