EP2991528A2 | 2016-03-09 | |||
EP0120496A1 | 1984-10-03 | |||
DE102007051385A1 | 2008-04-30 |
CLAIMS 1. A coffee grinding machine (10) comprising: - a grinding chamber (12) with grinding members (14A, 14B) cooperating to grind coffee beans, - a motor (30) configured to move at least one (14B) of the grinding members with respect to the other grinding member (14A), - a removable hopper (100) mounted upstream of said grinding chamber (12) and configured to contain coffee beans to be ground, the hopper (100) further comprising a lid (104), - a fixed sensor (110) and an activator device (120) cooperating with said fixed sensor (110), wherein the fixed sensor and the activator device (120) are configured so as to allow the operation of the motor (30) only when the hopper (100) is correctly mounted and the lid (104) is closed, wherein said activator device (120) is mounted integral with respect to the lid (104) and, when the lid (104) is closed, the activator device (120) is within the volume of the hopper (100) at a distance (d) close to said fixed sensor (110). 2. The coffee grinding machine (10) according to claim 1 , wherein said fixed sensor (110) extends towards the hopper (100) and is contained inside a protuberance (105) formed within a side wall of the hopper (100). 3. The coffee grinding machine (10) according to claim 2, wherein said protuberance terminates with a non-horizontal wall (105'). 4. The coffee grinding machine (10) according to any one of the preceding claims, wherein said fixed sensor (1 10) comprises an axis inclined with respect to a vertical axis. 5. The coffee grinding machine (10) according to any one of the preceding claims, wherein said fixed sensor (1 10) comprises a normally open magnetic sensor and said activator device (120) comprises a magnet. 6. The coffee grinding machine (10) according to any one of the preceding claims, wherein said fixed sensor (1 10) comprises an inductive sensor and/or a mechanical sensor, for example a microswitch, and/or a capacitive sensor. 7. The coffee grinding machine (10) according to any one of the preceding claims, further comprising a safety relay (46), wherein said fixed sensor (110) is configured to interrupt directly the power to the motor (30) by using said safety relay (46), to which the fixed sensor (1 10) is wired. 8. The coffee grinding machine (10) according to claim 7, also comprising a further wiring between the fixed sensor (110) and control electronics (45) so that the signal for opening/closing the fixed sensor (1 10) is intercepted by the electronics (45) and may be displayed to an operator. 9. The coffee grinding machine (10) according to any one of the preceding claims, comprising a motor control device (47) provided with a Safe Torque Off function. |
BACKGROUND
The present invention relates to the sector of machines for grinding coffee beans. Such a machine for grinding coffee beans may be a separate machine or may be incorporated in a machine for the production of coffee-based beverages. Such a machine for grinding coffee beans is also known simply as a "coffee grinding machine", "coffee grinder" or "mill". The present invention relates more particularly to a hopper for a coffee grinding machine which has a safety sensor and also relates to a coffee grinding machine comprising such a hopper. PRIOR ART
As is known, for the preparation of an espresso coffee, a certain amount of ground coffee, usually called a dose, is used. The dose of ground coffee is filled inside a filter, typically in the form of a cup which is open at the top and has a bottom with micro perforations. Typically, the dose of coffee is pressed inside the filter so as to form a puck of coffee powder. The filter is in turn supported by a filter holder which is configured to be removably engaged with a dispensing unit of an espresso coffee machine. The espresso coffee is obtained by passing hot water under pressure through the puck of coffee powder.
The coffee powder is obtained by means of a coffee grinding machine. In a known coffee grinding machine, the coffee beans are ground by causing them to pass through grinding members. Grinding members of the flat, conical or cylindrical type are known. Typically, the grinding members of a coffee grinding machine comprise a fixed member and a member rotating with respect to the fixed member. For example, in a coffee grinder with conical grinders, one grinder remains fixed and stationary, while the other grinder is rotated by a motor.
The coffee beans to be ground are typically loaded into a container, which is called a hopper.
The hopper has a top opening, usually provided with a lid for closing it, and a bottom opening, so that the coffee beans to be ground may reach the grinding members.
WO2014162236A2 describes a machine for the production of beverages, comprising a removable container for ingredients. In some embodiments, the lid of the removable container for coffee beans comprises a detectable element which may be detected by a detection member arranged inside or on the housing of the machine 3. The detection member may be interfaced with an electronic control unit. The electronic control unit may be connected to a motor of the coffee grinder and, by means of one or more electric connectors, to other instruments of the coffee machine.
SUMMARY OF THE INVENTION
The Applicant has noticed that, in order to ensure the safety of the bartender, some hoppers are shaped at the bottom so as to prevent the bartender from accidentally inserting his/her fingers between the grinding members. If this were to happen while the coffee grinding machine is in operation, the bartender would be injured.
