Stirring device

Abstract

To provide a stirring device capable of effectively mixing the contents of an inner pot.SOLUTION: A stirring device 1 comprises an inner pot 10, a stirring mechanism 20, a motor 30, and a control device 40. The stirring mechanism includes a shaft 22 rotatably supported inside the inner pot and a plurality of stirring blades 24 connected to the shaft. The motor is connected to the shaft of the stirring mechanism. The control device drives the motor at a first speed V1 during a first period P1 and drives the motor at a second speed V2, different from the first speed V1, during a second period P2 subsequent to the first period P1. At least one of the first period P1 and the second period P2 is longer than one rotation cycle of the shaft of the stirring mechanism. When the larger absolute value among the first speed V1 and the second speed V2 is defined as VH and the other is defined as VL, the stirring device satisfies the relational expression of -1≤(VL / VH)<1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a stirring device. [Background technology]

[0002] Conventionally, cooking devices that stir ingredients while heating them are known. For example, Patent Document 1 below discloses a stirring device configured to stir ingredients contained in a heating pot according to a predetermined stirring pattern using an agitator connected to a servo motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-073587 Summary of the Invention [Problem to be solved by the invention]

[0004] However, there is room for improvement in the stirring efficiency of such cooking devices. [Means for solving the problem]

[0005] According to the present invention, the following inventions are provided. [1] A stirring device comprising an inner pot, a stirring mechanism, a motor, and a control device, wherein the stirring mechanism has a shaft rotatably supported inside the inner pot and a plurality of stirring blades connected to the shaft, the motor is connected to the shaft of the stirring mechanism, and the control device drives the motor at a first speed during a first period and drives the motor at a second speed different from the first speed during a second period after the first period, at least one of the first period and the second period being a period longer than one cycle of one rotation of the shaft of the stirring mechanism, and wherein the stirring device satisfies the relational expression -1≦(VL / VH)<1, where VH is the one with the larger absolute value of the first speed and VL is the other (however, when the absolute value of the first speed is equal to the absolute value of the second speed, any one of the first speed and the second speed is designated as VH). [2] The stirring device according to [1], wherein the second period is a period that follows the first period, and (VL / VH)>0. [3] The stirring device according to [2], wherein 0.1≦(VL / VH)<1. [4] The stirring device according to [3], wherein 0.1≦(VL / VH)≦0.6. [5] The stirring device according to any one of [2] to [4], wherein the length of the first period is the same as the length of the second period. [6] The stirring device according to any one of [2] to [5], wherein the control device drives the motor by repeating a set of the first period and the second period multiple times. [7] The stirring device according to [2], wherein the control device stops the motor during a third period between the first period and the second period. [8] The stirring device according to [7], wherein 0.1≦(VL / VH)<1. [9] The stirring device according to [8], wherein 0.1≦(VL / VH)≦0.8.

[10] The stirring device according to any one of [7] to [9], wherein the length of the first period is the same as the length of the second period.

[11] The stirring device according to any one of [7] to

[10] , wherein the third period is shorter than both the first period and the second period.

[12] An agitation device according to any one of [7] to

[11] , wherein the control device stops the motor in a fourth period following the second period, and then drives the motor by repeating the first period, the third period, and the second period in this order.

[13] The stirring device according to [1], wherein the second period is a period that follows the first period, and (VL / VH)=0.

[14] The stirring device according to [1], wherein (VL / VH)<0.

[15] The stirring device according to

[14] , wherein -1≦(VL / VH)≦-0.1.

[16] The stirring device according to

[14] or

[15] , wherein the control device drives the motor by repeating a set of the first period and the second period multiple times.

[17] The stirring device according to any one of [1] to

[16] , wherein the shaft extends horizontally inside the inner pot.

[0006] According to the present invention, it is possible to provide a stirring device that can achieve stirring that can effectively mix the contents of a kettle. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram illustrating an exemplary stirring device according to an embodiment of the present invention. [Figure 2] 2 is a schematic cross-sectional view of the agitator 1 shown in FIG. 1 cut perpendicularly to the shaft 22. FIG. [Figure 3] 10 is a flowchart illustrating an example of control of the rotation of the shaft 22 by the control device 40. [Figure 4]This figure shows the results of a simulation of the mixing of two materials when the motor 30 is driven by switching the rotation speed. This figure shows the change over time in the mixing of hot water at 100°C and cold water at 0°C. [Figure 5] FIG. 10 is a diagram showing the results of a simulation of mixing two materials when the motor 30 is driven by switching the rotation speed, and shows the change in stirring moment over time. [Figure 6] This figure shows, as a comparative example, the results of a simulation of the mixing of two materials when the motor 30 is driven at a constant rotation speed. This figure shows the change over time in the mixing of hot water at 100°C and cold water at 0°C. [Figure 7] FIG. 10 is a diagram showing, as a comparative example, the results of a simulation of mixing two materials when the motor 30 is driven at a constant rotation speed, and shows the change in stirring moment over time. [Figure 8] FIG. 10 shows another example of the simulation results of mixing two materials when the motor 30 is driven by switching the rotation speed. This figure shows the change over time in the mixing of hot water at 100°C and cold water at 0°C. [Figure 9] FIG. 10 is a diagram showing another example of the simulation results of mixing two materials when the motor 30 is driven by switching the rotation speed, and this diagram shows the change in stirring moment over time. [Figure 10] This figure shows the results of a simulation of the mixing of two materials when the rotation of shaft 22 is reversed every 1.5 revolutions of shaft 22. The figure shows the change over time in the mixing of hot water at 100°C and cold water at 0°C. [Figure 11] FIG. 10 is a diagram showing the results of a simulation of mixing two materials when the rotation of the shaft 22 is reversed every 1.5 revolutions of the shaft 22, and shows the change in stirring moment over time. [Figure 12] This figure shows, as a comparative example, the simulation results when stirring is performed with the rotation speed of the motor 30 fixed at +16.5 rpm, and shows the change over time in the mixing of hot water at 100°C and cold water at 0°C. [Figure 13]FIG. 10 is a diagram showing, as a comparative example, the simulation results when stirring is performed with the rotation speed of the motor 30 fixed at +16.5 rpm, and shows the change in stirring moment over time. [Figure 14] This figure shows the results of a simulation of mixing two materials when the first speed V1 is +7.5 rpm and the second speed V2 is -30 rpm. This figure shows the change over time in the mixing of hot water at 100°C and cold water at 0°C. [Figure 15] FIG. 10 is a diagram showing the results of a simulation of mixing two materials when the first speed V1 is set to +7.5 rpm and the second speed V2 is set to -30 rpm, and shows the change in stirring moment over time. [Figure 16] 15 is a diagram showing an example in which the magnitude of the rotation speed during forward rotation and reverse rotation of the motor 30 is interchanged, as compared with the example shown in FIG. 14. FIG. [Figure 17] 16 is a diagram showing an example in which the magnitude of the rotation speed during forward rotation and reverse rotation of the motor 30 is interchanged, as compared with the example shown in FIG. 15. FIG. [Figure 18] 10 is a flowchart illustrating another example of control of the rotation of the shaft 22 by the control device 40. [Figure 19] This figure shows the results of a simulation of the mixing of two materials when the motor 30 is driven by switching the rotation speed with a third period P3 in between, during which the motor 30 is stopped. This figure shows the change over time in the mixing of hot water at 100°C and cold water at 0°C. [Figure 20] This figure shows the results of a simulation of mixing two materials when the motor 30 is driven at different rotational speeds, with a third period P3 in between during which the motor 30 is stopped. This figure shows the change in the mixing moment over time. [Figure 21] This figure shows, as a reference example, another example of the simulation results of mixing two types of materials when the motor 30 is driven by switching the rotation speed with a third period P3 in between in which the motor 30 is stopped. This figure shows the change over time in the mixing of hot water at 100°C and cold water at 0°C. [Figure 22]FIG. 10 is a diagram showing, as a reference example, another example of the simulation results of mixing two materials when the motor 30 is driven by switching the rotation speed with a third period P3 in between, during which the motor 30 is stopped. This diagram shows the change in the mixing moment over time. DETAILED DESCRIPTION OF THE INVENTION

