JP4908762B2 - Volumetric pump for food cream and food production apparatus equipped with the same - Google Patents

Description

The present invention relates to a positive displacement pump used for pumping food cream and a food production apparatus including the positive displacement pump.
In the present invention, the food cream comprises a mixture of fat such as milk fat and vegetable fat and water. Specific examples thereof include creams such as whipping creams, and soft cream mixes and ice cream mixes having the same physical properties as creams.
The food in the present invention is produced using the above-mentioned cream for food as a raw material or a part of the raw material. Specific examples thereof include whipped cream, soft cream, ice cream and the like.

2. Description of the Related Art Conventionally, as a whipped cream manufacturing apparatus, there is known an apparatus for continuously whipping a cream by applying a shearing force by passing it through a resistor having a narrow gap while pumping the cream. In order to clean this type of whipped cream manufacturing apparatus, it is widely performed by washing one or more kinds of water, hot water (about 40 ° C.) or a room temperature cleaning liquid specified by the manufacturer, and then sequentially flowing through the apparatus. Has been done. However, in this method, since the temperature of the cleaning liquid or the like is about 40 ° C. or lower, the fat remaining in the apparatus is difficult to melt at this temperature, and it is difficult to completely remove the fat. For this reason, it is recommended to disassemble the device about once a week and clean the disassembled parts with a brush or the like.
In order to completely remove fat without disassembling the apparatus, it is effective to raise the temperature of the cleaning liquid or the like to the melting point of fat (about 35 ° C.) or higher, preferably 40 ° C. or higher. Furthermore, if the temperature of the cleaning solution or the like can be increased to 80 ° C. or higher, a sterilizing effect that kills microorganisms such as bacteria, mold, and yeast can be obtained, so that disinfection in the apparatus can be performed more easily, Even without the use of a chemical solution or the like, it becomes possible to satisfactorily maintain the sanitary condition in the apparatus over a longer period.

In the case of a whipped cream manufacturing apparatus, in order to apply a sufficient shearing force to the cream, the discharge pressure during the manufacturing operation needs to be 0.5 MPa or more. Further, in order to ensure the flow rate of the cleaning liquid or the like, the discharge pressure during the cleaning operation needs to be 0.2 MPa or more.
However, a circumscribed gear pump is mainly used as a pump for pumping in a conventional whipped cream manufacturing apparatus. In this type of external gear pump, a pair of meshed gears (external gears) are provided as rotors in a pump chamber formed in a casing, and between a fixed casing and rotating gear teeth. The fluid is sealed and transferred from the suction port side to the discharge port side. If the clearance between the casing and the gear is large, it may cause a decrease in discharge pressure due to fluid leakage from the discharge port side to the suction port side. It is designed giving priority to obtaining a discharge pressure as follows.

By the way, when two kinds of liquids with different temperatures are passed through the circumscribed gear pump, two side plates are provided in contact with both sides of the gear pair in the axial direction, and the gear is sandwiched by planes perpendicular to the shaft to heat the material. A general method is to reduce the change in the capacity of the pump by balancing the pressure in the pump in response to the change in clearance due to expansion.
Patent Document 1 describes a configuration in which a linear expansion coefficient of a rotor is made smaller than a linear expansion coefficient of a housing in a positive displacement pump used as a vacuum pump or the like for exhausting a compressible fluid (a gas such as air). Yes.
JP-A-11-106343

The temperature of the food cream pumped during the manufacturing operation is about 5 ° C. On the other hand, when a cleaning liquid of about 80 ° C is passed during the cleaning operation, the friction between the gear and the casing is caused by the thermal expansion of the material used. The dynamic resistance becomes too large, the pump may stop during operation, the driving motor that drives the gear may be overloaded, and sometimes the pump itself may be damaged.
However, it is difficult to provide a side plate with a small-sized pump, and in the case of a machine part for food, it is not preferable for hygiene to provide an inadvertent liquid pool portion at a location where food contacts.
The pump described in Patent Document 1 is a case where the fluid to be transferred is a compressible fluid (that is, gas), but the fluid to be transferred is incompressible, such as food cream or hot water for washing. When a large amount of a certain liquid is contained, it is difficult to keep the clearance within a predetermined range at a high temperature.

  The present invention has been made in view of the above circumstances, and suppresses a change in the pump performance due to the thermal expansion of the material without providing a side plate, so that a sufficient discharge pressure can be obtained when flowing a high-temperature fluid. It is an object of the present invention to provide a positive displacement pump for cream and a food production apparatus including the same.

