Grinding system for grinding a particulate food material, provided with a feeding device

Abstract

The present disclosure relates to a grinding system for grinding a granular food material, comprising: - a first movable grinding wheel (7), - a second grinding wheel (6), - a rotating shaft (9) configured to drive the rotation of the first movable grinding wheel (7), the first movable grinding wheel (7) comprising a grinding portion (14) configured to allow the grinding of the granular material against the second grinding wheel (6), the grinding system further comprising a feeding device (1) for the grinding system of the granular material, the feeding device comprising: - a fastening element (2) for fastening to the rotating shaft (9), and - a feeding element comprising a proximal portion (4), an elbow portion (13) and a distal feeding portion (5), a recess (12) separating the distal feeding portion (5) from the fastening element (2).

Description

Technical Field

[0001] This application relates to the field of grinding systems for grinding granular materials, particularly for grinding coffee beans to produce ground coffee. More specifically, this application relates to a grinding system for grinding granular food materials equipped with a feeding device. Background Technology

[0002] A grinding system typically consists of a movable grinding wheel and a fixed grinding wheel, both usually conical. This system is particularly found in some coffee machines to produce ground coffee from coffee beans. The two grinding wheels are mounted to rotate relative to each other about a common axis. One grinding wheel is driven to rotate by a motor, while the other remains stationary relative to the axis, allowing beans driven by gravity towards a converging area between the two grinding wheels to be ground.

[0003] The amount of beans that can be ground between the grinding wheels depends directly on the rotational speed of the movable grinding wheel: the higher the speed, the faster the coarse beans are ground, and the larger the volume of beans that can freely flow to the convergence zone. To increase the amount of beans that can be ground, the rotational speed of the movable grinding wheel must be increased. However, this increase has several drawbacks.

[0004] First, it inevitably increases the noise generated by the motor driving the movable grinding wheel, causing discomfort to the user, especially when the grinding system in question is part of a household appliance.

[0005] Furthermore, increasing the rotational speed of the movable grinding wheel is only possible for motors capable of providing sufficient mechanical torque. Therefore, this may be prohibitive in terms of the type of motor that a grinding system must include. For example, it might be desirable to use certain DC motors that allow for stable rotational speeds, but such motors can only achieve limited speeds.

[0006] Finally, increasing the rotational speed of the movable grinding wheel changes the particle size of the ground beans. To maintain the optimal sensory characteristics of the ground beans and the beverages made from them, it may be desirable to increase the grinding throughput without altering the particle size. For example, in the case of a coffee grinding system, it may be desirable to increase the grinding throughput to obtain a larger volume of ground coffee within a given time, without changing the thickness of the ground particles, which has a considerable impact on the texture and flavor of the coffee.

[0007] Existing technologies have envisioned certain solutions to increase the grinding capacity of grinding systems in household appliances. For example, there are grinding systems that include worm gears, which allow feeding into the convergent zone between grinding wheels. However, for a predetermined rotating speed of the movable grinding wheel, the increase in throughput allowed by such systems remains limited. Summary of the Invention

[0008] Therefore, a grinding system is needed that allows for an increase in the amount of beans that can be ground without increasing the rotational speed of the movable grinding wheel in the grinding system.

[0009] Therefore, a grinding system for grinding granular food materials is proposed, comprising: - First movable grinding wheel - Second grinding wheel, - A rotating shaft configured to drive the first movable grinding wheel to rotate. The first movable grinding wheel includes a grinding section configured to allow grinding of granular material against the second grinding wheel. The grinding system also includes a feeding device for grinding granular materials, the feeding device comprising: - Fastening elements for securing to the rotating shaft of the grinding system, and - Feed element, the feed element comprising: - The elongated proximal portion, which extends away from the fastener in the reference plane. - The elbow portion, which extends from the proximal portion in the reference plane, and - The distal feed section extends from the elbow section and forms a non-zero angle with the proximal section; a recess separates the distal feed section from the fastening element. The fastening element, proximal portion, elbow portion, and feed portion are all made of the same material.