[0008] The following describes embodiments of the present invention. The various features shown in the following embodiments can be combined with each other. Furthermore, each feature can be an independent invention.

[0009] <1. Basic configuration of the mixing device> The present invention is directed to an agitation device that mixes objects by rotating a stirrer. A typical example of such an agitation device is a cooking device called a steam kneader, which agitates ingredients while heating them. Control performed by an agitation device according to an embodiment of the present invention can be advantageously applied to cooking devices such as steam kneaders. The following description will be given using a steam kneader as an example of an agitation device.

[0010] FIG. 1 shows an exemplary stirring device according to an embodiment of the present invention. The stirring device 1 shown in FIG. 1 includes an inner hook 10, a stirring mechanism 20, a motor 30, and a control device 40. For ease of explanation, FIG. 1 shows not only the exterior of the inner hook 10 but also the interior of the inner hook 10 by cutting away a portion of the inner hook 10. Also, FIG. 1 depicts three arrows indicating the directions of the mutually orthogonal X-axis, Y-axis, and Z-axis. In this example, the Z-axis shown in the figure is parallel to the vertical direction.

[0011] The agitator 1 is an example of a steam kneader, and further includes a jacket 50 that covers a portion of the inner pot 10 from below. The jacket 50 includes a steam supply pipe 52 (steam pipe) that supplies steam to the space defined by the inner pot 10 and the jacket 50. By supplying steam, the agitator 1 can heat the object (food material in this case) placed in the inner pot 10.

[0012] The stirring mechanism 20 of the stirring device 1 includes a shaft 22 and a plurality of stirring blades 24. As shown in Fig. 1, each of the stirring blades 24 is connected to the shaft 22 via a corresponding arm 23. Each arm 23 extends in a generally radial direction of the shaft 22 in a plane perpendicular to the axial direction of the shaft 22, and supports the stirring blade 24.

[0013] In the configuration illustrated in Fig. 1, the inner pot 10 has a generally cylindrical shape extending laterally. In the example shown in Fig. 1, the shaft 22 of the stirring mechanism 20 extends horizontally (here, in the direction of the X-axis in the figure) inside the inner pot 10, penetrating both ends of the cylindrical shape of the inner pot 10 and one end of which reaches the control box 60. Here, "horizontal" in this specification is not limited to being strictly perpendicular to the vertical direction, but is also interpreted to include a range of about ±5° from the direction perpendicular to the vertical direction.

[0014] The shaft 22 is rotatably supported inside the inner hook 10 by a bearing or the like provided in the inner hook 10. As shown schematically in FIG. 1, the shaft 22 is connected to a motor 30 so as to be rotatable about its own axis. A typical example of the motor 30 is a servo motor. The shaft 22 may be connected to the motor 30 indirectly via a transmission or the like, or may be connected directly.

[0015] In this example, the motor 30 is disposed in a control box 60. In the example shown in FIG. 1, the control box 60 also contains a control device 40. Typical examples of the control device 40 include a microcomputer and a programmable logic controller (PLC). In this example, the control device 40 has, on its front surface, an operation panel 62 that displays the operating status of the agitator 1. The operation panel 62 may be an interface such as a touch panel that receives instructions from an operator.

[0016] When the stirring device 1 is in operation, the control device 40 supplies a drive signal to the motor 30 to control the operation of the motor 30, in other words, the rotation of the shaft 22 of the stirring mechanism 20. As will be described in detail later, in an embodiment of the present invention, the control device 40 changes one or both of the direction and speed of rotation of the shaft 22 at regular intervals.

[0017] FIG. 2 is a schematic cross-section of the agitator 1 taken perpendicular to the shaft 22. In the configuration illustrated in FIG. 2, the arms 23 and agitator blades 24 of the agitator mechanism 20 are arranged at 90° intervals around the central axis of the shaft 22. The edge of the agitator blade 24 is in contact with the cylindrical inner wall surface 10c of the inner pot 10, or a small gap (e.g., 0.5 mm or less) is formed between the edge and the inner wall surface 10c. As the agitator blade 24 rotates around the shaft 22, the ingredients contained in the inner pot 10 are pushed by the agitator blade 24 and agitated and mixed inside the inner pot 10.

