Weighing system for a device capable of delivering a predetermined mass and corresponding method - Patents.com

Abstract

The invention relates to a system 10 for weighing a predetermined mass of food product, the system 10 comprising an electric stepper motor 30 supported by a chassis 11 and having an output shaft, a food receiving member 22 movable along a movement axis between a position for receiving the food product and a position for tilting the food product out, and an electronic control unit for controlling the electric motor. According to the invention, the receiving member cannot move independently of the output shaft, the weighing system is configured such that in the receiving position the receiving member and the food product apply a static torque to the output shaft, and the electronic control unit is configured to apply a resistive torque to the output shaft for a predetermined mass of food product, such that the output shaft changes position when the static torque is at least equal to the resistive torque.

Description

[Technical field]

[0001] The present invention relates to a weighing system for weighing a predetermined mass of food for an apparatus capable of delivering said mass, the apparatus being particularly suitable for preparing beverages, such as baby bottles, based on milk powder. [Background technology]

[0002] There are various weighing systems for food products used in beverage preparation. Many weighing systems comprise a conduit through which a worm screw extends, the worm screw being driven in rotation by a drive means. The worm screw is particularly suitable for dosing food powder, such as milk powder for baby bottle preparation. The weighing system further comprises a hopper into which a certain amount of milk powder is dispensed, the hopper being intended to feed the worm screw through an opening provided in the wall of the conduit. The rotation and / or number of rotations of the worm screw in the conduit allows a predetermined amount of milk powder to be dispensed towards the food outlet.

[0003] However, the amount of product dispensed by the worm screw is not accurate. The feeding of the milk powder is performed based on the average density without considering the particle size distribution of the powder or the granular rheology. Milk powder has various particle size distributions and / or densities depending on the nutritional requirements of the child. In addition, there is a large variation in the mass of milk powder actually dispensed due to the variation in density in the dry state and due to the mass of water absorbed by the powder depending on its storage conditions upstream of the hopper (inside the device and outside the device). The presence of moisture in the milk powder strongly changes the way the milk flows. In addition, when the worm screw stops, a certain amount of powder comes out of the end section of the worm screw and is dispensed after the worm screw motor is stopped. All these factors distort the measurement of the mass of milk powder dispensed.

[0004] A weighing system for weighing milk powder is also known, comprising a measuring chamber and a plate, which can rotate freely about a rotation axis and is placed in the measuring chamber. A hopper is intended to supply the milk powder to the measuring chamber. The plate is connected at one end to a pressure-sensitive powder weighing means, which is connected to an electronic control unit. The other end of the plate is connected to an abutment means. When the mass of powder falling by gravity reaches a desired value by the pressure-sensitive means, the electronic control unit commands the rotation of a stepper motor carrying a cam designed to abut against the abutment means. The abutment means, which is actuated by the cam, then drives the plate to rotate. This amount of powder is discharged through a discharge orifice in the measuring chamber. However, the desired amount of milk powder is not accurate, since the measurement does not take into account the various particle size distributions, densities and / or rheology of the granules of milk powder, as mentioned above. Furthermore, this system is complex and expensive, since it involves several components for measuring the exact mass and for supplying this exact mass.

[0005] Other examples of weighing systems are described in documents DE-A1-1549301 and DE-U1-29620108. In document DE-A1-1549301, the weighing system comprises various elements for operating various actions, such as, inter alia, a bar arranged at a certain distance from a magnet for determining the mass of the food to be weighed, a receiving member for receiving the food to be weighed, connected to a counterweight, and a micro-relay for holding the receiving member for a certain time during discharge. The counterweight allows the receiving member to return to its original position. The distance between the bar and the magnet, which is used to determine the mass to be reached, is a dimensional quantity. Such systems are unreliable and expensive. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] DE-A1-1549301 [Patent Document 2] DE-U1-29620108 Summary of the Invention [Problem to be solved by the invention]

[0007] It is an object of the present invention to provide a weighing system which is accurate, reliable and economical. [Means for solving the problem]

[0008] The object of the present invention is achieved according to the present invention by a weighing system for weighing and discharging a predetermined mass of food, the device comprising: - a chassis; - an electric stepper motor carried by the chassis and having an output shaft capable of adopting multiple positions along a displacement axis; - a receiving member for receiving food, movable along an axis of displacement between a receiving position for receiving the food and a discharge position for discharging the food, the receiving member being configured to accommodate or hold a predetermined mass of food at the receiving position and to drop this mass at the discharge position; - an electronic control unit for controlling the electric motor, the electronic control unit being configured such that the receiving member is fixed in displacement with respect to the output shaft, the weighing system being configured such that in said receiving position the receiving member and the food product it contains or holds exert a static torque on the output shaft, the electronic control unit being configured to exert a resistive torque on the output shaft for a given mass of the food product, such that the output shaft changes position when the static torque is at least equal to the resistive torque; Equipped with.

