JP2020020760A - Food product mixer having rotation control function by torque detection and control system thereof - Google Patents

Abstract

To provide a food product mixer which automatically mixes a food which is required for delicate stirring and mixing processing such as whip cream and an optimum mixing control system.SOLUTION: A mixer which stirs a food with a stirrer includes: a torque sensor which measures rotation torque applied to the stirrer from an electric motor for driving and outputs a torque signal; and an arithmetic control unit which performs prescribed arithmetic processing on the torque signal and outputs a control signal to the electric motor on the basis of the arithmetic result. The arithmetic control unit has a filter section which removes a minute time change component of the torque signal and smooths the torque signal, a differential arithmetic section which differentiates an output signal from the filter section and calculates speed and acceleration of an increase of rotation torque, an inflection point detection section which detects an inflection point of an increase characteristic curve of the rotation torque on the basis of the arithmetic result of the differential arithmetic section, and a rotation control section which outputs a rotation stop signal to the electric motor when the inflection point is detected.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a food mixer for stirring and kneading dairy products such as whipped cream or egg foods such as meringue, and a control method thereof.

  In the food manufacturing industry, when dairy products such as whipped cream or egg white foods such as meringue are agitated and kneaded, a very delicate agitation treatment has conventionally been required. This is because if the stirring and kneading are insufficient, the unique taste and flavor of these products cannot be produced, while if the stirring and kneading proceed excessively, the food to be stirred will be excessively foamed. This is because the constituent particles of the food material are separated and do not form a body as a product. Therefore, a mixer operator performing such operations required years of experience and extremely high craftsmanship.

  In recent years, in order to overcome the bottleneck in manufacturing relying on the intuition and skill of the operator and promote automation of such food manufacturing, for example, a technique for controlling the stirring of foodstuffs as disclosed in Patent Document 1 has been disclosed. I have. Incidentally, the gist of the invention according to the disclosed technology focuses on a change in rotational torque when stirring is performed by a mixer.

  That is, a constant threshold is set for the rotational torque of the mixer, and when the actual rotational torque falls between the predetermined threshold A and the predetermined threshold B, the rotation of the drive motor in the mixer is stopped. Here, the threshold values A and B are values that have been researched and studied in advance so that the mixing of foodstuffs is completed in the best condition if the rotational torque of the mixer falls within this range.

JP 2001-275549 A

  However, the conventional technique disclosed in Patent Document 1 uses a method of estimating the torque from the power consumption of the drive motor of the mixer, instead of actually measuring the rotational torque of the stirrer used for stirring the foodstuff, The estimated torque used for the control and the actual rotational torque of the stirrer tended to be different values.

  Needless to say, the values of the predetermined thresholds A and B also change depending on the type of the ingredients to be mixed and the amount of stirring. Therefore, it has been difficult to achieve universal automation of mixing by the technology according to the disclosed invention without being affected by the type and amount of the object to be stirred. In particular, when the object to be stirred is a dairy product such as whipped cream or an egg white food such as meringue, it is delicate to perform the mixing process, and it has been particularly difficult.

  SUMMARY OF THE INVENTION The present invention has been made in order to solve such problems, and a food mixer for automatically mixing foods requiring delicate agitation such as whipped cream or meringue, and an optimal food mixer. It is an object of the present invention to provide a food mixer control system capable of realizing a proper mixing state.

A food mixer according to the first aspect of the present invention is a food mixer for stirring and kneading various foods using a stirrer,
A torque measurement unit that measures a rotation torque applied to the stirrer from the motor for rotation drive and outputs a torque measurement signal;
An arithmetic control unit that performs a predetermined arithmetic processing on the torque measurement signal and outputs a control signal to the electric motor based on the arithmetic result.

Further, the food mixer according to the second aspect of the present invention, in the first aspect,
The arithmetic and control unit,
A filter unit that removes a minute time-varying component of the torque measurement signal and smoothes the torque measurement signal,
A differential operation unit that differentiates an output signal from the filter unit to calculate a speed and an acceleration at which the rotational torque increases,
An inflection point detection unit that detects an inflection point of the rotational torque increase characteristic curve based on a calculation result of the differentiation calculation unit;
A rotation control unit that outputs a rotation stop signal to the electric motor when the inflection point is detected by the inflection point detection unit.