[0018] Other details of the agitator 1 will be described later. Hereinafter, when viewed along the central axis of the shaft 22 from the opposite side of the motor 30, the direction of rotation will be defined as clockwise rotation about the shaft 22 as the positive direction and counterclockwise rotation as the negative direction. That is, the direction from the Y axis toward the Z axis around the X axis in the figure will be referred to as positive rotation for convenience. Note that in this specification, the rotations per unit time of the shaft 22, including the direction of rotation, will be referred to as the "rotational speed" or simply "speed," and will be expressed using a positive or negative sign and the number of rotations per minute. In other words, in this specification, two "speeds" that are equal in absolute value but not the same sign are different speeds. Hereinafter, the "+" sign indicating a positive rotation direction may be omitted unless otherwise necessary.

[0019] 2. Example of Control of the Stirring Mechanism 20 3 shows an example of control of the rotation of the shaft 22 by the control device 40. In this embodiment of the present invention, the control device 40 executes control such that the rotation of the motor 30 is at a first speed V1 during a first period P1 having a certain length, and at a second speed V2 during a second period P2 having a certain length following the first period P1. In this switching of the rotation speed of the motor 30, the start and end of the first period P1 are determined not by whether the actual rotation speed of the rotor of the motor 30 is at the first speed V1, but by the rising and falling edges of a drive signal for operating the motor 30 at the first speed V1. The same applies to the second period P2 and the third and fourth periods described below.

[0020] As will be described in detail below, in an embodiment of the present invention, the control device 40 controls the rotation of the motor 30 so that the relationship -1≦(VL / VH)<1 is satisfied, where VH is the one with the larger absolute value of the first speed V1 or the second speed V2, and VL is the other. Note that when |V1|=|V2|, any one of the first speed V1 and the second speed V2 may be set to VH, and the other may be set to VL. By setting the ratio of VL to VH within a predetermined range, appropriate "turbulence" is generated in the movement of the contents (typically ingredients) in the inner pot 10, enabling efficient stirring.

[0021] The first speed V1 and the second speed V2 may each be appropriately selected from rotational speeds that can be set according to the specifications of the stirring device 1. The first speed V1 may be, for example, a speed selected from the range of -32.5 rpm to 32.5 rpm. The absolute value of the first speed V1 may typically be in the range of 5.0 rpm to 32.5 rpm. The second speed V2 may also be a speed selected from the range of -32.5 rpm to 32.5 rpm, and its absolute value may be in the range of 5.0 rpm to 32.5 rpm.

[0022] In an embodiment of the present invention, at least one of the first period P1 and the second period P2 is set to be longer than the time required for the shaft 22 to make one rotation around the central axis (hereinafter simply referred to as "one cycle"). As will be explained below, when operating the stirring device 1 by switching the rotation speed of the shaft 22, by setting at least one of the first period P1 and the second period P2 to be longer than one cycle, it becomes possible to effectively stir the ingredients contained in the inner pot 10. For simplicity, it is assumed below that the speed ratio between the rotation of the motor 30 and the rotation of the shaft 22 is 1.

[0023] (2-1. Control Example 1) In the example shown in FIG. 3, after the agitator 1 is powered on, the control device 40 drives the motor 30 at a rotation speed of a first speed V1 (step S1). The operation at the first speed V1 is continued until the result of the determination as to whether a predetermined time has elapsed is "YES" (step S2). When it is determined in step S2 shown in FIG. 3 that the predetermined time has elapsed, the control device 40 switches the rotation speed of the motor 30 to a second speed V2 different from the first speed V1 (step S3). The operation at the second speed V2 is continued until the result of the determination as to whether a predetermined time has elapsed is "YES" (step S4).

[0024] Here, the direction of rotation of the shaft 22 connected to the motor 30 is the same during the first period P1 and the second period P2. That is, in this example, the sign of the second speed V2 is the same as the sign of the first speed V1, and therefore, the relationship (VL / VH)>0 holds. Furthermore, the second period P2 is a period following the first period P1. In other words, the control device 40 controls the rotation of the motor 30 so as to change the rotation of the motor 30 in a step function manner, rather than gradually changing the rotation from the first speed V1 to the second speed V2. By switching the rotation of the motor 30 between two different speeds in a very short period of time, it is possible to intentionally disrupt the movement of the ingredients in the inner pot 10 due to the pushing of the mixing blade 24, thereby achieving efficient mixing of the ingredients.

[0025] The first period P1 and the second period P2 may be repeated multiple times. By repeating the stirring for the first period P1 following the second period P2, it is possible to intentionally cause another disturbance in the movement of the ingredients when the rotation speed of the motor 30 is switched from the second speed V2 to the first speed V1.

[0026] In this example, when the control device 40 receives a determination result in step S4 that a predetermined time has elapsed, the control device 40 proceeds to step S5. In step S5 of FIG. 3, the control device 40 compares a predetermined threshold with the number of times a set of a first period P1 in which the motor 30 is driven at a first speed V1 and a second period P2 in which the motor 30 is driven at a second speed V2 has been repeated, and determines whether the number of times the set has been repeated exceeds the threshold. If the number of times the set has been repeated exceeds the threshold (the determination result is "YES"), the entire process ends. On the other hand, if the number of times the set has been repeated is equal to or less than the threshold, the control device 40 repeats the process from step S1. Instead of comparing the number of times the set of ...

[0027] In switching the rotation speed of the motor 30, the passage of a predetermined time is used as the criterion for determining whether to switch the rotation speed. In addition to the time-based control described here, a sensor such as a rotary encoder may be provided on the shaft 22 or the rotor of the motor 30, and the determination as to whether to switch the rotation speed of the motor 30 may be made based on the magnitude of the rotation angle of the shaft 22. However, time-based control can achieve the desired control with a simpler configuration without requiring a rotary encoder or the like. A weight sensor or the like may be provided on the agitator 1, and the length of the first period P1 and / or the second period P2 may be changed depending on the weight of the contents in the inner pot 10.

