RU2798460C2 - Machine for grinding coffee for dispensing a portion of stratified (layered) ground coffee and associated method - Google Patents

Abstract

FIELD: coffee machines.

SUBSTANCE: present invention relates to a coffee bean grinder and a method for grinding coffee beans to produce ground coffee using such a coffee bean grinder. The technical result is the creation of a machine for grinding coffee, capable of changing the corresponding organoleptic characteristics of espresso coffee obtained from the ground product. The technical result is achieved by the fact that the device for grinding coffee beans and forming a portion (D) of ground coffee in a filter basket (FT) with a lower layer of ground coffee having a first average particle size, and with an adjacent layer of ground coffee having a second average particle size, comprises grinding elements for grinding coffee beans, an electric motor for driving at least one grinding element relative to another grinding element, and a device configured to change the rotational speed of the electric motor between a first rotational speed and a second rotational speed during grinding coffee beans to form a portion (D) wherein the second average particle size is smaller than the first average particle size and the first rotational speed is greater than the second rotational speed, or the second average particle size is greater than the first average particle size and the first rotational speed is lower than the second rotational speed, and the technical result is achieved by a method of grinding coffee beans to obtain ground coffee using such a device.

EFFECT: creation of a machine for grinding coffee, capable of changing the corresponding organoleptic characteristics of espresso coffee obtained from the ground product.

13 cl, 7 dwg

Description

Prerequisites

The present invention relates to a machine for grinding coffee beans. The coffee bean grinder may be a stand-alone machine or may be integrated into a coffee-based beverage machine. Such a machine is known as a "coffee grinder", "coffee grinder" or "coffee grinder". More specifically, the present invention relates to a coffee grinder capable of dispensing a portion of suitably stratified (layered) ground coffee.

Prior Art

As you know, for the preparation of espresso coffee use a certain amount of ground coffee, commonly referred to as "portion". A portion can be single, double or multiple. A portion of ground coffee is loaded into a filter basket, usually made in the form of a cup, open at the top and having micro-perforations at the bottom. Typically, a portion of coffee is compressed inside a filter basket to form a tablet of coffee powder. The filter, in turn, is supported by a releasably engaged filter holder located inside the dispenser of the espresso coffee machine. Espresso is made by forcing pressurized hot water through a tablet of coffee powder.

Coffee powder is obtained using a coffee grinder. In a known coffee grinder, the coffee beans are ground by passing through the grinding elements. Known grinding elements of a flat, conical or cylindrical type. Typically, the grinding elements of a coffee grinder include a fixed element and an element that rotates relative to the stationary element. For example, in a coffee grinder with conical grinding elements, one burr is fixed and stationary, while the other burr is driven by a motor. Some coffee grinders have the ability to change the distance between the grinders to change the particle size of the coffee powder.

US 2016/220067 A1 describes a variable speed coffee grinder.

EP 2 810 592 A1 describes a coffee grinder, in particular for an automatic coffee machine.

WO 2017/055 433 A1 describes a variable speed coffee grinder.

DE 35 03 011 A1 describes a device for setting the gap in the burr of a grain mill.

CN 107 692 874 A describes a device for speed control in a shredder.

Brief description of the invention

The Applicant has carried out experiments with ground coffee powder. For the purposes of the present invention, ground coffee powder is considered to be formed essentially by particles or granules that have a theoretical characteristic size. This theoretical characteristic dimension will also be referred to as "equivalent diameter" in the following description. In addition, as an alternative to the full term "ground coffee powder" and other similar expressions, the abbreviated term "ground product" may be used.

The Applicant has found that all known coffee grinding machines, regardless of manufacturer or type of grinding element, produce a ground product containing granules which can vary widely in size. The range of equivalent diameters covers three orders of magnitude, from a few microns to more than one millimeter.

This relatively high number of granules can be expressed as a profile referred to as "particle size profile" or "particle size curve", which has a shape (regardless of the coffee grinder used) similar to that shown in FIG. 1.

The curve showing the particle size profile is referred to as the bimodal profile. The high peak (on the right) is called the "first mode" and the lower peak (on the left) is called the "second mode".

As briefly mentioned above, ground coffee is intended for use in an espresso machine that dispenses coffee-based beverages.