Further, the control method of the electric motor for rotationally driving the food mixer according to the third aspect of the present invention,
A control method of a food mixer that stirs and kneads various ingredients using a stirrer,
A torque measurement signal capturing step of capturing a torque measurement signal from a torque sensor that measures a rotation torque applied to the stirrer from a motor for rotational drive;
Excluding the minute time-varying component of the torque measurement signal, a filter processing step of generating a filtered output signal by smoothing the torque measurement signal,
A differential operation processing step of differentiating the output signal after the filter processing to calculate an increase speed of the signal and an increase acceleration,
An inflection point detecting step of detecting an inflection point of the characteristic curve of the rotational torque based on the operation result of the differential operation processing step,
A rotation control step of outputting a rotation stop signal to the electric motor when the inflection point is detected.

  Further, in the food mixer according to the fourth aspect of the present invention, in the first or second aspect, the various ingredients are mainly dairy products such as whipped cream or egg white / yolk products such as meringue. It is characterized by:

  Further, in the control method of the electric motor for rotationally driving a food mixer according to the fifth aspect of the present invention, in the third aspect, the various ingredients are mainly dairy products such as whipped cream or egg whites such as meringue.・ It is characterized by being an egg yolk product.

  According to the present invention having the above solution, even for ingredients requiring delicate stirring and kneading treatment of dairy products, egg whites and yolk foods, etc., without relying on the intuition and skill of the operator for optimal mixing. This can be done automatically.

(1) Configuration of Food Mixer According to the Present Invention An embodiment which is the best mode for realizing a food mixer according to the present invention will be described below with reference to the drawings attached to the specification of the present invention. .

  First, FIG. 1 schematically shows the appearance and structure of a food mixer 10 (hereinafter, simply referred to as “the present mixer 10”) based on the present invention. Incidentally, FIG. 1 is a schematic diagram of the front and side surfaces of the present mixer 10, and the schematic side view is a perspective view of a part of the inside. It should be noted that the appearance and structure of the mixer 10 are not limited to the shape shown in FIG. 1 but may be arbitrarily changed according to the actual use form.

  As shown in FIG. 1, the present mixer 10 mainly includes an electric motor 11 for rotational drive, a torque sensor 12, an arithmetic and control unit 13, and a stirrer mounted at the end where the rotation axis is extended via the torque sensor 12. 14 (not shown because it is located inside the stirring bowl 15).

  As the electric motor 11, any motor can be used as long as it is a three-phase 200V motor having an output of about 1 to 2 kW which is used in a usual commercial food mixer. In the present embodiment, the electric motor 11 is driven and controlled by general-purpose inverter control, but may be driven by another control method. The rotation output of the electric motor 11 is transmitted to the torque sensor 12 after being reduced to an appropriate rotation speed by a reduction gear mechanism (not shown).

  The torque sensor 12 is a sensor that measures the rotational torque of a rotating shaft by using a magnetostrictive effect due to a stress applied to a magnetostrictive material such as a ferromagnetic material. In the present embodiment, the measurement range is 200 N · m, but it goes without saying that various measurement ranges can be used according to the actual use mode. Further, in this embodiment, a non-contact type torque sensor applying the magnetostrictive effect is used as described above, but a contact type torque sensor using a slip ring may be used.

  The rotating shaft of the electric motor is further extended vertically downward through the torque sensor 12 and connected to a stirrer 14 (not shown) located inside the bowl 15. As the stirrer 14, hook-shaped or various other shapes can be used depending on the type of the food to be stirred. In the case of this embodiment, the purpose is to knead, stir, and foam the dairy products and the like. Therefore, a whipper made of 20 stainless steel materials of φ3.5 mm specially used for the purpose is used as the stirrer.