[0028] Figures 4 and 5 show the results of a simulation of the mixing of two materials when motor 30 is driven with the rotation speed switched. On the other hand, Figures 6 and 7 show, as a comparative example, the results of a simulation of the mixing of two materials when motor 30 is driven with a constant rotation speed. The stirring device was assumed to have a configuration similar to the example shown in Figure 1, including an inner pot having a roughly cylindrical shape (inner diameter: 650 mm) and a stirring mechanism with a total of six stirring blades.

[0029] FIG. 4 shows the results of calculations of the time required for the contents of inner pot 10 to be completely mixed when stirring is initiated from an initial state in which, for example, the left half of the cylindrical shape of inner pot 10 is filled with hot water at 100°C and the right half is filled with cold water at 0°C. The total amount of content (here, water) contained in inner pot 10 is assumed to be 350 kg. Here, the first period P1 and the second period P2 are both set to 5 seconds, the first speed V1 = 7.5 rpm, and the second speed V2 = 30 rpm. As can be seen from these set values, second period P2 is longer than one rotation cycle of shaft 22, and during second period P2, shaft 22 makes approximately 2.5 rotations around its central axis.

[0030] The temperature of 50°C on the vertical axis in Figure 4 corresponds to the state in which the hot and cold waters are completely mixed. Here, the time required for the temperature of the contents in the inner pot 10 to fall within the range of 50°C ± 2.5°C from the start of agitation was defined as the time required for the completion of mixing. In the example shown in Figure 4, the time required for the completion of mixing was 90.8 seconds from the start of agitation (indicated by the vertical dashed line in Figure 4; the same applies below). On the other hand, Figure 6 shows the simulation results for a comparative example in which the rotation speed of the motor 30 was kept constant at 30 rpm. When the rotation speed of the motor 30 was kept constant at 30 rpm, the time required for the completion of mixing was 91.8 seconds. In other words, switching the rotation speed of the motor 30 is more advantageous in shortening the agitation time than maintaining a constant rotation speed of the motor 30.

[0031] Figure 5 shows the magnitude of the moment that the shaft 22 receives from the contents of the inner pot 10 during stirring. The value on the vertical axis in Figure 5 represents the sum of the moments around the central axis of the shaft 22 that the contents of the inner pot 10 exert on each stirring blade 24; for convenience, this sum is referred to as the "stirring moment" in this specification. The graph shows the change in the stirring moment over a 20-second period in which the set of first period P1 and second period P2 was repeated twice. The average value of the stirring moment over 20 seconds was calculated to be 39.04 N·m (shown by the horizontal dashed line in Figure 5; the same applies below).

[0032] On the other hand, Figure 7 shows, as a comparative example, the change in stirring moment over time when the rotation speed is constant at 30 rpm. The average value of the stirring moment when the rotation speed of motor 30 remains at 30 rpm is 56.76 N·m, and the average value of the stirring moment over 20 seconds is lower in the example shown in Figure 5. In the example shown in Figure 5, the average value of the rotation speed over 20 seconds is 18.75 rpm, and when compared in terms of work per unit time, (39.04 N·m * 18.75 rpm) / (56.76 N·m * 30 rpm) ≒ 0.4 (where "*" indicates multiplication), so a reduction of approximately 60% has been achieved.

[0033] In general, increasing the rotation speed of the stirrer when mixing ingredients can shorten the time required to complete the mixing. However, simply increasing the rotation speed of the stirrer increases damage to the ingredients and also increases mechanical load and power consumption. In contrast, the control shown in Figure 3 can reduce the average load on the shaft 22 during mixing while shortening the time required for mixing. In other words, by changing (e.g., decreasing) the rotation speed of the shaft 22 at set intervals, it is possible to achieve mixing performance similar to that achieved when the stirrer is rotated at a high rotation speed while suppressing increases in mechanical load. Moreover, improved mixing efficiency based on this control can be achieved without adding additional accessories such as stirring blades to the mixing mechanism 20.

[0034] 8 and 9 show the results of a simulation of the mixing of two materials when the motor 30 is driven with the rotational speed switched between V1 = 13.5 rpm and V2 = 30 rpm every five seconds. Of these, FIG. 8 shows the change over time in the mixing of hot water at 100°C and cold water at 0°C. FIG. 9 shows the change over time in the mixing moment. In this example, both the first period P1 and the second period P2 are longer than one rotation cycle of the shaft 22.

[0035] In the example shown in Fig. 8, the time required to complete mixing was 79.8 seconds. In other words, the mixing time was shorter than when the rotation speed of motor 30 was maintained constant, and the mixing time was even shorter than the example (90.8 seconds) in Fig. 4 where first speed V1 = 7.5 rpm and second speed V2 = 30 rpm. This is presumably because a higher speed was used as first speed V1.

[0036] In this example where V1 = 13.5 rpm, the average value of the stirring moment over 20 seconds was 44.32 N m. This is a slightly higher value than the example in Figure 5 where the rotation speed was changed with V1 = 7.5 rpm (39.04 N m), but it is smaller than the value (56.76 N m) obtained when the rotation speed of motor 30 was kept constant at 30 rpm.

[0037] 6 and 7 and 8 and 9, it can be seen that slowing the rotational speed of motor 30 for a certain period of time, rather than maintaining the rotational speed of motor 30 constant, can reduce the average stirring moment acting on shaft 22 while shortening the time required to mix ingredients. In other words, it is possible to reduce the mechanical load on shaft 22 and motor 30 while improving stirring efficiency. In this case, it can be seen that stirring efficiency can be more effectively improved by making both the period in which motor 30 is driven at a relatively high rotational speed and the period in which motor 30 is driven at a relatively low rotational speed longer than one rotation cycle of shaft 22.

