JP2001254695A - Turbo pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a turbo pump having a simple constitution, reducing a disk friction loss at a low cost, and improving the efficiency of the pump. SOLUTION: This turbo pump provided with an impeller 1 for providing kinetic energy to fluid is characterized that the impeller 1 is provided with a water repellent surface and formed with narrow grooves of tens μm or less in the surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbo pump which imparts water repellency to the surface of an impeller to reduce a friction loss caused by rotation and achieve high efficiency.

[0002]

2. Description of the Related Art Conventionally, in order to increase the head of a turbo type pump, it has been practiced to increase the rotation speed of an impeller to increase the speed, or to increase the diameter of the impeller to increase the peripheral speed. Therefore, this conventional technique will be described.

FIG. 6 is a structural view of a conventional turbo pump. 6, reference numeral 101 denotes an impeller that receives rotational torque from a driving source (not shown) such as an electric motor disposed on the outer periphery and applies kinetic energy to a fluid;
01 is a shaft for rotatably supporting 01, 103 is this shaft 1
02 is a bearing that is inserted into the bearing 02 and rotatably holds the impeller 101. When an electric motor is used as the drive source,
A stator for forming a rotating magnetic field is placed on the outer periphery, and the impeller 10
A configuration in which a permanent magnet or the like is provided in 1 is appropriate. 10
Reference numeral 4 denotes a shaft 102 fixed in a cantilever shape and an impeller 10
A casing having a diffuser for accommodating 1 therein and collecting and increasing the pressure of the fluid discharged from the impeller 101, and guiding the fluid to the pump discharge port after the pressure is increased;
Reference numeral 105 denotes a rear shroud forming a part of the impeller 101. In addition, a plurality of blades 106 are provided in the impeller 101 to give kinetic energy to the fluid.

Next, the operation and operation of the conventional turbo type pump will be described. When a rotation torque is input from the driving source, the impeller 101 rotates, and the plurality of blades 106 provided in the impeller 101 rotate. The rotation of the blades 106 increases the angular momentum of the fluid, and the fluid given kinetic energy is discharged from the outer periphery of the impeller 101. The increase in the kinetic energy is proportional to the sum of the squared differences of the components of the absolute velocity, the relative velocity, and the peripheral velocity of the flow in the blade 106. In the turbo type pump as shown in FIG. 6, the peripheral speed component tends to be relatively large as compared with the absolute speed component and the relative speed component, so that the kinetic energy is generally governed by the impeller diameter and the rotation speed. . Therefore, as described above, such a conventional turbo-type pump increases the amount of kinetic energy received by increasing the rotation speed of the impeller or increasing the diameter of the impeller, thereby increasing the diffuser. Into pressure,
The aim was to increase the head. However, since increasing the diameter of the impeller leads to an increase in size, the electric motor must be DC
A higher head was achieved by increasing the number of revolutions by using a motor or the like.

[0005] Next, as another conventional method for increasing the head of a turbo-type pump, there is a method for reducing the pump loss and increasing the efficiency to achieve a higher head. One of the losses of the turbo-type pump is a disc friction loss. In order to reduce the disc friction loss, conventionally, it has been proposed to apply a water-repellent coating to the surface of the impeller or the casing wall (Japanese Patent Application Laid-Open No. Hei 9 (1999)). -195983). Furthermore, Transactions of the Japan Society of Mechanical Engineers (B) 65 [635] (1999-7)
"Friction resistance characteristics of super-water-repellent rotating disk in container" Ogata, Watanabe, p. 2391-2397 also reports the effect of reducing the resistance of a polymer additive and the effect of reducing the resistance of a super-water-repellent disk, and suggests the application of the resistance-reducing effect of the super-water-repellent disk to turbomachinery. I have.

[0006]

As described above, in the conventional turbo type pump, attempts have been made to increase the head and the efficiency by changing the diameter and the number of revolutions of the impeller. But,
If the diameter of the blade is easily increased to increase the head, both the pump and the motor become large. At present, downsizing of pump-incorporated devices is progressing, but if a pump to be incorporated therein is forcibly reduced in size, the efficiency of both the pump and the motor will be reduced. Energy saving is also required for pump-incorporated devices, but it is difficult to achieve energy saving unless efficiency is improved, and it is desired to increase the efficiency of turbo-type pumps from the viewpoint of energy saving as well as miniaturization.