[0009] Thus, this solution makes it possible to achieve the above mentioned objectives. In particular, the value of the desired mass to be reached induces a static load torque that causes a loss of synchronism of the motor. "Loss of synchronism" refers to the phenomenon of desynchronization of the rotor of the motor, which can occur in the case of shocks or when the torque applied to the shaft of the motor is equal to or greater than the position-holding torque of the motor. The motor can no longer maintain its position and slips and loses synchronism, thereby involuntarily causing the motor to change its step. The present invention makes use of this phenomenon to accurately detect the exact mass of the food product discharged into the receiving member. The implementation and installation of such a system is simple and economical, since it makes use of a physical phenomenon that is classically observed in motors. The measurement of the torque of the motor follows linear laws, thus making this solution an adaptive system. With regard to simplicity, a stepper motor makes it possible to activate several actions / functions, namely setting the mass to be reached, holding the receiving member until the predetermined mass is reached, tilting the receiving member, and returning the receiving member to the predetermined position. Stepper motors occupy very little space and therefore make the systems very compact. In addition, stepper motors make it possible to set electromagnetic quantities with significantly higher reliability than dimensional quantities.

[0010] The system has the following properties, either alone or in combination: an electronic control unit is arranged to control the displacement of the output shaft and therefore the displacement of the receiving member between the receiving position and the ejection position when the mass of the food product reaches a predetermined value; - a given mass of food contained in the receiving member and the receiving member has a centre of gravity located at a given distance from the axis A of displacement. the receiving member comprises connection means fixed to a drive shaft, said drive shaft being rotatably connected to an output shaft of an electric motor, capable of rotational movement; the receiving member is in the form of a bucket; the receiving member is in the form of a receiving wall; - The receiving wall has a flat or curved receiving surface. - the chassis comprises a platform provided with an opening through the wall of the platform on either side, through which the food product is intended to fall by gravity; - the weighing system comprises detection means capable of detecting at least one position of the output shaft of the stepper motor, the detection means being connected to the electronic control unit. - The given mass is between 3g and 100g. - the receiving member is mounted on the output shaft so that the centre of gravity of the assembly formed by the mass of the receiving member and the food product is defined in a plane passing through the axis A of displacement of the output shaft which forms a predetermined forward angle with respect to a horizontal plane passing through the axis A of displacement. - the discharge angle of the receiving member between the receiving position and the discharge position is between 0° and 180°. the weighing system comprises a vibration device intended to enable the food product to be completely discharged from the receiving member to the discharge position.

[0011] The invention further relates to a machine for preparing a food-based beverage, the machine comprising a weighing system according to any of the aforementioned characteristics.

[0012] The nature of the device is that it comprises a food storage tank and a mixing chamber for receiving a predetermined mass of food from the receiving member at a discharge position.

[0013] The invention further relates to a method for weighing and discharging a predetermined mass of food product by means of a weighing system, the weighing system comprising at least one electric stepping motor having an output shaft and a receiving member fixed with respect to the displacement of the output shaft, the method comprising the steps of: - providing a food product; - discharging a quantity of food onto or into a receiving member; - weighing the food product, applying a resistive torque to the output shaft for a given mass of food product by the electronic control unit; applying a static torque to the output shaft by the receiving member and the food product contained or held by the receiving member; Varying the position of an output shaft of the electric motor when the static torque is at least equal to the resistive torque; A weighing step comprising: Includes.

[0014] The method comprises the following steps and / or features, either alone or in combination: - The food contains milk powder. - Discharging a measured mass of food. - An electronic control unit controls the electric motor.