In order to solve the above-mentioned problems, the present invention is a positive displacement pump used for pumping food cream, and a casing having a pump chamber formed therein, and the food cream is sucked into the pump chamber from the suction port. and a rotor provided rotatably in the pump chamber so as to discharge the food cream from the outlet while the casing is a resin having a larger linear expansion coefficient than the linear expansion coefficient of the rotor A positive displacement pump for food cream is provided, which is made of polytetrafluoroethylene or polyetheretherketone , and the rotor is made of metal.
Moreover, this invention provides the foodstuff manufacturing apparatus characterized by including the positive displacement pump for creams for foodstuffs mentioned above.

According to the present invention, a high discharge pressure can be obtained during a manufacturing operation (low temperature), and a sufficient discharge pressure can be obtained by maintaining a clearance within a predetermined range during a cleaning operation (high temperature). Can do.
It can be applied to a pump with a simple internal structure without providing a side plate, and since there is no galling of the rotor and the power consumption of the drive motor does not increase, a small motor can be selected. Can be reduced in size and cost.

The present invention will be described below with reference to the drawings based on the best mode.
FIG. 1 is a drawing showing an example of a positive displacement pump for food cream according to the present invention (hereinafter sometimes simply referred to as a “positive displacement pump”), wherein (a) is a partially cutaway sectional view, and (b) is a sectional view. Sectional drawing which follows the SS line | wire of (a), (c) is the elements on larger scale of the A section of (b).

As shown in FIG. 1, the positive displacement pump 10 of this embodiment includes a pump lid 12 having a suction port 11, a casing 13 in which a pump chamber 25 is formed, and a bearing block 16 in which a bearing 15 is accommodated. The shaft 23 is rotatably supported by the bearing 15, the drive gear 21 is attached to one end of the shaft 23 inserted into the pump chamber 25, and the driven gear 22 is engaged with the drive gear 21.
The other end of the shaft 23 opposite to the side on which the drive gear 21 is mounted is exposed to the outside of the bearing block 16, and a drive motor (not shown) for rotating the shaft 23 is provided here. It is done.
The casing 13 has a support shaft portion 24 protruding from the pump chamber 25, and the driven gear 22 is rotatably supported by the support shaft portion 24.

The drive gear 21 and the driven gear 22 are rotors of the positive displacement pump 10, and the suction port 11 and the other side are arranged on one side (left side of FIG. 1B) where the drive gear 21 and the driven gear 22 are engaged. A discharge port 14 is provided (on the right side of FIG. 1B).
This positive displacement pump 10 sucks fluid (food cream) from the suction port 11 into the pump chamber 25 by rotating the shafts 23 and rotating the rotors 21 and 22 in the pump chamber 25. The fluid is sealed between the rotors 21 and 22 and the inner surface 26 of the pump chamber 25 to transfer the fluid from the suction port 11 side to the discharge port 14 side.
Although an example using a pair of gears 21 and 22 as a rotor is shown here, the present invention is a positive displacement pump (screw pump or piston pump) using a screw, a rotary piston, a lobe rotor, or the like as a rotor. , Lobe pumps, etc.).

The casing 13 is made of a material having a linear expansion coefficient larger than that of the rotors 21 and 22. When the rotors 21 and 22 are made of a metal such as stainless steel (SUS), the casing 13 is formed in order to prevent corrosion due to contact of different metals in water and to sufficiently increase the difference in linear expansion coefficient. It is preferable to use a resin (particularly engineering plastic) as the material to be used. Further, by adopting a resin as the material of the casing 13, it is possible to reduce the weight of the pump and the food production apparatus.
Among resin materials used for food machinery, a material having relatively high mechanical strength and heat resistance, usable in the Food Sanitation Law, and having a large linear expansion coefficient is polytetrafluoroethylene (PTFE). ) And polyether ether ketone (PEEK).
For example, the linear expansion coefficient of SUS304 is about 1.73 × 10 ⁻⁵ (1 / ° C.), whereas the linear expansion coefficient of PTFE is about 9.9 × 10 ⁻⁵ (1 / ° C.), which is a PEEK line. The expansion coefficient is about 5.0 × 10 ⁻⁵ (1 / ° C.).
The ratio obtained by dividing the linear expansion coefficient of the casing 13 by the linear expansion coefficient of the rotors 21 and 22 (hereinafter sometimes referred to as “linear expansion coefficient ratio”) is preferably in the range of 2.5 to 6.0. If the “linear expansion coefficient ratio” is less than 2.5, the clearance between the inner surface 26 of the pump chamber 25 and the rotors 21 and 22 cannot be sufficiently maintained at a high temperature, and the frictional resistance between the rotors 21 and 22 and the casing 13 is reduced. This may cause an increase or galling of the rotors 21 and 22. On the other hand, if the “linear expansion coefficient ratio” is greater than 6.0, the clearance between the inner surface 26 of the pump chamber 25 and the rotors 21 and 22 becomes too large at a high temperature, and a sufficient discharge pressure may not be obtained.