[0010] The presence of a distal feed section extending from the elbow, thus not directly extending the proximal portion, allows for the forced passage of beans toward the grinding section of the system. This results in a higher bean throughput without requiring an increase in the rotational speed of the movable grinding wheel. This allows a given amount of granular material to be ground in a shorter time without being exposed to the disadvantages of increased rotational speed. Furthermore, the presence of the distal feed section allows for better agitation of the beans, and therefore improves their descent toward the system section that grinds them.

[0011] According to some embodiments, the distal feed portion extends beyond the reference plane and defines a non-zero angle with the reference plane, preferably between 10° and 45°, more preferably between 15° and 30°.

[0012] According to some embodiments, the projection of the distal feed portion in the intermediate plane of the fastening element extends from the elbow portion to the free end of the distal feed portion approaching the fastening element.

[0013] According to some embodiments, the minimum distance between the fastening element and the distal feed portion is greater than or equal to 0.5 mm and less than or equal to 8 mm.

[0014] According to some embodiments, the fastening element defines the rotation axis of the feed device, and the proximal portion extends along the elongation direction, the projection of the elongation direction onto the intermediate plane of the fastening element being parallel to the radial direction relative to the rotation axis, the projection of the elongation direction onto the intermediate plane of the fastening element being located at a non-zero distance from the radial direction.

[0015] According to some embodiments, the distal feed portion has a curved outer edge.

[0016] According to some embodiments, the fastening element includes a central hole configured to fasten the feed device to the rotating shaft.

[0017] According to some embodiments, the grinding system includes a plurality of feed elements equidistantly distributed around the fastening element.

[0018] According to some embodiments, the grinding system includes two or three feed elements.

[0019] According to some embodiments, the second grinding wheel is fixed, and the first movable grinding wheel and the fixed second grinding wheel define a common axial direction.

[0020] According to some embodiments, the first movable grinding wheel includes a plurality of teeth extending along the radial direction of the first movable grinding wheel, and the projection of the proximal portion onto a plane orthogonal to the axis of rotation includes the projection of the vertex of one of the teeth onto the plane orthogonal to the axis of rotation.

[0021] According to some embodiments, the first movable grinding wheel includes a plurality of teeth extending along the radial direction of the first movable grinding wheel, and the projection of the vertex of each tooth onto a plane orthogonal to the axis of rotation is located outside the projection of the proximal portion onto the plane orthogonal to the axis of rotation.

[0022] According to some embodiments, the grinding system includes a DC motor configured to drive a rotating shaft.

[0023] According to some embodiments, the grinding system includes a detection system configured to: - The intensity of the current consumed by the motor driving the first movable grinding wheel is measured; the measured current intensity represents the rotational speed of the first movable grinding wheel. - Compare the measured current intensity with the reference current intensity, and - Generate a signal representing the presence or absence of beans in the grinding section based on the comparison results.

[0024] According to some embodiments, the feed device is secured to the rotating shaft by tightening an external threaded portion around the rotating shaft.

[0025] According to some embodiments, in the installation configuration of the grinding system, the distal feed portion extends from the elbow portion toward the free edge of the distal feed portion away from the grinding portion. Attached Figure Description

[0026] Figure 1 A grinding system for grinding granular materials is shown.

[0027] Figure 2a The second grinding wheel of the grinding system is shown.

[0028] Figure 2b The first movable grinding wheel of the grinding system is shown.

[0029] Figure 3 A feeding device for a grinding system is shown, which includes a single feeding element.

[0030] Figure 4 A feeding device for a grinding system is shown, which includes two feeding elements.

[0031] Figure 5 A feeding device for a grinding system is shown, which includes three feeding elements.

[0032] In the accompanying drawings, the same or similar elements are indicated by the same reference numerals. Detailed Implementation

[0033] Figure 1 A grinding system for grinding granular food materials to obtain powdered materials is shown. This system is specifically designed for grinding coffee beans to obtain ground coffee.