[0015] The invention will be better understood and other objects, details, nature and advantages of the invention will become more apparent on reading the following detailed descriptive description of embodiments of the invention, given purely as illustrative and non-limiting examples, with reference to the accompanying schematic drawings, in which: [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a front view of a device according to the invention, intended to deliver a precise mass of food and to prepare a beverage using this precise mass; [Diagram 2] FIG. 1 is a perspective view of a weighing system for weighing an accurate determined mass of food products according to the present invention. [Diagram 3] 1 is a perspective view substantially from below of an illustrative receiving member for receiving food items according to the present invention; FIG. [Figure 4] 1 is a perspective view substantially from above showing an example of a receiving member for receiving food items according to the present invention; [Diagram 5]1 is a perspective view showing an example of a motor mounted on a chassis of a weighing system and a detection means for detecting at least one position of an output shaft of the motor according to the present invention; FIG. [Figure 6] 1 is a perspective cross-sectional view showing an example of a weighing system according to the present invention; [Figure 7] 1 shows an axial section of a weighing system according to the invention with a receiving member in a receiving position; [Figure 8] 1 shows an axial section of a weighing system according to the invention with a receiving member in an ejection position; [Figure 9] 3 is a schematic axial section view showing another embodiment of a receiving member of a weighing system according to the invention in the form of a receiving wall for closing a receptacle; FIG. [Figure 10] 3 is a schematic axial section view showing another embodiment of a receiving member of a weighing system according to the invention in the form of a receiving wall for closing a receptacle; FIG. [Figure 11] FIG. 4 is a partial cross-sectional view showing a sensing means for sensing the position of an output shaft of an electric motor of a weighing system according to the present invention; [Figure 12] 1 shows the various steps of a method for weighing and discharging a predetermined mass of food product according to the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Figure 1 shows an apparatus 1 for the preparation of beverages based on food, such as powders, liquids, etc. The food is preferably, but not exclusively, infant formula. The apparatus is intended in particular to deliver a precise mass of food to prepare the beverage.

[0018] The device 1 comprises a frame 2, a food storage tank 3 and a water tank (not shown). The frame 2 has a base 5 arranged to receive a container 6 into which the beverage is discharged. The container 6 may be a baby bottle. The food storage tank 3 is arranged above the base 5 along a longitudinal axis X (here vertical with respect to the plane of FIG. 1 and according to the situation of use of the device arranged on a work surface). In this example, the water tank is arranged downstream of the base 5 along a first transverse axis Y (here horizontal and perpendicular to the plane of FIG. 1). The first transverse axis Y is perpendicular to the longitudinal axis X. To enable weighing and discharging a predetermined mass of food in an accurate manner for preparing the beverage, the device comprises a weighing system 10, which will be explained later in the description.

[0019] A predefined and precise mass of food is provided to the mixing chamber 7 and water of a predefined temperature is injected into the mixing chamber 7 to facilitate the mixing of the food (in this case milk powder and water). The water may be injected under pressure. The mixing chamber 7 is arranged along a longitudinal axis X between the base 5 and the weighing system 10. The mixing chamber 7 comprises a nozzle 8 intended to dispense the beverage arranged at a certain distance from the base 5. The nozzle 8 is opposite the base 5 along the longitudinal axis X. The nozzle 8 extends along the longitudinal axis from the bottom of the chamber towards the base. For this purpose, the device 1 comprises a hydraulic circuit (not shown) comprising a conduit with an inlet orifice connected to the water tank and an outlet orifice connected to the mixing chamber 7. The hydraulic circuit comprises a pump enabling the withdrawal of water from the water tank and the circulation of the water through the conduit, as well as means for heating the water. These heating means are arranged on the conduit and between the pump and the mixing chamber 7.

[0020] The weighing system 10 is shown in FIG. 2. The weighing system 10 is described in the context of installation in an apparatus using a Cartesian coordinate system X, Y, T. The weighing system 10 comprises a chassis 11 arranged in an enclosure 4 (shown in dotted lines) of a frame 2, the enclosure being located above the mixing chamber 7 along a longitudinal axis X. The chassis 11 comprises a platform 12 with a first surface 13 defined in a plane perpendicular to the longitudinal axis X. The chassis 11 comprises legs 14 making it possible to stabilize the platform 12 and to maintain it at a certain distance from the bottom of the enclosure 4. In this example there are four legs. Each leg 14 is elongated along the longitudinal axis between a first end 14a and a second end 14b. The first end 14a carries a base plate 15 intended to rest on the bottom of the enclosure 4, the second end 14b being attached to the platform 12 by a mounting member. To accomplish this, the platform 12 includes an orifice 16, each of which receives a second end 14b of a leg 14. The mounting members include a nut, each of which is press-fit into the orifice 16, with the internal threads of the nut cooperating with external threads provided at the second end 14b of each leg. Of course, the mounting members could include other mounting members, such as studs, screws, adhesives, welds, etc.

