HK1072532B - Coffee grinder assembly for a coffee machine - Google Patents

Description

Coffee grinder assembly for a coffee maker

Technical Field

The present invention relates to a coffee grinder assembly comprising a housing, a first lower grinding wheel support member and a first lower grinding wheel, and a second upper grinding wheel support member and a second upper grinding wheel. Rotatably receiving at least one of the first and second grinding wheels into the housing. The first lower grinding wheel support member and the first lower grinding wheel each include first mating connection means for securing the first lower grinding wheel to the first lower grinding wheel support member, and the second upper grinding wheel support member and the second upper grinding wheel each include second mating connection means for securing the second upper grinding wheel to the second upper grinding wheel support member.

Background

A coffee grinder assembly of the type described above is mainly made of plastic material, and therefore its grinding wheel is made of a hard, non-abrasive material, such as hardened steel. The quality of the coffee powder prepared with such a coffee grinder assembly depends in particular on the resistance to abrasion of the grinding wheel used on said coffee grinder assembly, since as said grinding wheel wears away gradually the grain size of the coffee powder changes, resulting in a degradation of the quality of the ground coffee powder and of the coffee beverage prepared with said coffee powder.

In order to secure the grinding wheel to the associated grinding wheel support member, a plurality of holes are typically provided in the grinding wheel which pass through the grinding wheel and receive attachment means such as screws, rivets or the like. The drawback of providing a connection hole may arise in the case that they require a large number of theoretically available grinding surfaces of the grinding wheel, since the engagement of the grinding wheel is disturbed by said hole. In addition, the harder the grinding wheel-which property is required in itself-the more difficult it is to create the attachment holes in the grinding wheel by machining. Finally, the provision of the connection hole has the additional drawback that the coffee powder is concentrated in said hole and in said connection means; of course, this phenomenon is highly undesirable for hygienic reasons.

Patent document EP1065962 discloses a coffee grinder with a coffee grinder assembly of the type described above. The coffee grinder assembly includes a bevel gear, and two coaxially mounted grinding wheels having helical teeth. One of the grinding wheels is stationary and the other grinding wheel is rotatable. Both grinding wheels are provided with coupling holes suitable for receiving coupling screws, in such a way as to fix said grinding wheels to the relative grinding wheel support member. In particular, fig. 4 of this document clearly shows that the connection hole is located at a toothed portion of the grinding wheel.

Us patent No. 6164574 discloses a grinding machine for grinding materials such as salt grains or pepper seeds, the roughness of which can be adjusted and its grinding wheel can be disassembled for cleaning. The mill has a middle section, which is used as a container for the material to be milled, and an upper section connected to the middle section by means of connecting and adjusting elements. In addition, the grinding machine has a lower portion designed to be detachable from the intermediate portion for cleaning the grinding wheel. The grinding wheel includes an upper grinding wheel, the lower side of which is placed on the intermediate portion, and a lower grinding wheel, which is screwed with the connecting and adjusting member by means of a pivot pin. The pivot pin is non-rotatably connected to the upper portion. Rotating the upper portion drives the grinding wheel.

In order to fix the grinding wheels on their relative support members, the grinding wheels are provided with four grooves distributed along their periphery, which engage with correspondingly mounted cam members provided on the relative support members. A drawback of this design is that the grinding wheel is not correctly positioned either in the axial direction or in the radial direction, as a result of which the grinding wheel may move within the supporting part of the grinding wheel under the influence of the torsional forces occurring during the grinding operation.

Disclosure of Invention

It is an object of the present invention to provide a coffee grinder assembly for a coffee machine, wherein the grinding wheel does not have any connecting holes extending through the grinding wheel, so that the grinding wheel can always be correctly positioned and fixed in axial and radial directions.

In order to meet the above and other objects, the present invention provides a coffee grinder assembly comprising a housing, a first lower grinding wheel support member and a first lower grinding wheel, and a second upper grinding wheel support member and a second upper grinding wheel, at least one of said first lower grinding wheel and said second upper grinding wheel being rotatably received in said housing.

The first lower grinding wheel support member and the first lower grinding wheel each include first mating connection means for securing the first lower grinding wheel to the first lower grinding wheel support member, and the second upper grinding wheel support member and the second upper grinding wheel each include second mating connection means for securing the second upper grinding wheel to the second upper grinding wheel support member.

The first and second mating connection devices are designed as a rotary lock, wherein the mutual rotation between the first lower grinding wheel support member and the first lower grinding wheel and between the second upper grinding wheel support member and the second upper grinding wheel provides in each case a lock which, in the locked state, is driven under the influence of a torsional force occurring during the grinding operation, which torsional force causes both the first lower grinding wheel and the second upper grinding wheel to be pressed axially and into the associated first lower grinding wheel support member and second upper grinding wheel support member.