Clearly, a powder that has a large amount of fine particles results in a lower water flow and hence less beverage in the same dispensing time compared to a powder that has more coarse particles.

Typically, each bartender adjusts his/her coffee grinder accordingly to obtain the particle size that he/she thinks produces the optimum drink.

Regardless of whether the machine has flat, conical or cylindrical burrs, the smaller the distance between the grinding elements, the greater the number of fine particles and the smaller the number of coarse particles. For a larger distance between the grinding elements, the opposite is true (i.e., fewer small particles and more coarse particles).

Usually the bartender adjusts the grinder setting when the coffee beans that are loaded into the hopper before grinding change. A change in coffee may be caused by the use of a different variety or a different package of the same variety.

The purpose stated by the Applicant is to desensitize the coffee grinder to changes in the coffee beans to be ground.

Another object defined by the Applicant is to provide a coffee grinding machine capable of changing the respective organoleptic characteristics of espresso coffee obtained from the ground product.

According to the Applicant, these objectives are achieved with a coffee grinder capable of changing the particle size curve during the grinding of a coffee portion.

US 2016/220067 A1 paragraph [0019] states that a variable speed motor coffee grinder can produce finely ground coffee with greater accuracy and less variation at a lower speed than prior art high speed coffee grinders. Different methods of preparing coffee, such as espresso, require that the coffee beans are cut into appropriate particles with an even distribution. Existing high speed grinders tend to break rather than cut the coffee beans, especially when the engine is starting, which results in variable particle size.

US2016/220067 A1 describes a coffee grinder that uses a variable speed motor, the speed and starting torque can be adjusted by a programmable controller to accommodate different coffee brewing methods or coffee bean types while maintaining the ability to grind at a high speed when accuracy is not important.

In contrast to these technologies, the present invention aims to create a portion of ground coffee directly in the filter basket with different layers having different particle sizes.

According to a first aspect of the invention, there is provided a machine for grinding coffee beans and forming a portion of ground coffee in a filter basket with a bottom layer of ground coffee having a first average particle size and with an adjacent layer of ground coffee having a second average particle size, comprising:

- grinding elements for grinding coffee beans;

- an electric motor for driving at least one grinding element relative to the other grinding element, and

- a device configured to change the rotational speed of the electric motor between the first rotational speed and the second rotational speed during the grinding of coffee beans to form a dose,

and

the second average particle size is less than the first average particle size and the first rotational speed is greater than the second rotational speed, or

the second average particle size is greater than the first average particle size; and the first rotational speed is less than the second rotational speed.

An adjoining layer is a layer that is adjacent to and on top of the first layer. The first layer is generated first (so that the ground coffee lies essentially at the bottom of the filter basket), and the adjacent layer is generated immediately after the first, so that the corresponding ground coffee lies on the first layer. On top of the adjacent layer, one or more layers can be provided such that the average particle size of the ground coffee in these layers differs from the average particle size of the ground coffee in the adjacent layer.

In various embodiments, the coffee grinder further comprises a revolution counter for counting the number of revolutions of the grinding element relative to another grinding element, wherein the speed changer is configured to change the rotation speed from the first rotation speed to the second rotation speed depending on the given number of relative rotations of this a grinding element and another grinding element.

The specified number of relative revolutions can be any number - integer and fractional. Preferably, the set number of relative revolutions is calculated as a function of the total set time for grinding the portion. Additionally, preferably, the given number of relative revolutions is calculated as a function of the total number of layers in the portion.

It should be noted that the first speed is the speed reached by the engine after the threshold speed calculated from the start of the engine. This number of revolutions can be set as any number between 0.5 and approx. 3.0 (for example, 0.5; 1.0; 1.5; 2.0; 2.5 and 3).

For example, if the threshold number of revolutions is set to 1.0, the total number of revolutions is set to 5, and the total number of layers is set to 2, the specified number of relative revolutions can be 2. In other words, during the first revolution, the first rotational speed is reached, this first the speed is maintained for two revolutions, and then, for the remaining two revolutions, the second speed is maintained. However, the grinding can be adjusted so that the number of revolutions for the first layer is different from the number of revolutions for the adjacent layer. The number of layers can be more than two.