[0034] The grinding system includes two grinding wheels 6 and 7, which work together to grind granular materials. These two grinding wheels 6 and 7 respectively... Figure 2a and Figure 2b The diagram shows this in more detail. The first grinding wheel 7 is rotatable and mechanically integrated with a rotating shaft 9 adapted to be driven by a motor. The second grinding wheel 6 is fixed, so that when the first grinding wheel 7 is driven by the rotating shaft 9, the first grinding wheel 7 is displaced relative to the second grinding wheel 6. Figure 1 and Figure 2a and Figure 2b In the embodiment shown, grinding wheel 6 and grinding wheel 7 each have a rotary frustocone shape—in the use position of the grinding system, the first movable grinding wheel 7 has a downward opening shape, while the second grinding wheel 6 has an upward opening shape.

[0035] A bean receiving area is defined between the outer wall 16 of the first movable grinding wheel 7 and the inner wall 15 of the second grinding wheel 6, suitable for receiving a certain amount of beans to be ground. The lower part of the outer wall 16 of the first movable grinding wheel 7 defines a grinding section 14, the diameter of which is sufficiently close to the diameter D of the inner wall 15 of the second grinding wheel 6, so as to allow particulate material to be ground between the two grinding wheels 6 and 7 when it reaches the grinding section 14 under the action of gravity.

[0036] The first movable grinding wheel 7 and the second grinding wheel 6 together define the axial direction, denoted by a. The rotation axis 9 extends along this axial direction a. The radial direction r is defined as any direction perpendicular to and passing through the axial direction a. The circumferential direction c is defined as any direction perpendicular to the axial direction a and not passing through it.

[0037] To facilitate grinding granular materials, the inner wall 15 of the second grinding wheel 6 has a serrated shape. When the beans are pushed against the inner wall 15 by the rotation of the first movable grinding wheel 7, the teeth 17 of the inner wall 15 concentrate the force applied by the inner wall 15 on a localized area of ​​the beans, thereby facilitating the grinding of the beans.

[0038] The outer wall 16 of the first movable grinding wheel 7 also includes teeth configured to facilitate the grinding of granular materials. The teeth extend substantially in the radial direction r and have apexes 8. They serve the same force-concentrating function as the teeth 17 of the second grinding wheel 6.

[0039] According to some embodiments, the rotating shaft 9 is configured to be connected to a DC motor, which allows the movable grinding wheel 7 to operate more quietly than when using an AC motor. Furthermore, the use of a DC motor allows for better stability of the rotational speed. However, the rotating shaft 9 is preferably configured to be selectively connected to either an AC motor or a DC motor.

[0040] The grinding system also includes a bean shortage detection system. This system includes a current sensor suitable for determining the current consumed by the motor. When the amount of beans present in the bean receiving area is abnormally low, the motor consumes less current than when the area is full. The processing unit regularly receives signals from the current sensor indicating the motor's current consumption and compares these signals with a reference intensity corresponding to motor operation when the receiving area is full. Therefore, the processing unit can detect the absence or abnormally low quantity of beans in the receiving area.

[0041] like Figure 3 As shown, the grinding system includes a feed device 1 fastened to the rotating shaft 9 by fastening element 2. The feed device 1 is configured to force the beans poured into the bean receiving area towards the grinding section 14, thereby ensuring that the largest possible amount of beans is ground within a given time. In other words, the feed device 1 allows for an increase in the grinding capacity of the grinding system. One advantage of the feed device 1 is that it allows for satisfactory grinding capacity, including when using a DC motor (this type of motor is not allowed to reach the same high speeds as AC motors). Due to the use of a DC motor, a grinding system that is both quiet and has a stable rotational speed is obtained while maintaining a high grinding capacity.

[0042] In the illustrated embodiment, the fastening element 2 takes the form of a ring including a central hole 3 into which the rotating shaft 9 is inserted. During operation of the grinding system, this allows the rotating shaft to be surrounded by material around its entire circumference, thereby preventing any disengagement of the feed device 1 relative to the rotating shaft 9.

[0043] According to one embodiment, the feeding device 1 is fastened by tightening around the external threaded portion of the rotating shaft 9. In this case, the fastening element 2 includes a threaded inner wall that is complementary to the thread of the external threaded portion of the rotating shaft 9. According to another embodiment, the fastening element 2 is flat and is held on the rotating shaft 9 by clamping between the movable grinding wheel 7 and the head of the rotating shaft 9.

