Method for producing a coffee mill, and coffee mill

Abstract

The invention relates to a method for producing a coffee mill and to a coffee mill. In the method, a first component group of a coffee mill, which has a first grinding element, and a second component group of a coffee mill, which has a second grinding element, are provided, and the first component group is connected to the second component group to form a coffee mill, wherein a grinding gap with a height forms between the first and second grinding elements. Furthermore, a change in height of the grinding gap in dependence on the temperature is determined, wherein, when the first and / or second component group are / is provided, at least one measure is performed in order to bring about a change in height of the grinding gap of the coffee mill in dependence on the temperature of ≤ 0.30 µm / K. It is thus possible to provide a coffee mill which ensures that a desired degree of grinding of coffee is kept as constant as possible when the coffee mill heats up during operation.

Description

[0001] Method for producing a coffee grinder and coffee grinder

[0002] A method for producing a coffee grinder and a coffee grinder are provided. In the method, a first component group of a coffee grinder, which has a first grinding element, and a second component group of a

[0003] A coffee grinder is provided which has a second grinding element, and the first component group is connected to the second component group to form a coffee grinder, wherein a grinding gap with a height is formed between the first and second grinding elements. Furthermore, a determination of a change in the height of the grinding gap as a function of the temperature takes place, wherein when providing the first and / or second component group at least one measure is carried out to ensure that a change in the height of the grinding gap of the coffee grinder as a function of the temperature is < 0.30 pm / K. A coffee grinder can thus be provided which ensures that a desired degree of grinding of coffee is kept as constant as possible when the coffee grinder heats up during operation.Currently, coffee grinders (as a stand-alone device or as a component incorporated into an automatic coffee machine) are typically made of metallic materials, ceramic materials and / or polymeric materials.

[0004] Due to the waste heat generated during operation of the coffee grinder (e.g., from the activity of the coffee grinder's motor and / or from the grinding process on the coffee grinder's grinding discs), the individual parts and components of the coffee grinder heat up and expand. The degree of thermal expansion depends on the specific thermal expansion coefficient of the materials from which the coffee grinder's components are made.

[0005] Due to the characteristic design of a coffee grinder, i.e., a connection of the first grinding disc to a first component group of the coffee grinder and a connection of the second grinding disc to a second component group of the coffee grinder, a change in the height of the grinding gap occurs, i.e., a distance between the grinding discs or an expansion of the grinding gap in the direction of a rotational axis of at least one of the grinding discs (i.e., in the axial direction of at least one of the grinding discs). Since coffee grinders can reach temperatures of up to 80°C during operation, a change in the height of the grinding gap during operation can be very significant.

[0006] If a desired grinding degree is set, for example, at room temperature (20 °C), the temperature difference during operation of the coffee grinder is up to 60 K, which can have a relatively strong effect on the height of the grinding gap, i.e. it can cause an undesirably strong increase or decrease in the height of the grinding gap during operation of the coffee grinder. For example, if the height of the grinding gap in a state-of-the-art coffee grinder were to change by 0.55 pm / K, the absolute change in the height of the grinding gap if the temperature of the coffee grinder were to increase by 60 K would be a full 33 pm. Since in disc grinders, for example, the grinding gaps are typically in the range between 0 pm and 200 pm, this would correspond to a relative change in height in the grinding gap of > 16.5%.

[0007] However, the height of the grinding gap influences the selection result (i.e. the grain size distribution of ground coffee), i.e. a temperature-related increase in the height of the grinding gap leads to a larger grain size of the ground coffee and a temperature-related reduction in the height of the grinding gap leads to a smaller grain size of the ground coffee. Such a temperature-related change in the height of the grinding gap during operation of the coffee grinder is undesirable, since the grain size (or grain size distribution) should remain as constant as possible at a value set by a user or the coffee grinder. This is the only way to ensure that the ground coffee beans can be used to brew coffee that has the properties desired by the user or is of the highest possible quality.

[0008] In the prior art, no special attention has been paid to preventing a temperature-related change in the height of the grinding gap during operation of coffee grinders and the resulting deviation from a desired grinding result or the resulting deterioration in the quality of a coffee brewed with coffee powder provided by the coffee grinder.

[0009] To date, the only known attempt is to change the grinding level of a coffee grinder during operation using an active adjustment mechanism to compensate for a temperature-related change in the height of the grinding gap. However, this measure is inaccurate and requires (electrical) energy. As a result, a temperature-related change in the height of the grinding gap cannot be reliably prevented, and coffee grinders based on this mechanism are energy-intensive and prone to failure, making their operation uneconomical.

[0010] Based on this, the object of the present invention was to provide a method for producing a coffee grinder that overcomes at least one disadvantage of the prior art. In particular, the method should make it possible to provide a coffee grinder that, when the coffee grinder is heated during operation, ensures that the desired degree of grinding of the coffee is kept as constant as possible, preferably approximately constant, and that the ground coffee is used to brew coffee with the desired and / or best possible properties.

[0011] The problem is solved by the method having the features of claim 1 and the coffee grinder having the features of claim 10. The dependent claims show advantageous further developments.