  The bowl 15 is a stainless steel bowl-shaped container for storing the food to be stirred, and may have various capacities depending on the actual embodiment. Note that the bowl 15 has a structure that can be moved up and down over a predetermined length in the vertical direction by an auxiliary electric motor different from the above-described electric motor 11 for rotation in order to put and take out the food to be stirred. Since the elevating mechanism (not shown) is not directly related to the gist of the present invention, its description is omitted.

  The arithmetic and control unit 13 is a main part of the present invention, and its configuration is schematically shown in the block diagram of FIG. As shown in the figure, the arithmetic and control unit 13 mainly includes a filter unit 131, a differential operation unit 132, an inflection point detection unit 133, a rotation control unit 134, and a monitoring / control operation panel 135. In addition, the arithmetic and control unit 13 also includes, for example, parts such as a power supply unit and an auxiliary motor control unit (neither is shown), but does not directly relate to the gist of the present invention. The description is omitted.

  The filter unit 131 is a part that removes a minute time-varying component included in the torque output signal from the torque sensor 12, that is, has a function of smoothing the output signal. As a result, noise components and positive / negative peak components included in the torque output signal can be removed, so that the torque output signal T (t) is captured as a time characteristic curve that smoothly changes with the passage of time t. It becomes possible.

  The filter unit 131 can be realized by, for example, a low-pass filter circuit (smoothing circuit) including a resistor R and a capacitor C as shown in FIG. In the low-pass filter circuit shown in FIG. 3, since the high-frequency component contained in the signal is attenuated, the ratio between the input signal Vi and the output signal Vo has a frequency characteristic as shown in FIG. That is, high-frequency noise components included in the input are removed, and the torque output signal is smoothed (filtered).

The differential operation unit 132 calculates a first differential function T ′ (t) of the torque output signal T (t).
T ′ (t) = dT (t) / dt
And the second derivative function T ((t) of T (t)
T "(t) = d ² T (t) / dt ²
Is a part for performing a differential operation for obtaining. Incidentally, by performing the differential operation process on the torque output signal T (t), it is possible to analyze the increasing change tendency of the characteristic curve.

The differential operation unit 132 can be realized by, for example, a differential circuit including an operational amplifier (operational amplifier) A, a resistor R, and a capacitor C as illustrated in FIG.
In the differentiating circuit shown in the figure, the relationship between the input signal Vi and the output signal Vo is
Vo = −RC · (dVi / dt)
Therefore, the differential value of the input signal is obtained as the output. Note that a higher-order differentiation operation can be realized by cascading the differentiating circuits in a plurality of stages.

  The inflection point detection unit 133 is a part that detects an inflection point at which the characteristic curve of the torque output signal T (t) changes from a positive increasing trend to a negative increasing trend. Such inflection points can be detected by determining the respective polarities (plus and minus polarities) of the above-described first derivative function T ′ (t) and second derivative function T ″ (t). , A positive increasing tendency indicates a state in which the rate of increase of T (t) is gradually increasing, and a negative increasing tendency indicates a state in which the rate of increase of T (t) is decreasing gradually. Things.

Incidentally, when the characteristic curve of the torque output signal T (t) shows a positive increasing tendency, the polarities of the two differential functions are as follows.
First derivative function: T '(t)> 0
Second derivative function: T "(t)> 0

When the characteristic curve of T (t) shows a negative increasing tendency, the polarities of the two differential functions are as follows.
First derivative function: T '(t)> 0
Second derivative function: T "(t) <0

  The inflection point detection unit 133 can be constituted by, for example, a logical operation circuit as shown in FIG. That is, the primary differential function T 'is connected to the plus input of the comparator (comparator) 1, and the output of the secondary differential function T "is also connected to the minus input of the comparator (comparator) 2 (comparison input of each comparator). Is connected to a zero (0) potential.) Then, by obtaining the logical product (AND) output of both comparators, the characteristic curve becomes an inflection point, that is, T ′ (t)> 0, T ″ (t) < It can be detected that the condition of 0 has been reached.

  When the inflection point detection unit 133 detects the inflection point of the characteristic curve of the torque output signal T (t), the rotation control unit 134 outputs a stop control signal to the control inverter of the electric motor 11 based on the detection signal. This is the part to output.