[0038] In Control Example 1 described here, the range of (VL / VH) is, for example, 0.1 or more and less than 1, preferably 0.1 or more and 0.6 or less, and more preferably 0.25 or more and 0.45 or less. The lower limit of (VL / VH) is not limited to this example and may be, for example, 0.05, 0.1, 0.15, 0.2, or 0.25. The upper limit of (VL / VH) is also not limited to this example and may be, for example, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, or 0.95. (VL / VH) may be in the range of 0.25 or more and less than 1.

[0039] In the examples described with reference to FIGS. 4-5 and 8-9, the length of the first period P1 and the length of the second period P2 are the same. If the period with a larger absolute value of the rotation speed were relatively longer, the average value of the mixing moment would increase compared to when the lengths of the first period P1 and the second period P2 were the same. This would be disadvantageous in terms of power consumption. Conversely, if the period with a smaller absolute value of the rotation speed were relatively longer, a reduction in power consumption could be expected, but it would take more time to complete mixing. In other words, this would result in a decrease in mixing performance. From the perspective of achieving power savings while maintaining mixing performance, it is advantageous to make the lengths of the first period P1 and the second period P2 the same.

[0040] (2-2. Control Example 2) In the example described above with reference to Figures 4-5 and 8-9, the rotation direction is constant, but the magnitude of the rotation speed is changed between the first period P1 and the second period P2. However, this is not limiting, and the control device 40 may execute control such that the rotation of the motor 30 is reversed at regular intervals. In other words, the first speed V1 and the second speed V2 may have opposite signs, and in this case, the relationship (VL / VH)<0 holds.

[0041] The control flow in the example described here is basically the same as that described with reference to FIG. 3. However, the rotation of the shaft 22 is reversed between the first period P1 and the second period P2. For example, if the rotor of the motor 30 rotates in the forward direction during the first period P1, the rotor of the motor 30 is rotated in the reverse direction during the second period P2. By reversing the rotation of the motor 30, for example, at regular intervals, the movement of the ingredients in the inner pot 10 can be intentionally disrupted during the transition between the first period P1 and the second period P2, as in the example described with reference to FIG. 3, thereby achieving efficient mixing. Reversing the rotation of the shaft 22 can significantly disrupt the movement of the ingredients, even if the absolute values ​​of the first speed V1 and the second speed V2 are relatively small.

[0042] 10 and 11 show the results of a simulation of the mixing of two materials when the rotation of shaft 22 is reversed every 1.5 revolutions of shaft 22. Of these, FIG. 10 shows the change over time in the mixing of 100°C hot water and 0°C cold water, and FIG. 11 shows the change over time in the stirring moment. In this example, too, the length of first period P1 is equal to the length of second period P2. Also, as in the example described above with reference to FIGS. 4-5 and 8-9, control device 40 drives motor 30 by repeating the pair of first period P1 and second period P2 multiple times.

[0043] Here, the simulation was performed with the first speed V1 = +16.5 rpm during the first period P1 when the motor 30 is rotated forward, and the second speed V2 = -16.5 rpm during the second period P2 when the motor 30 is rotated reversely. In the example shown in Fig. 10, the time required to complete mixing was 66.8 seconds.

[0044] 12 and 13 show, as a comparative example, the simulation results when mixing was performed with the rotation speed of motor 30 fixed at +16.5 rpm. FIG. 12 shows the change over time in mixing 100°C hot water and 0°C cold water. In this example, it took 154 seconds for mixing to be completed. In other words, by reversing the rotation of motor 30, a time reduction of approximately 57% was achieved compared to when the rotation direction of motor 30 was fixed. As such, it can be seen that reversing the rotation of motor 30 can efficiently mix ingredients even when the rotation speed of motor 30 is medium or low, thereby shortening the time required to mix ingredients.

[0045] Next, looking at the change in stirring moment over time, in the example shown in Figure 11, the average value of the stirring moment over 20 seconds was 33.20 N m. In contrast, in the example shown as a comparative example in Figure 13, in which the rotation speed of motor 30 was fixed at +16.5 rpm, the average value of the stirring moment over 20 seconds was 33.42 N m. In other words, even when the rotation of motor 30 is reversed at regular intervals, it can be seen that there is no significant difference in average load compared to when the rotation direction is fixed.

[0046] When reversing the rotation of motor 30 during mixing, the absolute value of first speed V1 and the absolute value of second speed V2 can be made different. Figures 14 and 15 show the results of a simulation of mixing two materials when first speed V1 is +7.5 rpm and second speed V2 is -30 rpm. Of these, Figure 14 shows the change over time in the mixing of 100°C hot water and 0°C cold water, and Figure 15 shows the change over time in the mixing moment.

[0047] Here, the first period P1 and the second period P2 are both periods required for 1.5 rotations of the shaft 22. That is, the length of the first period P1 is 12 seconds, while the length of the second period P2 is 3 seconds. Figures 14 and 15 show the simulation results when mixing is performed after the end of the second period P2, with the rotation speed of the motor 30 being changed back to the first speed V1.

[0048] In the example shown in FIG. 14, the time required to complete mixing was 89.4 seconds, which was longer than the example shown in FIG. 10 (66.8 seconds). However, this was significantly shorter than the time required when the rotation direction of the motor 30 was fixed (154 seconds) as shown in FIG. 12. Next, regarding the mixing moment, in the example shown in FIG. 15, the average value of the mixing moment over 20 seconds was 24.87 N·m, which was smaller than the value of 33.20 N·m in the example described with reference to FIG. 11. This is presumably because a rotational speed with a smaller absolute value was adopted for the first speed V1. In the example shown in FIG. 15, the average value of the mixing moment over 15 seconds, which is the sum of the initial first period P1 and the subsequent second period P2, was 27.61 N·m.