[0012] According to the invention, a method for producing a coffee grinder is provided, comprising or consisting of the following steps: a) providing a first component group of a coffee grinder having a first grinding element connected to the first component group; b) providing a second component group of a coffee grinder having a second grinding element connected to the second component group; c) connecting the first component group to the second component group to form a coffee grinder, wherein the first grinding element is arranged above the second grinding element and a grinding gap is formed between the first and second grinding elements, wherein the grinding gap has a height; and d) determining a change in height of the grinding gap as a function of the temperature;characterized in that when providing the first component group and / or the second component group, at least one of the following measures is carried out in order to ensure that a change in height of the grinding gap of the coffee grinder as a function of the temperature is < 0.30 pm / K:;

[0013] Selecting a specific height for at least one component of the first and / or second component group, wherein the specific height refers to a length in the direction of the axis of rotation of at least one of the grinding elements;

[0014] Selecting a specific material for at least one component of the first and / or second component group; and selecting a specific height and / or a specific material for a compensation element that is connected to the first and / or second component group, wherein the specific height refers to a length in the direction of the rotation axis of at least one of the grinding elements.

[0015] The method according to the invention can provide a coffee grinder that ensures that the desired coffee grinding degree is maintained as consistently as possible when the coffee grinder is heated during operation. The coffee grinder produced using the method according to the invention can provide ground coffee that can be used to brew a coffee beverage with the desired and / or best possible properties.

[0016] According to the invention, the term "grinding gap" is understood in particular to mean the space between the first grinding element and the second grinding element. According to the invention, the height of the grinding gap is understood in particular to mean the smallest distance between the first grinding element and the second grinding element (i.e., their smallest distance in the grinding gap). This distance can be a distance in the direction of a rotational axis of at least one of the grinding elements (e.g., in a disc grinder) or can be a distance in a direction substantially perpendicular to a rotational axis of at least one of the grinding elements (e.g., in a conical grinder).

[0017] In the coffee machine manufactured using the method according to the invention, the height of the grinding gap changes only minimally from the set value depending on the temperature of the coffee grinder. Consequently, the quality of the ground coffee and the brewing result of a coffee brewed with the ground coffee powder can be maintained at a very high level, even during operation of the coffee grinder, which involves heating up the coffee grinder.

[0018] Adjusting the grinding gap height using an active adjustment mechanism is therefore unnecessary, making the coffee grinder more energy-efficient and less error-prone (i.e., more economical). Furthermore, a grinding degree set by a user or the coffee grinder can be maintained more reliably during operation than with an active adjustment mechanism. In principle, even complete compensation of thermal expansion with respect to the grinding gap height is possible, i.e., in this case, a change in the grinding gap height is 0 pm / K.

[0019] The measure implemented in the method according to the invention can comprise or consist of a selection of a specific height for at least one component of the first and / or second component group and a selection of a specific material for at least one component of the first and / or second component group, wherein the specific height refers to a length in the direction of the rotational axis of at least one of the grinding elements. In this case, the provision of a compensation element during the manufacture of the coffee grinder may be unnecessary, which allows the coffee grinder to be manufactured in a structurally simpler and more cost-effective manner.

[0020] Furthermore, the measure carried out in the method according to the invention can comprise or consist of a selection of a specific height and / or a specific material for a compensation element that is connected to the first and / or second component group, wherein the specific height relates to a length in the direction of the axis of rotation of at least one of the grinding elements. In this case, a selection of a specific height for at least one component of the first and / or second component group and a selection of a specific material for at least one component of the first and / or second component group can be unnecessary, which allows more design flexibility in the manufacture of the coffee grinder and enables the use of specific, desired (e.g., advantageous) materials in the manufacture of the coffee machine.

[0021] The first grinding element and / or the second grinding element can be a grinding disc. In this case, the first grinding element and the second grinding element can form at least part of a disc grinder. Alternatively, the first grinding element and / or the second grinding element can be part of a conical grinder. In this case, the first grinding element and the second grinding element can form at least part of a conical grinder.In the method according to the invention, the determination of the change in height of the grinding gap as a function of temperature can comprise the following steps: i) determining a first height of the grinding gap at a first temperature, wherein the first temperature is preferably 20 °C; ii) determining a second height of the grinding gap at a second temperature, wherein the second temperature is higher than the first temperature, wherein the second temperature is preferably 50 °C, particularly preferably 60 °C, very particularly preferably 70 °C, in particular 80 °C; iii) determining a difference between the second height of the grinding gap and the first height of the grinding gap; iv) determining the change in height of the grinding gap as a function of temperature according to the following formula:.

[0022] Altitude change [pm / K] = Ah [pm] : AT [K] where

[0023] Ah [pm] = difference between the second height of the grinding gap and the first height of the grinding gap; and

[0024] AT [K] = difference between the second temperature and the first temperature.

[0025] Furthermore, in the method according to the invention, the determination of the height change of the grinding gap as a function of the temperature can comprise the following steps: i) Determination of an expansion of each component of the first component group according to the formula

[0026] Expansion [pm / K] = Li [m] • a [pm / mK] where

[0027] Li [m] = length of the respective component of the first component group, in the direction of the rotational axis of at least one of the grinding elements; and a [pm / mK] = specific thermal expansion coefficient of the respective component of the first component group; ii) determination of a first mathematical sum of the expansion of each component of the first component group; iii) determination of an expansion of each component of the second component group according to the formula

[0028] Expansion [pm / K] = L2 [m] • a [pm / mK] where 1-2 [m] = length of the respective component of the second component group, in the direction of the axis of rotation of at least one of the grinding elements; and a [pm / mK] = specific thermal expansion coefficient of the respective component of the second component group; iv) determining a second mathematical sum from the expansion of each component of the second component group; and v) determining the change in height of the grinding gap as a function of the temperature by forming the difference between the first mathematical sum and the second mathematical sum.

