Coffee mill and automatic coffee machine having a coffee mill

Abstract

A coffee grinder, in particular for the installation in a fully-automatic coffee machine, including an electric drive motor (1) for driving a grinding unit, wherein a reduction gear (4) formed as a planetary gear is arranged between drive motor (1) and grinding unit, with the sun gear (3) of this planetary gear being drivable by the drive motor (1). The planetary gear includes multiple planetary rods (8) arranged in the circumferential direction around the sun gear (3), these rods including a first axial portion (7) meshing with the sun gear (3) as well as an axially neighboring, second axial portion (9) with a second diameter different from, preferably smaller than, a first diameter of the first axial portion (7), with this second axial portion meshing with a stationary ring gear (11). The toothed racks are arranged to drive an output element (15) with their first axial portions (7).

Claims

1. A coffee grinder for installation in fully-automatic coffee machines, including an electric drive motor (1) for driving a grinding unit, wherein a reduction gear (4) formed as a planetary gear is arranged between the drive motor (1) and the grinding unit, with a sun gear of this planetary gear (3) being drivable by the drive motor (1), wherein the planetary gear comprises multiple planetary rods (8) arranged in a circumferential direction around the sun gear (3), these rods including a first axial portion (7) meshing with the sun gear (3) as well as an axially neighboring, second axial portion (9) with a second diameter different from a first diameter of the first axial portion (7), with this second axial portion meshing with a stationary ring gear (11), and wherein toothed racks are arranged to drive an output element (15) with their first axial portions (7).

2. The coffee grinder of claim 1, wherein the sun gear (3), the first axial portions (7) and the output element (15) comprise a helical toothing (5) having teeth, in which axial tooth ends of the teeth are spaced in the circumferential direction.

3. The coffee grinder of claim 1, wherein the second axial portions (9) are arranged radially neighboring a shaft coupling the drive with the sun gear (3), which axially extends through an interspace region between the second axial portions (9).

4. The coffee grinder of claim 1, wherein the toothed racks are formed in a monolithic manner.

5. The coffee grinder of claim 4, wherein the toothed racks are injection-molded plastic parts.

6. The coffee grinder of claim 1, wherein the planetary gear has a reduction ratio of more than 20:1.

7. The coffee grinder of claim 6, wherein the reduction ratio is more than 25:1.

8. The coffee grinder of claim 6, wherein the reduction ratio is more than 30:1.

9. The coffee grinder of claim 6, wherein the reduction ratio is between 30:1 and 50:1.

10. The coffee grinder of claim 1, wherein the stationary ring gear (11) is formed on an inner circumference of a gear case (12), which radially surrounds the first (7) and second axial portions (9) on the outside.

11. The coffee grinder of claim 10, wherein the gear case (12) is rotationally-fixed to a case of the drive motor (1).

12. The coffee grinder of claim 11, wherein the gear case (12) is fixed axially to the case of the drive motor (1).

13. The coffee grinder of claim 1, wherein the output element (15) is at least sectionally formed as a hollow shaft.

14. The coffee grinder according to claim 1, wherein a friction clutch is arranged between the planetary gear and the grinding unit and/or wherein the output element (15) is arranged so as to drive an ejector disk (17), which is coupled with a rotatable grinding element via the friction clutch.

15. A fully-automatic coffee machine, including a coffee grinder according to claim 1 as well as a brewing unit for leaching coffee powder produced by means of the coffee grinder.

16. The coffee grinder of claim 1, wherein the second diameter is smaller than the first diameter.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The figures show in:

(2) FIG. 1: an exploded view of the combination of drive motor, planetary gear as well as ejector disk of a coffee grinder for the integration on a fully-automatic coffee machine (the illustration of further grinding unit components such as a grinding cone and a grinding ring is omitted for a better understanding),

(3) FIG. 2: a longitudinal sectional view of the combination of FIG. 1,

(4) FIG. 3: a sectional illustration along the section S-D of FIG. 2, and

(5) FIG. 4: a sectional illustration along section E-E of FIG. 2, wherein this viewing direction is the one that defines the clockwise and anti-clockwise rotary directions.

DETAILED DESCRIPTION

(6) The same elements and elements having the same function are indicated with the same reference numerals throughout the figures.

(7) An electric drive motor 1 of a coffee grinder of a fully-automatic coffee machine is shown in FIG. 1 in the drawing plane on the left.