[0049] 16 and 17 show an example in which the rotational speeds of the motor 30 are reversed between forward and reverse rotation, as compared with the examples shown in FIGS. 14 and 15. Specifically, FIG. 16 shows the temporal change in the mixing of 100°C hot water and 0°C cold water when the first speed V1 is +30 rpm and the second speed V2 is −7.5 rpm, while FIG. 17 shows the temporal change in the stirring moment when the first speed V1 is +30 rpm and the second speed V2 is −7.5 rpm. In this example, both the first period P1 and the second period P2 are the periods required for 1.5 rotations of the shaft 22. Specifically, the length of the initial first period P1 is 3 seconds, and the length of the second period P2 is 12 seconds. As can be seen from FIG. 17, in this example, pairs of the first period P1 and the second period P2 are repeated (however, the graph shows the period from the start of stirring to 20 seconds).

[0050] In the example shown in Figure 16, the time required to complete mixing was 69.4 seconds, which was even shorter than the time required to complete mixing (89.4 seconds) in the example shown in Figure 14. Also, in the example shown in Figure 17, the average value of the stirring moment over 20 seconds was 28.52 N·m, which was slightly larger than the example shown in Figure 15 (24.87 N·m), but when compared with the average value over 15 seconds, it was 23.55 N·m, which was smaller than the example shown in Figure 15 (27.61 N·m).

[0051] Here, if we focus on one cycle consisting of a set of the first period P1 and the second period P2, (((30 rpm * 3 seconds) + (7.5 rpm * 12 seconds)) / 15 seconds) = 12 rpm, so in terms of the absolute value of the rotation speed, it can be said that the average rotation speed is lower than 16.5 rpm. However, even with a lower rotation speed, the time required to complete mixing is shorter than in the comparative example in which the rotation direction is fixed. These results show that by selecting specific values ​​for the first speed V1 and the second speed V2, it is possible to advantageously reduce mechanical load while ensuring mixing efficiency.

[0052] In this way, by switching the rotation direction of motor 30 (which may also be referred to as the rotation direction of shaft 22), it is possible to expect the effect of improving stirring efficiency while avoiding an increase in mechanical load. As in the examples described with reference to FIGS. 4-5 and 8-9, the absolute values ​​of first speed V1 and second speed V2 may be determined appropriately depending on the specifications of stirrer 1. For example, one of first speed V1 and second speed V2 may be set to the maximum rotation speed (or minimum rotation speed) that can be set in stirrer 1, and the other may be set to a rotation speed with the opposite sign to that rotation speed. In particular, the control described with reference to FIGS. 10-11 has the advantage that it can be relatively easily implemented using a circuit that reverses the polarity of voltage, such as a double-pole double-throw switch (DPDT switch), and can be applied to stirrers that do not have a conversion circuit such as an inverter.

[0053] In the control example 2 described here, the range of (VL / VH) is, for example, (-1) or more and (-0.1) or less, typically (-1) or more and (-0.25) or less. The lower limit of (VL / VH) is not limited to this example and may be, for example, -1, -0.95, -0.9, or -0.85. The upper limit of (VL / VH) is also not limited to this example and may be, for example, -0.4, -0.35, -0.3, -0.25, -0.2, -0.15, or -0.1.

[0054] (2-3. Control Example 3) 3, the motor 30 is driven at a first speed V1 during a first period P1, followed immediately by a second period P2 during which the motor 30 is driven at a second speed V2. Similarly, when the second period P2 transitions back to the first period P1, there is no other period between these periods. However, this is not limiting, and as described below, a period during which the motor 30 is driven at a rotational speed different from V1 or V2, or a period during which the motor 30 is stopped, may be inserted between the first period P1 and the second period P2.

[0055] FIG. 18 shows another example of control of the rotation of the shaft 22 by the control device 40. In the example shown in FIG. 18, after the agitator 1 is powered on, the control device 40 drives the motor 30 at a rotation speed of a first speed V1 (step S31). Operation at the first speed V1 continues until the result of the determination as to whether a predetermined time has elapsed is "YES" (step S32). If it is determined in step S32 shown in FIG. 18 that the predetermined time has elapsed, the control device 40 stops the motor 30 for a predetermined period (hereinafter referred to as a "third period P3") (step S33). If it is determined in step S33 that the predetermined time has elapsed since the motor 30 was stopped (step S34), the control device 40 switches the rotation speed of the motor 30 to a second speed V2 different from the first speed V1 (step S35).

[0056] The subsequent processing may be similar to the example described with reference to FIG. 3. That is, the control device 40 determines whether a predetermined time has elapsed since operation at the second speed V2 (step S36). If the determination result in step S36 is "YES," the control device 40 executes a determination as to whether the number of repetitions of the set of the first period P1, the third period P3, and the second period P2 exceeds a predetermined threshold (step S37). If the determination result in step S37 is "NO," the control device 40 repeats the processing from step S31. As will be described later, a fourth period in which the motor 30 is stopped may be inserted between the second period P2 and the first period P1. If the determination result in step S37 is "YES," the control device 40 ends control of the motor 30 and, for example, notifies the operator of the completion of mixing.

[0057] As shown in FIG. 18, a third period P3 during which the motor 30 is stopped may be inserted between a first period P1 during which the motor 30 is driven at a first speed V1 and a second period P2 during which the motor 30 is driven at a second speed V2. Even in this example, between the time when the motor 30 is driven at the first speed V1 and the time when the motor 30 is stopped, intentional turbulence can be generated in the flow of the contents in the inner pot 10. Furthermore, when the stopped motor 30 is subsequently driven at the second speed V2, a change in the rotation speed of the shaft 22 occurs, thereby intentionally generating turbulence in the flow of the contents in the inner pot 10. This type of control does not keep the contents in the inner pot 10 constantly moving, improving stirring efficiency, and is particularly advantageous for cooking with ingredients that tend to fall apart when cooked.

[0058] Figures 19 and 20 show the results of a simulation of the mixing of two materials when the motor 30 was driven at different rotational speeds, with a third period P3 in between, during which the motor 30 was stopped. Figure 19 shows the temporal change in the mixing of 100°C hot water and 0°C cold water, and Figure 20 shows the temporal change in the mixing moment. The simulation was performed with the first period P1, in which the motor 30 was driven at the first speed V1, and the second period P2, in which the motor 30 was driven at the second speed V2, both set to 4 seconds, and the third period P3 set to 2 seconds. Here, V1 = 10.5 rpm, V2 = 16.5 rpm, and V1 and V2 have the same sign. The average rotational speed for the first 20 seconds after the start of mixing was 9.15 rpm. The second period P2 is longer than one rotation cycle of the shaft 22.