[0029] In the method, the specific height for at least one component of the first and / or second component group can be selected such that the change in height of the grinding gap as a function of the temperature is < 0.25 pm / K, preferably < 0.20 pm / K, particularly preferably < 0.15 pm / K, very particularly preferably < 0.10 pm / K, in particular < 0.05 pm / K, optionally 0 pm / K.

[0030] Furthermore, in the method, the specific material for at least one component of the first and / or second component group can be selected such that the change in height of the grinding gap as a function of the temperature is < 0.25 pm / K, preferably < 0.20 pm / K, particularly preferably < 0.15 pm / K, very particularly preferably < 0.10 pm / K, in particular < 0.05 pm / K, optionally 0 pm / K.

[0031] Apart from that, in the method, the specific height and / or the specific material for a compensation element can be selected such that the change in height of the grinding gap as a function of the temperature is < 0.25 pm / K, preferably < 0.20 pm / K, particularly preferably < 0.15 pm / K, very particularly preferably < 0.10 pm / K, in particular < 0.05 pm / K, optionally 0 pm / K.

[0032] The first component group can be selected such that it causes (through thermal expansion) an increase in the height of the grinding gap depending on a temperature increase of the first component group (i.e. the entirety of the components of the first component group can be selected such that they cause an increase in the height of the grinding gap when the temperature increases).

[0033] The first component group can comprise a grinder housing and / or a motor housing of the coffee grinder, preferably both a grinder housing and / or a motor housing of the coffee grinder.

[0034] The mill housing can be connected to the first grinding element on the one hand and the motor housing on the other hand.

[0035] The first grinding element may contain or consist of ferritic steel and / or a ceramic (e.g., an Al2O3 ceramic). Furthermore, the first grinding element may have a height, in the direction of the rotational axis of at least one of the grinding elements, in the range of 5 to 10 mm, preferably in the range of 7 to 9 mm.

[0036] The mill housing can contain or consist of aluminum, ferritic steel, and / or a ceramic (e.g., an AlCl ceramic), preferably containing or consisting of ferritic steel. Furthermore, the mill housing can have a height, in the direction of the rotational axis of at least one of the grinding elements, in the range of 15 to 30 mm, preferably in the range of 20 to 25 mm.

[0037] The motor housing may contain or consist of aluminum and / or a ceramic (e.g., an AhCh ceramic). Furthermore, the motor housing may have a height, in the direction of the rotational axis of at least one of the grinding elements, in the range of 40 to 80 mm, preferably in the range of 50 to 70 mm.

[0038] The second component group can be selected such that it causes a reduction in the height of the grinding gap (through thermal expansion) as a function of a temperature increase of the second component group (i.e., the entirety of the components of the second component group can be selected such that they cause a reduction in the height of the grinding gap when the temperature increases). The second component group can comprise a grinding element carrier connected to the second grinding element, a motor shaft, and / or a motor shaft bearing seat, preferably comprising both a grinding element carrier connected to the second grinding element, a motor shaft, and a motor shaft bearing seat.

[0039] The motor shaft can be connected to the grinding element carrier on the one hand and to the motor shaft bearing seat on the other hand.

[0040] The second grinding element may contain or consist of ferritic steel and / or a ceramic (e.g., an A^Ch ceramic). Furthermore, the second grinding element may have a height, in the direction of the rotational axis of at least one of the grinding elements, in the range of 5 to 10 mm, preferably in the range of 7 to 9 mm.

[0041] The grinding element carrier may contain or consist of aluminum. Furthermore, the grinding element carrier may have a height, in the direction of the rotational axis of at least one of the grinding elements, in the range of 2 to 8 mm, preferably in the range of 4 to 6 mm.

[0042] The motor shaft may contain or be made of austenitic steel. Furthermore, the motor shaft may have a height, in the direction of the rotational axis of at least one of the grinding elements, in the range of 40 to 70 mm, preferably in the range of 50 to 60 mm.

[0043] The motor shaft bearing seat can contain or be made of aluminum. Furthermore, the motor shaft bearing seat can have a height, in the direction of the rotational axis of at least one of the grinding elements, in the range of 1 to 5 mm, preferably in the range of 2 to 4 mm.

[0044] A compensation element containing or consisting of a plastic can be used in the process. Plastic has the advantage of a relatively high specific thermal expansion coefficient. This means that the height of the compensation element can be low, allowing the coffee grinder to be provided very compactly. Plastic has the additional advantage of a relatively low specific density, which allows the weight of the compensation element and thus the coffee grinder to be low. Furthermore, plastic has the further advantage of being a relatively inexpensive material, allowing the coffee grinder to be provided more cost-effectively and thus more economically.

[0045] The plastic is preferably a thermoplastic. The plastic is particularly preferably selected from the group consisting of polyphenylene sulfide (PPS), polycarbonate (PC), polyamide (PA), polypropylene (PP), HD polyethylene (HDPE) and combinations thereof. In particular, the plastic is polyphenylene sulfide (PPS). PPS is advantageous because it not only has a relatively high specific thermal expansion coefficient (50 pm / mK), but also advantageous mechanical properties. This makes the compensation element durable and can achieve the compensation effect even with relatively small dimensions (i.e., a low height). HDPE is advantageous because the height of the compensation element can be very low due to the high specific thermal expansion of HDPE (200 pm / mK), and thus the coffee grinder can be provided very compactly and cost-effectively. However, HDPE has disadvantageous mechanical properties compared to PPS.

