WEIGHING SYSTEM FOR A DEVICE FOR DISPENSING A PREDETERMINED MASS AND CORRESPONDING METHOD

Description

Scope of the invention

[0001] The present invention relates to a weighing system for a predetermined mass of a food product, for an apparatus capable of dispensing this predetermined mass of food product. The apparatus is particularly intended for preparing a beverage such as a baby bottle made from powdered milk. Technical background

[0002] Various food product weighing systems exist for beverage preparation. Many weighing systems include a conduit containing an auger, which is driven by a drive mechanism. Augers are particularly well-suited for dosing food powders, such as milk powder for infant formula. The weighing system also includes a hopper into which a quantity of milk powder is supplied and fed to the auger through an opening in the conduit wall. The rotation and / or number of revolutions of the auger within the conduit determines the delivery of a predetermined quantity of milk powder to a food product outlet.

[0003] However, the quantity of product delivered by the auger is not precise. In fact, the milk powder delivery is based on its average density, without taking into account the particle size or granular rheology of the powders. Milk powders have different particle sizes and / or densities depending on the child's nutritional needs. Furthermore, there are significant variations in the mass of milk powder actually delivered due to variations in density in its dry state, as well as the amount of water absorbed by the powder depending on its storage conditions upstream of the hopper (both inside and outside the machine). The presence of moisture in the milk powder considerably alters its flow. In addition, when the auger stops, some powder escapes from the end section of the auger and is delivered after the auger motor has stopped.All these factors distort the measurement of the mass of milk powder that is delivered.

[0004] A milk powder weighing system is also known, comprising a measuring chamber and a free-rotating platform that rotates around an axis of rotation installed within the measuring chamber. A hopper supplies the measuring chamber with milk powder. The platform is connected at one end to pressure-sensitive powder weighing means, which are connected to an electronic control unit. The other end of the platform is connected to stop means. When the mass of powder falling by gravity reaches a value determined by the pressure-sensitive means, the electronic control unit commands the rotation of a stepper motor carrying a cam designed to bear against the stop means. The stop means, actuated by the cam, then cause the platform to rotate. The powder is discharged through a discharge port in the measuring chamber.However, the desired quantity of milk powder is not precise because the measurement does not take into account the different particle sizes, densities, and / or granular rheology of the milk powder, as mentioned above. Furthermore, this system is complex and expensive because it involves several components to measure and dispense a precise 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 includes various elements for performing different actions, such as a rod positioned at a distance from a magnet to determine the mass of a food item to be weighed, a receiving element for the food item to be weighed that is connected to a counterweight, and microrelays to hold the receiving element for a predetermined time during dispensing. The counterweight returns the receiving element to its position. The distance between the rod and the magnet for determining the target mass is a dimensional quantity. Such a system lacks reliability and is expensive.

[0006] The aim of the present invention is to provide a weighing system that is accurate, reliable, and economical. Summary of the invention

[0007] This objective is achieved in accordance with the invention by means of a weighing system designed to weigh and dispense a predetermined mass of a food product, the device comprising: a chassis, a stepper motor mounted on the chassis and having an output shaft capable of adopting different positions along a movement axis, a food product receiving device that is movable along the movement axis between a food product receiving position and a food product discharge position, the receiving device being configured to contain or retain a determined mass of the food product in the receiving position and to release this mass in the discharge position, an electronic control unit for controlling the electric motor, the receiving member being fixed in movement to the output shaft and the weighing system being configured so that, in said receiving position, the receiving member and the food product it contains or retains apply a static torque on the output shaft, and the electronic control unit being configured so as to apply a resisting torque, for a predetermined mass of the food product, on the output shaft so that, when the static torque is at least equal to the resisting torque, the output shaft changes position.

[0008] Thus, this solution makes it possible to achieve the aforementioned objective. In particular, reaching the desired mass value induces a static load torque that causes the motor to stall. By "stall," we mean a phenomenon of rotor desynchronization that can occur in the event of an impact or when a torque applied to the motor shaft is equal to or greater than the motor's holding torque. The motor is no longer able to maintain its position and experiences slippage or stalling, resulting in an unintentional change in its pitch. The invention uses this phenomenon to accurately detect the precise mass of the food product discharged into the receiving device. The implementation and installation of such a system is simple and economical because it utilizes physical phenomena commonly found in motors.The motor's torque measurement follows a linear law, making this solution an adaptive system. In terms of simplicity, the stepper motor performs several actions / functions: setting the target mass, holding the receiving element until the target mass is reached, tilting the receiving element, and returning it to its original position. The stepper motor occupies little space, resulting in a very compact system. Furthermore, the stepper motor allows for the control of an electromagnetic quantity, which is far more reliable than a dimensional one.