[0021] A food storage tank 3 is advantageously mounted on the platform 12. The storage tank 3 defines a storage volume for storing food. The platform 12 comprises on either side an opening 17 passing through its wall along a longitudinal axis X. The storage tank 3 comprises a discharge orifice (not shown) opening on one side into the storage volume of the storage tank and on the other side into the opening 17 in the platform 12. Advantageously, sealing means (not shown) for sealing the discharge orifice are provided to occupy an open and a closed position of the discharge orifice. These sealing means are controlled by an electronic control unit 18 (see Figures 1, 6 and 11). The electronic unit is mounted in the device 1, in particular on the frame 2. The sealing means may comprise at least one door pivoting about an axis parallel to the plane of the first surface 13 of the platform 12 or sliding in the plane of the first surface 13. Furthermore, it can be seen that a hopper 19 extends from a second surface 20 (see Figure 5) of the platform 12 along the longitudinal axis X. The opening 17 opens into a hopper 19 which extends the opening 17. In this example, the hopper 19 has a frustoconical cross-section (in the plane formed by the longitudinal axis and the first transverse axis Y) that tapers to an exit orifice 21 (see Figures 5 and 8) of the hopper 19 which is opposite the opening 17 defined in the platform 12 (along the longitudinal axis X).

[0022] 2, 3 and 4, the weighing system 10 comprises a receiving member 22 for receiving food delivered by the storage tank 3. The receiving member 22 is movable between a food receiving position and a food discharging position along a displacement axis. Here, the receiving member 22 is rotationally displaced about the displacement axis. Advantageously, but not exclusively, the receiving member 22 is in the form of a bucket. The shape of the bucket allows for good control of the reception of the food and contents. In particular, the receiving member 22 comprises a receiving wall 23, two lateral partitions 24 extending from the lateral edges of the receiving wall 23, and an upstream partition 25 rising from the upstream edge of the receiving wall 23. The receiving wall 23 is the bottom of the receiving member and is curved. The lateral partitions 24 are opposite each other along the second transverse axis T and comprise internal surfaces 24a defined in substantially parallel planes. The terms "upstream" and "downstream" are defined with respect to the first transverse axis Y. The inner surfaces 24a face towards each other. The upstream partition 25 is further connected to the upstream edges of the lateral partitions 24. The upstream partition 25 has an inner surface 25a defined in a plane perpendicular to the plane of the inner surfaces 24a of the lateral partitions 24. The upstream partition 25, the two lateral partitions 24 and the receiving wall 23 form a volume for receiving a quantity of food. At least the upstream partition 25 and the lateral partitions 24 each have a free edge 26 that defines a boundary of an opening 27 of the receiving member 22 opening into the receiving volume. The receiving wall 23 has a curved concave inner surface 23a facing towards the bucket opening 27. The inner surface 23 serves as a receiving surface for receiving food.

[0023] In Figures 2, 5 and 6, the weighing system 10 comprises an electric motor 30 intended to drive the displacement of the receiving member 22 between a receiving position and a discharge position. The electric motor 30 is carried by the chassis 11 as shown. The chassis 11 comprises a housing 31 (see Figure 6) in which the motor is removably arranged. As shown more precisely in Figure 6, the chassis 11 comprises a support wall 32 extending from the second surface 20 of the platform 12 along a longitudinal axis X. The support wall 32 comprises an inner surface 32a defined in a plane perpendicular to the second transverse axis T. Projections 33 extend from the inner surface 32a of the support wall 32 and at least partially define the boundaries of the housing 31 suitable for receiving the electric motor 30. These projections 33 integrally form a cylindrical wall having a circular cross section (along the plane XY (formed by the longitudinal axis X and the first transverse axis Y)) and an axis parallel to the second transverse axis T. In this example, there are three protrusions 33. Alternatively, a single cylindrical wall extends from the inner surface 33a of the support wall 32.

[0024] With reference to Figures 3, 4 and 6, the electric motor 30 comprises an output shaft 34 with a displacement axis A parallel to the second transverse axis T. The receiving member 22 is fixed in displacement with respect to the output shaft 34 of the motor. For this purpose, as shown in Figures 3 and 4, the receiving member 22 comprises a connection means 35 for connection to the output shaft 34 of the motor 30. In this example, the receiving member 22 comprises two lateral wings 36 extending the lateral partition 24 downstream. The lateral wings 36 extend substantially along the first transverse axis Y. Each lateral wing 36 comprises an inner surface 36a defined in a plane perpendicular to the second transverse axis T. The inner surfaces 36a of the two lateral wings 36 face towards each other. The connection means 35 comprises a hollow tube 37 extending between the two lateral wings 36 of the receiving member 22. A drive shaft 38 is connected to the output shaft 34 of the motor 30 and is fixed with respect to the displacement of the output shaft 34. The drive shaft 38 is coaxial with the displacement axis A. The drive shaft 38 is fixed to the receiving member 22, so that the receiving member 22 is displaced simultaneously with the shaft 38. In particular, the drive shaft 38 is arranged inside the hollow tube 37. The drive shaft 38 has a diameter substantially equal to the inner diameter of the hollow tube 37. Alternatively, not shown, the connection means 35 comprises ears connected to the receiving wall 23, each ear comprising a through hole along the second transverse axis T. The drive shaft 38 passes through the ears and is fixed to the ears so as to be able to drive the displacement of the receiving member.