(8) The drive motor 1 is coupled with a sun gear of a reduction gear 4 formed as a planetary gear via a motor shaft 2. It is discernable that the sun gear 3, on the outer circumference thereof, has a helical toothing 5, by means of which it meshes a mating, likewise helical, toothing 6 of first axial portions 7 of planetary rods 8 monolithic on the outer circumference. The planetary rods 8 formed in the circumferential direction around the sun gear 3 and each comprise besides a first helically toothed axial protrusion 7 an axially neighboring, in this case directly adjacent second axial portion 9, which has a smaller diameter than the neighboring first axial portion 7. The second axial portions 9 in each case mesh, via their respective outer toothing 10, a rotationally-fixed ring gear 11, specifically an inner toothing (see FIG. 2), which is arranged in one piece with and on the inner circumference of a gear case 12, which is axially fixed to a motor case 14 of the drive motor 1 via fixing screws 13.

(9) The mating toothing 6 of the first axial portions 7 mesh with a output element 15 which is configured as a hollow shaft, which closes, on the face side, the gear case 12 axially extending over the entire length of the planetary rods 8 on the axial side facing away from the drive motor 1. An ejector disk 17 of the grinding unit is coupled to the output element 15 in a rotationally-fixed manner, which ejector wings 18 are distributed over the circumference in order to eject milled material, i.e. coffee powder, in the radial direction outward, toward a brewing unit which is not shown. Here, a friction clutch is realized preferably between ejector disks 17 and a grinding element, in particular a grinding ring or a cone of a friction clutch arranged therein. In the exemplary embodiment shown, the planetary rods comprise a rod rotary axis 19, which axially extends through the respective planetary rod 8 and are received in axially neighboring brackets 20 (see FIG. 2). FIG. 1 shows a fixing element formed as a screw, indicated at reference numeral 16, for axially securing a grinding element to the ejector disk 17.

(10) FIG. 2 shows that the output element 15 is supported in the radial direction outward on the gear case 12 via a roller bearing 21 configured as a ball bearing, which forms the stationary ring gear 11 by comprising an inner toothing formed integrally with the gear case 12.

(11) FIG. 2 further shows that a shaft formed by the motor shaft 2 as well as a lower portion of the sun gear 3 extends through the second axial portions 9 or an interspace defined by them (radial inner space/center) in the axial direction, so that the sun gear 3 gets into a toothing engagement with the mating helical toothing 6 of the first axial portions 7.

(12) When the drive motor 1 is operated, the sun gear 3 rotates in the direction of the gear or in the direction of the drive motor, with a viewing direction from a grinding unit, i.e. from right or left in FIGS. 1 and 2, e.g. in the anti-clockwise direction, as indicated in FIG. 2 and FIG. 4, namely around a rotary axis or an axis of rotation R, parallel to which the rod rotary axes 19 are arranged. Due to the helical toothing engagement of the helical toothing 5 and the mating helical toothing 6, the planetary rods 8 rotate around their respective rod rotary axis 19 in the clockwise direction. As the planetary rods 8 mesh via the toothing of their second axial portions 9 with the stationary ring gear 11, the planetary rods 8 move in the circumferential direction about the axis of rotation R, namely in the anti-clockwise direction, as can be taken from the illustration of FIG. 3, in which it is to be observed that the viewing direction of the above-mentioned illustration of FIG. 3 is opposite the viewing direction of FIG. 4 for the definition of the rotary directions. Here, the rotary direction D.sub.1 of the shaft 2 as well as the resulting rotary direction D.sub.2 of the planetary rods 8 about their respective planetary rod rotary axis 19 are discernable. Due to the meshing arrangement of the second axial portions 9 with the stationary ring gear 11, the planetary rod arrangement 19 rotates in a rotary direction D.sub.3 that coincides with the rotary direction D.sub.1. Die to the helical toothing engagement between the mating toothing 6 and an inner helical toothing 22 of the output element 15, the latter is rotated in the direction D.sub.4, which coincides with the rotary direction D.sub.2.

(13) The specific illustrated variant of the planetary gear comprises a reduction ratio of 32.4:1.

REFERENCE NUMERALS

(14) 1 Electric motor 2 Motor shaft 3 Sun gear 4 Reduction gear 5 Helical toothing 6 Mating helical toothing 7 First axial portions 8 Planetary rods 9 Second axial portions with smaller diameter than the first axial portions 10 External toothing 11 Stationary ring gear (stationary inner toothing) 12 gear case 13 Fixing screws 14 Motor case 15 Output element 16 Fixing element 17 Ejector disk 18 Ejector wing 19 Rod rotary axes 20 Brackets 21 Roller bearing 22 Helical inner toothing R Axis of rotation (rotary axis of the sun gear) D.sub.1 Rotary direction of the sun gear around the axis of rotation D.sub.2 Rotary direction of the planetary rods around rod rotary axes D.sub.3 Rotary direction of the planetary rods around the axis of rotation R D.sub.4 Rotary direction of the drive element