The Applicant has noticed that this measure is certainly advantageous since it increases the safety of the bartender, but on the other hand it prevents the hopper from being thoroughly cleaned and coffee left-overs from being removed in certain substantially inaccessible points. This is disadvantageous since the coffee left-overs may create mould, bacteria, bad odours and unhygienic conditions.
In addition to or as an alternative to the aforementioned solution based on the internal form of the hopper, solutions are known where a sensor is provided, said sensor allowing start-up of the motor of the coffee grinding machine only when the hopper is correctly mounted on the machine. In this way, the coffee grinding machine does not start up if the hopper is not correctly mounted. This solution is also advantageous since it increases the safety of the bartender. However, the Applicant has noted that bartenders tend to keep the lid of the hopper open in order to load more easily coffee beans to be ground or mix them (for example so that they fall towards the grinders). This behaviour clearly results in the deterioration of the organoleptic properties of the coffee beans inside the hopper and therefore also the quality of the espresso coffee. In fact, the coffee beans, when the lid is open, absorb moisture, bad odours (for example when the machine is installed close to a kitchen), dust and smog.
The solution described in WO2014162236A2 provides a degree of safety greater than that of other solutions without a sensor. However, the Applicant has realized that the position of the detection member allows a bartender who wishes to exclude the safety device to do so in a relatively easy manner. In fact, the detection member is in a position which can be easily accessed by the bartender. In order to bypass the sensor, even "permanently", it is merely required to place a magnet on top of the detection member when the lid is open. This enables the grinders to be operated even when the lid is open. It is even possible to operate the grinders without the hopper in position, creating a very dangerous situation.
The aim of the Applicant is to provide a coffee grinding machine comprising a hopper which not only protects the operator from any accidental damage caused by accidental contact with the grinding members, but also induces the operator to behave in such a way as to increase the organoleptic yield of the coffee and/or induces the operator to act in a way which reduces the variability in performance of the coffee grinding machine.
In order to induce the operator to work and behave in a way which increases the organoleptic yield of the coffee and/or reduces the variability in performance of the coffee grinding machine the Applicant has established that it is important for the hopper which contains the coffee beans should remain closed as far as possible. In other words, it is important to create inside the hopper a "micro climate" due to both the protective action of the hopper itself and the release of gases and aromas from the beans.
The idea of the Applicant is to provide a sensor able to detect the presence of the lid of the hopper when the latter is correctly closed.
The detection of the lid by the sensor indicates that the hopper is also correctly positioned. In this way, if the sensor is engaged this means that the hopper is correctly positioned and closed.
Removing the hopper or opening the lid causes the circuit to be opened and therefore the safety function is ensured.
Moreover, the use of a sensor in the lid obliges the operator to work with the hopper closed.
According to the present invention, a coffee grinding machine is provided, said coffee grinding machine comprising:
- a grinding chamber with grinding members cooperating to grind coffee beans;
- a motor configured to move at least one of the grinding members with respect to the other grinding member;
- a removable hopper mounted upstream of said grinding chamber and configured to contain coffee beans to be ground, the hopper further comprising a lid;
- a fixed sensor and an activator device cooperating with said fixed sensor, wherein the fixed sensor and the activator device are configured so as to allow the operation of the motor only when the hopper is correctly mounted and the lid is closed.
In embodiments, the activator device is mounted integral with respect to the lid and, when the lid is closed, the activator device is within the volume of the hopper at a distance close to said fixed sensor, in a bottom (lower) position with respect to the plane of the lid. This arrangement increases considerably the safety since, in order to bypass the sensor, the only way would be to position the activator device close to the fixed sensor, inside the hopper.
In embodiments, the fixed sensor extends towards the hopper and is contained inside a protuberance formed within a side wall of the hopper.
In embodiments, the protuberance terminates with a non-horizontal wall.
In embodiments, the fixed sensor comprises an axis inclined with respect to a vertical axis.
In embodiments, the sensor comprises a normally open magnetic sensor and said activator device comprises a magnet.
In embodiments, said sensor comprises an inductive sensor and/or a mechanical sensor, for example a microswitch, and/or a capacitive sensor.
In embodiments, the coffee grinding machine further comprises a safety relay, wherein said sensor is configured to directly interrupt the power to the motor by using said safety relay, to which the sensor is wired.
The coffee grinding machine may also comprise a further wiring between the sensor and the control electronics so that the signal for opening/closing the sensor is intercepted by the electronics and may be displayed to an operator.
The coffee grinding machine may also comprise a motor control device provided with a Safe Torque Off function. BRIEF DESCRIPTION OF THE DRAWINGS
A detailed description of the invention now follows, being provided purely by way of a non-limiting example, to be read with reference to attached figures in which:
- Figure 1 is a schematic view of a coffee grinding machine according to an embodiment of the present invention;
- Figure 2a shows the hopper of the machine according to Figure 1 in the closed configuration;
- Figure 2a shows the hopper of the machine according to Figure 1 in the open configuration;
- Figures 3a-3d show four functional solutions of electric and/or electronic diagrams which can be adopted with the coffee grinding machine according to Figure 1.