[0025] The electric motor 30 is a rotary stepper motor or a linear stepper motor. It is very economical to use a stepper motor. In this example, the motor 30 is a rotary stepper motor. The output shaft 34 performs a rotation about an axis of displacement A. Similarly, the receiving member 22 pivots about this axis of displacement A. The stepper motor allows for a controlled and precise rotation of the output shaft and is easily controlled. The stepper motor comprises at least one rotor and one stator. The rotor is coupled to the output shaft 34. The stator carries at least two electric coils or electromagnets that create a magnetic field. The magnetic field is generated by a current that appears when the motor is supplied with a given voltage. The direction of the magnetic field circulating in the coils of the stator drives the rotation of the rotor. The output shaft 34 of the electric motor 30 rotates at a certain angle in response to each electric pulse, thereby making it possible to adopt a variety of angular positions called steps. The motor 30 can have a predetermined number of steps. The angle can be between 0.9° and 45°. The output shaft 34 of the motor can take between 8 and 400 steps per revolution, depending on the motor.

[0026] The electric stepper motor 30 may include a permanent magnet stepper motor, a variable reluctance stepper motor, or a hybrid stepper motor. Preferably, the electric motor 30 is a hybrid stepper motor with constant reluctance or a permanent magnet stepper motor. A hybrid stepper motor includes permanent magnets, allowing for increased reluctance torque over a stepper motor without permanent magnets. A hybrid motor is more efficient and requires less current to achieve the same torque.

[0027] The motor 30 is connected to an electronic control unit 18 intended to control the motor 30. The electronic control unit 18 further enables supplying power to the motor 30. The electronic control unit 18 comprises a power supply module intended to supply a voltage to the electric motor and a control module for controlling the rotation of an output shaft 34 of the electric motor. The electronic control unit 18 is connected to a source of power, such as a home network, for example via an electric cable (not shown) of the device 1.

[0028] FIG. 7 shows the receiving member 22 in the receiving position. In this position, the receiving member 22 is configured to accommodate or hold a predetermined mass of food product. The receiving member 22 is of course empty. In this position, the receiving surface (internal surface 23a) of the receiving member 22 is substantially opposite the opening 17, and the food product is intended to fall by gravity through this opening 17 into the receiving member 22. In this example, the free edge is defined in a plane perpendicular to the longitudinal axis, which plane is parallel to a plane P1 passing through the axis of displacement A of the output shaft 34. More precisely, the centre of gravity CGV of the empty receiving member 22 is defined in a plane P1 passing through the axis of displacement of the output shaft 34. It is assumed that the plane P1 is horizontal and perpendicular to the longitudinal axis X when the weighing system 10 is installed in the device 1. The centre of gravity CGV of the receiving member 22 is determined by the barycentre of the elements that make up the receiving member 22. Here, the barycentre of the receiving member 22 is equal to the centre of gravity CGV.

[0029] Fig. 8 shows the receiving member 22 in the ejection position. In the ejection position, the receiving member 22 is configured to drop this predetermined mass. In the ejection position, the receiving surface (internal surface 23a) is at a certain distance from the opening 17. The receiving wall 23 faces towards and substantially contacts the second surface 20 of the platform 12. This figure shows that the receiving member 22 is pivoted along the axis of displacement A at a ejection angle of about 180° relative to a horizontal plane P1 passing through the axis of displacement. The ejection angle is between 0° and 180°. Advantageously, the ejection angle is between 60° and 135°.

[0030] In one embodiment, the weighing system 10 comprises a vibration device (not shown) designed to allow complete ejection (or removal) of the food product from the receiving member 22 in the ejection position. This vibration device is particularly advantageous if the pivot angle is less than 170° relative to the horizontal plane P1. The vibration device is electrically connected to the electronic control unit 18, which controls the vibration device when it is informed of the ejection position.

