Powder spray coating device and powder feeding device therefor

1. A powder supply system for powder spraycoating equipment comprising:

a closed or closable powder receptacle fitted with a powder chamber for coating powder, wherein

the powder receptacle comprises a cleaning fixture to automatically remove residual powder from the powder chamber using compressed cleaning air;

at least one mechanically guided plunger configured to move in a reciprocable manner along a guided path between one chamber end and an opposite chamber end relative to the powder chamber;

the plunger includes a front end-face with at least one compressed cleaning air outlet configured to aim toward at least one chamber wall for causing compressed cleaning air issuing from the compressed cleaning air outlet to impact the chamber wall to blow residual powder away from said chamber wall; and

at least one residual powder outlet disposed at the opposite chamber end and configured to remove compressed cleaning air and powder contained in said compressed cleaning air from the powder chamber.

2. The powder supply system as claimed in claim 1 , wherein the powder chamber comprises at least one powder feed aperture.

3. The powder supply system as claimed in claim 1 , wherein said at least one compressed cleaning air outlet is configured to issue compressed cleaning air at a front end-face side of the plunger.

4. The powder supply system as claimed in claim 1 , wherein said at least one compressed cleaning air outlet is configured to issue compressed cleaning air from an outward-pointing external peripheral zone of the plunger, wherein the peripheral zone extends transversely to the guided path.

5. The powder supply system as claimed in claim 1 , wherein the plunger exhibits an outer periphery, at least at a plunger portion entering the powder chamber, matched to an inner periphery of said powder chamber and the outer periphery extending as far as the inner periphery on all sides.

6. The powder supply system as claimed in claim 1 , wherein the at least one residual powder outlet is disposed in the front end-face at cross-sectional center of the plunger, the at least one compressed cleaning air outlet being configured transversely to the cross-sectional center farther outward than the at least one residual powder outlet.

7. The powder supply system as claimed in claim 1 , further comprising at least one level sensor for detecting a powder level in the powder chamber.

8. The powder supply system as claimed in claim 1 , further comprising a controlled valve in the at least one residual powder outlet to alternatively close and open said outlet.

9. The powder supply system as claimed in claim 2 , wherein the plunger is fitted with at least one compressed flushing air outlet aperture disposed opposite the at least one powder feed aperture, and the plunger is configured to point the at least one compressed flushing air outlet into the at least one powder feed aperture only when said plunger enters the powder chamber to a predetermined depth of penetration.

10. The powder supply system as claimed in claim 9 , wherein several powder feed apertures are arrayed mutually apart and in a first row and several compressed flushing air outlet apertures are arrayed in a second row and at the same mutual distance apart as the powder feed apertures, said first and second rows running parallel to each other and parallel to the guided path of the plunger.

11. The powder supply system as claimed in claim 1 , wherein the plunger constitutes a chamber end face at one of the chamber ends.

12. The powder supply system as claimed in claim 1 , further comprising a compressed airjet pump disposed in the residual powder outlet, or in a residual powder outlet duct, configured to induce a partial vacuum in the residual powder outlet through which compressed cleaning air and residual powder contained in the powder chamber are aspirated out of the powder chamber into the residual powder outlet.

13. The powder supply system as claimed in claim 1 , further comprising a compressed conveying air intake configured to introduce compressed air into the residual powder outlet or a residual powder outlet duct.

14. The powder supply system as claimed in claim 1 , wherein a chamber end-face wall configured opposite the front end face of the plunger is fitted with a plurality of feed apertures configured to introduce compressed air into the powder chamber.

15. The powder supply system as claimed in claim 1 , further comprising a second plunger configured to be opposite the first plunger and reciprocable from the opposite chamber end into the powder chamber.

16. The powder supply system as claimed in claim 9 , wherein each of the at least one powder feed aperture is fitted with the compressed cleaning air outlet aperture, and each powder feed aperture is associated with a given aperture of the compressed flushing air outlet apertures.

17. The powder supply system as claimed in claim 6 , wherein one of the at least one compressed cleaning air outlet is configured perpendicular to the guided path.

18. The powder supply system as claimed in claim 1 , wherein at least two chamber walls define the guided path extending from one chamber end to the opposite chamber end.

19. The powder supply system as claimed in claim 1 , wherein the at least one powder feed aperture is configured to connect to a plurality of compressed air valves.

20. The powder supply system as claimed in claim 1 , wherein the cross-section of the plunger has a shaped selected from the group consisting of rectangular, circular, polygonal and oval.

21. The powder supply system as claimed in claim 1 , wherein the at least one compressed cleaning air outlet is configured to be outside the powder chamber when the plunger is at the opposite chamber end.

22. The powder supply system as claimed in claim 1 , wherein

the plunger is disposed in a manner that an outer periphery of the plunger is matched to an inner periphery of the powder chamber in a manner that a peripheral gap remains in-between, and

the at least one compressed cleaning air outlet is configured to issue compressed air into said peripheral gap.