Here, the inner surface 26 of the pump chamber 25 has an arc-shaped portion along the circumscribed circle C of the rotors 21 and 22 (when the rotor is a gear, a tip circle). The inner diameter of this portion and D _2.
The inner surface 26 of the pump chamber 25 is d, the clearance between the inner surface 26 of the pump chamber 25 and the circumscribed circle C of the rotors 21 and 22 (hereinafter sometimes simply referred to as “clearance”) at the temperature during the manufacturing operation. 21, 22 the diameter of the circumscribed circle C when the _{D 1,} the percentage represented by the d / _{D 1} × 100% (hereinafter sometimes referred to as "clearance ratio".) is from 0.3 to 0.6% has an inner diameter D ₂ such that the range of. A more preferable range of the “clearance ratio” is 0.4% to 0.5%.
As is clear from FIG. 1C, the clearance d is d = (D ₂ −D ₁ ) / 2 with respect to the outer diameter D ₁ of the rotors 21 and 22 and the inner diameter D ₂ of the pump chamber 25. Have a relationship.
Outer diameter _{D 1} of the rotor, because the size of the pump, about 20~60mm are preferred. In this case, a suitable dimension as the clearance d at the time of manufacturing operation is, for example, about 0.10 to 0.20 mm.
If the “clearance ratio” is less than 0.3%, the clearance between the inner surface 26 of the pump chamber 25 and the rotors 21 and 22 cannot be sufficiently maintained at a high temperature, and the frictional resistance between the rotors 21 and 22 and the casing 13 increases. There is a risk of galling of the rotors 21 and 22. On the other hand, if the “clearance ratio” exceeds 0.6%, the clearance between the inner surface 26 of the pump chamber 25 and the rotors 21 and 22 becomes too large at high temperatures, and there is a possibility that sufficient discharge pressure cannot be obtained.

When the high-temperature fluid is transferred, the entire circumference of the rotors 21 and 22 is covered with the high-temperature fluid. Therefore, the temperature of the rotors 21 and 22 is higher than that of the casing 13 that receives the heat of the fluid only from the inner surface 26 of the pump chamber 25. Is considered to be large. On the other hand, by making the linear expansion coefficient of the casing 13 larger than the linear expansion coefficient of the rotors 21 and 22, the degree of thermal expansion of the casing 13 is approximately the same as the degree of thermal expansion of the rotors 21 and 22. As described above, the clearance at the high temperature (during the washing operation) is maintained at the same level or higher than the clearance at the low temperature (during the manufacturing operation).
For this reason, not only a high discharge pressure can be obtained during the manufacturing operation (flowing the low-temperature fluid), but also a sufficient discharge pressure can be obtained during the cleaning operation (flowing the high-temperature fluid).
In the case of a whipped cream manufacturing apparatus, in order to apply a sufficient shearing force to the cream, the discharge pressure during the manufacturing operation is desirably 0.5 MPa or more. In order to secure the flow rate of the cleaning liquid or the like, the discharge pressure during the cleaning operation is desirably 0.2 MPa or more.

The above-mentioned positive displacement pump can be suitably used not only for a transport device that transports food cream by pressure, but also for a food production device that uses food cream as a raw material or a part of the raw material. A whipped cream manufacturing apparatus will be described as an example of such a food manufacturing apparatus.
FIG. 2 is an external view of the whipped cream manufacturing apparatus 30, and FIG. 3 is a schematic diagram illustrating the configuration of the whipped cream manufacturing apparatus 30. As shown in FIG. 2, the manufacturing apparatus 30 includes a raw material inlet 32 provided on the upper surface of a rectangular parallelepiped apparatus main body 31 and a product suspended downward from a protruding portion 33 protruding from the side surface of the apparatus main body 31. And an outlet 34.

