Abstract
The invention relates to a method for operating a food processor (1) with a base unit (2) having an electric motor and a preparation vessel (3) that can be arranged on a vessel retainer of the base unit (2), wherein the vessel retainer has allocated to it a weighing apparatus (4), which records the weight of the preparation vessel (3), wherein a calculating means of the food processor (1) determines a weight from a measured value measured by the weighing apparatus (4). In order to advantageously use the weighing apparatus (4) to recognize a current state of the food processor (1), it is proposed that the calculating means ascertain a time weight gradient based on at least two weights determined at different times.
Claims
1. A method for operating a food processor (1) with a base unit (2) having an electric motor and a preparation vessel (3) that can be arranged on a vessel retainer of the base unit (2), wherein the vessel retainer has allocated to it a weighing apparatus (4), which records the weight of the preparation vessel (3), wherein a calculating means of the food processor (1) determines a weight from a measured value measured by the weighing apparatus (4), wherein the calculating means ascertains a time weight gradient based on at least two weights determined at different times.
2. The method according to claim 1, wherein the calculating means compares the weight gradient with a defined reference gradient, which characterizes a time-dependent weight reduction caused by lifting the food processor (1) from a placement area (5).
3. The method according to claim 2, wherein the reference gradient is smaller than the weight gradient that arises while separating the preparation vessel (3) from the base unit (2).
4. The method according to claim 2, wherein if the determined weight gradient drops below the reference gradient, a lifting of the food processor (1) is inferred.
5. The method according to claim 1, wherein weight gradients are determined using measured values whose measuring points are spaced at most 0.5 seconds apart.
6. The method according to claim 2, wherein at least two other weight gradients are determined spaced apart in time if a value drops below the reference gradient, in particular at a time interval of at least 0.5 seconds.
7. The method according to claim 6, wherein a non-operating electric motor is inferred upon chronologically sequentially determining a weight gradient within the range of the reference gradient, in particular given chronologically essentially constant sequential measuring signals.
8. The method according to claim 6, wherein an operating electric motor is inferred upon determining chronologically sequential weight gradients within the range of the weight gradient ascertained before a drop below the reference gradient.
9. The method according to claim 7, wherein the user is given the option of turning on a transport mode and/or turning off the food processor (1) if a non-operating electric motor is detected, and/or wherein the user is given the option of turning off the electric motor if an operating electric motor is detected.
10. An electric motor-operated food processor (1) with a base unit (2) having an electric motor, a calculating means and a preparation vessel (3) that can be arranged on a vessel retainer of the base unit (2), wherein the vessel retainer has allocated to it a weighing apparatus (4), which records the weight of the preparation vessel (3), wherein the calculating means is designed and set up to implement a method according to claim 1.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The invention will be explained in more detail below based upon exemplary embodiments. Shown on:
[0020] FIG. 1 is perspective view of a food processor according to the invention,
[0021] FIG. 2 is a partially cut, side view of the food processor,
[0022] FIG. 3 is a magnified cutout of the food processor according to FIG. 2,
[0023] FIG. 4 is the cutout of the food processor depicted on FIG. 3 while lifting the food processor from a placement area,
[0024] FIG. 5 is a resistance-time diagram while lifting the food processor with the electric motor turned on,
[0025] FIG. 6 is a resistance-time diagram while lifting the food processor with the electric motor turned off,
[0026] FIG. 7 is a flowchart of a method according to the invention for operating the food processor.
DESCRIPTION OF THE EMBODIMENTS
[0027] FIG. 1 shows an electric motor-operated food processor 1, which is here designed as a combined cooker-mixer. The food processor 1 has a base unit 2, with which a preparation vessel 3 is connected. The preparation vessel 3 has allocated to it a heater (not shown), here preferably integrated into the vessel floor of the preparation vessel 3. Also arranged inside the preparation vessel 3 is an agitator 11, which can be used to comminute, mix and/or otherwise prepare the preparation items present in the preparation vessel 3. The preparation vessel 3 further has allocated to it a cover 9, which can be fixedly joined with the preparation vessel 3 by means of locking elements 10. In addition, the preparation vessel 3 has a handle 8 with which a user grips the preparation vessel 3. The base unit 2 further has a display 6 for displaying status parameters of the food processor 1, suggested recipes, current parameters of the preparation item located in the preparation vessel 3, and the like. A switch 7, for example here designed as a rotary push knob, serves to activate and deactivate an electric motor (not shown) of the food processor 1 and/or the food processor 1 as a whole. In addition, the switch 7 can be used to select and confirm a command or parameter indicated on the display 6.