DETAILED DESCRIPTION
Figure 1 shows in very schematic form the main components of a coffee grinding machine 10 according to embodiments of the present invention.
The machine 10 comprises a grinding chamber 12 with an upper inlet IN for the coffee to be ground, a first grinder 14A and a second grinder 14B cooperating with the first grinder 14A and an output conveyor 16 which receives the ground coffee from the grinders 14A and 14B and conveys it so that it is collected and used. For example, as shown in Figure 1 , the ground coffee may be conveyed towards a filter 21 supported by a filter holder 20 of any type.
According to the embodiment shown in Figure 1 , the first grinder 14A is a fixed grinder while the second grinder 14B is movable, for example rotatable.
The coffee grinding machine 10 comprises an electric motor 30 for rotating the second grinder 14B. According to embodiments the motor is a single-phase motor. For example, the motor 30 is an electric motor comprising one of the following types: universal, direct current, single phase or three-phase alternating current, brushless, BLDC, stepper or other type.
The reference number 40 indicates a set of various electrical and/or electronic components. Some of these components are shown, for example, with reference to Figures 3a-3d.
According to a first embodiment (Figure 3a), the set of components 40 comprises a component 45 in turn comprising a board with a processing unit (CPU) and/or a viewing device (for example a display). The set of components 40 also comprises a relay 46 or other similar switch. The wiring 41 from a proximity sensor 1 10 (which will be described more clearly below) connects the component 45 and the relay 46. The relay is powered by a power supply cable 43 which is connected to the motor 30 via a cable 42.
According to a second embodiment (Figure 3b), the set of components 40 comprises a component 45 in turn comprising a board with a processing unit (CPU) and/or a viewing device (for example a display). The set of components 40 also comprises a relay 46 or other similar switch. The cable 41 from the proximity sensor 110 connects the component 45 which is connected to the relay 46. The relay 46 is powered by a power supply cable 43 which is connected to the motor 30 via a cable 42.
According to a third embodiment (Figure 3c), the set of components 40 comprises a component 45 in turn comprising a board with a processing unit (CPU) and/or a viewing device (for example a display). The set of components 40 also comprises an inverter 47 or other similar electronic apparatus able to convert an incoming direct current into an outgoing alternating current and to vary the amplitude and frequency parameters thereof. The cable 41 from the proximity sensor 1 10 connects the component 45 and the inverter 47. The inverter 47 is powered by a power supply cable 43 which is connected to the motor 30 via a cable 42.
According to a fourth embodiment (Figure 3d), the set of components 40 comprises a component 45 in turn comprising a board with a processing unit (CPU) and/or a viewing device (for example a display). The set of components 40 also comprises an inverter 47 or other similar electronic apparatus able to convert an incoming direct current into an outgoing alternating current and to vary the amplitude and frequency parameters thereof. The cable 41 from the proximity sensor 1 10 connects the component 45 which is connected to the inverter 47. The inverter 47 is powered by a power supply cable 43 which is connected to the motor 30 via a cable 42.
Therefore, according to embodiments, the coffee grinding machine 10 also comprises a frequency changer device 47 for controlling the speed of rotation. For example, this frequency changer device comprises an inverter. This frequency changer device 47 allows variation of the grinding speed so as to allow grinding to be performed in a uniform manner at a first speed or a second speed.
According to embodiments, the coffee grinding machine also comprises an angular position transducer, for example an encoder, associated with the electric motor so as to measure precisely the speed of rotation of the motor 30.
According to embodiments, the variation of the speed may be performed by the bartender, via a suitable interface, functionally included within the set of components 40. The interface may for example comprise a pushbutton (or a plurality of pushbuttons) for selecting a predetermined speed of rotation, a rotatable knob for selecting (continuously or stepwise) a plurality of rotation speeds, a touchscreen display for choosing from among various options/speeds which are available. The interface is connected to the inverter 47 (directly or via other devices, such as a processor 45), in order to modify the power supply frequency of the motor 30 and therefore the speed of the latter. Advantageously, it may be possible to select a rotation speed from among those provided by the manufacturer or a speed which is chosen by the user. Advantageously a memory may be provided for storing rotation speed values.
A hopper 100 is provided upstream of the grinding chamber 12. The hopper 100 may have any form, but preferably the hopper 100 is shaped substantially in the manner of a funnel 103 or cone so as to convey the beans to be ground towards the grinding chamber.
