Shaker

Abstract

Shaker comprising a frame, a tray for receiving one or more samples and a drive for the tray, in which a tray shaft is mounted eccentrically in a drivable hollow shaft. The tray shaft is fixedly connected to the tray and secured against rotation relative to the frame.

Claims

1. A shaker comprising a frame, a tray for receiving one or more samples, a drive for the tray, in which a tray shaft is mounted eccentrically in a hollow shaft, the hollow shaft is drivable by the drive, a connecting element which is fastened to the tray shaft so as to be non-rotatable in order to secure the tray shaft against rotation relative to the frame, a second hollow shaft which is mounted on the frame, and a second tray shaft which is mounted eccentrically in the second hollow shaft and is secured to the connecting element in a non-rotatable manner, the second tray shaft having the same eccentric position relative to the second hollow shaft as the tray shaft has relative to the hollow shaft, wherein the tray shaft is fixedly connected to the tray and secured against rotation relative to the frame.

2. The shaker according to claim 1, comprising a cover between the tray and the drive.

3. The shaker according to claim 2, wherein the cover is sealed against the hollow shaft to prevent contamination of the drive.

4. The shaker according to claim 2, wherein the cover comprises a trough.

5. The shaker according to claim 2, whereby only the tray shaft is located between the tray and the cover.

6. The shaker according to claim 1, wherein the connecting element contains a coupling rod.

7. The shaker according to claim 1, wherein the connecting element comprises an elastic element for compensating for distance changes between its two attachment points at the tray shaft and the second tray shaft.

8. The shaker according to claim 7, wherein the elastic element is a spring, in particular a leaf spring.

9. The shaker according to claim 1, the hollow shaft having a belt pulley for the drive via a toothed belt.

10. The shaker according to claim 9, wherein another belt pulley is fastened to the second hollow shaft for being driven by the toothed belt.

11. The shaker according to claim 1, comprising a gear transmission for driving the hollow shaft.

12. The shaker according to claim 11, wherein the gear transmission also drives the second hollow shaft.

13. The shaker according to claim 1, comprising at least one counterweight on the hollow shaft for balancing an unbalance occurring due to eccentric mass distribution.

14. The shaker according to claim 13, wherein the at least one counterweight is located on the side of a cover facing the drive.

15. The shaker according to claim 13, comprising another counterweight on the tray shaft for balancing an unbalance occurring due to eccentric mass distribution.

16. The shaker according to claim 1, wherein the eccentricity of the tray shaft relative to the hollow shaft is at most 25 mm.

17. The shaker according to claim 1, wherein the eccentricity of the tray shaft relative to the hollow shaft is 1.5 mm.

18. The shaker according to claim 1, wherein a shaking frequency of the tray due to the drive is at least 1000 rpm.

19. The shaker according to claim 1, wherein a shaking frequency of the tray due to the drive is at least 1400 rpm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further embodiments, advantages and applications of the invention result from the dependent claims and from the following description of the figures.

(2) FIG. 1 shows a view from below of a shaker according to an embodiment of the invention with frame, drive and eccentrically mounted connecting element, and

(3) FIG. 2 shows a vertical section through the shaker of FIG. 1 along the diagonal A-A′, which goes through the shafts of the two larger pulleys.

DETAILED DESCRIPTION

(4) A preferred embodiment of the invention is shown in FIG. 1 and FIG. 2. FIG. 1 shows a view from below of a shaker according to an embodiment of the invention with frame 1, drive 3-6 and eccentrically mounted connecting element 11. The shaker comprises a frame 1 made of metal or plastic, for example, which stands on four feet 2.

(5) Frame 1 is fitted with a motor, e.g. an electric motor, which drives a pulley 3. Two further pulleys 4 and 5 are driven via a toothed belt 6, which prevents slippage. These pulleys are mounted on shafts which are described in more detail below.

(6) FIG. 2 shows a vertical section through the shaker along the diagonal A-A′ passing through the shafts of the two pulleys 4 and 5. The first belt pulley 4 driven by the toothed belt 6 is mounted on a hollow shaft 7, which is rotatably mounted on the frame 1 via ball bearings 16. The second belt pulley 5, driven by the toothed belt 6, is mounted on a second hollow shaft 18, which is also preferably mounted on the frame 1 so that it can rotate via ball bearings 16.

(7) Inside the hollow shaft 7 there is a tray shaft 8, the rotation axis of which is parallel to that of the hollow shaft 7. The tray shaft 8 is mounted eccentrically in the hollow shaft 7, e.g. with an offset of the rotation axes of 1.5 mm, which leads to a circular movement of the tray shaft 8, in the example with a total amplitude of 3 mm. Needle bearings 15 and/or ball bearings 19 are used for the low-friction bearing of the tray shaft 8 in the hollow shaft 7.

(8) A tray 9 is firmly connected to the tray shaft 8 and serves as a platform or holder for sample vessels to be shaken. For this purpose, the tray 9 can be equipped with a sample holder or it may have mounting options for Erlenmeyer flasks, test tubes or other ampoules. The tray 9 can be removed for cleaning purposes.

(9) In addition, the tray shaft 8 is firmly connected to a coupling rod 11, whereby the attachment 13 of the coupling rod 11 to the tray shaft 8 cannot be rotated. The coupling rod serves as a connecting element to a second tray shaft 14. The second tray shaft 14 is eccentrically mounted in the second hollow shaft 18, analogously and with the same eccentricity as in the arrangement of tray shaft 8 and hollow shaft 7. The second tray shaft 14 is also secured to the coupling rod 11 so that both the tray shaft 8 and the second tray shaft 14 are secured against rotation relative to the frame 1. The coupling rod 11 is preferably a sheet metal welded to the tray shaft 8 and the second tray shaft 14.

(10) The two belt pulleys 4 and 5 on the hollow shaft 7 and the second hollow shaft 18 run in phase due to the drive through the toothed belt 6. As a result, although the tray shaft 8 and the tray 9 connected to it rotate relative to the hollow shaft 7, they retain their spatial orientation in relation to the frame 1 while undergoing a circular deflection.

(11) The connection of the coupling rod 11 with the second tray shaft 14 is ideally made by a leaf spring 12, which as an elastic element can compensate for distance changes e.g. due to thermal expansion or inaccurate production.

(12) Between tray 9 and frame 1 including the drive mechanism, there is a cover 10 which is firmly connected to frame 1 and sealed at the passage of the tray shaft 8. The cover 10 protects the drive mechanism from contamination by solids and liquids, e.g. in the event that a sample vessel on the tray 9 tips over and liquid is spilled of spattered. The cover 10 is preferably designed as a trough which is sealed against solids and liquids on the hollow shaft 7. Inside the trough, there is only the tray 9, a part of the tray shaft 8 and the samples in the vessels on the tray 9. This means that only these elements have to be cleaned if they are contaminated, while the drive mechanism, which would be difficult to clean, remains clean.

(13) In addition, at least one counterweight 17 is attached to the hollow shaft 7, which compensates for an unbalance caused by the eccentric mass distribution of tray 9, sample holders, samples and tray shaft 8. In addition, a counterweight can also be attached to the tray shaft 8 to achieve dynamic balancing of the system. Balancing the unbalance protects the bearings, reduces noise emissions and extends the service life of the drive.

(14) The described design of the shaker makes it possible to achieve high shaking frequencies of more than 1000 rpm and in particular of 1000 to 1600 rpm or more due to the drive.

(15) While in the present application preferred embodiments of the invention are described, it should be noted that the invention is not limited to these and can also be executed in another way within the scope of the following claims.