[0009] The system includes the following features, taken alone or in combination: The electronic control unit is configured to control the movement of the output shaft and the movement of the receiving element between the receiving position and the discharge position when the mass of food product reaches a predetermined value. The predetermined mass of food product contained in the receiving element and the receiving element itself have a center of gravity located at a predetermined distance from the axis of movement A. The receiving element includes connecting means attached to a drive shaft, said drive shaft being rotationally coupled to the output shaft of the rotating electric motor. The receiving element is shaped like a bucket. The receiving element is shaped like a receiving wall. The receiving wall has a flat or curved receiving surface.The chassis includes a platform with an opening through the platform wall on both sides, through which the food product is intended to fall by gravity. The weighing system includes sensing means capable of detecting at least one position of the stepper motor's output shaft, these sensing means being connected to the electronic control unit. The predetermined mass is between 3g and 100g. The receiving member is mounted on the output shaft such that the center of gravity of the assembly, formed by the receiving member and the mass of food product, lies in a plane passing through the axis of movement A, which forms a predetermined angle with a horizontal plane passing through the axis of movement A of the output shaft. The tipping angle of the receiving member between the receiving position and the tipping position is between 0° and 180°.The weighing system includes a vibrating device designed to allow the complete discharge of the food product from the receiving organ into the discharge position.

[0010] The invention also relates to an apparatus for preparing a beverage based on a food product, the apparatus comprising a weighing system according to any one of the preceding characteristics.

[0011] According to a characteristic of the device, it includes a food product storage tank and a mixing chamber intended to receive a predetermined mass of food product from the receiving device in the discharge position.

[0012] The invention further relates to a method for weighing and dispensing a predetermined mass of a food product by means of a weighing system, the weighing system comprising at least one stepper electric motor having an output shaft and a receiving member which is fixed in movement to the output shaft, the method comprising the following steps: a step of supplying a food product, a step of unloading a quantity of food product onto or into the receiving device, a step of weighing the food product consisting of: - applying a resisting torque for a predetermined mass of the food product, on the output shaft by the electronic control unit, - applying a static torque on the output shaft by the receiving device and the food product it contains or retains, and - changing the position of the output shaft of the electric motor when the static torque is at least equal to the resisting torque.

[0013] The process includes the following steps and / or characteristics taken alone or in combination: The food product contains milk powder. A step involves pouring the measured mass of food product. The electronic control unit drives the electric motor. Brief description of the figures

[0014] The invention will be better understood, and other objects, details, features and advantages thereof will become more apparent upon reading the detailed explanatory description that follows, of embodiments of the invention given by way of purely illustrative and non-limiting examples, with reference to the accompanying schematic drawings in which: [ Fig. 1 ] There figure 1 is a front view of an apparatus designed to deliver a precise mass of a food product and to prepare a beverage with that precise mass according to the invention; [ Fig. 2 ] There figure 2is a perspective view of a weighing system for a precise and determined mass of a food product according to the invention; [ Fig. 3 ] There figure 3 illustrates in perspective, substantially below, an example of a food product receiving organ according to the invention; [ Fig. 4 ] There figure 4 illustrates in perspective, substantially above, an example of a food product receiving organ according to the invention; [ Fig. 5 ] There figure 5 represents, in perspective view, an example of a motor installed on a chassis of a weighing system and means for detecting at least one position of the motor's output shaft according to the invention; [ Fig. 6 ] There figure 6 is a cross-sectional and perspective view of an example of a weighing system according to the invention; [ Fig. 7 ] There figure 7 represents an axial cross-sectional view of the weighing system with a receiving member in a receiving position according to the invention; [ Fig. 8 ] There figure 8 is an axial cross-sectional view of the weighing system with a receiving element in the tipping position according to the invention; [ Fig. 9 ] There figure 9 illustrates schematically and in axial section another embodiment of a receiving element of a weighing system having the form of a receiving wall for closing a receptacle according to the invention; Fig. 10 ] There Figure 10 illustrates schematically and in axial section, another embodiment of a receiving element of a weighing system having the form of a receiving wall for closing a receptacle according to the invention; [ Fig. 11 ] There figure 11 is seen in partial and transverse section of the means for detecting the positions of the output shaft of the electric motor of the weighing system according to the invention; and [ Fig. 12 ] There figure 12represents the different stages of a weighing and pouring process of a predetermined mass of food product according to the invention. Detailed description of the invention