The loss of the turbo-type pump includes mechanical loss and fluid loss inside and outside the impeller. In particular, in a small-sized, low-specific-speed turbo-type pump, the fluid loss caused by the friction between the impeller and the fluid occupies a considerable weight with respect to the total loss (Japanese Patent Publication No. 61-51680). It is known that the loss due to the fluid friction (disk friction loss) is proportional to the fifth power of the outer diameter of the impeller and proportional to the square of the rotational speed. Increasing the impeller diameter, on the contrary, results in a dramatic increase in fluid loss, which severely reduces the efficiency of the pump. As an example, the impeller diameter is 6
In the case of an electric small pump having an output of 20.5 W at the rated operation at 0 mm, the loss at the rated rotation speed (5000 rpm) is considered to be about 10 W, and the loss other than the motor loss is 1
The disk friction loss accounts for about 5%. The above-mentioned conventional technology for reducing disc friction loss is two methods of reducing this fluid loss, but adding a polymer additive is not always possible regardless of the type or use of the fluid. In addition, the technology for reducing resistance with a super-water-repellent disk is a problem that when rotating at high speed to increase the head, the flow near the impeller reaches a turbulent flow area, and in this state, a sufficient loss reduction cannot be expected. was there.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a turbo-pump having a simple structure, inexpensively reducing disc friction loss, and realizing high efficiency of the pump.

[0009]

In order to solve the above-mentioned problems, a turbo pump according to the present invention has an impeller having a water-repellent surface, and the surface has a narrow groove of several tens μm or less. Is formed.

This makes it possible to reduce the disc friction loss with a simple structure and at a low cost, and to realize a high efficiency pump.

[0011]

DETAILED DESCRIPTION OF THE INVENTION The invention described in claim 1 of the present invention is a turbo pump provided with an impeller for giving kinetic energy to a fluid, wherein the impeller has a water-repellent surface. And, since the turbo pump is characterized in that a narrow groove of several tens of μm or less is formed on the surface, slippage occurs between the water-repellent surface and the fluid due to bubbles retained in the narrow groove. Once generated, fluid friction on the impeller surface can be reduced, thereby reducing disk friction loss simply and inexpensively.

According to a second aspect of the present invention, since the impeller is formed of a water-repellent resin, the impeller is formed of a water-repellent resin. By simply molding the fluid, the fluid friction generated on the impeller surface can be reduced, and the disc friction loss can be reduced.

According to a third aspect of the present invention, there is provided a turbo pump having an impeller for imparting kinetic energy to a fluid, wherein the impeller is formed of a water-repellent resin, and A turbo type pump characterized in that the surface roughness on the outer peripheral side of the car is formed large and the surface roughness on the inner peripheral side is formed small. Because the surface roughness is increased on the side, air bubbles enter into the unevenness of the surface, causing slip between the water-repellent surface and the fluid, and reducing the fluid friction,
Where the peripheral velocity on the inner peripheral side is small and the laminar flow state occurs, the surface roughness is reduced, so that the fluid friction can be reduced, the disc friction loss can be reduced as a whole, and the pump can be made more efficient.

According to a fourth aspect of the present invention, there is provided a turbo pump having an impeller for imparting kinetic energy to a fluid, wherein the impeller has a radial shape having a water-repellent inner surface. Since the narrow groove is formed and the impeller is a turbo type pump characterized by having a hydrophilic surface except for the narrow groove, bubbles are not attached due to hydrophilicity other than the narrow groove, Since bubbles adhere only to the narrow groove, even when operating in a turbulent flow region due to bubbles remaining in the narrow groove, a slip is reliably generated between the water-repellent surface and the fluid,
Fluid friction on the surface of the impeller can be reduced, so that disc friction loss can be reduced simply and inexpensively.

Embodiment 1 Hereinafter, a turbo pump according to Embodiment 1 of the present invention will be described with reference to the drawings.
FIG. 1A is a perspective view of a turbo pump according to Embodiment 1 of the present invention, and FIG. 1B is a partially enlarged sectional view of a portion A.

In FIG. 1, reference numeral 1 denotes an impeller which receives rotational torque from a driving source (not shown) such as an electric motor disposed on the outer periphery and gives kinetic energy to a fluid;
Is a small groove formed on the surface of the impeller 1 provided with a front shroud (not shown) in addition to the rear shroud 2 and 4 is an air bubble adhered to the small groove 3. In the first embodiment, the characteristic portions of the present invention are mainly the portions described above, but other configurations are basically the same as those of the conventional turbo pump described in FIG. The description is omitted from the description of the conventional technology.