By providing the above-mentioned rotary closure to secure each grinding wheel to its associated support member, the effective grinding area of the grinding wheel is increased because space-consuming connecting holes present on the grinding wheel are avoided. In addition, difficult and time consuming drilling of the connection holes can be avoided, which is particularly advantageous for very hard grinding wheels. In addition, it is ensured that the grinding wheel does not come loose under the influence of torsional forces occurring during the grinding operation, but is more securely mounted and positioned on the associated grinding wheel support member. Finally, the design of the invention also takes into account the hygienic requirements of the grinding and cutting area.

In a preferred embodiment of the invention, the grinding wheel comprises radially distributed projections of the insert-lock type cooperating with corresponding recesses provided on the relative support member. The grinding wheel can be quickly and easily fixed to the associated support member.

Further, preferably, the first lower grinding wheel and the second upper grinding wheel are made of a carbide material or a cemented carbide material.

Drawings

Embodiments of the coffee grinder assembly of the present invention will be further described with reference to the accompanying drawings, in which:

FIG. 1 shows an exploded view of a coffee grinder assembly;

FIG. 2 shows a top view of the upper grinding wheel support member with the grinding wheel secured thereto;

FIG. 3 is a longitudinal sectional view of the upper grinding wheel support section shown in FIG. 2 with the grinding wheel secured thereto; and

fig. 4 shows an enlarged portion of the cross-sectional view shown in fig. 3.

Detailed Description

The coffee grinder assembly shown in fig. 1 mainly comprises an electric drive motor 1, a driven rotary disk 2, a housing 3, a lower grinding wheel support 4, a lower grinding wheel 5, a shaft 6, an upper grinding wheel 7, an upper grinding wheel support 8 and a feed screw 9. The screws needed to connect the above components, as well as other components such as seals, bearings, etc., are not shown for clarity.

Since the design and operation of the coffee grinder assembly is well known to those skilled in the art, only the features necessary for the present invention will be discussed further below.

The lower and upper grinding wheel support members 4, 8 are preferably made of a plastic material and serve to receive and fixedly support the lower and upper grinding wheels 5, 7, respectively. Unlike the holes of the known coffee grinder assemblies for fixing the respective grinding wheel to the grinding wheel support member to which it is associated, radial projecting members 10, 11 are provided on the grinding wheels 5, 7 for fixing said grinding wheel to the grinding wheel support member 4, 8 to which it is associated.

Grooves 12, 13 are provided in both the lower and upper grinding wheel support members 4, 8, and are sized and positioned to correspond to the radial projections 10, 11 provided on the grinding wheels 5, 7. The radially projecting parts 10, 11 engage with the recesses 12, 13 and establish an insertion lock between them. In the exploded view shown in fig. 1, the grooves 12, 13 provided on the lower and upper grinding wheel support members 4, 8 are hardly visible because they are hidden. Both the grooves 12, 13 and the radial projections 10, 11 have inclined wedge surfaces 10a, 11a, as a result of which, when the grinding wheel and the grinding wheel support member are rotated relative to each other, the lower and upper grinding wheels 5, 7 are pressed axially, i.e. in the direction of the longitudinal central axis of the grinding assembly, into the associated grinding wheel support member 4, 8 in order to engage the insert lock.

The lower grinding wheel support member 4 has six vertically distributed projections 15. Three of them comprise the aforementioned groove-shaped recesses 12 for receiving and securing the lower grinding wheel 5 by its radially distributed projections 10. The upper grinding wheel support member 8 likewise has three slotted recesses 13 for receiving and securing the upper grinding wheel 7 by its radially extending projections 11. However, the slit-shaped grooves 12 provided in the lower grinding wheel support member 4 and the upper grinding wheel support member 8 are only partially visible in the schematic view of fig. 1. The slit-shaped grooves 12, 13 together with the radially extending projections 10, 11 of the respective grinding wheels 5, 7 form some kind of insertion locking mechanism, which is designed in such a way that: the grinding wheels 5, 7 are firmly fixed in the grooves 12, 13 by the effect of the torque exerted on the radially distributed protrusions 10, 11 during operation of the grinding wheels 5, 7. For radially centering the grinding wheels 5, 7, annular grooves 21 are provided on both grinding wheels, which grooves engage with annular projections 20 provided on the lower and upper grinding wheel support members 4, 8, respectively, as will be explained further below.

