JP7651166B2 - Structure of the rotating blades in food mixers - Google Patents

Description

The present invention relates to a mixer for food ingredients, and more specifically, to the shape and structure of the rotating blades that are attached to large commercial vertical mixers that crush, mix, and knead the ingredients to be mixed.

In the food manufacturing industry, large vertical mixers with a rotating blade installed at approximately the center of the bottom of the mixing vessel, as shown in the attached Figure 14, are often used. This type of mixer is mainly composed of a mixing vessel a in which the ingredients are crushed, mixed, and kneaded, a rotating blade b installed at approximately the center of the bottom of the mixing vessel a, a drive unit c containing an electric motor and reduction gear mechanism that rotates the rotating blade b, and a control unit d equipped with various electronic circuits and an operation panel that control the mixing operation.

The reason why such large commercial mixers are called "vertical mixers" is because the rotating blades b are driven by a vertical rotating shaft at approximately the center of the bottom of the mixing vessel a of the mixer. The materials used for each part of such food mixers are mainly stainless steel, from the viewpoints of strength, corrosion resistance, and hygiene for food and ingredients.

In this mixer, the rotating blade b has the function of crushing, breaking, and shredding the ingredients to be mixed, and mixing and kneading them, and various shapes are used. That is, a rotating blade of an appropriate shape is selected according to the type of ingredients to be mixed and the food application, and is attached as an attachment to the rotating shaft a2 that protrudes into the mixing vessel a from approximately the center of the bottom of the mixing vessel a. One specific shape of the rotating blade b is shown in the attached Figure 15.

The rotary blade b in Fig. 15 has a structure in which multiple blades (two in the example of Fig. 15) b1, each having a planar shape as shown in the attached Fig. 16, are stacked vertically with a ring-shaped spacer b2 in between. As shown in Fig. 16, the planar shape of blade b1 curves in the opposite direction to the direction of rotation as it moves from the central axis of rotation to the centrifugal side of rotation, forming a so-called "magatama-shaped" shape. The rotation axis is located approximately in the center of the so-called "magatama through hole" of this magatama-shaped shape.

As mentioned above, the actual rotating blade b is used by stacking two blades b1 one above the other with a spacer b2 between them and attaching them to the central axis of rotation. In this case, in order to maintain a balance in the rotational moment of the rotating blade during mixing, the two blades b1 are fixed in positions that are axially symmetrical (point symmetrical) with respect to the central axis of rotation.

When using this mixer to mix various ingredients such as cream, cake batter, or fruit pulp, first the various ingredients are put into the mixing vessel a, the opening and closing lid a1 on the top of the mixing vessel is closed, and then a specified operation instruction is given from the control unit d. As a result, inside the mixing vessel a, the rotating blade b is rotated by an electric motor or reduction gear mechanism built into the drive unit c, and the ingredients being mixed are crushed, mixed, and kneaded based on a specified process for a specified period of time.

In addition, during the series of processing steps, as necessary, for example, the mixing vessel a is subjected to a cooling/heating process using cold water or hot water, or a process of blowing a gas such as air into the inside of the mixing vessel a is performed. Note that illustrations and explanations of the equipment and parts required for these processes are omitted because they are not directly related to the gist of the present invention. Incidentally, by carrying out these processes, it is possible to create a unique flavor and texture for each of the various mixed ingredients.

However, when mixing is performed with such a mixer, as mentioned above, the horizontal positions of the two blades arranged symmetrically about the axis of the rotating blade b differ above and below the vertical direction of the central axis of rotation. This causes a misalignment in the point of action of the rotational moment relative to the central axis of each blade. This can cause eccentric vibration of the rotating shaft (rotating shaft yaw motion), a phenomenon known as "shaft wobble," when the rotation speed of the mixer is increased.

On the other hand, when mixing ingredients with a mixer, the specific gravity of the ingredients after mixing is often an issue. In other words, the lower the specific gravity, the more air is contained in the ingredients after mixing, which can result in a smoother taste and better texture, like cake batter.

To increase the amount of air contained in the ingredients being stirred, i.e. to reduce their specific gravity, it is effective to increase the number of times the blades cross the ingredients being stirred during the mixing process. This increases the number of times the blades tear apart the pile of ingredients being stirred in the mixing vessel, increasing the opportunities for the air around the ingredients to be mixed into the ingredients being stirred.