[0059] In the example of Fig. 19, the time required to complete mixing was 87.8 seconds. On the other hand, according to the simulation results of the comparative example shown in Fig. 12, in which mixing was performed with the rotation speed of motor 30 fixed at 16.5 rpm, 154 seconds were required to complete mixing. This shows that by setting the first speed and the second speed to different values, improvement in mixing efficiency was achieved even while providing the third period P3 in which motor 30 was stopped.

[0060] See Figure 20. In this example, the average value of the stirring moment over 20 seconds was 19.83 N m, which is smaller than the average value of the stirring moment over 20 seconds of 33.42 N m (see Figure 13) obtained when stirring was performed with the rotation speed of motor 30 fixed at 16.5 rpm. It was found that by inserting a third period P3 in which motor 30 is stopped between first period P1 and second period P2, it is possible to improve stirring efficiency while also lowering the average value of the stirring moment and reducing the mechanical load.

[0061] The technology described in Patent Document 1 aims to achieve precise stirring, as if cooked by a human, by increasing the stirring blade's movement speed when the stirring blade approaches the bottom of the cooking pot. However, simply increasing the relative speed of the stirring blade with respect to the ingredients would apply excessive force to the ingredients, causing them to lose their shape. In contrast, control such as the example described with reference to Figures 19 and 20 enables efficient stirring of the contents (typically ingredients) in the inner pot 10 while reducing average damage to the contents.

[0062] In the example shown in Figures 19 and 20, the length of the third period P3 is half the length of each of the first period P1 and the second period P2. In other words, the third period P3 is shorter than both the first period P1 and the second period P2. By shortening the period during which the motor 30 is stopped, the time during which the ingredients are in contact with the inner wall surface 10c of the inner pot 10 can be reduced, thereby reducing the likelihood of the ingredients burning. Here, because irregular movement of the ingredients in the inner pot 10 occurs between the rotation and stoppage of the stirring blade 24, shortening the third period P3 compared to the period during which the motor 30 is driven does not directly cause a decrease in stirring efficiency. Note that the lengths of the first period P1 and the second period P2 do not necessarily have to be the same. Of course, the length of the first period P1 may differ from the length of the second period P2.

[0063] Furthermore, in this example, immediately after the second period P2, in which the motor 30 is driven at the second speed V2, a fourth period, in which the motor 30 is stopped, is provided. As can be seen from FIG. 20, a set of the first period P1, the third period P3, and the second period P2 is then repeatedly executed. By inserting a period in which the motor 30 is stopped each time the rotation speed of the motor 30 is changed, irregular movement of the ingredients in the inner pot 10 occurs when the motor 30 switches from driving to stopping and from stopping to driving, thereby enabling more efficient stirring of the ingredients. In this example, the length of the fourth period, sandwiched between the repeated sets of the first period P1, the third period P3, and the second period P2, is 2 seconds, the same as the length of the third period P3. In this example, the average stirring moment in the 12-second cycle of the first period P1, the third period P3, the second period P2, and the fourth period was 19.36 N·m. However, it is not essential that the length of the fourth period be the same as the length of the third period P3, and the length of each period in which the motor 30 is stopped may be determined appropriately taking into consideration the improvement of stirring efficiency and the prevention of burning.

[0064] 21 and 22 show another example of the simulation results of mixing two materials when the motor 30 is driven with the rotation speed switched between the third period P3 during which the motor 30 is stopped. Similar to FIG. 19, FIG. 21 shows the temporal change in the mixing of 100°C hot water and 0°C cold water. Similarly to FIG. 20, FIG. 22 shows the temporal change in the mixing moment. While the examples shown in FIGS. 19 and 20 have different values ​​for the first speed V1 and the second speed V2, in this example, V1 = V2 = 16.5 rpm. The average rotation speed for the first 20 seconds after mixing begins is 11.55 rpm. The other conditions are the same as those in the example described with reference to FIGS. 19 and 20.

[0065] In the example shown in FIG. 21, the time required to complete mixing was 93.8 seconds, which was longer than the example shown in FIG. 19, but was shorter than the time required to complete mixing when mixing was performed with the rotation speed of motor 30 fixed at 16.5 rpm (154 seconds, see FIG. 12). In the example shown in FIG. 22, the average value of the mixing moment over 20 seconds was 24.53 N m, which was smaller than the average value of 33.42 N m (see FIG. 13) obtained when mixing was performed with the rotation speed of motor 30 fixed at 16.5 rpm. In this example, the average value of the mixing moment over the 12-second cycles of the first period P1, third period P3, second period P2, and fourth period was 23.59 N m.

[0066] Comparing the work per unit time between the example shown in FIG. 20 and the comparative example shown in FIG. 13, we find that (19.83 N·m * 9.15 rpm) / (33.42 N·m * 16.5 rpm) is approximately 0.329. In other words, a reduction of approximately 67% has been achieved compared to when the rotational speed is fixed. Furthermore, (19.83 N·m * 9.15 rpm) / (24.53 N·m * 11.55 rpm) is approximately 0.640, meaning that the example shown in FIG. 20 achieves a reduction of approximately 36% compared to the reference example shown in FIG. 22.

[0067] As in the examples described with reference to FIGS. 4-5 and 8-9, in Control Example 3, the range of (VL / VH) can be a range of 0.25 or more and less than 1. In Control Example 3, the range of (VL / VH) is typically 0.1 or more and 0.8 or less, and in the examples shown in FIGS. 19-20, (VL / VH) is approximately 0.64. (VL / VH) may be a range of 0.1 or more and 0.65 or less. VL may be the minimum value that can be set in the stirring device 1, and VH may be the maximum value that can be set in the stirring device 1. As in Control Example 1, the lower limit of (VL / VH) may be, for example, 0.05, 0.1, 0.15, 0.2, or 0.25, and the upper limit of (VL / VH) may be, for example, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, or 0.95.