[0046] Furthermore, the compensation element can have a thermal expansion coefficient of > 40 pm / mK, preferably > 50 pm / mK. The higher the specific thermal expansion coefficient, the smaller the dimensions (i.e., the height) of the compensation element can be to achieve the desired compensation effect.

[0047] The method according to the invention can be characterized in that the coffee grinder is not equipped with a control unit that is configured to correct a temperature-related change in the degree of grinding.

[0048] According to the invention, a coffee grinder is further provided, containing or consisting of: a) a first component group of a coffee grinder, which has a first grinding element connected to the first component group; b) a second component group of a coffee grinder, which has a second grinding element connected to the second component group, wherein the first component group is connected to the second component group to form a coffee grinder, wherein the first grinding element is arranged above the second grinding element and a grinding gap is formed between the first and second grinding elements, wherein the grinding gap has a height; c) optionally: a compensation element on the first and / or second component group; characterized in that a change in height of the grinding gap of the coffee grinder as a function of the temperature is < 0.30 pm / K.

[0049] In the coffee grinder according to the invention, the height change of the grinding gap depending on the temperature can be < 0.25 pm / K, preferably < 0.20 pm / K, particularly preferably < 0.15 pm / K, very particularly preferably < 0.10 pm / K, in particular < 0.05 pm / K, optionally 0 pm / K. The smaller the height change of the grinding gap depending on the temperature, the better it can be ensured that a desired degree of coffee grinding is maintained as constant as possible during operation of the coffee grinder.

[0050] The first component group of the coffee grinder can be suitable for causing (by thermal expansion) an increase in the height of the grinding gap depending on an increase in temperature of the first component group (i.e. the entirety of the components of the first component group can be suitable for causing an increase in the height of the grinding gap when the temperature increases).

[0051] The first component group of the coffee grinder can comprise a grinder housing and / or a motor housing of the coffee grinder, preferably comprising both a grinder housing and a motor housing of the coffee grinder.

[0052] The grinder housing of the coffee grinder can be connected to the first grinding element on the one hand and the motor housing on the other.

[0053] The first grinding element of the coffee grinder can contain or consist of ferritic steel and / or a ceramic (e.g., an A^Ch ceramic). Furthermore, the first grinding element can have a height, in the direction of the axis of rotation of at least one of the grinding elements, in the range of 5 to 10 mm, preferably in the range of 7 to 9 mm. The grinder housing of the coffee grinder can contain or consist of aluminum, ferritic steel and / or a ceramic (e.g., an AC ceramic), preferably contain or consist of ferritic steel. Furthermore, the grinder housing can have a height, in the direction of the axis of rotation of at least one of the grinding elements, in the range of 15 to 30 mm, preferably in the range of 20 to 25 mm.

[0054] The motor housing of the coffee grinder can contain or be made of aluminum and / or a ceramic (e.g., an AC ceramic). Furthermore, the motor housing can have a height, in the direction of the rotational axis of at least one of the grinding elements, in the range of 40 to 80 mm, preferably in the range of 50 to 70 mm.

[0055] The second component group of the coffee grinder can be suitable for causing (by thermal expansion) a reduction in the height of the grinding gap depending on an increase in temperature of the second component group (i.e. the entirety of the components of the second component group can be suitable for causing a reduction in the height of the grinding gap when the temperature increases).

[0056] The second component group can comprise a grinding element carrier connected to the second grinding element, a motor shaft and / or a motor shaft bearing seat, preferably comprising both a grinding element carrier connected to the second grinding element, a motor shaft and a motor shaft bearing seat.

[0057] The motor shaft of the coffee grinder can be connected to the grinding element carrier on the one hand and to the motor shaft bearing seat on the other hand.

[0058] The second grinding element of the coffee grinder can contain or consist of ferritic steel and / or a ceramic (e.g., an AC ceramic). Furthermore, the second grinding element can have a height, in the direction of the rotational axis of at least one of the grinding elements, in the range of 5 to 10 mm, preferably in the range of 7 to 9 mm. The grinding element carrier of the coffee grinder can contain or consist of aluminum. Furthermore, the grinding element carrier can have a height, in the direction of the rotational axis of at least one of the grinding elements, in the range of 2 to 8 mm, preferably in the range of 4 to 6 mm.

[0059] The motor shaft of the coffee grinder can contain or be made of austenitic steel. Furthermore, the motor shaft can have a height, in the direction of the rotational axis of at least one of the grinding elements, in the range of 40 to 70 mm, preferably in the range of 50 to 60 mm.

[0060] The motor shaft bearing seat of the coffee grinder can contain or be made of aluminum. Furthermore, the motor shaft bearing seat can have a height, in the direction of the rotational axis of at least one of the grinding elements, in the range of 1 to 5 mm, preferably in the range of 2 to 4 mm.

[0061] The compensation element can contain or consist of a plastic. The plastic is preferably a thermoplastic. Particularly preferably, the plastic is selected from the group consisting of polyphenylene sulfide (PPS), polycarbonate (PC), polyamide (PA), polypropylene (PP), high-density polyethylene (HDPE), and combinations thereof. In particular, the plastic is polyphenylene sulfide (PPS).

[0062] Furthermore, the compensation element can have a thermal expansion coefficient of > 40 pm / mK, preferably > 50 pm / mK.

[0063] The coffee grinder according to the invention can be characterized in that it does not have a control unit configured to correct a temperature-related change in the degree of grinding.

[0064] The coffee grinder according to the invention can be characterized in that it is manufactured using the method according to the invention.

