Electronic expansion valve

1. An electronic expansion valve, including a valve needle and a valve needle sleeve fixedly connected with the valve needle, the electronic expansion valve comprising:

a leading screw including an annular groove provided at a lower end of the leading screw and extending in a circumferential direction;

a washer movably provided in the annular groove, wherein a thickness of the washer is less than a height of the annular groove, and wherein the valve needle sleeve abuts against an upper surface of the washer; and

a spring contacting the washer and the valve needle.

2. The electronic expansion valve according to claim 1 , wherein a step surface is provided at the lower end of the leading screw, a screw sleeve is fixedly provided on the leading screw below the step surface, and the annular groove is formed between the upper end surface of the screw sleeve and the step surface; and the washer is a circular structure and has a through hole which mates with the annular groove through clearance fit.

3. The electronic expansion valve according to claim 1 , wherein the annular groove is provided on a side surface of the lower end of the leading screw; the washer has a U-shaped structure, and a U-shaped opening of the washer is inserted into the annular groove.

4. The electronic expansion valve according to claim 1 , wherein the valve needle is provided with an inner hole, into which the valve needle sleeve is inserted, so that the valve needle sleeve is fixedly connected with the valve needle; the spring is arranged in the inner hole of the valve needle, and a lower end of the spring is contacted with a bottom of the inner hole of the valve needle.

5. The electronic expansion valve according to claim 1 , wherein the valve needle sleeve has a cylinder structure with a through hole, the valve needle sleeve has an inward-folding edge at a top end which abuts against the upper surface of the washer; the valve needle is fixedly provided at a lower end of the valve needle sleeve; and the spring is arranged in the through hole of the valve needle sleeve.

6. The electronic expansion valve according to claim 4 , wherein a rigid ball is provided in the inner hole of the valve needle, and the rigid ball is positioned between the bottom of the inner hole of the valve needle and the spring.

7. The electronic expansion valve according to claim 5 , wherein a rigid ball is provided in the through hole of the valve needle sleeve, and the rigid ball is positioned between the valve needle and the spring.

8. An electronic expansion valve including a valve needle and a valve needle sleeve fixedly connected with the valve needle, the electronic expansion valve comprising:

a leading screw including a step surface provided at a lower end of the leading screw;

a screw sleeve affixed to the leading screw below the step surface, wherein an annular groove extending in a circumferential direction is formed between an upper surface of the screw sleeve and the step surface;

a washer movably provided in the annular groove, wherein a thickness of the washer is less than a height of the annular groove, and wherein the valve needle sleeve abuts against an upper surface of the washer.

9. The electronic expansion valve according to claim 8 , wherein the washer is a circular structure and has a through hole which mates with the annular groove through a clearance fit.

10. The electronic expansion valve according to claim 8 , further comprising a spring provided between the washer and the valve needle.

11. The electronic expansion valve according to claim 10 , wherein the spring contacts the washer and the valve needle.

12. The electronic expansion valve according to claim 8 , wherein the valve needle is provided with an inner hole, into which the valve needle sleeve is inserted to fixedly connect the valve needle sleeve with the valve needle.

13. The electronic expansion valve according to claim 12 , further comprising a spring provided between the washer and the valve needle, and wherein the spring is arranged in the inner hole of the valve needle, and a lower end of the spring contacts a bottom of the inner hole of the valve needle.

14. An electronic expansion valve including a valve needle and a valve needle sleeve fixedly connected with the valve needle, the electronic expansion valve comprising:

a leading screw including an annular groove provided on a side surface of a lower end of the leading screw and extending in a circumferential direction, wherein the annular groove includes an upper surface, a lower surface, and a side surface;

a washer movably provided in the annular groove, wherein a thickness of the washer is less than a height of the annular groove, and wherein the valve needle sleeve abuts against an upper surface of the washer; and

the washer has a U-shaped structure, and a U-shaped opening of the washer is inserted into the annular groove.

15. The electronic expansion valve according to claim 14 , further comprising a spring provided between the washer and the valve needle.

16. The electronic expansion valve according to claim 15 , wherein the spring contacts the washer and the valve needle.

17. The electronic expansion valve according to claim 14 , wherein the valve needle sleeve comprises a cylinder structure with a through hole.

18. The electronic expansion valve according to claim 17 , wherein the valve needle sleeve comprises an inward-folding edge at a top end which abuts against the upper surface of the washer.

19. The electronic expansion valve according to claim 18 , wherein the valve needle is fixedly provided at a lower end of the valve needle sleeve.

20. The electronic expansion valve according to claim 19 , further comprising a spring provided between the washer and the valve needle, and wherein the spring is arranged in the through hole of the valve needle sleeve.