In the above-mentioned conventional example, when focusing on the horizontal rotational plane of one blade b1, when the blade b1 rotates once inside the mixing vessel, the blade crosses the pile of ingredients only once. Therefore, in order to increase the number of times that the blade b1 crosses the pile of ingredients, it was necessary to increase the rotation speed of the rotating blade. However, increasing the mixer rotation speed not only increases the power consumption, but also has the disadvantage that the temperature of the ingredients increases due to friction during mixing, resulting in a deterioration in the flavor and texture of the ingredients.

In order to improve these drawbacks, for example, technology such as that shown in Patent Document 1 has been disclosed. In this disclosed technology, a rotating blade is shown at the bottom of the container of an ingredient mixer (food processor), with the planar shape of each blade curving in the opposite direction to the rotation direction as it moves from the central axis of rotation to the centrifugal side.

JP 2018-64760 A

However, the technology shown in Patent Document 1 does not aim to solve the issues raised in this case, but is mainly intended to reduce the load on rotating parts such as the motor of a food processor. Furthermore, the rotary blades in this technology always combine two blades of the same shape and treat them as one rotary blade, and are configured so that the desired effect is achieved by rotating each blade in the opposite direction. Therefore, it does not suggest a fundamental solution to the problems with the present invention mentioned above.

The present invention aims to solve the above-mentioned problems by providing a structure for the rotating blades of a large vertical food mixer that uses a simple structure to solve the yawing (shaft wobble) of the rotation center shaft during mixing, and that can mix a large amount of air into the mixed food during the mixing process, lowering the specific gravity of the mixed food.

The structure of the rotary blade attached to the food mixer according to the first aspect of the present invention is as follows:
A rotary blade structure comprising a plurality of blade portions extending from a central axis of rotation along a radial direction of rotation within a horizontal rotational plane of the same rotary blade, the blade portions having a planar shape that is point-symmetrical with respect to the central axis of rotation , the blade portions each comprising an outer curved portion facing in the direction of rotation and an inner curved portion facing away from the direction of rotation, the radius of curvature of the outer curved portion being greater than the radius of curvature of the inner curved portion,
The outer edge lower surface of the outer curved portion has a predetermined inclination angle (taper) toward the vertical direction, the outer edge upper surface of the inner curved portion has a predetermined inclination angle (taper) toward the vertical direction, and the blade (blade) portion has a predetermined angle of attack facing the horizontal rotation plane of the blade (blade) portion in the direction of rotation, the predetermined inclination angle and the set angle of attack are both in the angle range of 22° to 32°, and the range in which the inclination angle (taper) is set is 1/4 to 1/3 of the blade width length in the rotation direction of the blade (blade) portion.

The present invention, which is equipped with the above-mentioned solutions, can prevent axial vibration during mixing in a large vertical food mixer, and can reduce the specific gravity of the mixed ingredients after mixing, producing foods with a smooth texture. In addition, there is less need to rotate at relatively high speeds, and it is also possible to omit the cooling process for the mixing vessel during mixing.

The following describes the best mode for implementing the present invention with reference to the drawings attached to this specification.

(1) Structure of the Rotary Blade of the Food Mixer Based on the Present Invention The structure of the rotary blade 1 of the food mixer based on the present invention (hereinafter simply referred to as the present rotary blade 1) is shown in the attached Fig. 1. As shown in the figure, the present rotary blade 1 is mainly composed of a blade 11, a fixing bracket 12, and a rotary shaft base 13. It is preferable to use stainless steel materials for the materials used in each component of the present rotary blade 1 from the viewpoints of strength, corrosion resistance, and hygiene with respect to the food to be mixed.

Next, a perspective view of the blade 11 alone is shown in attached Figure 2. The blade 11 is intended to crush, break, mix, and knead the ingredients being mixed, and has two blade (blade) parts that extend in the radial direction around the rotation axis. Each blade (blade) part has a planar shape that is point symmetric (axially symmetric) with respect to the center of the rotation axis.

Furthermore, the planar shape of each blade (edge) portion consists of an outer curved portion facing the direction of rotation and an inner curved portion facing away from the direction of rotation, and the radius of curvature of the outer curved portion is greater than the radius of curvature of the inner curved portion (i.e., the radius of curvature of the outer curved portion is smaller than that of the inner curved portion).