[0065] The subject matter according to the invention will be explained in more detail with reference to the following figure and the following example, without wishing to restrict it to the specific embodiments shown here. The figure schematically shows a coffee grinder according to the invention. The coffee grinder contains a first component group A, which has a first grinding element A, 1 connected to the first component group A, and a second component group B, which has a second grinding element B, 2 connected to the second component group B. The first component group A is connected to the second component group B to form a coffee grinder. The first grinding element A, 1 is arranged above the second grinding element B, 2 and a grinding gap 3 is formed between the first grinding element A, 1 and the second grinding element B, 2. The grinding gap 3 has a height H in the direction of a rotation axis D of the second grinding element B, 2.

[0066] The first component group A here consists of a grinder housing A, 5 and a motor housing A, 6 of the coffee grinder and is suitable for increasing the height H of the grinding gap 3 as a function of a temperature increase in the first component group A. This is due to the fact that the grinder housing A, 5 and the motor housing A, 6 expand as a result of the temperature increase, and as a result their length in the direction of a rotational axis D of the second grinding element B, 2 increases. Since the motor housing A, 6 is connected to the grinder housing A, 5 and the grinder housing A, 5 is connected to the first grinding element A, 1, the first grinding element A, 1 is lifted, i.e. moves away from the second grinding element B, 2, as a result of which the grinding gap 3 is enlarged or the height H of the grinding gap 3 increases.

[0067] The second component group B here consists of a grinding element carrier B, 7 connected to the second grinding element B, 2, a motor shaft B, 8 and a motor shaft bearing seat B, 9 and is suitable for reducing the height H of the grinding gap 3 as a function of a temperature increase of the second component group B. This is due to the fact that the grinding element carrier B, 7, the motor shaft B, 8 and the motor shaft bearing seat B, 9 expand due to an increase in temperature and thus their length in the direction of a rotational axis D of the second grinding element B, 2 increases. Since the motor shaft bearing seat B, 9 is connected to the motor shaft B, 8, the motor shaft B, 8 is connected to the grinding element carrier B, 7 and the grinding element carrier B, 7 is connected to the second grinding element B, 2, the second grinding element B, 2 is thereby raised, ie moves towards the first grinding element A, 1, whereby the grinding gap 3 is reduced or the height H of the grinding gap 3 is reduced.Since in the present case the temperature-related enlargement of the grinding gap 3 caused by the grinder housing A, 5 and the motor housing A, 6 is greater than the temperature-related reduction of the grinding gap 3 caused by the grinding element carrier B, 7, the motor shaft B, 8 and the motor shaft bearing seat B, 9, a plastic compensation element A, 4 (e.g. a plastic disc) is arranged on the first component group, specifically on the grinder housing A, 5. The temperature-related expansion of the compensation element A, 4 causes the influences of the temperature-related expansion of the first component group (A) and the second component group (B) to compensate each other, i.e., there is no change in the height H of the grinding gap 3 of the coffee grinder depending on the temperature (i.e., the height change is 0 pm / K).In other words, the height H of the grinding gap 3 can be kept constant at a set value by the compensation element A, 4 even when the component groups A, B of the coffee grinder heat up.

[0068] Example 1 - Method for producing a coffee grinder according to the invention without a compensation element

[0069] In this manufacturing example, the length and material of components of the first component group, which increase the height of the grinding gap as a function of temperature, are matched to the length and material of components of the second component group, which decrease the height of the grinding gap as a function of temperature. The length refers to the length of the respective components in the direction of the rotational axis of at least one of the grinding discs, since the length of the components in this direction influences a temperature-dependent change in the height of the grinding gap.

[0070] First, an extension of each component of the first component group is calculated according to the formula

[0071] Expansion [pm / K] = Li [m] • a [pm / mK], where Li [m] = length, in the direction of the axis of rotation of at least one of the grinding elements, of the respective component of the first component group; and a [pm / mK] = specific thermal expansion coefficient of the respective component of the first component group.

[0072] Example lengths, materials, specific thermal expansion coefficients and the expansion of the components of the first component group are shown in the following table.

[0073] 1. Example of the first component group

[0074] 2. Example of the first component group

[0075] In these two examples, the thermal expansion for the first component group (or for all of its components) is 1.118 pm / K. Based on this information, the lengths and materials of the components in the second component group can be selected so that they also have a thermal expansion of 1.118 pm / K as a whole. Since the first component group causes the grinding gap to increase as a function of temperature and the second component group causes the grinding gap to decrease as a function of temperature, both expansions compensate each other in this case, so that the expansion of the grinding gap (or the change in the height of the grinding gap) is 0 pm / K, meaning that the height of the grinding gap does not change as a function of temperature.

[0076] Examples of possible lengths, materials, specific thermal expansion coefficients and expansions of the components of the second component group are shown in the following tables.

[0077] 1. Example for the second component group

[0078] 2. Example for the second component group

[0079] These tables show that by selecting the lengths of the components and their materials, the expansion of the second component group can be adapted to the expansion of the first component group, resulting in the same expansion. This ensures that the grinding gap height does not change depending on temperature (grinding gap expansion = 0 pm / K).

[0080] Example 2 - Method for producing a coffee grinder according to the invention with a compensation element

[0081] Unlike Example 1, there may be a desire to shorten the length of the motor housing and / or the grinder housing, for example, in order to make the coffee grinder more compact in height. Furthermore, there may be a desire to manufacture the motor housing from aluminum instead of ferritic steel to make the coffee grinder lighter. Examples of desired lengths, materials, specific thermal expansion coefficients, and expansions of the components of the first component group and the second component group are shown in the following tables.