In various embodiments, the coffee grinder further comprises a timer, wherein the speed change device is configured to change the speed from the first to the second depending on a predetermined period of time calculated from the start of the electric motor.

The predetermined period of time can be calculated as a function of the total predetermined time for grinding a portion. Additionally, preferably, a given period of time can be calculated as a function of the total number of layers in the portion.

Preferably, a threshold time is taken into account. This threshold time is the time from starting the engine to reaching the first speed. This threshold time may be a fraction of the total time to grind the portion. In different versions, the threshold time can be from approx. 1/7 to approx. 1/4 total time for chopping a portion. For example, the threshold time can be from approx. 1/6 to approx. 1/5 of the total time for chopping a portion. If the total time is approx. 6 s, the threshold time can be from 1 s to 1.2 s.

For example, if the total time is 6 s, the threshold time is 1 s, and the total number of layers is 2, then the change from the first to the second frequency can occur after 3.5 s from the start of the engine.

In various embodiments, the coffee grinding machine further comprises a weighing element for calculating the mass of a portion of ground coffee, while the speed change device is configured to change the rotation speed from the first to the second depending on the mass of the first part of the coffee portion that was ground at the first rotational speed. .

In addition, in this case, preferably, a threshold value is taken into account and the weight of the coffee portion is calculated after the threshold time or the threshold number of revolutions. The threshold time may be a fraction of the total time to grind the portion, as described above. The threshold RPM may be a fraction of the total RPM for churning the batch, as discussed above.

The speed change device may be configured to change the speed of the motor in steps or continuously.

In various embodiments, the coffee grinder further comprises an interface for selecting a speed profile for grinding a portion of coffee.

In different versions of the coffee grinder, a sensor for determining the speed of the electric motor.

According to a second aspect of the present invention, there is provided a method for grinding coffee beans to obtain a ground coffee portion in a filter basket, wherein the bottom layer has a first average particle size and the adjacent ground coffee layer has a second average particle size, the method comprising the steps of:

(a) providing grinding elements for grinding coffee beans;

(b) creating an electric motor to rotate one grinding element relative to the other grinding element; And

(c) during grinding, at least one grinding element is rotated relative to the other grinding element at a first rotational speed and then at a second rotational speed,

wherein the second average particle size is smaller than the first average particle size and the first rotational speed is greater than the second rotational speed, or

the second particle size is larger than the first particle size and the first rotational speed is lower than the second rotational speed.

In some embodiments, the present invention further comprises counting the number of revolutions of the grinding element relative to another grinding element, and changing the rotational speed from the first rotational speed to the second rotational speed depending on the given number of relative revolutions of this grinding element and the other grinding element.

In some embodiments, the present invention further comprises changing the rotational speed from the first rotational speed to the second rotational speed depending on a predetermined period of time calculated from the start of the motor.

In some embodiments, the present invention further comprises changing the rotational speed from the first rotational speed to the second rotational speed depending on the weight of the first portion of the coffee portion that was ground at the first rotational speed.

This speed change from the first speed to the second speed may be performed continuously or in steps.

In some embodiments, instead of a device configured to change the rotational speed of the motor between a first rotational speed and a second rotational speed during the grinding of coffee beans to form a portion, an actuator may be used, configured to change the distance between one grinding element and another grinding element during grinding coffee beans to obtain a serving of ground coffee.

The actuator may be configured to change the distance between the grinding elements continuously or stepwise during the grinding of coffee beans to obtain a portion of ground coffee.

The distance between the burrs may vary from a first distance to at least a second distance during the grinding of a portion, wherein the first distance is less than the second distance to obtain at least a first portion of the ground coffee portion having a first particle size and a second portion of the ground coffee portion having second particle size.

Preferably, the coffee grinder may also include an interface for selecting a speed profile or distance profile for grinding a portion of coffee.

Advantageously, the coffee grinder may also include a sensor for detecting the speed of the motor.

According to another aspect, instead of changing the speed of the motor during grinding of coffee beans to obtain a portion of ground coffee, the distance between the grinding elements is changed during grinding of coffee beans to obtain a portion of ground coffee.

The distance between the burrs can be changed continuously or in steps during the grinding of coffee beans to obtain a portion of ground coffee.