As shown in FIG. 1, fine fine grooves 3 are formed on the surface of the rear shroud 2, and the representative dimensions of the fine grooves 3 are several tens μm or less. However, those having a representative dimension of at least several μm are suitable. Narrow groove 3
Is typically the average of the groove widths. Since liquid such as water generally has a large surface tension with respect to gas, it cannot penetrate into the fine narrow groove 3, and air bubbles 4 adhere to the inner surface (recessed portion) of the fine groove 3 and stay there. If the bubble 4 collapses, the collapsed gas is present in a film form so as to cover the narrow groove 3. In any case, since gas is present in the narrow groove 3, an interface phenomenon between the solid, liquid and gas near the surface of the impeller 1 causes slippage of the fluid, and this slip causes rotation of the impeller 1. This reduces the frictional resistance that occurs.

Such a decrease in frictional resistance due to the interface phenomenon is particularly remarkable when the rotation speed of the impeller 1 is relatively low and the flow belongs to a laminar flow region. However, when the rotation speed of the impeller 1 increases and the flow belongs to the turbulent flow region, the stagnation of the bubbles 4 decreases, so that the slip of the fluid decreases and the frictional resistance does not decrease much. Therefore, the turbo pump according to the first embodiment has a rotation speed that is not so high and includes a boundary where the flow around the impeller 1 transitions from a laminar flow region to a turbulent flow region depending on the operation state. It is suitable to be used for those operated at When such an operation is performed, the liquid enters the narrow groove 3 due to the surface tension and the water repellency because the inner surface of the narrow groove 3 of the first embodiment has the water repellent property. No, bubble 4
Can be attached in the narrow groove 3 so that the frictional resistance is reduced. If the representative dimension of the groove exceeds several tens of μm, the liquid can enter the narrow groove 3 and the effect of reducing the frictional resistance is reduced. Therefore, the narrow groove 3 on the surface of the rear shroud 2 is stably formed. It needs to be formed to several tens μm or less.

The turbo-type pump having a water-repellent surface as in the first embodiment can be easily coated by brush-coating or silk-printing a water-repellent paint. In other words, the paint is simply brush-coated or silk-printed, and after drying, the surface is tens of μm without any particular operation.
Are formed. Examples of the coating exhibiting water repellency include those containing a fluorine resin, a silicone resin, and a copolymer of a fluorine-containing unsaturated monomer and a silicon-containing polymerizable unsaturated monomer as components.

(Embodiment 2) Next, a turbo pump according to Embodiment 2 of the present invention will be described. FIG. 2 (a)
2 is a perspective view of a turbo pump according to Embodiment 2 of the present invention, FIG. 2B is a partially enlarged cross-sectional view of a portion A, and FIG. 3 is a partial enlarged view of the operation of the turbo pump according to Embodiment 2 of the present invention. It is sectional drawing.

As shown in FIGS. 2 (a) and 2 (b), it is desirable that the narrow groove 3 has a rectangular cross section and the direction in which the groove is directed is substantially perpendicular to the flow. It is formed so as to be substantially perpendicular to the rotation direction of the vehicle 1. The cross-sectional shape is not particular. Therefore, the pattern in the longitudinal direction of the narrow groove 3 has a radial shape oriented in a radial direction about the rotation axis of the impeller 1. As shown in FIG. 3, 5 is a hydrophilic film having hydrophilicity, and 6 is a water repellent film having water repellency. Note that, similarly to the first embodiment, the characteristic parts of the turbo pump of the second embodiment are basically the above-described parts, and the other configurations are the same as those of the conventional turbo pump described in FIG. Therefore, the detailed description is omitted from the description of the conventional technology.