[0028] FIG. 2 shows the food processor 1 with the preparation vessel 3 in a partially broken side view. The food processor 1 stands with its feet 15 on a placement area 5, for example a kitchen countertop. Evident on this figure is the agitator 11, which here is designed as a blade assembly with a plurality of blades. The agitator 11 rotates around a rotational axis, which simultaneously is a longitudinal axis of the preparation vessel 3. Arranged in the base unit 2 of the food processor 1 below the preparation vessel 3 is a weighing apparatus 4, which is mounted on bearing areas 13, 14 of the food processor that can be displaced relative to each other. The weighing apparatus 4 has a weighing beam 12 with two notches 16 running parallel to each other. The notches 16 yield materially weakened areas of the weighing beam 12, which allow an expansion or compression of the weighing beam 12. The weighing apparatus 4 or bearing areas 13, 14 are loaded with the weight of the preparation vessel arranged above them, so that the weighing beam 12 expands or compresses given a change in weight, e.g., as the result of filling preparation items. A strain gauge 17 is arranged on the upper side of the weighing beam 12 facing away from the notches 16, and its resistance changes given an expansion or compression of the weighing beam 12, and hence also of the strain gauge 17. This resistance can be further processed by a calculating means of the food processor 1 and converted into a weight. Publication DE 10 2009 059 242 A1 provides a detailed description of detecting the tensile and compressive stresses by means of the strain gauge. The function of the weighing apparatus disclosed therein, including various embodiments, correspondingly applies to the described food processor 1 here as well.
[0029] FIG. 3 shows a magnified partial area of the food processor 1 below the preparation vessel 3. In the depicted state of the food processor 1 standing on the placement area 5, the weighing apparatus 4, in particular the weighing beam 12, has a shape and position exaggeratedly shown for clarification purposes. The food processor 1 stands with its feet 15 on the placement area 5. As a result, the bearing area 14 present on the housing of the food processor 1 is preloaded, and presses an end area of the weighing beam 12 toward the top, i.e., in the direction of the preparation vessel 3. The preload on the weighing beam 12 simultaneously leads to a deformation of the strain gauge 17. The deformation of the strain gauge 17 in turn leads to a change in resistance, which can be evaluated by way of the calculating means of the food processor 1. The resistance of the strain gauge 17 characterizes the contact between the food processor 1 and placement area 5, along with the current weight of the preparation vessel 3 and any preparation items that might be located therein. With the food processor 1 standing on the placement area 5, a preparation item located inside of the preparation vessel 3 can thus be weighed in the usual manner.
[0030] In addition, the weighing apparatus 4 can also be used to determine a lifting of the food processor 1 from the placement area 5. This lifting is depicted on FIG. 4. The lifting of the feet 15 of the food processor 1 from the placement area 5 causes a displacement of the bearing area 14 relative to the bearing area 13 of the food processor 1. The weighing beams 12 and strain gauge 17 arranged thereon correspondingly deform. This deformation is exaggeratedly illustrated on FIG. 4, so as to explain the principle. It here goes without saying that the bends in the weighing beam 12 shown on FIGS. 3 and 4 are only exemplary in nature. Of course, it is also possible for the weighing beam 12 to not be bent in a state of the food processor 1 standing on the placement area 5, while the weighing beam 12 does bend when lifting the food processor 1 from the placement area 5.