[0082] The tables above show that the first component group has a greater thermal expansion as a function of temperature than the second component group.

[0083] This is primarily due to the fact that the motor housing is made of aluminum, and aluminum has a higher specific thermal expansion coefficient than the ferritic steel used for the motor housing (see Example 1). Shortening the length of both the motor housing and the mill housing cannot compensate for this significant influence of aluminum as the motor housing material, i.e., it cannot reduce the expansion value to 1.118 pm / K. An even greater reduction in the length of the motor housing and / or the mill housing may be either undesirable or even impossible.

[0084] Since the first component group is responsible for increasing the height of the grinding gap depending on the temperature, the grinding gap in such a coffee grinder would therefore increase depending on the temperature, specifically by 1.652 pm / K - 1.118 pm / K = 0.534 pm / K.

[0085] In order to compensate for this effect in a way other than, for example, a further reduction in the length of the motor housing and / or mill housing, the expansion of the second component group can be increased, here by 0.534 pm / K to the value 1.652 pm / K of the first component group.

[0086] This can be achieved by a compensation element attached to the second component group. This compensation element would therefore have to exhibit a temperature-dependent expansion of 0.534 pm / K. In principle, all conceivable materials and lengths for the compensation element are possible.

[0087] If the compensation element is to be made of a specific material (with a specific specific thermal expansion coefficient), the required height of the compensation element (or length of the compensation element in the direction of the axis of rotation of at least one of the grinding discs) can be calculated using the following formula:

[0088] L [m] = Desired expansion [pm / K] : a [pm / mK] where

[0089] L = length, in the direction of the axis of rotation of at least one of the grinding discs, of the compensation element a = specific thermal expansion coefficient of the respective component of the second component group

[0090] Desired expansion = difference in expansion as a function of temperature between the first component group and the second component group (here: 0.534 pm / K).

[0091] For example, if the goal is to minimize the height of the compensation element, i.e., its length along the axis of rotation of at least one of the grinding discs, in order to provide a coffee grinder that is as compact as possible in terms of height, it is advantageous to select the compensation element from a material that has a relatively high specific thermal expansion coefficient. Plastics are a suitable example here, since plastics have a relatively high specific thermal expansion coefficient.

[0092] Examples of possible plastics are listed in the following table, from which it can be seen that the required height of the compensation element (or its length in the direction of the axis of rotation of at least one of the grinding discs) made of plastic depends on the specific thermal expansion coefficient of the plastic.

[0093] If the compensation element is to have a specific length, the necessary material from which the compensation element must be made can be calculated using the following formula, i.e. more precisely, the necessary specific thermal expansion coefficient that the material must have can be determined: a [pm / mK] = Desired expansion [pm / K] : L [m] where

[0094] L = length, in the direction of the axis of rotation of at least one of the grinding discs, of the compensation element a = specific thermal expansion coefficient of the respective component of the second component group

[0095] Desired expansion = difference in expansion as a function of temperature between the first component group and the second component group. For example, if the goal is for the compensation element to have a length of only 3.7 mm or 2.8 mm, the required specific thermal expansion coefficient can be determined, thus enabling a suitable material for the compensation element to be made of.

[0096] The compensation element can, for example, be attached to the grinding element of the second component group (= second grinding element), preferably between the grinding element and the mill housing. Alternatively, the compensation element can be attached, for example, between the mill housing and the motor housing.

[0097] The only decisive factor is that the compensation element is connected to the second component group in such a way that the height of the compensation element can influence a change in the height of the grinding gap depending on the temperature.

[0098] List of reference symbols

[0099] A: first component group;

[0100] B: second component group;

[0101] D: axis of rotation of at least one of the grinding elements;

[0102] H: height of the grinding gap;

[0103] 1: first grinding element (e.g. first grinding disc);

[0104] 2: second grinding element (e.g. second grinding disc);

[0105] 3: grinding gap;

[0106] 4: Compensation element

[0107] 5: Mill housing;

[0108] 6: Engine housing;

[0109] 7: Grinding element carrier (e.g. grinding disc carrier);

[0110] 8: Motor shaft; 9: Motor shaft bearing seat.

Claims

Patent claims 1. A method for producing a coffee grinder, comprising or consisting of the following steps: a) providing a first component group (A) of a coffee grinder having a first grinding element (A, 1) connected to the first component group (A); b) providing a second component group (B) of a coffee grinder having a second grinding element (B, 2) connected to the second component group; c) connecting the first component group (A) to the second component group (B) to form a coffee grinder, wherein the first grinding element (A, 1) is arranged above the second grinding element (B, 2) and a grinding gap (3) is formed between the first grinding element (A, 1) and the second grinding element (B, 2), the grinding gap (3) having a height (H); and d) determining a change in the height of the grinding gap as a function of the temperature;characterized in that when providing the first component group (A) and / or the second component group (B), at least one of the following measures is carried out in order to ensure that a change in height of the grinding gap (3) of the coffee grinder as a function of the temperature is < 0.30 pm / K:; Selecting a specific height for at least one component of the first component group (A) and / or the second component group (B), wherein the specific height refers to a length in the direction of the axis of rotation (D) of at least one of the grinding elements; Selection of a specific material for at least one component of the first component group (A) and / or second component group (B); and Selection of a specific height and / or a specific material for a compensation element (4) which is connected to the first component group (A) and / or second component group (B), wherein the specific height relates to a length in the direction of the axis of rotation (D) of at least one of the grinding elements.

