Door closer

1. A door closer, comprising:

a first connecting plate and a second connecting plate,

wherein the first connecting plate is connectable to an external door frame, the second connecting plate is connectable to a door body connecting portion,

wherein a connecting rod assembly and a return spring are mounted in the door body connecting portion,

wherein one end of the connecting rod assembly passes through the second connecting plate and is hinged to the first connecting plate,

wherein when a door is opened, an external door body drives the first connecting plate and the second connecting plate to rotate, and after the connecting rod assembly pulls the door body connecting portion, the return spring is compressed, and

wherein when the door is closed, the return spring pulls the door body to close automatically,

wherein the door body connecting portion further comprises a housing, and a base is mounted in the housing,

wherein a plurality of guide sliding blocks are symmetrically disposed at one end of the housing, and the plurality of guide sliding blocks are fixed to the second connecting plate,

wherein a hydraulic rod is further mounted in the housing, and

wherein a sliding groove is further disposed on the housing, and the base is placed in the sliding groove.

2. The door closer according to claim 1 , wherein each of the plurality of guide sliding blocks is provided with a through hole, one end of the hydraulic rod is placed in the through hole, and the other end of the hydraulic rod is connected to the base.

3. The door closer according to claim 2 , wherein a hinged seat is fixed to the base, and the connecting rod assembly is hinged to the hinged seat.

4. The door closer according to claim 3 , wherein the connecting rod assembly is divided into a curved rod and a connecting rod, and two ends of the connecting rod are respectively hinged to the hinged seat and the curved rod.

5. The door closer according to claim 4 , wherein a connecting seat is fixed to the first connecting plate.

6. The door closer according to claim 5 , wherein through grooves are symmetrically disposed on the first connecting plate and the second connecting plate, and the curved rod passes through one or more of the through grooves and then is hinged to the connecting seat.

7. The door closer according to claim 4 , wherein rolling bearings are symmetrically mounted at a joint of the curved rod and the connecting rod.

8. The door closer according to claim 7 , wherein a guide groove is disposed on each of the plurality of guide sliding blocks, and one or more of the rolling bearings are placed in the guide groove, and wherein the guide groove is an oblique guide groove, and an arc-shaped guide surface is disposed on the guide groove.

9. The door closer according to claim 8 , wherein a positioning boss is further disposed on each of the plurality of guide sliding blocks, and an arc surface is disposed on the positioning boss.

10. The door closer according to claim 8 , wherein a second guide sliding block is further disposed between the plurality of guide sliding blocks, and the guide groove is disposed on both sides of the second guide sliding block.

11. The door closer according to claim 4 , wherein a first bending portion and a second bending portion are respectively disposed at two ends of the curved rod.

12. The door closer according to claim 1 , wherein a speed regulating switch is disposed on the hydraulic rod.

13. The door closer according to claim 1 , wherein the first connecting plate and the second connecting plate are disposed in a hinged mode.

14. The door closer according to claim 1 , wherein the return spring is disposed on both sides of the hydraulic rod.

15. The door closer according to claim 1 , wherein a first cavity is disposed on the housing, second cavities are symmetrically disposed on two sides of the first cavity, the hydraulic rod is placed in the first cavity, and the return spring is placed in the second cavity.

16. The door closer according to claim 1 , wherein the connecting rod assembly includes a plurality of connecting rod assemblies symmetrically disposed on two sides of the housing.