[0015] On the figure 1 An apparatus 1 is illustrated for preparing beverages from food products such as powders, liquids, etc. The food product is preferably, but not exclusively, infant formula powder. The apparatus is specifically designed to dispense a precise mass of the food product to prepare the beverage.

[0016] 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 configured to receive a container 6 into which the beverage is poured. The container 6 can be a baby bottle. The food storage tank 3 is arranged above the base 5 along a longitudinal axis X (here vertical with reference to the plane of the figure 1 and depending on the situation of use of the device placed 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 the figure 1The first transverse axis Y is perpendicular to the longitudinal axis X. In order to accurately weigh and dispense a predetermined mass of food product for beverage preparation, the apparatus includes a weighing system 10, which is described later in this description.

[0017] The predetermined and precise mass of food product is delivered to a mixing chamber 7 into which water at a specific temperature is injected to facilitate the mixing of the food product (here, milk powder and water). The water may be injected under pressure. The mixing chamber 7 is arranged between the base 5 and the weighing system 10 along the longitudinal axis X. The mixing chamber 7 includes a nozzle 8 for dispensing the beverage, which is positioned at a distance from the base 5. The nozzle 8 is positioned 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 apparatus 1 includes a hydraulic circuit (not shown) comprising a pipe with an inlet connected to the water reservoir and an outlet connected to the mixing chamber 7.The hydraulic circuit includes a pump for extracting water from the water tank and circulating it through the pipe, as well as water heating elements. These heating elements are located on the pipe and are arranged between the pump and the mixing chamber 7.

[0018] The weighing system 10 is shown on the figure 2The weighing system 10 is described in an installation situation within the apparatus with an orthogonal coordinate system X, Y, T. The weighing system 10 comprises a frame 11 which is arranged in a chamber 4 (shown in dashed lines) of the frame 2, the chamber being located above the mixing chamber 7 along the longitudinal axis X. The frame 11 includes a platform 12 with a first surface 13 defined in a plane orthogonal to the longitudinal axis X. The frame 11 includes feet 14 which stabilize the platform 12 and keep the platform 12 at a distance from the bottom of the chamber 4. In this example, there are four feet 14. Each foot 14 is elongated along the longitudinal axis between a first end 14a and a second end 14b. The first end 14a carries a base 15 intended to bear against the bottom of the enclosure 4 and the second end 14b is fixed to the platform 12 by means of fixing devices.For this purpose, the platform 12 includes openings 16, each of which receives the second end 14b of a leg 14. The fasteners include nuts, each press-fitted into an opening 16, and whose internal threads mesh with an external thread provided at the second end 14b of each leg. Of course, the fasteners may include other fasteners such as studs, screws, adhesives, welds, etc.

[0019] The food product storage tank 3 is advantageously mounted on the platform 12. The storage tank 3 defines a storage volume for storing the food product. The platform 12 includes an opening 17 that passes through its wall on both sides along the longitudinal axis X. The storage tank 3 includes a discharge port (not shown) that opens, on one side, into the storage volume of the storage tank and, on the other side, into the opening 17 of the platform 12. Advantageously, means for closing the discharge port (not shown) are provided to occupy an open and a closed position of the discharge port. These closing means are controlled by an electronic control unit 18 (see diagram). Figures 1 , 6 And 11). The electronic unit is mounted in the device 1 and in particular on the frame 2. The closing means may include doors which pivot around an axis parallel to the plane of the first surface 13 of the platform 12 or at least a door sliding in the plane of the first surface 13. We can also see that a hopper 19 extends, along the longitudinal axis X, from a second surface 20 (cf. figure 5 ) of platform 12. The opening 17 leads into the hopper 19 which extends from it. In the present example, the hopper 19 has a frustoconical cross-section (in the plane formed by the longitudinal and first transverse axes Y) which narrows towards an outlet orifice 21 (cf. Figures 5 And 8 ) of the hopper 19. The outlet 21 of the hopper 19 is opposite (along the longitudinal axis X) to the opening 17 defined in the platform 12.