[0031] In another embodiment, shown diagrammatically in Fig. 9, the receiving member 22 comprises a receiving wall 23' which is fixed in displacement relative to the output shaft 34 of the electric motor 30. The receiving wall 23' is intended to close or seal a receptacle 47, which is likewise fixed in displacement relative to the output shaft 34 of the motor 30. The receiving wall 23' carries a receiving surface 23a intended to receive the food falling from the storage tank 3 by gravity and to weigh the mass of the food, as will be explained later. The receptacle 47 receives the food after the amount of food has been weighed and the receiving wall 23' has been displaced to the discharge position. More precisely, the receiving wall 23' is rotatably fixed relative to the output shaft 34 of the motor 30. The receiving wall 23' can be connected directly to the output shaft 34 via connection means 35 (ears, hollow tube) or can be connected (via connection means 35) to a drive shaft 38 which is connected to the output shaft 34. The container 47 has an opening 47a bounded by a wall 47b and a bottom 47c, the wall 47b rising from the bottom 47c. The receiving wall 23' is arranged at the height of the opening 47a to close the container 47. The receiving wall 23' further has dimensions substantially equal to the dimensions of the opening 47, while allowing the container 47 to tilt inside when reaching the mass of food. The container 47 is arranged above the mixing chamber 7 along the longitudinal axis X. The center of gravity CGV of the receiving member 22 is defined in a horizontal plane P1 passing through the axis A of displacement of the output shaft 34. The center of gravity CGV of the receiving member coincides with the barycentre of the receiving wall 23'. In this example, the receiving surface 23a is flat. However, the receiving surface 23a can also have a concave shape to better hold the food. This configuration allows a larger amount of food to be measured.

[0032] The receiving member 22 is made of a polymer material or a composite material with a polymer matrix. Examples of materials are polycarbonate (PC) or acrylonitrile butadiene styrene (ABS) or a mixture of these. The advantage of these polymer materials is that they are very light but sturdy. The material may be polypropylene (PP), polyoxymethylene (POM), polyamide (PA), etc.

[0033] Generally speaking, the electric stepper motor 30 experiences resistive torque (or reluctance torque) and synchronous torque. Reluctance torque results from the resistance to the passage of magnetic flux in the stator and rotor. The electric motor 30 is supplied with a predetermined voltage to maintain each angular position. This predetermined voltage is a function of the resistive torque applied to the output shaft 34 of the electric motor 30.

[0034] The weighing system 10 is configured to determine the mass of the food product by desynchronizing the motor, i.e. by inducing a step change or an angular pivot, during which a resistive torque is applied to the output shaft 34 by the electronic control unit 18. To do this, the weighing system 10 is configured such that the receiving member 22 and the food product accommodated or held by the receiving member 22 in said receiving position will apply a static torque to the output shaft 34, and the electronic control unit 18 is configured to apply a resistive torque to the output shaft 34. In this way, the electric motor 30 (output shaft 34) changes position when the static torque is at least equal to the resistive torque. In particular, the resistive torque corresponds to a predetermined mass of food product. This predetermined mass is the mass that must be discharged into the mixing chamber 7 to prepare the beverage.

[0035] It can further be seen that by controlling the synchronous torque of the electric motor 30 (and the electronic unit) of the weighing system it is possible to adapt the weighing of the food product. In other words it is possible to modify the mass value to be determined. In some weighing systems using dimensional quantities the mass to be determined is fixed. Such weighing systems are also significantly more accurate than systems using dimensional quantities.

[0036] The value of the predetermined mass is between 3 g and 100 g. Preferably, the value is 8 g.

[0037] According to Fig. 7, the receiving member 22 is configured such that the food product 39, in this case milk powder, forms a slope in or on the receiving member 22 after discharge (from the storage tank 3). A given mass of food product 39 and the receiving member 22 have a centre of gravity CGP located at a given distance d from the axis of displacement A. The distance d is substantially constant. The centre of gravity CGP of the assembly is arranged along the longitudinal axis X below the centre of gravity (CGV) of the receiving member 22 and below the horizontal plane P1. The reverse distance d to the centre of gravity CGP multiplied by the weight of the mass of the assembly (formed by the mass of the food product and the mass of the receiving member) constitutes the mechanical moment applied to the output shaft 34 of the motor 30. This moment is a static torque applied to the output shaft 34 of the motor 30.

[0038] According to the embodiment example shown in FIG. 10, the receiving member 22 (with receiving wall 23') defines a flail at a certain angle with respect to a horizontal plane passing through the axis A of the displacement of the motor 30. In other words, the receiving member 22 is mounted on the output shaft 34 with a certain advance angle α (alpha). This angle α is between 1.8° and 8°. As shown, the slope of the powder is arranged above the receiving surface 23a of the receiving wall 23'. The center of gravity CGT of the food forming the slope is arranged above the receiving surface 23a. The point of application of the force F exerted by the slope is defined above the receiving surface 23a and passes through the center of gravity CGV' of the receiving member 22. The receiving member 22 is connected to the output shaft 34 in such a way that the center of gravity CGP of the assembly (powder and receiving member 22) is located above the horizontal plane P1 passing through the axis of displacement of the motor. The center of gravity CGP is defined in a plane passing through the axis A of the displacement, which forms an advance angle α with respect to the plane P1. Thus, when the motor loses synchronism, the static torque increases instead of decreasing. The moment (F*d*cos(a)) increases without increasing the mass of the food. This arrangement makes it possible to improve the sensitivity of the weighing system.