2. Method according to the preceding claim, characterized in that the determination of the change in height of the grinding gap (3) as a function of temperature comprises the following steps: i) Determination of a first height (H) of the grinding gap (3) at a first temperature, wherein the first temperature is preferably 20 °C; ii) Determination of a second height (H) of the grinding gap (3) at a second temperature, wherein the second temperature is higher than the first temperature, wherein the second temperature is preferably 50 °C, particularly preferably 60 °C, most preferably 70 °C, in particular 80 °C; iii) Determination of a difference between the second height (H) of the grinding gap (3) and the first height (H) of the grinding gap (3); iv) Determination of the change in height of the grinding gap (3) as a function of temperature according to the following formula: Altitude change [pm / K] = Ah [pm] : AT [K] where Ah [pm] = difference between the second height (H) of the grinding gap (3) and the first height (H) of the grinding gap (3); and AT [K] = difference between the second temperature and the first temperature.

3. Method according to one of the preceding claims, characterized in that the determination of the height change of the grinding gap (3) as a function of the temperature comprises the following steps: i) Determination of the extension of each component of the first component group (A) according to the formula Expansion [pm / K] = Li [m] • a [pm / mK] where Li [m] = length of the respective component of the first component group (A), in the direction of the rotational axis (D) of at least one of the grinding elements (B, 2); and a [pm / mK] = specific thermal expansion coefficient of the respective component of the first component group (A); ii) determining a first mathematical sum from the expansion of each component of the first component group (A); iii) determining an expansion of each component of the second component group (B) according to the formula Expansion [pm / K] = L2 [m] • a [pm / mK] where L2 [m] = length of the respective component of the second component group (B), in the direction of the axis of rotation (D) of at least one of the grinding elements (B, 2); and a [pm / mK] = specific thermal expansion coefficient of the respective component of the second component group; iv) determining a second mathematical sum from the expansion of each component of the second component group (B); and v) determining the change in height of the grinding gap (3) as a function of the temperature by forming the difference between the first mathematical sum and the second mathematical sum.

4. Method according to one of the preceding claims, characterized in that the specific height for at least one component of the first component group (A) and / or second component group (B) is selected such that the change in height of the grinding gap (3) in Depending on the temperature, < 0.25 pm / K, preferably < 0.20 pm / K, particularly preferably < 0.15 pm / K, very particularly preferably < 0.10 pm / K, in particular < 0.05 pm / K, optionally 0 pm / K.

5. Method according to one of the preceding claims, characterized in that the specific material for at least one component of the first component group (A) and / or second component group (B) is selected such that the change in height of the grinding gap (3) as a function of the temperature is < 0.25 pm / K, preferably < 0.20 pm / K, particularly preferably < 0.15 pm / K, very particularly preferably < 0.10 pm / K, in particular < 0.05 pm / K, optionally 0 pm / K.

6. Method according to one of the preceding claims, characterized in that the specific height and / or the specific material for a compensation element (A, 4) is selected such that the change in height of the grinding gap (3) as a function of the temperature is < 0.25 pm / K, preferably < 0.20 pm / K, particularly preferably < 0.15 pm / K, very particularly preferably < 0.10 pm / K, in particular < 0.05 pm / K, optionally 0 pm / K.

7. Method according to one of the preceding claims, characterized in that the first component group (A) is selected such that it causes an increase in the height (H) of the grinding gap (3) depending on a temperature increase of the first component group (A), wherein the first component group (A) preferably comprises a mill housing (A, 5) and / or a motor housing (A, 6) of the coffee grinder, wherein particularly preferably i) the mill housing (A, 5) is connected to the first grinding element (A, 1) on the one hand and to the motor housing (A, 6) on the other hand; and / or ii) the first grinding element (A, 1) contains or consists of ferritic steel and / or a ceramic and / or has a height, in the direction of the rotational axis (D) of at least one of the grinding elements (B, 2), in the range of 5 to 10 mm, preferably in the range of 7 to 9 mm; and / or iii) the mill housing (A, 5) contains or consists of aluminum, ferritic steel and / or a ceramic, preferably contains or consists of ferritic steel, and / or has a height in the direction of the axis of rotation (D) of at least one of the grinding elements (B, 2) in the range from 15 to 30 mm, preferably in the range from 20 to 25 mm; and / or iv) the motor housing (A, 6) contains or consists of aluminum and / or a ceramic and / or has a height in the direction of the axis of rotation (D) of at least one of the grinding elements (B, 2) in the range from 40 to 80 mm, preferably in the range from 50 to 70 mm.

8. Method according to one of the preceding claims, characterized in that the second component group (B) is selected such that it causes a reduction in the height (H) of the grinding gap (3) as a function of a temperature increase of the second component group (B), wherein the second component group (B) preferably comprises a grinding element carrier (B, 7) connected to the second grinding element (B, 2), a motor shaft (B, 8) and / or a motor shaft bearing seat (B, 9), wherein particularly preferably i) the motor shaft (B, 8) is connected to the grinding element carrier (B, 7) on the one hand and to the motor shaft bearing seat (B, 9) on the other hand; and / or ii) the second grinding element (B, 2) contains or consists of ferritic steel and / or a ceramic and / or has a height, in the direction of the axis of rotation (D) of at least one of the grinding elements (B, 2), in the range of 5 to 10 mm, preferably in the range of 7 to 9 mm;and / or iii) the grinding element carrier (B, 7) contains or consists of aluminum and / or has a height, in the direction of the axis of rotation (D) of at least one of the grinding elements (B, 2), in the range of 2 to 8 mm, preferably in the range of 4 to 6 mm; and / or; iv) the motor shaft (B, 8) contains or consists of austenitic steel and / or has a height, in the direction of the axis of rotation (D) of at least one of the grinding elements (B, 2), in the range of 40 to 70 mm, preferably in the range of 50 to 60 mm; and / or v) the motor shaft bearing seat (B, 9) contains or consists of aluminum and / or has a height, in the direction of the axis of rotation (D) of at least one of the grinding elements (B, 2), in the range of 1 to 5 mm, preferably in the range of 2 to 4 mm.