[0020] With reference to figures 2 , 3 and 4The weighing system 10 includes a receiving element 22 for the food product supplied by the storage tank 3. This receiving element 22 is movable along an axis of displacement between a food product reception position and a food product discharge position. Here, the receiving element 22 moves by rotating around the axis of displacement. The receiving element 22 advantageously, but not exclusively, has the shape of a bucket. This bucket shape allows for better control of the food product reception and its contents. In particular, the receiving element 22 includes 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 an upstream edge of the receiving wall 23. The receiving wall 23 is here the bottom of the receiving element and is curved.The side partitions 24 are opposed along a second transverse axis T and include internal surfaces 24a defined in substantially parallel planes. The terms "upstream" and "downstream" are defined with respect to the first transverse axis Y. The internal surfaces 24a are opposite each other. The upstream partition 25 is also connected to the upstream edges of the side partitions 24. The upstream partition 25 includes an internal surface 25a defined in a plane that is perpendicular to the plane of the internal surfaces 24a of the side partitions 24. The upstream partition 25, the two side partitions 24, and the receiving wall 23 form a receiving volume for a quantity of food product. At least the upstream partition 25 and the side partitions 24 each include a free edge 26 delimiting an opening 27 leading into the receiving volume of the receiving element 22.The receiving wall 23 includes a curved and concave internal surface 23a which is oriented towards the opening 27 of the cup. The internal surface 23 acts as a receiving surface for the food product.

[0021] On the figures 2 , 5 and 6 The weighing system 10 includes an electric motor 30 for driving the movement of the receiving member 22 between the receiving position and the tipping position. The electric motor 30 is supported by the frame 11 as illustrated. The frame 11 includes a housing 31 (see figure 6 ) in which the engine is arranged in a removable manner. More specifically illustrated on the figure 6The chassis 11 includes a support wall 32 extending from the second surface 20 of the platform 12 along the longitudinal axis X. The support wall 32 includes an internal surface 32a defined in a plane perpendicular to the second transverse axis T. Projections 33 extend from the internal surface 32a of the support wall 32 and at least partially delimit the housing 31 suitable for receiving the electric motor 30. These projections 33 have a circular cross-section (along a plane XY (formed by the longitudinal axis X and the first transverse axis Y)) and together form a cylindrical wall with an axis parallel to the second transverse axis T. In the present example, there are three projections 33. Alternatively, a single cylindrical wall extends from the internal surface 33a of the support wall 32.

[0022] With reference to figures 3, 4 And 6The electric motor 30 comprises an output shaft 34 having a displacement axis A that is parallel to the second transverse axis T. The receiving member 22 is fixed in movement to the output shaft 34 of the motor. For this purpose, and as shown in the figures 3 and 4The receiving member 22 includes means 35 for connecting to the output shaft 34 of the motor 30. In the present example, the receiving member 22 includes two lateral wings 36 which extend downstream from the lateral partitions 24. The lateral wings 36 extend substantially along the first transverse axis Y. Each lateral wing 36 includes an internal surface 36a which is defined in a plane perpendicular to the second transverse axis T. The internal surfaces 36a of the two lateral wings 36 are opposite each other. The connecting means 35 include a hollow tube 37 extending between the two lateral wings 36 of the receiving member 22. A drive shaft 38 is coupled to the output shaft 34 of the motor 30 and is fixed to the output shaft 34 during movement. The drive shaft 38 is coaxial with the axis of movement A. The drive shaft 38 is fixed to the receiving member 22 so that the latter moves 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 internal diameter of the hollow tube 37. According to an alternative (not shown), the connecting means 35 comprise lugs attached to the receiving wall 23, and each lug comprises holes passing through it along the second transverse axis T. The drive shaft 38 passes through the lugs and is fixed to them so as to be able to drive the movement of the receiving element.