[0044] According to another embodiment, the rotating shaft 9 includes an internal thread, and the fastening element 2 is held by a screw whose external thread is complementary to the internal thread of the rotating shaft 9. The screw 2 is screwed onto the rotating shaft, and the fastening element is disposed around the rotating shaft 9. The screw may include a head with an outer diameter larger than the inner diameter of the fastening element (e.g., the diameter of the hole forming the ring of the fastening element 2).

[0045] The feeding device 1 also includes a feeding element that ensures the feeding of beans into the bean receiving area. The feeding element is essentially in the form of a curved blade, defined by a proximal portion 4, a bend portion 13, and a distal feeding portion 5. The various parts of the feeding element are integrally formed and made of metal, providing the feeding element with sufficient rigidity and mechanical resistance relative to the forces it experiences during use.

[0046] The proximal portion 4 extends from the fastening element 2. When the fastening element 2 is in the form of a ring, the proximal portion 4 extends from the outer circumference of the ring. The proximal portion is planar, therefore in the reference plane P... ref The proximal portion 4 is elongated, meaning it defines an elongation direction b away from the fastening element 2. The length of the proximal portion 4 along the elongation direction is greater than the width of the proximal portion perpendicular to the elongation direction. Both the length and width of the proximal portion 4 lie in the reference plane P. ref The function of the proximal portion 4 is to hold the feed portion 5 at a certain distance from the rotation axis 9. The elongation characteristics of the proximal portion 4 and the presence of the recess 12 between the fastening element 2 and the distal feed portion 5 advantageously allow the inertial torque of the proximal portion 4 about the rotation axis to be minimized without compromising the effectiveness of the feed ensured by the feeding device, since the feeding action it applies occurs essentially at a certain distance from the rotation axis 9, where centrifugal force is most likely to cause the beans to rise away from the grinding portion 14, and where the distal feed portion 5 is suitable for applying a larger feeding force.

[0047] The proximal portion 4 can extend in the intermediate plane of the fastening element 2 (i.e., the reference plane P). ref(coinciding with the intermediate plane), or extending in a plane intersecting the intermediate plane of the fastening element 2, such that the axial position of the proximal portion 4 changes from the fastening element 2 all the way to the elbow portion 13. The "intermediate plane" refers to a plane orthogonal to the axial direction of the ring—therefore, in the installation configuration of the grinding system, orthogonal to the rotation axis 9—and divides the ring into two parts of equal thickness along the axial direction. Figure 3 An embodiment is shown in which the proximal portion 4 coincides with the reference plane P, which is the intermediate plane of the fastening element 2. ref Extending from the middle.

[0048] According to one embodiment, the proximal portion 4 extends in the radial direction r. Alternatively, as... Figure 3 As shown, when the feed device is projected onto the intermediate plane of the fastening element 2, the elongation direction b of the proximal portion 4 is separate from the radial direction r but parallel to the radial direction r. In particular, still considering the projection onto the intermediate plane of the fastening element 2, the elongation direction b deviates from the radial direction r, such that the outer edge 18 of the proximal portion 4 is tangent to the ring formed by the fastening element 2 at a point on the circumference intersecting the radius f perpendicular to the elongation direction b.

[0049] The elongation direction b passes through the intermediate plane of the proximal portion 4, which divides the proximal portion 4 into two parts of equal width.

[0050] The elbow portion 13 extends from the proximal portion 4, specifically from the end of the proximal portion 4 opposite to the fastening element 2. The elbow portion 13 ensures engagement between the proximal portion 4 and the distal feed portion 5. The elbow portion 13 is located on the reference plane P defined by the proximal portion 4. ref Inner tangent. Due to the presence of the elbow portion 13, when considering the feed element in the reference plane P... ref In a two-dimensional projection, the distal portion 5 does not extend within the extension of the proximal portion 4, but instead defines a non-zero angle γ with the proximal portion 4. This allows the distal feed portion 5 to extend closer to, or even along, the circumferential direction c. Therefore, when the feeding device moves due to the rotation of the rotating shaft 9, the distal feed portion 5 applies a feeding force on a larger quantity of beans compared to the case where the distal feed portion 5 extends within the extension of the proximal portion 4. The feeding effect is thus improved. The fact that the distal feed portion 5 forms a non-zero angle γ with the proximal portion 4 also means that a recess 12 is defined between the fastening element 2 and the distal feed portion 5.