Therefore, the planar shape of the blade (blade) portion gradually curves back in the direction of rotation as it moves in the centrifugal direction from the central axis of rotation. Note that the blade 11 shown in Figure 2 can be interpreted as having two blade (blade) portions that extend axially symmetrically from the central axis, so for convenience, the rotating blade shown in Figure 1 is referred to as a rotating blade with a "two-wing" structure, likening it to a general propeller.

The present invention is characterized in that the outer edge underside of the outer curved portion of the blade (blade) is provided with a predetermined inclination angle (taper) θ directed vertically downward, as shown in the schematic cross-sectional view of the blade in Figure 3(a). Since the outer curved portion of the blade (blade) faces the direction of rotation of the rotary blade, the ingredients to be mixed are pressed against the outer curved portion of the blade (blade) at high speed during the mixing process.

Therefore, by providing such an inclination angle θ on the outer edge underside of the outer curved portion, the ingredients to be stirred that are below the horizontal rotation plane of the blade 11 are guided by the inclination of the inclination angle θ and pushed down toward the bottom of the mixing vessel, as shown by the arrow in Figure 3 (a). In other words, the pile of ingredients to be stirred in the mixing vessel is effectively cut and separated by the blade (edge) portion coming into contact with it.

By the way, the inclination angle θ is based on the results of actual experiments.
By setting the angle θ in the range of about 22 degrees < θ < 32 degrees, the effect of cutting and piling up and separating the ingredients being mixed is enhanced, which is considered to be preferable for performing the mixing process.

In addition, regarding the length α of the tapered portion of the blade (blade), the longer the length, the stronger the pushing down and guiding effect on the food being stirred, but the thinner the blade (blade) will be, and the strength of the blade may decrease. Therefore, based on the results of various experiments, it is considered preferable to set the value of α to about 1/4 to 1/3 of the width of the blade (blade) in the direction of rotation, on average.

On the other hand, to achieve a similar effect, the upper outer edge surface of the inner curved portion of the blade 11 facing away from the direction of rotation may also be provided with a downward inclination angle (taper) β as shown in FIG. 3(b). As a result, the flow of the mixed ingredients passing over the upper surface of the blade (blade) portion is guided in the direction of the arrow in FIG. 3(b) by the inclination angle β, and the mixed ingredients are directed toward the bottom of the mixing vessel.

Furthermore, in order to enhance the above-mentioned effects, the blade of the rotary cutter may be regarded as an aerofoil, and a mechanical analogy may be applied to an aerofoil moving in a fluid such as air or water. That is, as shown in the attached FIG. 4, an angle of attack γ may be set for the aerofoil with respect to the horizontal plane of rotation over the entire length of the blade (blade) part, facing the direction of rotation of the blade (blade).

As a result, the flow of ingredients being cut by the blade (edge) portion and passing through the underside of the blade is guided by the attack angle γ toward the bottom of the mixing vessel as shown by the arrow in the figure. On the other hand, the flow of ingredients being mixed passing through the upper surface of the blade, after leaving the rear outer edge of the blade, is similarly directed toward the bottom of the mixing vessel due to the influence of the attack angle γ. It is considered preferable that the values of β and γ are approximately the same as the aforementioned θ.

In addition, in the present invention, the planar shape of the blade 11 is not limited to the shape shown in FIG. 2. For example, as shown in the attached FIG. 5, it is possible to have a blade (blade) portion with a so-called four-sided structure that extends in four directions along the direction of the rotation radius from the central axis of rotation. Incidentally, when a mixing process is performed using the blade 11 shown in FIG. 5, the number of times that the blade (blade) portion crosses the pile of ingredients to be mixed during one rotation of the blade 11 is twice as many as the blade in FIG. 2.

This promotes the cutting and piling-up separation effect of the mixed ingredients during the mixing process, and even though the mixing is done in a short time and at a low speed, it is possible to obtain mixed ingredients that have been more thoroughly mixed and kneaded. Furthermore, the mixing of air into the pile of mixed ingredients is also promoted, making it possible to reduce the specific gravity of the mixed ingredients through the mixing process.

