Door opener having an anti-loose linking unit

A door opener comprising:

• a driving device including a motor and a first transmission member configured to be driven by the motor;
• a first connecting member including a connecting hole coupled with the first transmission member;
• a first push rod including a first end and a second end, wherein the first end includes a through-hole, wherein the first connecting member is mounted to the first end of the first push rod, wherein the connecting hole of the connecting member is aligned with the through-hole of the first end of the first push rod, wherein the second end of the first push rod is configured to be operatively connected to a door, wherein the first push rod is configured to actuate the door to pivot to an open position or a closed position;
• a connecting screw including a head, wherein the connecting screw extends through the through-hole of the first end of the first push rod and the connecting hole of the first connecting member and is in threading connection with the first transmission member, wherein the head of the connecting screw abuts the first end of the first push rod, wherein when the motor operates, the first transmission member, the first connecting member, the first push rod, and the connecting screw pivot jointly about a rotating axis of the first transmission member;
• and
• an anti-loose member including a polygonal hole, wherein the anti-loose member is non-rotatably mounted in the first end of the first push rod, wherein the head of the connecting screw is non-rotatably coupled in the polygonal hole of the of the anti-loose member, wherein the connecting screw is not pivotable relative to the first transmission member when the motor operates, and wherein the first connecting member is prevented from disengaging from the first transmission member.