The lower grinding wheel 5 and the upper grinding wheel 7 have teeth 25, which in each case are arranged on the surface of the grinding wheels 5, 7 facing the opposite grinding wheel 7, 5. However, in the exploded view of figure 1, only the teeth 25 on the upper surface of the lower grinding wheel 5 are visible, however, it will be appreciated that the upper grinding wheel 7 has a correspondingly toothed lower surface. The grinding wheels 5, 7 are preferably both made of a ceramic-based material which is very wear resistant and has a longer service life than conventional grinding wheels made of hard metal. Therefore, even under heavy load conditions, it is not generally necessary to replace the grinding wheels 5, 7 during the lifetime of the coffee grinder. Since the radially distributed protruding portions 10, 11 are provided at the peripheral portions of the grinding wheels 5, 7, the necessity of providing connection holes on the grinding wheels 5, 7 is eliminated. As a result, the effective grinding area is significantly increased and costly and difficult drilling operations of the hard vitrified grinding wheels 5, 7 are not required.

In order to provide a positive connection between the lower grinding wheel support member 4 and the rotary plate 2 driven by the motor 1, the lower grinding wheel support member 4 comprises a projection 16 with peripheral teeth, the projection 16 being adapted to engage with a hole 17 provided in the rotary plate 2 and having corresponding internal teeth. The rotor 2 is driven by a motor 1 having a worm gear 19 which engages with peripheral teeth 18 provided on the rotor 2.

Unlike the lower grinding wheel support member 4, the upper grinding wheel support member 8 is not rotatable but fixed to the housing 3. In order to prevent the upper grinding wheel support member 4 from rotating, it comprises a cam 22 which engages with a corresponding groove 23 provided on the housing 3. Finally, an upper feed screw 9 is screwed onto the threaded upper end of the shaft 6, while the lower threaded end of the shaft 6 is fixed to the rotary plate 2 by means of a nut (not shown).

The lower side of the rotary plate 2 preferably has a permanent magnet (not shown) cooperating with a sensor (not shown) fixed to said housing in order to determine the number of revolutions during operation of the coffee grinder. Thus, the number of revolutions performed by the lower grinding wheel 5 during a coffee grinding revolution establishes a measure for determining the amount of ground coffee during one working cycle.

Fig. 2 shows a plan view of the upper grinding wheel support member 8 on which the upper grinding wheel 7 is fixed, and fig. 3 shows a cross-sectional view of the grinding wheel support member 8 and the grinding wheel 7 taken along the line a-a in fig. 2. Figure 2 clearly shows the slit-shaped groove 13 provided on the upper grinding wheel support member 8, which groove engages with the radially distributed protrusions 10 provided on the grinding wheel 7 (see figure 1) in order to fixedly attach the upper grinding wheel 7 to the support member 8. In fig. 3 is clearly shown an annular protrusion 20 provided on the upper grinding wheel support member 8 and a corresponding annular groove 21 provided on the upper grinding wheel 7, in particular, for centering the upper grinding wheel 7 relative to the upper grinding wheel support member 8. When the upper grinding wheel 7 is inserted into the upper grinding wheel support member 8, the protruding portion 20 of the support member 8 engages with the groove 21 of the grinding wheel 7 and radially aligns the grinding wheel 7 with the support member 8. Corresponding projections and recesses are also provided on the lower grinding wheel support member 4 and the lower grinding wheel 5, with the result that the two grinding wheels 5, 7 are coaxial once the coffee grinder assembly is finally assembled together.

Fig. 4 shows an enlarged portion of fig. 3. In this figure, it can be seen that the grinding wheel 7 has a smooth back face 14, one of its functions being as a support surface. Next, the grinding wheel support member 8 comprises an annular support surface 24 facing the grinding wheel 7, supporting the grinding wheel 7 in an axial direction, i.e. in the direction of the longitudinal central axis of the coffee grinder assembly. At the same time, the annular support surface 24 serves to position the grinding wheel 7 in the axial direction.

The grinding wheel 7 is loaded in the locking direction due to the torsional forces acting on the grinding wheel 7 during the grinding operation. In other words, by choosing the correct rotation direction of the grinding wheel, and due to the design of the rotation locking mechanism, the grinding wheel 7 is loaded in the locking direction. Therefore, the grinding wheel 7 is firmly fixed in the grinding wheel support member 8, and it can be ensured that the grinding wheel 7 is not accidentally loosened. In addition, due to this load, it is also ensured that the back surface of the grinding wheel 7 is moved against the support surface 24 of the grinding wheel support member 8 and stops there without a gap. As a result, no coffee powder accumulates between the grinding wheel 7 and the grinding wheel support member 8. The above is also true to be understood in connection with the grinding wheel 5 and its associated support member 4.