In FIG. 3, the code | symbol 41 is a tank which refrigerates and stores the cream 1 for foodstuffs. A raw material inlet 32 is provided in the upper portion of the tank 41. The tank 41 is connected to the suction port 11 of the pump 10 by a pipe 42. A three-way valve 43 connected to the air intake pipe 44 is provided in the middle of the pipe 42. The air intake pipe 44 is desirably provided with a sterilization filter that removes germs and foreign matters in the air, an air compressor, and the like. It is desirable to adjust the amount of air supplied from the air intake pipe 44 according to the flow rate of the cream 1 so that a desired overrun is obtained.
The discharge port 14 of the pump 10 is connected to a register 46 through a pipe 45. A cooling device 47 is provided around the register 46 in order to maintain the internal temperature at a low temperature. A flow path having a narrow gap is formed inside the register 46.
When the pump 10 is operated, the food cream 1 in the tank 41 is sucked through the pipe 42 and is pumped from the discharge port 14 together with clean air supplied through the air intake pipe 44. When the cream into which the air is introduced passes through the flow path inside the register 46, the cream is continuously whipped by receiving a shearing force to become a whipped cream. The whipped cream 2 prepared in the register 46 is discharged from the product outlet 34.

FIG. 4 is a time chart showing an example of a temperature change of the fluid passing through the pump when the whipped cream is manufactured. In addition, the temperature of warm water for washing | cleaning and a washing | cleaning liquid, the liquid passing time, the temperature of cream, and the time which continues manufacturing operation are only examples, and can be changed suitably.
According to the time chart shown in FIG. 4, hot water at 80 ° C. is allowed to flow for about 3 minutes for sterilization prior to production. During the production operation, a cream having a temperature of 5 ° C. is pumped over about 2 to 7 hours. At the time of cleaning after production, hot water at 60 ° C. is flowed for rinsing for about 3 minutes, and then the cleaning liquid heated to 60 ° C. is flowed for about 5 minutes, and further hot water at 60 ° C. is flowed for rinsing for about 3 minutes.

According to the whipped cream manufacturing apparatus 30 of the present embodiment, the casing 13 of the pump 10 is made of a material having a linear expansion coefficient larger than the linear expansion coefficient of the rotors 21, 22. when the clearance between the circumscribed circle C of the inner surface 26 and the rotor 21 of the pump chamber 25 d, the diameter of the circumscribed circle C of the rotor 21 and _{D 1,} expressed in d / _{D 1} × 100% that because the percentage has an inner diameter D _2, which falls within the range 0.3 to 0.6% of course high discharge pressure during a production run (at low temperature) can be obtained, even when the cleaning operation (at high temperature) Sufficient discharge pressure can be obtained while maintaining the clearance within a predetermined range. It can be applied to a pump with a simple internal structure without providing a side plate, and since there is no galling of the rotor and the power consumption of the drive motor does not increase, a small motor can be selected. Can be reduced in size and cost.

[Adequacy test of casing material]
In the positive displacement pump 10 having the configuration shown in FIG. 1, the casing 13 is manufactured from four types of materials such as PTFE, PEEK, polyacetal, and high density polyethylene, and each casing 13 is a gear (rotor) made of stainless steel (SUS304). Combined with 21,22.
Here, the linear expansion coefficient of SUS304 is 1.73 × 10 ⁻⁵ (1 / ° C.), the linear expansion coefficient of PTFE is 9.9 × 10 ⁻⁵ (1 / ° C.), and the linear expansion coefficient of PEEK is 5.0. × 10 ⁻⁵ (1 / ° C.), the coefficient of linear expansion of polyacetal is 9.0 × 10 ⁻⁵ (1 / ° C.), and the coefficient of linear expansion of high-density polyethylene is 12.0 × 10 ⁻⁵ (1 / ° C.). is there.

Of the casing materials shown in Table 1, PTFE and PEEK have no problem with heat resistance, and can be operated without any problems when pumping cream with a temperature of 5 ° C or flowing hot water with a temperature of 80 ° C. (In Table 1, this is indicated by “◯”).
On the other hand, in the case of polyacetal, since the heat resistance temperature of the resin itself is 80 to 85 ° C., there is no problem in pumping the cream having a temperature of 5 ° C. However, when hot water having a temperature of 80 ° C. is poured, the pump chamber 25 It was found that the sliding portion between the inner surface 26 of the rotor and the rotors 21 and 22 became hotter than this, and the casing 13 was deformed and was not suitable for use (indicated by “Δ” in Table 1).
In the case of high-density polyethylene, the heat resistance temperature of the resin is 60 to 80 ° C., which is inferior to polyacetal in heat resistance and is not suitable for flowing hot water at a temperature of 80 ° C. ").