The distance between the burrs can be changed from a first distance to at least a second distance during the grinding of a portion, wherein the first distance is less than the second distance so as to obtain at least a first portion of the ground coffee portion having a first particle size and a second portion of the ground coffee portion having a second particle size.

Brief description of the drawings

The following is a detailed description of a non-limiting example of the present invention with reference to the attached drawings where:

Fig. 1 is a diagram illustrating an example of a particle size profile on a logarithmic scale.

Fig. 2a is a schematic illustration of a shot of ground coffee obtained with a standard particle size profile in a filter basket inserted into a filter holder.

Fig. 2b is a schematic representation of a portion of ground coffee obtained with a particle size profile modified according to the present invention in a filter basket inserted into a filter holder.

Fig. 3 is a diagram of two particle size profiles on a linear scale obtained at different rotational speeds.

Fig. 4 is a graph of two particle size profiles on a linear scale, the first of which is obtained at a constant rotational speed, and the second is obtained by combining the ground product obtained at two different rotational speeds.

Fig. 5 is a schematic illustration of a coffee grinder according to embodiments of the present invention.

Fig. 6 is an illustration of some components of the machine of FIG. 5.

Detailed description

Fig. 1, which has been briefly described above, is a diagram showing an example of the particle size distribution of a serving of coffee powder. The curve representing the particle size profile is referred to as the bimodal curve. The high peak (on the right, relating to larger particles) is referred to as the "first mode", and the low peak (on the left, relating to smaller particles) is referred to as the "second mode".

Applicant has conducted research and surprisingly found that a coffee grinder capable of changing the particle size distribution curve so as to increase the amplitude of the first mode bell (the high peak on the right in Figure 1) reduces the sensitivity of the coffee grinder. In other words, increasing the amplitude of the first mode reduces the need to adjust the coffee particle sizes when there are different coffee beans in the hopper.

The Applicant did further research and unexpectedly found that proper placement of the ground product in the filter basket can further reduce the sensitivity of the coffee grinder. In particular, it has been shown that the best performance is achieved by placing large particles on the bottom and smaller particles on top.

Applicant has realized that a coffee grinder capable of changing the particle size distribution curve during portion grinding can desensitize the coffee grinder and achieve both goals.

According to the first embodiment of the present invention, the coffee grinding machine comprises grinding elements, the distance between which is adjustable and changes during the grinding of a portion. Preferably, the distance between the grinding elements can be adjusted electrically by means of an actuator (eg electric motor or linear actuator, eg piston 8) and a corresponding control circuit.

With the first variant of the coffee grinding machine, it is possible to grind the portion D by changing (during the grinding of the portion) the distance between the grinding elements (in steps or continuously) in order to obtain a ground product with a first wider mode. In fact, it has been found that when the distance between the millstones is reduced, the first mode is shifted to the region of smaller particles, and when this distance is increased, the first mode is shifted to the region of larger particles.

Therefore, for example, a coffee grinder that produces the first portion of a portion of powder with a large distance between the burrs and the remainder with a large distance between the burrs will generally generate a ground product with a wider first mode bell. Therefore, in general, starting from a certain distance between the millstones and decreasing this distance during the grinding of a portion, a ground product with a wider bell of the first mode will be obtained.

The change in the distance between the millstones during the grinding portion F can occur in steps or continuously. In the first embodiment of the coffee grinder, it is also possible to create a first layer of ground product using a larger distance to produce larger particles and a second layer using a shorter distance to produce smaller particles. Obviously, it is possible to obtain more than two layers, as indicated above, by continuously changing the distance between the stones during the grinding of portion D (single, double or multiple).

Portion D, shown in the drawing, obtained by grinding grains without changing the distance between the millstones. In FIG. 2a, the distribution of the ground product inside the filter is arbitrary and not controlled.

In FIG. 2b shows the distribution within the filter, with appropriate control, using the coffee machine of the present invention. In particular, the bottom layer is characterized by particles that are larger on average, and the upper layer is characterized by particles that are smaller on average. The bottom layer is obtained by holding the millstones at a greater distance than the distance at which the millstones are located during the second part of the batch grinding operation, when a top layer with finer average particles is obtained.