9. Method according to one of the preceding claims, characterized in that the compensation element (A, 4) i) contains or consists of plastic, wherein the plastic is preferably a thermoplastic, particularly preferably polyphenylene sulfide; and / or ii) has a specific thermal expansion coefficient of > 40 pm / mK, preferably > 50 pm / mK.

10. A coffee grinder, containing or consisting of: a) a first component group (A) of a coffee grinder, which has a first grinding element (A, 1) connected to the first component group (A); b) a second component group (B) of a coffee grinder, which has a second grinding element (B, 2) connected to the second component group (B), wherein the first component group (A) is connected to the second component group (B) to form a coffee grinder, wherein the first grinding element (A, 1) is arranged above the second grinding element (B, 2) and a grinding gap (3) is formed between the first grinding element (A, 1) and the second grinding element (B, 2), wherein the grinding gap (3) has a height (H); c) optionally: a compensation element (A, 4) on the first component group (A) and / or second component group (B); characterized in that a change in height of the grinding gap (3) of the coffee grinder as a function of the temperature is < 0.30 pm / K.

11. Coffee grinder according to claim 10, characterized in that the change in height of the grinding gap (3) as a function of the temperature is < 0.25 pm / K, preferably < 0.20 pm / K, particularly preferably < 0.15 pm / K, very particularly preferably < 0.10 pm / K, in particular < 0.05 pm / K, optionally 0 pm / K.

12. Coffee grinder according to one of claims 10 or 11, characterized in that the first component group (A) is suitable for causing an increase in the height (H) of the grinding gap (3) depending on a temperature increase of the first component group (A), wherein the first component group (A) preferably comprises a grinder housing (A, 5) and / or a motor housing (A, 6) of the coffee grinder, wherein particularly preferably i) the grinder housing (A, 5) is connected to the first grinding element (A, 1) on the one hand and to the motor housing (A, 6) on the other hand; and / or ii) the first grinding element (A, 1) contains or consists of ferritic steel and / or a ceramic and / or has a height, in the direction of the axis of rotation (D) of at least one of the grinding elements (B, 2), in the range of 5 to 10 mm, preferably in the range of 7 to 9 mm;and / or iii) the mill housing (A, 5) contains or consists of aluminum, ferritic steel and / or a ceramic, preferably contains or consists of ferritic steel, and / or has a height, in the direction of the axis of rotation (D) of at least one of the grinding elements (B, 2), in the range from 15 to 30 mm, preferably in the range from 20 to 25 mm; and / or iv) the motor housing (A, 6) contains or consists of aluminum and / or a ceramic and / or has a height, in the direction of the axis of rotation (D) of at least one of the grinding elements (B, 2), in; Range of 40 to 80 mm, preferably in the range of 50 to 70 mm.

13. Coffee grinder according to one of claims 10 to 12, characterized in that the second component group (B) is suitable for reducing the height (H) of the grinding gap (3) as a function of a temperature increase of the second component group (B), wherein the second component group (B) preferably comprises a grinding element carrier (B, 7) connected to the second grinding element (B, 2), a motor shaft (B, 8) and / or a motor shaft bearing seat (B, 9), wherein particularly preferably i) the motor shaft (B, 8) is connected to the grinding element carrier (B, 7) on the one hand and to the motor shaft bearing seat (B, 9) on the other hand; and / or ii) the second grinding element (B, 2) contains or consists of ferritic steel and / or a ceramic and / or has a height, in the direction of the axis of rotation (D) of at least one of the grinding elements (B, 2), in the range of 5 to 10 mm, preferably in the range of 7 to 9 mm;and / or iii) the grinding element carrier (B, 7) contains or consists of aluminum and / or has a height, in the direction of the axis of rotation (D) of at least one of the grinding elements (B, 2), in the range of 2 to 8 mm, preferably in the range of 4 to 6 mm; and / or iv) the motor shaft (B, 8) contains or consists of austenitic steel and / or has a height, in the direction of the axis of rotation (D) of at least one of the grinding elements (B, 2), in the range of 40 to 70 mm, preferably in the range of 50 to 60 mm; and / or v) the motor shaft bearing seat (B, 9) contains or consists of aluminum and / or has a height, in the direction of the axis of rotation (D) of at least one of the grinding elements (B, 2), in the range of 1 to 5 mm, preferably in the range of 2 to 4 mm.; 14. Coffee grinder according to one of claims 10 to 13, characterized in that the compensation element (A, 4) i) contains or consists of plastic, wherein the plastic is preferably a thermoplastic, particularly preferably polyphenylene sulfide; and / or ii) has a specific thermal expansion coefficient of > 40 pm / mK, preferably > 50 pm / mK.

15. Coffee grinder according to one of claims 10 to 14, characterized in that the coffee grinder is manufactured by a method according to one of claims 1 to 9.

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