[Testing the optimum clearance between the rotor and casing]
Further, in order to investigate the optimum clearance between the rotor and the casing, as shown in Table 2, the size of the clearance d was changed in three ways and tested.
In this test, the material of the gears (rotors) 21 and 22 was stainless steel (SUS304), and the material of the casing 13 was tested in two ways: PTFE and PEEK.
The “clearance ratio” in Table 2 means that the clearance between the inner surface 26 of the pump chamber 25 and the circumscribed circle C of the rotors 21 and 22 is d, and the diameter of the circumscribed circle C of the rotors 21 and 22 is D, as described above. _{When 1} is defined, it is defined by the percentage expressed by d / D ₁ × 100%. The values of clearance and “clearance ratio” in Table 2 are values at 4 to 6 ° C. (temperature during production operation).

When the “clearance ratio” is 0.46%, even if 5 ° C. cream and 80 ° C. hot water are alternately supplied to the pump, the pump stops during operation or the drive motor that rotates the rotor is overloaded. And the pump itself was not damaged, and it was possible to operate continuously and stably. When the cream at 5 ° C. was poured, the discharge pressure (0.5 MPa or more) necessary for whipping could be obtained, as well as the clearance at the temperature (4-6 ° C.) during the production operation Despite the design based on the dimensions of the casing, a discharge pressure (0.2 MPa or more) necessary for cleaning could be obtained when hot water of 80 ° C. was poured. In addition, it was possible to suppress an increase in the frictional resistance between the rotor and the casing due to thermal expansion, and to prevent the consumption current of the drive motor from exceeding a preset safety value.
By using the positive displacement pump of the present embodiment as the pump 10 of the whipped cream manufacturing apparatus 30 shown in FIG. 3, 30 kg / w of whipped cream with appropriate overrun and hardness and good shape retention of artificial flowers. We were able to manufacture continuously with high production capacity over time.

On the other hand, when the “clearance ratio” is 0.15%, the cream at 5 ° C. could be pumped without any trouble, but when hot water at 80 ° C. was poured, the friction between the rotor and the casing Increased, and galling occurred, making it impossible to drive.
Moreover, when the “clearance ratio” is 0.76%, the discharge pressure is insufficient because the clearance is too large, and the discharge pressure required for cream at 5 ° C. (0.5 MPa or more) and the discharge pressure required for hot water at 80 ° C. Any of (0.2 MPa or more) could not be obtained.

  INDUSTRIAL APPLICABILITY The present invention can be used for various food production apparatuses provided with a pump that pumps food cream.

(A) is a partial notch sectional view which shows an example of the positive displacement pump of this invention, (b) is sectional drawing which follows the SS line | wire of (a), (c) is A part of (b). FIG. The external appearance of the whipped cream manufacturing apparatus which concerns on an Example is shown, (a) is a top view, (b) is a left view, (c) is a front view, (d) is a right view. It is the schematic which shows the structure of the whipped cream manufacturing apparatus which concerns on an Example. It is a time chart which shows an example of the temperature change of the fluid which passes a pump at the time of whipped cream manufacture.

Explanation of symbols

C: circumscribed circle of rotor, d: clearance between inner surface of pump chamber and circumscribed circle of rotor, D ₁ ... diameter of circumscribed circle of rotor, D ₂ ... inner diameter of pump chamber, 1 ... cream for food, 2 ... Food (whipped cream), 10 ... positive displacement pump, 11 ... suction port, 13 ... casing, 14 ... discharge port, 21 ... driving gear (rotor), 22 ... driven gear (rotor), 25 ... pump chamber, 26 ... Inner surface of pump chamber, 30 ... food manufacturing apparatus.

Claims (2)

A positive displacement pump used for pumping food cream, and a casing having a pump chamber formed therein, and the food cream is sucked into the pump chamber from the suction port and the food cream is discharged from the discharge port. And a rotor provided rotatably in the pump chamber,
The casing is made of polytetrafluoroethylene or polyetheretherketone, which is a resin having a linear expansion coefficient larger than that of the rotor,
A positive displacement pump for food cream, wherein the rotor is made of metal.   A food manufacturing apparatus comprising the positive displacement pump for food cream according to claim 1.

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