In the second embodiment, the size of the narrow groove 3 is larger than that of the first embodiment, the groove width is several tens of microns or more, and the depth is the same. The turbo pump according to the second embodiment has a higher rotation speed than that of the first embodiment, and includes a boundary where the flow around the impeller 1 transitions from a laminar flow region to a turbulent flow region depending on an operation state. Suitably used for those operated in turbulent regions. For this reason, in Embodiment 2, the water repellent film 6 is applied to the inner surface of the narrow groove 3, and the hydrophilic film 5 is applied to the entire surface of the impeller 1 other than the narrow groove 3. As described above, the outer surface of the hydrophilic film 5 and the inner surface (concave portion) of the groove covered with the water repellent film 6 are employed in combination, so that the surface other than the narrow groove 3 (apparent top) is formed. The bubbles 4 are less likely to adhere to the portion of the hydrophilic film 5, and conversely, the bubbles are more likely to adhere to the inner surface of the narrow groove 3 by the water-repellent film 6. Therefore, even when the rotation speed of the impeller 1 is relatively high and the flow near the surface becomes turbulent, the bubble 4
Can be attached inside the groove. As described above, since the air bubbles 4 occupy a considerable portion of the surface of the impeller 1, the frictional resistance of the surface of the impeller 1 including the water and the rear shroud 2 near the surface of the impeller 1 is significantly reduced. To reduce disc friction loss. This makes it possible to increase the efficiency of the turbo pump at low cost.

In such a configuration in which the hydrophilic film 5 and the water repellent film 6 are combined, a relatively thick water repellent film 6 is coated on the surface of the impeller 1 by applying a water repellent paint, and then the hydrophilic paint is applied. After coating and curing, the surface can be easily formed by shaving off the hydrophilic film 5 with a comb-shaped blade or the like to form a groove. It is also possible to apply a hydrophilic paint to the outer surface of an impeller made of a water-repellent resin by using a silk printing technique to produce a similar configuration.

Embodiment 3 A turbo pump according to Embodiment 3 of the present invention will be described. FIG. 4 is a perspective view of a turbo pump according to Embodiment 3 of the present invention. The basic configuration is the same as in the first embodiment.

As shown in FIG. 4, the turbo-type pump according to the third embodiment comprises, for example, a fluorine resin, a silicon resin, and a copolymerizable component of a fluorine-containing unsaturated monomer and a silicon-containing polymerizable unsaturated monomer. It is prepared by molding a resin such as a copolymer contained as a resin. Each of these resins has a water-repellent property. Therefore, since the impeller 1 is molded from a resin having water-repellent properties, the entire outer surface of the impeller 1 of the turbo-type pump according to the third embodiment has water-repellency. In addition, fine irregularities having a typical size of several tens of μm or less are formed on the surface produced by resin molding due to the roughness of the surface finish, which functions as the narrow groove 3 described in the first embodiment, and retains bubbles. Let it.
As described above, since it is not necessary to separately form the water-repellent coating in a separate step, the efficiency of the turbo-type pump can be further improved at a lower cost.

(Embodiment 4) A turbo pump according to Embodiment 4 of the present invention will be described. FIG. 5 is a perspective view of a turbo pump according to Embodiment 4 of the present invention. The basic configuration is the same as that of the third embodiment.

The surface roughness described below is defined by the center line average roughness (JIS B0601) in each part randomly extracted from the surface of the object. As shown in FIG. 5, reference numeral 7 denotes a portion where the surface roughness is large on the outer peripheral side of the impeller 1, that is, a so-called rough surface. Reference numeral 8 denotes a portion of the inner peripheral side of the impeller 1 where the surface roughness is small, that is, a so-called smooth surface. Note that, similarly to the turbo pump according to the third embodiment, the turbo pump according to the fourth embodiment includes, for example, a fluororesin, a silicon resin, and a fluorine-containing unsaturated monomer and a silicon-containing polymerizable unsaturated monomer. It is prepared by molding a resin such as a copolymer contained as a copolymer component. As a result, fine irregularities with a center line average roughness of several tens of μm or less are formed on the surface produced by resin molding. An impeller 1 having two portions marked with can be manufactured. When the surface finish of the molding die is roughened, a portion 7 having a large surface roughness is formed on the outer peripheral side of the impeller 1. Further, when the surface finish of the molding die is made smooth, a portion 8 having a small surface roughness is formed on the inner peripheral side of the impeller 1.