[0023] The electric motor 30 is a rotary stepper motor or a linear stepper motor. Using a stepper motor is very economical. In this example, the motor 30 is a rotary stepper motor. The output shaft 34 rotates around the axis of travel A. Similarly, the receiving element 22 pivots around this axis of travel A. A stepper motor allows for controlled and precise rotation of the output shaft and is easy to drive. 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 electrical coils or electromagnets that produce a magnetic field. The magnetic field is generated by a current that appears when the motor is supplied with a predetermined voltage. The direction of the magnetic field circulating in the stator coils causes the rotor to rotate.The output shaft 34 of the electric motor 30 rotates through a constant angle in response to each electrical impulse, allowing it to adopt different angular positions, which are called steps. The motor 30 can have a predetermined number of steps. The angle can range from 0.9° to 45°. The output shaft 34 of the motor can perform between 8 and 400 steps per revolution, depending on the motor.

[0024] The 30 stepper motor can be a permanent magnet stepper motor, a variable reluctance stepper motor, or a hybrid stepper motor. Preferably, the 30 stepper motor is a hybrid stepper motor or a permanent magnet stepper motor with constant reluctance. The hybrid stepper motor incorporates permanent magnets and allows for increased reluctance torque compared to a stepper motor without permanent magnets. The hybrid motor offers better efficiency and requires less current to achieve the same torque.

[0025] The motor 30 is connected to the electronic control unit 18, which is used to operate it. The electronic control unit 18 also supplies power to the motor 30. To this end, the electronic control unit 18 includes a power supply module for providing voltage to the electric motor and a module for controlling the rotation of the output shaft 34 of the electric motor. The electronic control unit 18 is connected to an electrical power source, such as the household mains supply, via electrical cables from the device 1 (not shown).

[0026] There figure 7Figure 22 illustrates the receiving element in the receiving position. In this position, the receiving element is configured to contain or retain a specific mass of the food product. The receiving element is, of course, empty. In this position, the receiving surface (internal surface 23a) of the receiving element is substantially opposite the opening 17 through which the food product is intended to fall by gravity into the receiving element. In this example, the free edge is defined in a plane perpendicular to the longitudinal axis, and this plane is parallel to a plane P1 passing through the axis of movement A of the output shaft 34. More precisely, the center of gravity CGV of the empty receiving element 22 is defined in the plane P1 passing through the axis of movement of the output shaft 34.We consider that plane P1 is horizontal and perpendicular to the longitudinal axis X in the installation situation of the weighing system 10 in the device 1. The center of gravity CGV of the receiving element 22 is determined by the center of gravity of its constituent elements. Here, the center of gravity of the receiving element 22 is equal to the center of gravity CGV.

[0027] There figure 8Figure 22 illustrates the receiving element in the tipping position. In the tipping position, the receiving element 22 is configured to release a specific mass. In the tipping position, the receiving surface (internal surface 23a) is at a distance from the opening 17. The receiving wall 23 is opposite and, in this case, substantially in contact with the second surface 20 of the platform 12. We see in this figure that the receiving element 22 has pivoted, about the axis of movement A, through a tipping angle of approximately 180° with respect to the horizontal plane P1 passing through the axis of movement. The tipping angle is between 0° and 180°. Advantageously, the tipping angle is between 60° and 135°.

[0028] In one embodiment, the weighing system 10 includes a vibrating device (not shown) for enabling the complete emptying of the food product (or cleaning) from the receiving member 22 in the emptying position. This vibrating device is particularly advantageous when the pivot angle is less than 170° with respect to the horizontal plane P1. The vibrating device is electrically connected to the electronic control unit 18, which controls it when it is informed of the emptying position.