Furthermore, the present invention is not limited to the structure of the rotary blade 1 using only one blade 11. For example, as shown in the attached Figure 6, multiple blades 11 may be stacked in multiple stages in the vertical direction of the central axis of rotation, sandwiching a ring-shaped spacer member 14. Incidentally, in the example shown in Figure 6, three blades 11 with a so-called two-stage structure, as shown in Figure 2 above, are stacked in the vertical direction of the central axis of rotation, shifted by 120 degrees each.

By adopting this type of blade structure, the number of times the blade tears through the pile of mixed ingredients per rotation of the blade increases by three times compared to the example shown in Figure 1 (using only one blade with a two-tooth structure). This increases the opportunities for surrounding air to be drawn into the mixed ingredients, making it possible to reduce the specific gravity of the mixed ingredients after the mixing process.

In addition, by using such a blade with a multiplexed structure, the number of blades that come into contact with the material being mixed also increases, so even when the material being mixed contains a lot of hard solid material, such as fruit seed pulp, the mixing process can be completed in a short time and at a relatively low rotation speed.

(2) Operational verification test of the rotary blade structure of the food mixer according to the present invention Next, the operation and effects of the rotary blade structure of the food mixer according to the present invention during mixing processing will be explained based on the various verification test examples shown below.

(2-1) Demonstration Test Example 1
First, an example of a demonstration test in which a mixing process was performed using the two-pronged blade 11 shown in Fig. 1 is shown. In this demonstration test, a mixing process was performed using a food material (specifically, butter cream) made mainly from oil and fat, and the mixer was rotated at 500 (rpm) from the start of mixing.

In this demonstration test, the specific gravity of the mixed ingredients dropped to about 0.87 about 8 minutes after the start. Incidentally, the specific gravity of the mixed ingredients (mainly oily and fatty materials) before mixing was about 1.2. The mixed ingredients were almost completely mixed by the mixing process. For reference, Figure 7 attached shows a photograph of the state of the mixed ingredients immediately after they were put into the mixing vessel, and Figure 8 shows a photograph of the inside of the mixing vessel after about 8 minutes of mixing had passed.

In addition, the temperature of the mixed ingredients (mainly oily and fatty materials) at the start of mixing was 5.7 degrees Celsius, but rose to 14.6 degrees Celsius after the mixing process. Generally, in order to reduce the specific gravity of the mixed ingredients during mixing, it is essential to cool the entire mixing vessel by circulating cooling water and keep its temperature low in order to increase the amount of air taken in by the mixed ingredients. However, in this demonstration test, good specific gravity values of the mixed ingredients as described above were obtained, even though no special cooling process was performed on the entire mixing vessel with cooling water.

(2-2) Demonstration Test Example 2
Next, the results of a demonstration test using a rotary blade in which three blades of the so-called two-pronged structure shown in Fig. 6 were stacked vertically to the central axis of rotation, with the blades shifted by 120 degrees each, are shown below. Photographs of the actual rotary blades used in this test are shown in the attached Fig. 9 (horizontal photograph) and Fig. 10 (oblique photograph).

In this demonstration test, as in the above-mentioned Test Example 1, the ingredients to be stirred were butter cream, which is mainly made of fats and oils, and the rotation speed of the mixer was 500 (rpm), the same as in the previous test. In this demonstration test, the specific gravity of the ingredients to be stirred dropped to 0.85 about 4 minutes after the mixing process started, and the ingredients to be stirred were almost completely stirred and kneaded. As in the previous test, the attached Figure 11 shows a photograph of the state immediately after the ingredients to be stirred were put into the mixing vessel, and Figure 12 shows a photograph of the inside of the mixing vessel after the mixing process.

In addition, the temperature of the ingredients being mixed (mainly oily and fatty materials) was 7.8 degrees Celsius when mixing began, but rose to 14.3 degrees Celsius after the mixing process. As with the previous test, no special cooling process was performed on the entire mixing vessel in this demonstration test.

(2-3) Demonstration Test Example 3
Next, a description will be given of an additional test using the three-ply blade used in Test Example 2. In this verification test, after the start of the mixing process, the rotation speed of the mixer was changed in the following steps.
[First step] 500 (rpm): 4 minutes [Second step] 750 (rpm): 1 minute [Third step] 300 (rpm): 5 minutes Note that the main ingredients of the mixed food (butter and cream) used were the same as in the previous demonstration test.