In another embodiment of the present invention, the coffee grinder is configured to change the particle size during the grinding of a portion by changing the relative speed of the grinding elements. The term "relative rotation" is understood as the rotation of one element relative to another. Typically one grinding element remains stationary while the other grinding element rotates.

In FIG. 3 shows the influence of the speed of the grinding elements on the particle size. In particular, in FIG. 3 shows two particle size curves obtained with a constant distance between the millstones and with a change in the speed of rotation. Unlike FIG. 1, the curves in Fig. 3 are shown on a linear scale to highlight the differences in the first mode.

As shown in the drawing, at a reduced rotational speed, the first mode is shifted to the left, and its relative amount decreases in favor of the second mode.

At an increased rotational speed, the first mode shifts to the right and increases the relative amount.

The change in speed is preferably provided by a suitable electronic speed controller for electric motors. Many such devices, which may differ depending on the type of engine used, are commercially available. In an embodiment of the present invention, the coffee grinder comprises a three-phase asynchronous motor and, for speed control, an inverter or any known frequency converter.

In one embodiment of the present invention, the coffee grinder grinds the portion at a variable speed (stepped or continuous) to produce a portion of ground product with a first mode that is wider than normal.

In fact, with respect to the above comments, when the rotational speed decreases, the first mode shifts to the left, and when the rotational speed increases, the first mode shifts to the right. Therefore, for example, the coffee grinder of the present invention can be configured to produce a portion of a portion at a high rotation speed and another portion at a low rotation speed. Thus, a full batch produced will contain a ground product where the first fashion bell is wider.

In FIG. 4 is a chart showing a comparison of two particle size distribution curves. In particular, the drawing shows a first particle size distribution curve obtained with one rotational speed (dashed line) and a second particle size distribution curve obtained with two rotational frequencies. A particle size distribution curve obtained by combining powders obtained from two grinding operations performed at different speeds shows a greater dispersion (larger standard deviation) than a curve giving the same head loss but obtained by grinding at a constant speed.

According to the present invention, it is preferable to create, for example, the first layer (bottom layer) of the ground product with a higher rotational speed in order to obtain larger particles, and the second layer (upper layer) with a lower rotational speed in order to obtain finer particles. Particles related to the curve formed by the solid line shown in FIG. 3 will be in the first layer, and the particles related to the dashed curve will be in the second layer. Obviously, it is possible to create more than two layers or create a continuous change by continuously changing the speed.

According to the Applicant, increasing the amplitude of the bell corresponding to the first mode modifies the organoleptic aspect of the beverage. As is known, the particle size profile is in practice responsible for the amount of beverage dispensed at the same dispensing time and thus for the liquid consumption. In fact, the coffee powder results in a "pressure loss" or "pressure drop" which determines the consumption of the beverage.

According to the present invention, it is instead possible to exceed the capabilities of known coffee grinders and generate more particle size curves with the same head loss. For example, the two curves shown in Fig. 4 are characterized by two different bell amplitudes for the first mode.

This means that although the two curves shown in FIG. 4 give the same extraction time, different particle sizes give different contact area between water and coffee powder and hence different solubility.

The choice of particle stratification changes the overall head loss. By placing the two curves shown in Fig. 3, in reverse order, you can get two different head losses and therefore two different drinks. The wetting schedule of the coffee powder in the filter also results in another drain on the extraction cycle.

In FIG. 5 shows in a very schematic form the main components of a coffee grinder according to embodiments of the present invention. Position 2 indicates the electric motor for the relative rotation of the millstones 3 or displacement of the millstones 3; position 4 denotes an inverter for controlling the engine speed; position 5 indicates the control unit, and position 6 indicates the sensor (if necessary) speed.

In FIG. 5 also shows in schematic form the path that the ground coffee travels when the filter basket FT is installed in the filter holder PF.