[0029] According to another embodiment schematically represented on the figure 9The receiving element 22 comprises the receiving wall 23', which is fixed in movement to the output shaft 34 of the electric motor 30. The receiving wall 23' is designed to close or seal a receptacle 47, which is also fixed in movement to the output shaft 34 of the motor 30. The receiving wall 23' carries the receiving surface 23a, which is designed to receive the food product falling by gravity from the storage tank 3 and for weighing the mass of the food product as described below. The receptacle 47 receives the food product after the receiving wall 23' has moved into the pouring position once the quantity of food product has been weighed. More specifically, the receiving wall 23' is fixed in rotation to the output shaft 34 of the motor 30.The receiving wall 23' can be directly connected to the output shaft 34 via connecting means 35 (lugs, hollow tubes) or can be connected to the drive shaft 38 (via the connecting means 35), which is coupled to the output shaft 34. The receptacle 47 has an opening 47a, which is delimited by walls 47b and a base 47c from which the walls 47b extend. The receiving wall 23' is positioned at the opening 47a to close the receptacle 47. The receiving wall 23' also has dimensions substantially equal to those of the opening 47, while allowing it to tilt inside the receptacle 47 when the required mass of food product is reached. The receptacle 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 the horizontal plane P1 passing through the axis of movement A of the output shaft 34.The center of gravity CGV of the receiving organ corresponds to the center of gravity of the receiving wall 23'. In this example, the receiving surface 23a is flat. However, the receiving surface 23a could have a concave shape to better retain the food product. Such a configuration allows for the measurement of a larger quantity of food product.

[0030] The receiving element 22 is made of a polymer material or a composite material with a polymer matrix. Examples of such materials include Polycarbonate (PC) or Acrylonitrile Butadiene Styrene (ABS), or a mixture thereof. These polymer materials have the advantage of being very lightweight yet robust. Other materials may include Polypropylene (PP), Polyoxymethylene (POM), Polyamide (PA), etc.

[0031] In general, a stepper motor 30 is subjected to a resistive torque (or reluctance torque) and a synchronous torque. The reluctance torque results from the resistance to the passage of magnetic flux through 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.

[0032] The weighing system 10 is configured to determine the mass of the food product by disengaging the motor, i.e., triggering the change in pitch or angular pivoting, while a resisting torque is applied to the output shaft 34 by the electronic control unit 18. To achieve this, the weighing system 10 is configured so that, in the receiving position, the receiving element 22 and the food product it contains or retains apply a static torque to the output shaft 34, and the electronic control unit 18 is configured to apply a resisting torque to the output shaft 34. Thus, when the static torque is at least equal to the resisting torque, the electric motor 30 (the output shaft 34) changes position. Specifically, the resisting torque corresponds to a predetermined mass of the food product.This predetermined mass is the one that must be poured into the mixing chamber 7 to prepare the drink.

[0033] We also understand that controlling the synchronous torque of the electric motor 30 (and the electronic unit) of the weighing system allows for adaptive weighing of the food product. In other words, it is possible to modify the mass value to be determined. Indeed, for some weighing systems that use dimensional measurements, the mass to be determined is fixed. Such a weighing system is also much more precise than a system using dimensional measurements.

[0034] The predetermined mass value is between 3g and 100g. Preferably, the value is 8g.

[0035] Following the figure 7The receiving device 22 is configured so that the food product 39, here milk powder, after being discharged (from the storage tank 3), forms a slope in or on the receiving device 22. The predetermined mass of food product 39 and the receiving device 22 have a center of gravity CGP located at a predetermined distance d from the axis of movement A. The distance d is almost constant. The center of gravity CGP of the assembly is located below the center of gravity (CGV) of the receiving device 22 and below the horizontal plane P1 along the longitudinal axis X. The distance d multiplied by the weight of the assembly (formed by the mass of the food product and that of the receiving device), referred to the center of gravity CGP, constitutes a mechanical moment applied to the output shaft 34 of the motor 30. The moment becomes the static torque applied to the output shaft 34 of the motor 30.

[0036] Following an example of implementation shown on the Figure 10The receiving member 22 (with the receiving wall 23') defines a beam at an angle to a horizontal plane passing through the axis of travel A of the motor 30. In other words, the receiving member 22 is mounted on the output shaft 34 at a predetermined feed angle α (alpha). This angle α is between 1.8° and 8°. As illustrated, a slope of milk powder is arranged on the receiving surface 23a of the receiving wall 23'. The center of gravity CGT of the slope-shaped food product is located above the receiving surface 23a. The point of application of the force F exerted by the slope is defined on 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 so that the center of gravity of the assembly CGP (powder and receiving member 22) is above the horizontal plane P1 passing through the axis of movement of the motor.The center of gravity (CGP) is defined in a plane passing through the axis of movement A, which forms the lead angle α with plane P1. Thus, when the motor stalls, the static torque increases rather than decreases. The moment (F * d * cos(α)) increases without increasing the mass of the food product. This arrangement improves the sensitivity of the weighing system.