In addition, in fig. 4, it is clearly visible the annular projection 20 of the grinding wheel support member 8, which engages with the annular groove 21 provided on the grinding wheel 7 and ensures a precise radial positioning of the grinding wheel 7 with respect to the support member 8.

In addition to the bayonet locking mechanism described above with radially projecting locking parts, other types of rotational locking mechanisms may be used to lock the grinding wheel to its associated support part. For example, a threaded locking mechanism may be used to secure the grinding wheel to the associated support member. On the other hand, the locking means may be arranged in the axial direction of the grinding wheel, in particular on its back side facing the associated support member. In addition, a central positioning of the projection or projections is also possible. Finally, it is understood that the locking mechanism can be designed in a kinematically opposite manner: the grinding wheel may have a groove or grooves and the associated support member may include one or more corresponding projections which engage the groove on the grinding wheel.

Claims (11)

1. A coffee grinder assembly comprising a housing, a first lower grinding wheel support member and a first lower grinding wheel, and a second upper grinding wheel support member and a second upper grinding wheel, such that at least one of said first lower grinding wheel and said second upper grinding wheel is rotatably accommodated in said housing, said first lower grinding wheel support member and said first lower grinding wheel each comprising first mating connection means for securing the first lower grinding wheel in the first lower grinding wheel support member, and said second upper grinding wheel support member and said second upper grinding wheel each comprising second mating connection means for securing the second upper grinding wheel in the second upper grinding wheel support member, characterized in that each of said first mating connection means and said second mating connection means is designed for rotational locking, wherein said first lower grinding wheel support member and said first lower grinding wheel, and said second upper grinding wheel support member and said second upper grinding wheel are rotatably locked together The mutual rotation of the first and second upper grinding wheels provides the rotational lock which is driven in a locked condition under the influence of a torsional force occurring during the grinding operation, which torsional force causes both the first and second lower grinding wheels to be axially pressed and locked into the associated first and second upper grinding wheel support members.

2. The coffee grinder assembly according to claim 1, including a motor for driving the first lower grinding wheel rotatably received in the housing.

3. The coffee grinder assembly according to claim 1, wherein the second upper grinding wheel support member has a support surface facing the second upper grinding wheel, and the second upper grinding wheel has a smooth support surface facing the second upper grinding wheel support member, the second upper grinding wheel pressing against the support surface of the second upper grinding wheel support member under the influence of torsional forces occurring during grinding operations.

4. The coffee grinder assembly according to claim 1, wherein each of the first lower grinding wheel and the second upper grinding wheel has a radially distributed protrusion, and wherein each of the first lower grinding wheel support member and the second upper grinding wheel support member has a correspondingly positioned groove, the protrusion of the first lower grinding wheel engaging the groove of the first lower grinding wheel support member to form a first insertion lock, and the protrusion of the second upper grinding wheel engaging the groove of the second upper grinding wheel support member to form a second insertion lock.

5. The coffee grinder assembly according to claim 4, wherein the protruding portions of said first lower grinding wheel and said second upper grinding wheel comprise inclined wedge surfaces axially positioning said first lower grinding wheel and said second upper grinding wheel on the associated grinding wheel support member and radially pressing said first lower grinding wheel and said second upper grinding wheel against the support surface provided on the associated grinding wheel support member.

6. The coffee grinder assembly according to claim 1, wherein each of said first lower grinding wheel and said second upper grinding wheel has centering means for radially positioning said grinding wheel on the associated grinding wheel support member.

7. The coffee grinder assembly according to claim 6, wherein the centering means of the first lower grinding wheel and the second upper grinding wheel includes an annular groove, the associated first lower grinding wheel support member and second upper grinding wheel support member having respective annular projections that engage the annular groove of the first lower grinding wheel and the second upper grinding wheel to radially center the first lower grinding wheel and second upper grinding wheel relative to the associated first lower grinding wheel support member and second upper grinding wheel support member.

8. The coffee grinder assembly according to claim 6, wherein the centering means of the first lower grinding wheel and the second upper grinding wheel includes an annular projection, the associated first lower grinding wheel support member and second upper grinding wheel support member having respective annular grooves engaged with the annular projection of the first lower grinding wheel and second upper grinding wheel to radially center the first lower grinding wheel and second upper grinding wheel relative to the associated first lower grinding wheel support member and second upper grinding wheel support member.

9. The coffee grinder assembly of claim 1, wherein the first lower grinding wheel and the second upper grinding wheel are made of a ceramic-based material.

10. The coffee grinder assembly according to claim 1, wherein the first lower grinding wheel and the second upper grinding wheel are made of a carbide material or a cemented carbide material.

11. The coffee grinder assembly according to claim 1, wherein the second upper grinding wheel is stationary and the first lower grinding wheel is motor driven.