[0039] With reference to figures 5 and 11, the weighing system 10 comprises a detection means 40 capable of detecting at least one angular position of the output shaft 34 of the electric motor 30. The detection means 40 are connected to the electronic control unit 18, which is arranged to act on the motor 30 when a change in step or angular position of the motor is detected. The detection means 40 comprises an emitter of a light beam (visible or invisible) and a receiver of the light beam. The receiver is arranged opposite the emitter. The emitter and the receiver are connected to the electronic control unit 18. In this example, the detection means comprises an optical fork 41 with a first leg 41a on which the emitter is mounted and a second leg 41b on which the receiver is mounted. The light beam may be an infrared beam. The detection means 40 comprises an obstruction member 42 fixed to the output shaft 34. This obstruction member 42 is intended to be interposed in the path of the light beam depending on the angular position of the output shaft 34. In the illustrated embodiment, the obstruction member 42 comprises a disk having a central axis coaxial with the axis A of displacement of the output shaft 34 and rotatably fixed to the output shaft 34. In this way, when the motor 30 loses synchronism (when the motor changes steps), the disk pivots simultaneously with the output shaft 34. The disk comprises at least one first slot 43 extending radially from the peripheral edge 44 of the disk towards the central axis of the disk. The slot 43 is intended to be passed by the light beam (as shown by the dotted line in FIG. 11). For this purpose, a first leg 41a and a second leg 41b each extend on either side of a portion of the disk 42 along the transverse axis T. The optical fork 41 is mounted in a housing 45 formed in the platform 12 of the chassis 11. The housing 45 is open on the first surface 13 and on the second surface 20 of the platform. A portion of the disk extends laterally through the housing 45 between the emitter and the receiver. The obstruction member 42, in this case a disk, is easy to install and does not introduce any parasitic torque onto the motor output shaft 34. Alternatively, the obstruction member 42 comprises a cam.In particular, when the light beam passes through the slot, the electronic control unit 18 controls the maintaining of the position of the output shaft 34 of the motor by applying a resistive torque. In this case, the receiving member 22 is fed with food. When the light beam is interrupted, this means that the light beam is scanning the solid surface of the disk and the output shaft 34 has rotated at least one step (first angular position). In this case, the electronic control unit 18 controls the output shaft 34 to drive the receiving member 22 to the ejection position.

[0040] The detection means 40 are able to detect another angular position (second position) of the output shaft 34 of the electric motor 30. Advantageously, the disc comprises a second slot 46, visible in FIG. 6, intended to enable detection of the second position of the output shaft 34 and in particular of the receiving member 22. The first slot 43 and the second slot 46 are arranged at 180° to each other. This second slot 46 serves as a stroke end detection element for the receiving member 22 in the ejection position.

[0041] A method 100 for weighing and discharging a predetermined mass of food by the weighing system 10 described above will now be described. The method 100 is shown in FIG. 12. The method comprises a step 110 of providing food, during which the food is arranged in a storage tank 3 located above the weighing system 10. Preferably, the food comprises infant milk powder. The method comprises a step 120 of discharging a quantity of food onto or into the receiving member 22. In particular, the food is discharged so as to form a slope on the receiving surface 23a of the receiving member 22. The receiving surface 23a is flat or hollow as described above. During this step, the electronic control unit 18 sends a control command to the sealing means to open the discharge orifice of the storage tank 3. Thus, a quantity of food is discharged onto or into the receiving member 22 through the openings 17 in the platform 12 and in the hopper 19, which guide the food towards the receiving member 22. In the case of a bucket, the food 39 can be guided up into the receiving volume of the receiving member 22. The milk powder is discharged onto the receiving surface 23a of the receiving member 22 continuously or intermittently.

[0042] The method includes a step 130 of weighing a predetermined mass of food in the receiving member 22. This step 130 consists of performing a loss of synchronism of the motor. In particular, the weighing step 130 includes a sub-step of applying a resistance torque to the output shaft 34 of the motor 30 by the electronic control unit 18. This resistance torque is a function of the supply voltage. For example, a voltage of 12V is applied to the motor 30, which corresponds to a resistance torque of 16mNm. This resistance torque corresponds to a powder mass of about 8g. When the receiving member 22 and the food contained therein apply a static torque equal to the resistance torque, the output shaft 34 pivots to change the step. Milk powder continues to be discharged into the receiving member 22 as long as the mass of the powder in the receiving member 22 (or on the receiving surface 23a) together with the mass of the receiving member does not reach this predetermined value.