[0037] With reference to Figures 5 And 11The weighing system 10 includes 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 configured to act on the motor 30 upon detection of a change in step size or angular position of the motor. The detection means 40 include a light beam emitter (visible or invisible) and a light beam receiver. The receiver is positioned opposite the emitter. The emitter and receiver are connected to the electronic control unit 18. In this example, the detection means include an optical fork 41 having 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 include an obstacle element 42, which is fixed to the output shaft 34.This obstacle element 42 is designed to be interposed in the path of the light beam according to the angular position of the output shaft 34. In the example shown, the obstacle element 42 comprises a disk with a central axis coaxial with the axis of movement A of the output shaft 34 and fixed to the output shaft 34 for rotation. Thus, when the motor 30 stalls (the motor changes pace), the disk pivots at the same time as the output shaft 34. The disk includes at least one first slot 43 which extends radially from the periphery 44 of the disk towards the central axis of the disk. The slot 43 is designed to be traversed by the light beam (as shown in dashed line on the figure). figure 11To this end, the first leg 41a and the second leg 41b extend respectively on either side of a portion of the disc 42 along the transverse axis T. The optical fork 41 is installed in a housing 45 formed in the platform 12 of the frame 11. The housing 45 opens onto the first surface 13 and the second surface 20 of the platform. A portion of the disc extends through the housing 45 and transversely between the emitter and the receiver. The blocking element 42, here the disc, is easy to install and does not introduce any parasitic torque on the output shaft 34 of the motor. Alternatively, the blocking element 42 includes a cam. In particular, when the slot is crossed by the light beam, the electronic control unit 18 controls the maintenance of the position of the output shaft 34 of the motor by applying the resisting torque. In this case, the receiving organ 22 is supplied with food product.When the light beam is interrupted, it means that the light beam has swept across a full area of ​​the disk and that the output shaft 34 has rotated at least one step (first angular position). In this case, the electronic control unit 18 drives the output shaft 34 to move the receiving element 22 into the tipping position.

[0038] The detection means 40 are capable of detecting another angular position (second position) of the output shaft 34 of the electric motor 30. Advantageously, the disc includes a second slot 46 visible on the figure 6 designed to allow the 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 acts as a limit switch for the receiving member 22 in the tipping position.

[0039] We will now describe a process 100 for weighing and dispensing a predetermined mass of a food product using the weighing system 10 as described previously. The process 100 is illustrated in the figure 12The process includes a step 110 of supplying a food product. During this step, the food product is placed in the storage tank 3 located above the weighing system 10. Preferably, the food product consists of infant formula powder. The process includes a step 120 of unloading a quantity of food product onto or into the receiving device 22. In particular, the food product is unloaded so as to form a slope on the receiving surface 23a of the receiving device 22. The receiving surface 23a is flat or concave as described previously. During this step, the electronic control unit 18 sends a command to the closing means to open the unloading port of the storage tank 3.A quantity of food product is thus discharged onto or into the receiving unit 22 via the opening 17 of the platform 12 and the hopper 19, which guides the food product towards the receiving unit 22. The food product 39 can be guided into the receiving volume of the receiving unit 22 in the case of the bucket. Milk powder is poured continuously or discontinuously onto the receiving surface 23a of the receiving unit 22.

[0040] The process includes a weighing step 130 of a predetermined mass of the food product in the receiving member 22. This step 130 involves disengaging the motor. In particular, the weighing step 130 includes a substep in which the electronic control unit 18 applies a resistive torque to the output shaft 34 of the motor 30. This resistive torque is a function of the supply voltage. For example, a voltage of 12V, corresponding to a resistive torque of 16mNm, is applied to the motor 30. This resistive torque corresponds to a powder mass of approximately 8g. When the receiving member 22 and the food product contained in the receiving member apply a static torque equal to the resistive torque, the output shaft 34 pivots and changes pitch.As long as the mass of milk powder in the receiving organ 22 (or on the receiving surface 23a) with the mass of the receiving organ do not reach this predetermined value, the milk powder continues to be discharged into the receiving organ 22.