The bottom part 101 of the hopper 100 is preferably shaped so as to engage with the top part of the coffee grinding machine 10. For example, the engagement may be performed by means of a threading, bayonet joint or interlocking joint.
The top part 102 of the hopper 100 comprises a lid 104. The lid 104 may be coupled together with the body 103 of the hopper 100 in any known manner, for example by means of pressure/interlocking or by means of a hinge so as to allow the lid 104 to rotate about a hinging axis between an open position and a closed position.
According to the first embodiment, the coffee grinding machine 10 comprises a proximity sensor 110 on the body of the coffee grinding machine 10 and an element 120 which activates the sensor 1 10 arranged substantially inside the hopper 100. Preferably, in this embodiment, the lid 104 if the hopper 100 can be completely separated from it and is not hinged.
As is known, proximity sensors detect only the presence or absence of an object within their nominal range. Consequently, the electric output signal is of the on/off type since it must represent only the absent/present states.
The proximity sensors suitable for the present invention may be made being based on different types of technology, for example with inductive sensors, with capacitive sensors, with magnetic sensors, with ultrasound sensors or with optical sensors. According to preferred embodiments, the proximity sensor of the present invention is of the inductive or magnetic type. More preferably it is a reed magnetic sensor.
Inductive proximity sensors are based on the principle of the variation in reluctance of an electromagnet which occurs when an object made of ferromagnetic material is in the vicinity; the presence of ferromagnetic material within the magnetic field has the effect that the field itself is closed better, with consequent lowering of the reluctance. The internal circuits of the sensor detect the variation in reluctance and, once a certain threshold is exceeded, causes switching of the output signal.
A reed sensor is a (normally open) metal-contact switch which closes when there is a magnetic field. The magnetic proximity sensors operate by detecting the magnetic field generated by a permanent magnet mounted specifically on the object to be detected.
As mentioned above, preferably the electromagnet of the proximity sensor 1 10 is mounted on the body of the coffee grinding machine 10 and the hopper 100 is configured so as to form a protuberance 105 towards the inside for the electromagnet. In other words, the walls of the hopper 100 are closed, but shaped so that the electromagnet of the proximity sensor 1 10 extends towards the inside of the hopper. The protuberance forms a kind of shield for the proximity sensor 1 10.
Preferably, the proximity sensor 1 10 is inclined with respect to the vertical. Preferably, the proximity sensor is substantially perpendicular to a wall of the hopper. Preferably, the protuberance 105 terminates in an inclined, i.e. non-horizontal, surface 105'. According to the first embodiment of the present invention, the lid 104 comprises a body 120 which is made of ferromagnetic material and which extends towards the inside of the hopper and, more particularly, towards the electromagnet 110.
Thus, when the lid is closed, the proximity sensor 1 10 and the body 120 made of ferromagnetic material are at a distance d less than the range of the electromagnet and the circuit is closed, allowing the operation of the motor 30 for the grinding of coffee beans.
When the lid 104 is removed, the proximity sensor 1 10 and the body 120 made of ferromagnetic material move away from each other and are located at a distance D greater than the range of the electromagnet and the circuit is open, preventing the motor 30 from operating.
The solution described above not only satisfies the safety requisites, but also induces the operator to act in a more correct manner, reducing the number of times the hopper is opened when not strictly required, so as to ensure a greater stability of the temperature and moisture conditions inside the said hopper.
The present invention may also be implemented using different sensors and various wiring methods, as described above in connection with Figures 3.
In particular the Applicant considers the following technical solution to be advantageous:
• Sensor of the normally open magnetic type (the magnet is incorporated in the hopper lid).
· The sensor interrupts directly the power to the motor of the grinders by using a safety relay to which the sensor is wired.
• In addition to the above, a second wiring may be provided between the sensor the control electronics so that the signal for opening/closing the sensor is intercepted by the electronics and may be displayed to the operator.
Instead of the magnetic sensor, alternative sensors of the type: inductive sensors, mechanical sensors (microswitches), capacitive sensors, etc., could be used.
Instead of the wiring by means of a relay (Figures 3a and 3b) electronics with a certified safety function could be provided. In this case the guarantee as to no movement of the motor would be ensured not by the interruption of the power supply to the motor, but by the absence of the start signal.
A further alternative could be that of using a motor control device (for example the inverter 47) with a function which is commercially referred to by the abbreviation STO (Safe Torque Off). In this case by connecting the sensor to the safe input of the inverter a certified guarantee would be provided as to the absence of any torque (and therefore movement) of the grinders when the hopper is open. An inverter with the STO function is able to ensure that there is no motor torque. Where there is no specific command, the inverter guarantees (i.e. is certified to guarantee) the absence of torque. The cable which conveys the inverter activation signal from the electronics is intercepted by the safety sensor. If the sensor is open, the inverter does not receive the signal and the motor torque will definitely be zero.
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