As a result of this demonstration test, the specific gravity of the mixed ingredients after the mixing process (after the third step) dropped to 0.74. It is particularly noteworthy that in the latter half of the mixing process, a good specific gravity was obtained for the mixed ingredients despite the slow rotation speed of 300 (rpm). Figure 13 shows a photograph of the inside of the mixing vessel after the mixing process. Incidentally, with the conventional type of rotary blade shown in Figure 15 above, it was difficult to reduce the specific gravity after mixing to below 0.86, even when the mixing process was performed at high speed while cooling the mixing vessel.

In addition, in this test, the temperature of the food ingredients (mainly oily and fatty materials) when mixing began was 3.3 to 5.7 degrees Celsius, but rose to 15.8 degrees Celsius after the mixing process. As with the previous test, no special cooling process was performed on the entire mixing vessel in this demonstration test.

As explained above, by using the rotary blade structure according to the present invention, the food ingredients can be mixed and kneaded at low speed for a short time without high speed or long time mixing, and the flavor and texture of the food are not lost. In addition, since there is no need to cool the mixing vessel during mixing, there are expected to be benefits such as reduced power consumption, simplified operation, and improved work efficiency.

The embodiments of the present invention are not limited to the examples described above. For example, the shape, arrangement, and materials of each part constituting each example can be changed as appropriate in accordance with the actual implementation without departing from the spirit of the present invention.

The configuration of the present invention can be used in various food manufacturing industries that require stirring and kneading of ingredients, including the dairy product industry and the confectionery industry.

FIG. 2 is a perspective view showing the structure of a rotary blade in the food mixer according to the present invention. FIG. 2 is a perspective view showing a structure of a blade in the rotary blade of FIG. 1 . 1A-1D are schematic vertical cross-sectional views of various blades according to the invention; 1A-1D are schematic vertical cross-sectional views of various blades according to the invention; FIG. 11 is a perspective view showing a rotary blade having another structure according to the present invention. FIG. 11 is a perspective view showing another structure of a rotary blade according to the present invention. 1 is a photograph of the food material to be mixed before the start of the mixing process in Demonstration Test Example 1. 1 is a photograph of the mixed food material after mixing processing in Demonstration Test Example 1. 1 is a photograph (planar direction) showing the structure of the rotary blade used in Demonstration Test Examples 2 and 3. 1 is a photograph (oblique view) showing the structure of the rotary blade used in Demonstration Test Examples 2 and 3. 1 is a photograph of the food material to be mixed before the start of the mixing process in Demonstration Test Example 2. 1 is a photograph of the mixed food material after mixing in Demonstration Test Example 2. 1 is a photograph of the mixed food material after mixing in Demonstration Test Example 3. FIG. 1 is an explanatory diagram showing an example of a typical commercial vertical food mixer. FIG. 15 is a perspective view showing an example of a rotary blade used in the mixer of FIG. 14 . FIG. 16 is a perspective view showing the structure of a blade used in the rotary blade of FIG. 15 .

1 ... Rotary blade structure according to the present invention 11 ... Blade 11
12 ... Fixing metal fitting 13 ... Rotating shaft base 14 ... Spacer member a ... Mixing vessel a1 ... Mixing vessel opening and closing cover a2 ... Rotating shaft b ... Rotating blade b1 ... Blade b2 ... Spacer c ... Rotation drive unit d ... Rotation control unit

Claims (1)

A rotary blade structure comprising a plurality of blades extending from a central axis of rotation along a radial direction of rotation within a horizontal rotational plane of the rotary blade attached to a food mixer, the blades having a planar shape that is point-symmetrical with respect to the central axis of rotation, the blades being made up of an outer curved portion facing the direction of rotation and an inner curved portion facing away from the direction of rotation, the radius of curvature of the outer curved portion being larger than the radius of curvature of the inner curved portion,
A rotating blade structure for an ingredient mixer, characterized in that a predetermined inclination angle (taper) is provided in the vertical direction on the lower outer edge of the outer curved portion, a predetermined inclination angle (taper) is provided in the vertical direction on the upper outer edge of the inner curved portion, and the blade (blade) portion has a predetermined angle of attack facing the horizontal rotation plane of the blade (blade) portion in the direction of rotation, the predetermined angle of inclination and the set angle of attack are both in the angle range of 22° to 32°, and the range in which the angle of inclination (taper) is provided is 1/4 to 1/3 of the blade width length in the rotation direction of the blade (blade) portion.

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