[0041] The process 100 includes a discharge step 140 of the weighed powder mass. In particular, as soon as the specified mass is reached, the output shaft 34 changes its pitch or angular position without any action from the motor itself or command from the electronic control unit 18. Simultaneously, the blocking element 42, here the disc, interrupts the light beam between the emitter and its receiver. The detection means 40, and in particular the optical fork 41, sends a control signal relating to the position of the output shaft 34 to the electronic control unit 18. The latter sends a control command to the motor 30 to drive the rotation of the output shaft 34 and the receiving element 22 into the discharge position. Simultaneously with, or prior to, the discharge step 140, the process includes a discharge stop step 150 of the food product into the receiving element 22.In this case, the electronic control unit 18 sends a command order to the sealing means to close the discharge port of the storage tank 3.

Claims

1. A weighing system (10) for weighing and discharging a predetermined mass of a food product, the device comprising: - a chassis (11), - an electric stepping motor (30) carried by the chassis (11) and having an output shaft (34) capable of adopting different positions along a displacement axis (A), - a receiving member (22) for receiving a food product which is movable along the axis of displacement (A) between a receiving position for receiving the food product and a discharging position for discharging the food product, the receiving member (22) being configured to contain or retain a predetermined mass of the food product in the receiving position and to let this mass fall in the discharging position, - an electronic control unit (18) for controlling the electric motor (30), characterised in that the receiving member (22) is secured in terms of displacement to the output shaft (34) and in that the weighing system (10) is configured so that, in said receiving position, the receiving member (22) and the food product it contains or retains, apply a static torque to the output shaft (34), and that the electronic control unit (18) is configured so as to apply a resistive torque, for a predetermined mass of the food product, to the output shaft (34) so that, when the static torque is at least equal to the resistive torque, the output shaft (34) changes position.

2. The weighing system (10) according to the preceding claim, characterised 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 discharging position when the mass of food product reaches a predetermined value.

3. The weighing system (10) according to one of the preceding claims, characterised in that the predetermined mass of the food product contained in the receiving member (22) and the receiving member (22) have a centre of gravity (CGP) which is located at a predetermined distance (d) from the axis of displacement A.

4. The weighing system (10) according to one of the preceding claims, characterised in that the receiving member (22) comprises connecting means (35) secured to a drive shaft (38), said drive shaft (38) being coupled in rotation to the output shaft (34) of the electric motor (30) which is movable in rotation.

5. The weighing system (10) according to any one of the preceding claims, characterised in that the receiving member (22) is in the form of a bucket or of a receiving wall (23').

6. The weighing system (10) according to any one of the preceding claims, characterised in that the chassis (11) comprises a platform (12) provided with an opening (17) passing through the wall of the platform (12) on either side and through which the food product is intended to fall by gravity.

7. The weighing system (10) according to any one of the preceding claims, characterised in that it comprises 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. The weighing system (10) according to the preceding claim, characterised in that the predetermined mass is between 3 and 100g.

9. The weighing system (10) according to one of claims 3 to 8, characterised in that the receiving member (22) is mounted on the output shaft (34) so that the centre of gravity of the assembly (CGP) formed by the receiving member (22) and the mass of food product is defined in a plane passing through the axis of displacement A which forms a predetermined angle of advance with a horizontal plane (P1) passing through the axis of displacement A of the output shaft (34).

10. An apparatus (1) for preparing a beverage based on a food product, characterised in that it comprises a weighing system (10) according to any one of the preceding claims.

11. The apparatus (1) according to the preceding claim, characterised in that it comprises a storage tank (3) for food product and a mixing chamber (7) intended to receive a predetermined mass of food product from the receiving member (22) in the discharging position.

12. A method for weighing and discharging a predetermined mass of a food product by means of a weighing system (10), the weighing system (10) comprising at least one electric stepping motor (30) having an output shaft (34) and a receiving member (22) which is secured in terms of displacement to the output shaft (34), the method comprising the following steps: - a step (110) of providing a food product, - a step (120) of discharging a quantity of food product onto or into the receiving member (22), - a step (130) of weighing a food product consisting of ▪ applying a resistive torque to the output shaft (34) for a predetermined mass of 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 it contains or retains, ▪ changing the position of the output shaft (34) of the electric motor when the static torque is at least equal to the resistive torque.

13. The method according to the preceding claim, characterised in that the food product comprises milk powder.