[0043] The method 100 comprises a step 140 of weighing the powder and discharging the mass. In particular, as soon as this mass is reached, the output shaft 34 changes a step or angular position without any action from the motor itself or without a command from the electronic control unit 18. At the same time, the obstructing member 42, in this case a disk, interrupts the light beam between the emitter and its receiver. The detection means 40 and in particular the optical fork 41 send a control signal related to the position of the output shaft 34 to the electronic control unit 18. The electronic control unit 18 sends a control command to the motor 30 to drive the rotation of the output shaft 34 and the receiving member 22 to the discharging position. Simultaneously with or before the discharging step 140, the method comprises a step of stopping the discharge 150 of the food into the receiving member 22. In this case, the electronic control unit 18 sends a control command to the closing means to close the orifice for discharging the storage tank 3.

Claims

1. A weighing system (10) for weighing and discharging a predetermined mass of food product, said device comprising: A chassis (11); an electric stepping motor (30) carried by said chassis (11) and having an output shaft (34) capable of adopting various positions along a displacement axis (A); a receiving member (22) for receiving the food product, movable along the displacement axis (A) between a receiving position for receiving the food product and a discharge position for discharging the food product, the receiving member (22) being configured to accommodate or hold a predetermined mass of the food product at the receiving position and to drop the mass at the discharge position; an electronic control unit (18) for controlling said electric motor (30); Equipped with the weighing system (10) being configured such that, in the receiving position, the receiving member (22) and the food item contained or held by the receiving member (22) apply a static torque to the output shaft (34); and the electronic control unit (18) is configured to apply a resistive torque to the output shaft (34) for a predetermined mass of the food item, such that the output shaft (34) changes position when the static torque is at least equal to the resistive torque.

2. 2. The weighing system (10) of claim 1, characterized in that the electronic control unit (18) is configured to control the displacement of the output shaft (34) and the displacement of the receiving member (22) between the receiving position and the ejection position when the mass of food reaches a predetermined value.

3. 3. The weighing system (10) according to claim 1 or 2, characterized in that the predetermined mass of the food contained in the receiving member (22) and the receiving member (22) have a center of gravity (CGP) located at a predetermined distance (d) from the displacement axis A.

4. 4. A weighing system (10) according to claim 1, characterized in that the receiving member (22) comprises a connection means (35) fixed to a drive shaft (38), the drive shaft (38) being rotatably connected to the output shaft (34) of the electric motor (30) capable of rotational movement.

5. Weighing system (10) according to any one of claims 1 to 4, characterized in that the receiving member (22) is in the form of a bucket or a receiving wall (23').

6. 6. A weighing system (10) as claimed in any one of claims 1 to 5, characterized in that the chassis (11) comprises a platform (12) with openings (17) passing through the walls of the platform (12) on either side, such that the food product falls through the openings (17) by gravity.

7. 7. The weighing system (10) according to claim 1, further comprising detection means (40) capable of detecting at least one position of the output shaft (34) of the stepping motor, the detection means being connected to the electronic control unit (18).

8. 8. The weighing system (10) of claim 7, characterized in that the predetermined mass is between 3 g and 100 g.

9. A weighing system (10) as described in any one of claims 3 to 8, characterized in that the receiving member (22) is mounted on the output shaft (34) so ​​that the center of gravity (CGP) of the assembly formed by the receiving member (22) and the mass of the food product is defined in a plane passing through the displacement axis A of the output shaft (34) that forms a predetermined forward angle with respect to a horizontal plane (P1) passing through the displacement axis A of the output shaft (34).

10. An apparatus (1) for preparing a food-based beverage, characterized in that said apparatus (1) comprises a weighing system (10) according to any one of claims 1 to 9.

11. 11. The device (1) according to claim 10, characterized in that the device (1) comprises a storage tank (3) for food product and a mixing chamber (7) adapted to receive a predetermined mass of food product from the receiving member (22) in the discharge position.

12. A method for weighing and discharging a predetermined mass of food product by means of a weighing system (10), said weighing system (10) comprising at least one electric stepping motor (30) having an output shaft (34) and a receiving member (22) fixed with respect to the displacement of said output shaft (34), said method comprising the steps of: Providing food (110); Discharging (120) a quantity of food onto or into the receiving member (22); Weighing (130) the food product, applying a resistive torque to the shaft (34) for a predetermined mass of the food product by an electronic control unit (18); applying a static torque to the output shaft (34) by the receiving member (22) and the food product contained or held by the receiving member; Varying the position of the output shaft (34) of the electric motor when the static torque is at least equal to the resistive torque; A weighing step (130) comprising: A method comprising:

13. 13. The method of claim 12, wherein the food product comprises milk powder.

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