  The monitoring / control operation panel 135 is a part that displays the operation state of the mixer 10 and controls the operation thereof. The panel includes various control switches and monitor lamps (neither is shown). Have been. Further, the value of the above-described torque output signal is displayed in real time on the monitoring / control operation panel 135, and while the operator monitors the display value, the motor 11 is directly operated from the monitoring / control operation panel 135 by manual operation. It is also possible to control.

  In the above description, each part of the filter unit 131, the differential operation unit 132, the inflection point detection unit 133, and the rotation control unit 134 inside the operation control unit 13 is illustrated as a hardware configuration block. The embodiment of the invention is not limited to the configuration described above.

  For example, a microprocessor (not shown) for controlling the whole may be provided in the arithmetic and control unit 13, and the above-described operation processing of each part may be performed by software processing using the microprocessor. That is, the processing process by each part is configured as a series of processing programs, and the programs are stored in advance in a memory circuit (not shown) provided in the arithmetic and control unit 13 and controlled in chronological order according to the programs. The processing may proceed.

(2) Temporal characteristic change of rotational torque at the time of mixing foodstuffs Next, a temporal change of the rotational axis torque of the stirring motor during mixing of foodstuffs will be described. FIG. 4 shows a characteristic curve of rotational torque over time when a general food material is stirred. Incidentally, in FIG. 4, the vertical axis represents the magnitude of the rotational torque T (t) (N · m), and the horizontal axis represents the time t (second).

  When the stirring is started, the torque T (t) increases as the time t elapses as shown in FIG. Incidentally, the state of the increase in the torque T (t) is not monotonous, and increases in the right-hand direction in the time region A (that is, shows a positive increase tendency). When it reaches that rate, the rate of increase slows down (that is, it turns to a negative increasing trend). Further, when the time t2 elapses, the torque T (t) shows the maximum value, and then enters the time region C and starts decreasing.

  This is because the particles constituting the object to be stirred were separated due to excessive progress of the stirring process, and the viscosity resistance of the object to be stirred began to decrease. In this state, the texture and flavor of the foodstuff to be agitated are significantly impaired, and can no longer be distributed as a commercial product.

  In particular, when the object to be stirred is a dairy product such as whipped cream, it is necessary to carefully proceed with the stirring process. At time t2 when the torque is maximized in FIG. Would. It is said that with such a food material, an ideal mixing state can be obtained near time t1, which is the boundary between the time regions A and B. That is, the gist of the present invention is to obtain such an ideal mixing time by performing a predetermined calculation process on the torque characteristic curve.

(3) Control Method of Food Mixer Based on the Present Invention Next, the control method of the mixer based on the present invention (hereinafter, simply referred to as “the present method”) will be described with reference to the flowchart shown in FIG. A description will be given of a case where the processing is executed by software processing.

  In this method, first, in step S01, a torque output signal from the torque sensor 12 is captured. Note that the setting of the sampling time at the time of capturing the signal and the setting of the quantization condition at the time of A / D (analog / digital) conversion are not directly related to the gist of the present invention, and thus the description thereof is omitted.

It is assumed that the control process according to the present method is cyclically started from the start of the stirring process in the mixer by an interrupt timer every predetermined time (for example, every several hundred milliseconds). However,
When the electric motor 11 is started, the rotational torque may temporarily spike in a spike-like manner. Therefore, for a predetermined time (for example, about 10 seconds) from the start of the electric motor 11, the capture of the torque output signal from the torque sensor 12 is performed. It is preferable to prohibit.

  In the following step S02, a filter (smoothing) process is performed on the taken torque output signal. In such smoothing processing, the value of the torque output signal captured over a plurality of processing cycles may be stored in a memory (not shown) or the like, and the average value thereof may be used as an output after filtering, or Alternatively, while taking the moving average value of the fetched torque output signal, the value may be used as the output after filtering.

  In the next step S03, a differential operation process is performed on the time series T (t) of the output after the filter processing, and the above-described first differential function T ‘and second differential function T ″ are calculated.