[0068] As described above, in Control Example 3, a disturbance can be intentionally generated in the flow of the contents in the inner pot 10 between when the motor 30 is driven and when it is stopped. This can be said to correspond to the case where VL = 0 during operation of the agitator 1. In that sense, if the rotational speed of the motor 30 when it is stopped is considered to be 0 rpm, and VH is a non-zero value, then (VL / VH) = 0 can be established during operation of the agitator 1, thereby achieving efficient agitation. Note that even if the rotational speed of the motor 30 when it is stopped is not strictly 0 rpm, when VL is in the range of more than (-0.1) rpm and less than (0.1) rpm, for example, it can be considered that VL = 0 rpm.

[0069] As described above, according to the embodiment of the present invention, it is possible to effectively stir the contents of the inner pot 10. Other configurations of the stirring device 1 will be described in detail below.

[0070] <3. Other Configurations of the Stirring Device 1> Please refer to Figures 1 and 2. In the configuration illustrated in Figures 1 and 2, the inner pot 10 has a rectangular parallelepiped hopper 12 at the top that extends along the shaft 22. As shown in Figure 2, the top of the hopper 12 is open to the outside, and an operator of the mixing device 1 can put ingredients from the hopper 12 into the inner pot 10.

[0071] The inner pot 10 is configured to be rotatable within a certain range around the shaft 22. As shown by the two-dot dashed line in FIG. 2, the inner pot 10 can be tilted so that the opening at the top of the hopper 12 faces forward, and the movement of the inner pot 10 makes it easier to remove ingredients through the hopper 12. The inner pot 10 is tilted by a tilting mechanism (not shown in FIGS. 1 and 2) in the control box 60. An operator of the mixing device 1 can control the operation of the tilting mechanism via the operation panel 62 of the control box 60.

[0072] As described above, the steam supply pipe 52 is connected to the jacket 50 that covers the lower part of the inner pot 10. The supply and stop of steam through the steam supply pipe 52 is controlled by a steam valve 54 provided on the steam supply pipe 52. In addition to the steam supply pipe 52, the jacket 50 also has a drain 56 with a steam trap 58. Water produced by condensation in the space defined by the inner pot 10 and the jacket 50 is discharged from the steam trap 58 via the drain 56 to the outside of the stirring device 1.

[0073] 1 and 2 show an example of the mixing device 1 having an inner pot 10 in the shape of a cylinder laid on its side, but the shape of the inner pot 10 is not limited to this and may be, for example, a hemispherical or cylindrical shape with an open top. The present invention is not limited to so-called horizontal kneaders in which the shaft of the mixing mechanism extends generally horizontally, but can also be applied to so-called bent-axis kneaders in which the shaft of the mixing mechanism is inclined obliquely with respect to the vertical direction. By applying the control of each of the above examples to bent-axis kneaders, which generally have excellent mixing capabilities, more effective mixing can be achieved. The present invention is not limited to steam kneaders and can be applied to other mixing devices. Needless to say, the object of mixing is not limited to food ingredients. [Explanation of symbols]

[0074] 1: Stirring device 10: Inner pot 10c: (Inner pot) inner wall 12: Hopper 20: Stirring mechanism 22: Shaft 23: Arm 24: Stirring blade 30: Motor 40: Control device 50: Jacket 52:Steam supply pipe 54: Steam valve 56: Drain 58: Steam trap 60: Control box 62:Operation panel

Claims

1. A stirring device comprising an inner pot, a stirring mechanism, a motor, and a control device, The stirring mechanism includes: a shaft rotatably supported inside the inner hook; A plurality of stirring blades connected to the shaft; and the motor is connected to the shaft of the stirring mechanism; the control device drives the motor at a first speed during a first period, and drives the motor at a second speed different from the first speed during a second period after the first period; At least one of the first period and the second period is a period longer than one cycle of one rotation of the shaft of the stirring mechanism, When one of the first speed and the second speed having a larger absolute value is designated as VH and the other is designated as VL (however, when the absolute value of the first speed is equal to the absolute value of the second speed, any one of the first speed and the second speed is designated as VH), the stirring device satisfies the relational expression -1≦(VL / VH)<1.

2. The stirring device according to claim 1, the second period is a period that is continuous with the first period, A stirring device where (VL / VH)>0.

3. The stirring device according to claim 2, A stirring device, wherein 0.1≦(VL / VH)<1.

4. The stirring device according to claim 3, A stirring device, wherein 0.1≦(VL / VH)≦0.

6.

5. The stirring device according to claim 2 or 3, The length of the first period is the same as the length of the second period.

6. The stirring device according to claim 2 or 3, The control device drives the motor by repeating a set of the first period and the second period a plurality of times.

7. The stirring device according to claim 2, The control device stops the motor during a third period between the first period and the second period.

8. The stirring device according to claim 7, A stirring device, wherein 0.1≦(VL / VH)<1.

9. The stirring device according to claim 8, A stirring device, wherein 0.1≦(VL / VH)≦0.

8.

10. The stirring device according to claim 7 or 8, The length of the first period is the same as the length of the second period.

11. The stirring device according to claim 7 or 8, The third period is shorter than both the first period and the second period.

12. The stirring device according to claim 7 or 8, The control device stops the motor in a fourth period following the second period, and then drives the motor repeatedly through the first period, the third period, and the second period in this order.

13. The stirring device according to claim 1, the second period is a period that is continuous with the first period, A stirring device where (VL / VH)=0.

14. The stirring device according to claim 1, A stirring device wherein (VL / VH)<0.

15. 15. The stirring device according to claim 14, A stirring device, wherein −1≦(VL / VH)≦−0.

1.

16. The stirring device according to claim 14 or 15, The control device drives the motor by repeating a set of the first period and the second period a plurality of times.

17. The stirring device according to claim 1, claim 2, claim 7, claim 13 or claim 14, The shaft extends horizontally inside the inner pot.

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