According to various options, changing the speed/distance between the millstones can be performed by the bartender through the appropriate interface 7 (Fig. 6). The interface 7 may, for example, comprise a button (or a plurality of buttons) for selecting a target speed, a target distance between the burrs, a profile of the rpm, and a profile of the distances between the burrs. The interface, instead of buttons, may include a rotary knob to select (continuously or stepwise) multiple speeds (or distances between burrs), or a touch screen to select different speeds/speeds. The interface 7 is connected to the inverter 4 (directly or through other devices, such as the central processor 5) to change the frequency of the motor and, consequently, its speed. Preferably, you can create a variant in which you choose the speed offered by the manufacturer or the frequency specified by the user. Preferably, a memory device can be provided to store the rotational speed values and/or rotational speed profiles for grinding a portion (single, double or multiple) not at a constant rotational speed, but at two (or more) different frequencies or at a rotational speed that varies continuously.

The control unit 5 thus sets the inverter 4 to the speed of the motor 2. The system can operate as an open system, i.e. without measuring the actual engine speed, or as a closed system, i.e. by determining the engine speed using a special device, for example, sensor 6.

Claims (30)

1. Device (1) for grinding coffee beans and forming a portion (D) of ground coffee in a filter basket (FT) with a lower layer of ground coffee having a first average particle size, and with an adjacent layer of ground coffee having a second average particle size, containing : - grinding elements (3) for grinding coffee beans, - an electric motor (2) for driving at least one grinding element (3) relative to another grinding element (3), and - a device (4) configured to change the rotational speed of the electric motor (2) between the first rotational speed and the second rotational speed during the grinding of coffee beans to form portion (D), in which the second average particle size is less than the first average particle size and the first rotational speed is greater than the second rotational speed, or the second average particle size is greater than the first average particle size, and the first rotational speed is lower than the second rotational speed. 2. The device according to claim. 1, further containing a revolution counter for counting the number of revolutions of the grinding element (3) relative to another grinding element (3), wherein: the device (4) for changing the speed of rotation is configured to change the speed from the first speed to the second speed depending on the specified number of revolutions of the grinding element (3) relative to another grinding element (3). 3. The device according to claim 1, further comprising a timer, and the device (4) for changing the speed of rotation is configured to change the speed of rotation from the first speed to the second speed depending on the predetermined period of time calculated from the start of the electric motor. 4. The device according to claim. 1, further containing a weighing element for calculating the mass of a serving of ground coffee, and the device (4) for changing the rotation frequency is configured to change the rotation frequency from the first rotation frequency to the second rotation frequency depending on the mass of the first portion of the coffee portion, which was ground at the first rotation frequency. 5. The device according to any one of paragraphs. 1-4, in which the device (4) for changing the speed is configured to step change the speed of the electric motor (2). 6. The device according to any one of paragraphs. 1-4, in which the device (4) for changing the speed is configured to continuously change the speed of the electric motor (2). 7. The device according to any one of paragraphs. 1-6, further containing an interface for selecting a speed profile for grinding a portion (D) of coffee. 8. The device according to any one of paragraphs. 1-7, further containing a sensor (6) for determining the rotational speed of the electric motor (2). 9. A method of grinding coffee beans to obtain a portion (D) of ground coffee in a filter basket (FT) with a bottom layer of ground coffee having a first average particle size and an adjacent layer of ground coffee having a second average particle size, the method comprising the steps , where: (a) using the grinding elements (3) to grind the coffee beans; (b) using an electric motor (2) to rotate one grinding element (3) relative to the other grinding element (3), and (c) during grinding, at least one grinding element (3) is rotated relative to the other grinding element (3) at a first rotational speed and then at a second rotational speed. and the second average particle size is less than the first average particle size and the first rotational speed is greater than the second rotational speed, or the second average particle size is greater than the first average particle size, and the first rotational speed is lower than the second rotational speed. 10. The method according to claim 9, further comprising the step of counting the number of revolutions of the grinding element (3) relative to the other grinding element (3) and changing the rotational speed from the first rotational speed to the second rotational speed depending on the specified rotational speed of one grinding element relative to the second grinding element. 11. The method according to any one of paragraphs. 9, 10, further comprising the step of changing the speed from the first speed to the second speed depending on the predetermined period of time calculated from the start of the motor (2). 12. The method according to any one of paragraphs. 9, 10, 11, further comprising changing the rotational speed from the first rotational speed to the second rotational speed depending on the weight of the first portion of the coffee dose that was ground at the first rotational speed. 13. The method according to any one of paragraphs. 9-12, in which the change in speed from the first starting speed to the second speed is performed continuously or stepwise.

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