[0031] The weighing apparatus 4 of the food processor 1 can now be used according to the invention to detect a lifting of the food processor 1 from the placement area 5. To this end, the calculating means of the food processor 1 ascertains a time weight gradient out of at least two weight values determined at different times and the respective time difference. The weight gradient is defined as a difference in weight per time difference, and corresponds to a (positive or negative) incline on a graph in a resistance-time diagram. The determined weight gradient is then compared with a defined reference gradient, which is known to arise when the food processor 1 is lifted from the placement area 5. This reference gradient is filed in a memory of the food processor 1. The calculating means accesses this memory for comparison purposes. The weight gradient arising while the food processor 1 is lifted from the placement area 5 is negative, i.e., corresponds to a negative incline of a graph in the resistance-time diagram (R-t diagram). Such a diagram is presented on FIGS. 5 and 6 for various operating states of the food processor 1, specifically on FIG. 5 for a food processor 1 with activated electric motor at the time the food processor 1 is lifted from the placement area 5 (dashed, perpendicular line) and on FIG. 6 for a food processor with deactivated electric motor while lifting the food processor 1 (dashed, perpendicular line).
[0032] During operation of the food processor 1, weight gradients are determined from two chronologically sequential measured values at specific time intervals, for example every 0.2 seconds, wherein the calculated weight gradients are each compared with the reference gradient. If a calculated (negative) weight gradient is lower than the previously defined (also negative) reference gradient, a lifting of the food processor 1 is inferred. In the diagrams shown on FIGS. 5 and 6, such a weight gradient that characterizes a lifting of the food processor corresponds to a sudden, major drop in the graph, which is steeper than a drop given a separation of the preparation vessel 3 from the base unit 2, for example.
[0033] Once a lifting of the food processor 1 has been detected, it can further be determined whether the electric motor is operating or not at the time the food processor 1 was lifted. Depending thereupon, additional measures can be provided for the food processor 1. To this end, additional weight gradients are calculated even after a lifting of the food processor 1 has been detected, wherein measured values are for this purpose measured at time intervals measuring at least 0.5 seconds. Continuing the measurements makes it possible to determine how the weight gradients will develop further after the lifting of the food processor 1. As a result, an operating state of the electric motor of the food processor 1 can be detected, since the electric motor transmits vibrations to the food processor 1 during operation, which also act on the weighing apparatus 4. For this reason, the weight gradients differ from each other while the electric motor is operating and the electric motor is not operating.
[0034] As depicted on FIG. 5, when the electric motor of the food processor 1 is running, lifting the food processor 1 initially leads to a short-term drop in the resistance R measured by the strain gauge 17, wherein the resistance R subsequently rises again to a range that roughly corresponds to the value prior to lifting the food processor 1. By contrast, if the electric motor is not operating when the food processor 1 is lifted, as shown on FIG. 6, the drop in resistance R is not followed by a renewed rise. Rather, a resistance plateau comes about after the time that the food processor 1 was lifted. As a consequence, the progression of the weight gradient over time t can be used to determine whether the electric motor of the food processor 1 is currently running or not. The behavior of the food processor 1 can be further controlled based upon this information.
[0035] FIG. 7 presents a flowchart for the method of operating the food processor 1 upon detection of a lifting of the food processor 1 from the placement area 5. If it was detected that the electric motor of the food processor 1 is operating, a controller of the food processor 1 can automatically reduce the speed of the electric motor or even turn off the electric motor. If necessary, the display 6 to this end provides a user of the food processor 1 with an option that he or she can select and/or confirm to turn off the electric motor. In the event that the electric motor is already turned off while lifting the food processor 1, an option to turn on a transport mode of the food processor 1 and/or an option to completely turn off the food processor 1 can be displayed to the user. For example, the transport mode can involve locking the preparation vessel 3 with the cover 9, so that the food processor 1 can be transported without separating the preparation vessel 3 and/or the cover 9 from the food processor 1. If desired, the user can also activate the transport mode and turn off the food processor 1 via the display 6. Alternatively, however, he or she can also decide not to initiate any further actions for the food processor 1, so that the food processor 1 stays on, but the electric motor remains turned off.
REFERENCE LIST
[0036] 1 Food processor [0037] 2 Base unit [0038] 3 Preparation vessel [0039] 4 Weighing apparatus [0040] 5 Placement area [0041] 6 Display [0042] 7 Switch [0043] 8 Handle [0044] 9 Cover [0045] 10 Locking element [0046] 11 Agitator [0047] 12 Weighing beam [0048] 13 Bearing area [0049] 14 Bearing area [0050] 15 Foot [0051] 16 Notch [0052] 17 Strain gauge [0053] R Resistance [0054] t Time