[0051] The distal feed portion 5 extends from one end of the elbow portion 13 to the free edge 11 of the distal feed portion 5. The distal feed portion 5 has a curved outer edge 10, which is particularly curved such that its projection on the midplane of the fastening element 2 defines an arc around the rotation axis 9. Therefore, the curved outer edge 10 can extend in a direction corresponding to the circumferential direction, thereby ensuring a uniform feed of beans during the operation of the grinding system.

[0052] According to some embodiments, when considering the projection of the feed element onto the intermediate plane of the fastening element 2, the distal feed portion 5 extends from the elbow portion 13 all the way to the free edge 11 approaching the fastening element 2.

[0053] The first option to ensure this proximity is that the curved outer edge 10 defines an arc around the rotation axis 9, while the curved inner edge 19 of the distal feed portion 5 approaches the fastening element 2. In this case, still within the midplane of the fastening element 2, the width l5 of the distal feed portion 5, perpendicular to its extension direction, increases from the elbow portion 13 all the way to the free edge 11.

[0054] A second option to ensure this proximity is that the dimension of the distal feed portion 5 perpendicular to its elongation direction remains constant, in which case the projections of both the curved outer edge 19 and the curved inner edge 10 in the mid-plane of the fastening element 2 extend from the elbow portion 13 all the way to the free outer edge 11 approaching the fastening element 2.

[0055] The distal feed section 5 passes through a reference plane P defined by the proximal section 4. ref The non-zero angle β is defined and extended. This allows the distal feed portion 5 to exert a feeding effect on larger volumes of granular material: in effect, this inclination of the distal feed portion 5 allows it to contact beans positioned at a wider range of axial locations. In other words, the amount of granular material passing above or below the distal feed portion 5 without contacting it is minimized, and therefore not forced into the grinding portion 14.

[0056] Preferably, the angle β causes the distal feed portion 5 to extend from the elbow portion 13 to the free edge 11 away from the grinding portion 14. In other words, when the grinding system is placed on a table or work surface, the distal feed portion 5 extends upward from the elbow portion 13 to the free edge 11, and the grinding portion is located at a lower position than the distal feed portion 5 (and therefore closer to the table or work surface).

[0057] According to the embodiment, the proximal portion 4 may be more or less elongated. According to a so-called "close" configuration where the distal feed portion 5 is relatively close to the rotation axis 9, the minimum distance between the fastening element 2 and the distal feed portion 5 is between 0.5 and 4 mm, for example, equal to 2.5 mm. According to another so-called "offset" configuration where the distal feed portion 5 is relatively far from or offset from the rotation axis 9, the minimum distance between the fastening element 2 and the distal feed portion 5 is between 4 and 8 mm, for example, equal to 5.5 mm. "Minimum distance" means that the distance between the fastening element 2 and the distal feed portion 5 cannot be less than this value, regardless of the axis along which the distance is measured, and also regardless of the individual points on the distal feed portion 5 and the fastening element 2 where the distance is measured.

[0058] In other words, the minimum distance between the distal feed portion 5 and the fastening element 2 corresponds to the minimum width of the recess 12.

[0059] Reference plane P ref The angle β between the distal feed portion 5 and the mill portion 14 is between 10° and 45°, preferably between 15° and 30°. This angle range allows for a good compromise between two aspects: on the one hand, feeding beans in a wider range of axial positions, and on the other hand, the component of the force exerted on the beans by the distal feed portion 5, which is mainly axial and downward—this force is perpendicular to the distal feed portion 5—and is therefore sufficient to force the beans toward the mill portion 14.