When the impeller 1 is rotated at a high speed, the peripheral speed on the outer peripheral side of the impeller 1 is high, and the flow near the outer surface thereof is in a turbulent state. In addition, the peripheral speed is relatively slow on the inner peripheral side of the impeller 1, and the flow in the vicinity is in a laminar state. On the outer peripheral side, which is a turbulent region, the surface roughness is large and has water repellency. Therefore, once air bubbles enter the concaves and convexes on the surface, they easily adhere to the surface and stay there. The presence of these bubbles can effectively reduce the frictional resistance even in the turbulent region. Next, on the inner peripheral side, the peripheral speed is low, the surface roughness is small, so that a relatively laminar flow state can be maintained, and since there is also water repellency, fluid friction can be reduced by an interface phenomenon. .

Therefore, if the surface roughness is increased on the outer peripheral side and reduced on the inner peripheral side, it is possible to reduce the disk friction loss over the entire outer surface of the impeller 1 including the rear shroud 2, and the high efficiency of the turbo pump is improved. Can be achieved at low cost. Note that the boundary between the portion 7 where the surface roughness is increased and the portion 8 where the surface roughness is reduced is based on the Reynolds number Re (= ω · r · r / ν, ω) based on the normal rotation speed of the impeller 1. :
It is determined by the angular velocity of the impeller, r: radius of the rear shroud, ν: kinematic viscosity of the fluid), and the degree of surface roughness.

[0030]

As described above, in the turbo type pump according to the first aspect of the present invention, the slippage between the water-repellent surface and the fluid is generated by bubbles retained in the narrow groove, and the surface of the impeller The friction of the fluid can be reduced, and thereby the disc friction loss can be reduced simply and inexpensively, and the efficiency can be improved.

In the turbo type pump according to the second aspect of the present invention, fluid friction generated on the impeller surface can be reduced only by molding the impeller with a water-repellent resin, thereby reducing disc friction loss. Thus, high efficiency of the pump can be realized.

In the turbo pump according to the third aspect of the present invention, since the surface roughness is large on the outer peripheral side of the impeller where the peripheral speed is large and the turbulent flow occurs, air bubbles enter into the unevenness of the surface and the repellency is increased. Fluid friction can be reduced by generating a slip between the aqueous surface and the fluid, and where the peripheral speed on the inner peripheral side is small and in a laminar flow state, the surface roughness is also small, so the fluid friction can be reduced,
As a whole, disc friction loss can be reduced, and high efficiency of the pump can be realized.

In the turbo pump according to the fourth aspect of the present invention, air bubbles do not adhere due to hydrophilicity except in the narrow groove, and air bubbles adhere only in the narrow groove. A slippage is reliably generated between the water-repellent surface and the fluid, thereby reducing the fluid friction on the impeller surface, thereby easily and inexpensively reducing the disc friction loss and improving the efficiency. Can be achieved.

[Brief description of the drawings]

FIG. 1A is a perspective view of a turbo pump according to a first embodiment of the present invention. FIG.

FIG. 2A is a perspective view of a turbo pump according to Embodiment 2 of the present invention. FIG.

FIG. 3 is a partially enlarged cross-sectional view of a turbo pump according to Embodiment 2 of the present invention during operation.

FIG. 4 is a perspective view of a turbo pump according to Embodiment 3 of the present invention.

FIG. 5 is a perspective view of a turbo pump according to Embodiment 4 of the present invention.

FIG. 6 is a structural view of a conventional turbo type pump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 101 Impeller 2, 105 Rear shroud 3 Narrow groove 4 Bubbles 5 Hydrophilic film 6 Water repellent film 7 Part with large surface roughness 8 Part with small surface roughness 102 Shaft 103 Bearing 104 Casing 106 Feather

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tokumi Nagase 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture F-term in Matsushita Electric Industrial Co., Ltd. 3H033 AA01 BB03 BB06 CC01 DD06 DD25 DD26 EE08 EE19

Claims (4)

[Claims] 1. A turbo pump having an impeller for imparting kinetic energy to a fluid, wherein said impeller has a water-repellent surface, and said surface has a fine groove of several tens μm or less. A turbo type pump characterized by being formed. 2. The turbo pump according to claim 1, wherein said impeller is formed of a water-repellent resin. 3. A turbo-type pump having an impeller for imparting kinetic energy to a fluid, wherein the impeller is formed of a water-repellent resin and has a large surface roughness on the outer peripheral side of the impeller. And a surface roughness on the inner peripheral side is reduced. 4. A turbo pump having an impeller for imparting kinetic energy to a fluid, wherein said impeller is formed with radial narrow grooves having a water-repellent inner surface. A turbo-type pump having a hydrophilic surface except for a narrow groove.