  Further, in the following step S04, the polarity of each of the primary differential function T 'and the secondary differential function T "calculated in the previous step is checked to detect the inflection point of the torque characteristic curve. Taking the shown torque characteristic curve as an example, the state of the polarity change of the primary differential function T 'and the secondary differential function T "and the state of the characteristic curve change are shown in the table of FIG.

  Then, in the next step S05, when it is determined that the inflection point has been reached (in the case of YES, that is, when T '> 0, T "<0), the process proceeds to step S06, and the process proceeds to the electric motor 11. On the other hand, if it is determined in step S05 that the inflection point has not been reached (NO, that is, T ′> 0, T ″> 0) Suspends the processing of this method and temporarily shifts the state of the microprocessor to the WAIT (wait) state until the processing cycle is started by the next interrupt signal.

As described above, if the food mixer according to the present invention or the control method of the food mixer is used, the mixing, kneading or frothing of the ingredients required for soft and delicate mixing such as whipped cream and meringue is performed by the mixer. Can be performed automatically without being affected by the intuition and skill of the operator. Therefore, the occurrence of defective products due to insufficient stirring or excessive stirring can be effectively reduced.

  The embodiments of the present invention are not limited to the above-described embodiments. For example, the shape and arrangement of each part constituting each embodiment or the material thereof deviate from the gist of the present invention. It goes without saying that changes can be made as appropriate in accordance with the actual embodiment without doing so.

The configuration of the present invention described above can be used in various food industries that require stirring, kneading, or whipping of ingredients, including the dairy and confectionery industries.

1 is a schematic view of the appearance of a food mixer according to the present invention. FIG. 3 is a block diagram illustrating a configuration of an arithmetic and control unit of the food mixer according to the present invention. FIG. 3 is a diagram illustrating a configuration of each circuit in the arithmetic and control unit, and the like. 7 is a diagram illustrating a change in torque over time during mixing of food. 4 is a flowchart illustrating a control method of the food mixer according to the present invention.

10 Food mixer 11 according to the present invention Rotary drive motor 12 Torque sensor 13 Operation control unit 131 Filter unit 132 Differential operation unit 133 Inflection point detection unit 134 Rotation control unit 135 Monitoring / control operation Panel 15: Food storage bowl R: Resistance C: Capacitor A: Operational amplifier (operational amplifier)
CMP ... Comparator
AND… AND gate circuit

Claims (5)

A food mixer for stirring and kneading various ingredients using a stirrer,
A torque measurement unit that measures a rotation torque applied to the stirrer from the motor for rotation drive and outputs a torque measurement signal;
A mixer for performing a predetermined calculation process on the torque measurement signal and outputting a control signal to the electric motor based on the calculation result. The arithmetic and control unit,
A filter unit that removes a minute time-varying component of the torque measurement signal and smoothes the torque measurement signal,
A differential operation unit that differentiates an output signal from the filter unit to calculate a speed and an acceleration at which the rotational torque increases,
An inflection point detection unit that detects an inflection point of the rotational torque increase characteristic curve based on a calculation result of the differentiation calculation unit;
The food mixer according to claim 1, further comprising: a rotation control unit that outputs a rotation stop signal to the electric motor when the inflection point is detected by the inflection point detection unit. A control method of a food mixer that stirs and kneads various ingredients using a stirrer,
A torque measurement signal capturing step of capturing a torque measurement signal from a torque sensor that measures a rotation torque applied to the stirrer from a motor for rotational drive;
Excluding the minute time-varying component of the torque measurement signal, a filter processing step of generating a filtered output signal by smoothing the torque measurement signal,
A differential operation processing step of differentiating the output signal after the filter processing to calculate an increase speed of the signal and an increase acceleration,
An inflection point detecting step of detecting an inflection point of the characteristic curve of the rotational torque based on the operation result of the differential operation processing step,
A rotation control step of outputting a rotation stop signal to the electric motor when the inflection point is detected, the control method for a food mixer.   3. The food mixer according to claim 1, wherein the various ingredients are mainly dairy products such as whipped cream or egg white / yolk products such as meringue. 4. The food mixer control method according to claim 3, wherein the various ingredients are mainly dairy products such as whipped cream or egg white / yolk products such as meringue.

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