[0060] like Figure 1 As shown, when the first movable grinding wheel 7 includes teeth, and if we again consider the two-dimensional projection of the grinding system onto the midplane of the fastening element 2, the tooth tips 18 of the first movable grinding wheel 7 can be incised within the feed device (the so-called "aligned" configuration). According to an alternative embodiment, the projection of the feed device 1 does not include the projection of the tooth tips 18—therefore the feed device is located circumferentially between the two tooth tips 18 (the so-called "disaligned" configuration). Tests, which will be described later, have demonstrated that this "disaligned" configuration allows for a higher bean throughput through the grinding system than the "aligned" configuration.

[0061] Reference Figure 4 and Figure 5 According to some embodiments, the grinding system includes feed devices 1', 1'', which are equipped with a plurality of feed elements extending from the same fastening element 2. Figure 4 The feed device 1' is shown, which includes two separate feed elements that are the same as the aforementioned feed elements and are arranged according to their relative positions on the diameter of the rotation axis 9. Figure 5The feed device 1” is shown, which includes three separate feed elements, which are the same as the aforementioned feed elements and are arranged at 120° to each other about the rotation axis 9. In some configurations of the feed device, increasing the number of feed elements increases the grinding capacity of the grinding system—in particular, it has been observed that having three feed elements instead of two feed elements significantly increases the grinding capacity in some configurations of the feed device.

[0062] Examples and test results The inventors conducted a series of tests on different embodiments of the feeding device 1, 1', 1" and these tests demonstrated that the grinding throughput was increased due to the adoption of certain preferred features.

[0063] Table 1 below lists the different configurations tested for feed devices 1, 1', and 1" and two reference configurations without any feed device, labeled "Reference Configuration," one with a DC motor and the other with an AC motor. The "Increased Throughput" column indicates the percentage increase in average throughput observed for the same motor configuration (DC or AC motor) as the example under consideration, compared to the grinding system configuration without any feed device. The "Aligned Configuration" column indicates that it refers to the system with the previously defined "aligned" or "unaligned" configuration. The "Proximal Portion" column indicates that the proximal portion 4 is configured according to the "closer" or "offset" configuration as described above.

[0064] [Table 1]

[0065] The following conclusions were drawn from the test results: The motor used was a 230 V / 50 Hz motor. The throughput was measured based on the average of three grinding sessions, each lasting six seconds.

[0066] DC motor The presence of the feed element as described above allows for an increase in grinding throughput between 12% and 27%.

[0067] Comparing reference configurations I and III, we find that the reference plane P ref Increasing the angle β between the feed unit 5 and the remote feed section 5 from 20° to 30° does not change the increase in throughput associated with the presence of the feed device (12% increase in both cases relative to the reference configuration).

[0068] Comparing configurations II, IV, and V, we found that the throughput increase associated with increasing the number of feed elements changed from 12% for a single feed element to 25% for three feed elements.

[0069] Comparing reference configurations II and III, we found that the deviation configuration allows for a 12% increase in throughput, almost the same as the increase obtained for the close-to-the-configuration configuration.

[0070] Comparing Reference Configurations II and VI, we found that the aligned configuration allows for a 12% increase in throughput, compared to 27% for the unaligned configuration.

[0071] AC motor The presence of the feed element as described above allows for an increase in grinding throughput of between 12% and 21%.

[0072] Comparing reference configurations VII and IX, we find that the reference plane P ref Increasing the angle β between the remote feed section 5 and the feed section 5 from 20° to 30° will increase the throughput by 19% instead of 12%.

[0073] Comparing reference configurations VIII, X, and XI, we find that the increase in throughput associated with increasing the number of feed elements is relatively small compared to increases associated with other geometric features of the feed elements, but this increase is not zero. Therefore, increasing the number of feed elements is particularly advantageous when the grinding system is powered by a DC motor.

[0074] Comparing reference configurations VIII and IX, we find that the offset configuration allows for a 17% increase in throughput, compared to 12% for the proximity configuration of the proximal section 4. Therefore, the offset configuration is particularly advantageous when the grinding system is powered by an AC motor.

[0075] Comparing the reference configurations VIII and XII, we found that the aligned configuration allows for a 17% increase in throughput, compared to 21% for the unaligned configuration.

Claims

1. A grinding system for grinding granular food materials, comprising: - First movable grinding wheel (7). - Second grinding wheel (6) - A rotating shaft (9) configured to drive the first movable grinding wheel (7) to rotate. The first movable grinding wheel (7) includes a grinding portion (14) configured to allow abrasion against the second grinding wheel (6) to grind particulate material. The grinding system further includes a feeding device (1) for grinding granular materials, the feeding device comprising: - Fastening element (2) for fastening to the rotating shaft (9) of the grinding system, and - Feed element, the feed element comprising: - The elongated proximal portion (4), which lies in the reference plane (P ref Extending from the fastening element (2) away from the fastening element (2), - The elbow portion (13), which extends from the proximal portion (4) in the reference plane, and - A distal feed portion (5) extends from the elbow portion (13) and forms a non-zero angle (γ) with the proximal portion, and a recess (12) separates the distal feed portion (5) from the fastening element (2). The fastening element (2), the proximal portion (4), the elbow portion (13), and the feed portion (5) are made of the same material.

2. The grinding system according to claim 1, wherein, The distal feed portion (5) extends beyond the reference plane and defines a non-zero angle (β) with the reference plane, the angle (β) preferably being between 10° and 45°, more preferably between 15° and 30°.

3. The grinding system according to any one of claims 1 and 2, wherein, The projection of the distal feed portion (5) in the intermediate plane of the fastening element (2) extends from the elbow portion (13) to the free end (11) of the distal feed portion (5) approaching the fastening element (2).

4. The grinding system according to any one of claims 1 to 3, wherein, The minimum distance between the fastening element (2) and the distal feed portion (5) is greater than or equal to 0.5 mm and less than or equal to 8 mm.

5. The grinding system according to any one of claims 1 to 4, wherein, The fastening element (2) defines the rotation axis (a) of the feed device (1), and wherein the proximal portion (4) extends along the elongation direction (b), the projection of the elongation direction (b) onto the intermediate plane of the fastening element (2) being parallel to the radial direction (r) relative to the rotation axis (a), and the projection of the elongation direction (b) onto the intermediate plane of the fastening element (2) being located at a non-zero distance from the radial direction (r).

6. The grinding system according to any one of claims 1 to 5, wherein, The distal feed portion (5) has a curved outer edge (10).

7. The grinding system according to any one of claims 1 to 6, wherein, The fastening element (2) includes a center hole (3) configured to fasten the feed device (1) to the rotating shaft (9).

8. The grinding system according to any one of claims 1 to 7, comprising a plurality of feed elements equidistantly distributed around the fastening element (2).

9. The grinding system according to the preceding claim, comprising two or three feed elements.

10. The grinding system according to any one of the preceding claims, wherein, The second grinding wheel (6) is fixed, and the first movable grinding wheel (7) and the fixed second grinding wheel (6) define a common axial direction (a).

11. The grinding system according to any one of the preceding claims, wherein, The first movable grinding wheel (7) includes a plurality of teeth extending along the radial direction of the first movable grinding wheel (7), and wherein the projection of the proximal portion (4) onto a plane orthogonal to the rotation axis (9) includes the projection of the vertex (8) of one of the teeth onto a plane orthogonal to the rotation axis (9).

12. The grinding system according to any one of claims 1 to 10, wherein, The first movable grinding wheel (7) includes a plurality of teeth extending along the radial direction of the first movable grinding wheel (7), and wherein the projection of the vertex (8) of each tooth onto a plane orthogonal to the rotation axis (9) is located outside the projection of the proximal portion (4) onto a plane orthogonal to the rotation axis (9).

13. The grinding system according to any one of the preceding claims, comprising a DC motor configured to drive the rotating shaft (9).

14. The grinding system according to any one of the preceding claims, further comprising a detection system configured to: - Measure the intensity of the current consumed by the motor driving the first movable grinding wheel (7), the measured current intensity representing the rotational speed of the first movable grinding wheel (7). - Compare the measured current intensity with the reference current intensity, and - Generate a signal representing the presence or absence of beans in the grinding section (14) based on the comparison results.

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