JP2619642B2 - Eccentric screw pump - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an eccentric screw pump suitable for transporting a highly viscous fluid.

[Conventional technology]

Eccentric screw pumps are capable of pumping even highly viscous fluids and have the property of being quantitative.
It was used for pumping high viscous fluids such as pulp liquid, chemical liquids, and foods.

The structure of this eccentric screw pump, as shown in FIG.
A male screw rotor R having a circular cross section eccentric with respect to the rotation axis is provided inside a stator S having an oval cross section and a female screw inner surface having a pitch twice that of the rotor R,
The rotor R has two universal joints J,
J, the shaft F was connected via the connecting rod C, and was sealed with the shaft sealing portion H. When the rotor R is rotated by the shaft F, the rotor R rotates about the rotation axis and performs an eccentric motion with respect to the axis of the fixed stator S, thereby sucking the fluid into the suction port A.
From the nozzle to the discharge port B.

Further, the stator S is made of metal, rubber, or the like, and the rotor R, the connecting rod C, the shaft F, and the like are all made of metal.

[Problems of the prior art]

However, the conventional eccentric screw pump has a structure in which torque is transmitted to the rotor R by the shaft F, requires the shaft sealing portion H, and the handling liquid leaks.
There is an inconvenience that it is not suitable for handling liquids that have a high vapor pressure, may cause explosive ignition, toxic liquids, expensive liquids, liquids that change when exposed to outside air, and the like.

Further, the shaft F and the rotor R are connected by two universal joints J, J so that the rotor R can perform eccentric movement about the axis of the stator S. Since the universal joint J is in the pumping fluid, The fluid permeated the universal joint J and was prone to failure.

For example, in the case of an eccentric screw pump used for pumping pulp, it is difficult to rotate the universal joint J after about three months of use, and each time it is disassembled and cleaned,
The universal joint J had to be replaced with a new one, which was very troublesome.

Further, the conventional eccentric screw pump requires many parts such as two universal joints J, J, a connecting rod C, and a shaft F, and it is difficult to reduce the size because the structure is complicated.

In addition, since the rotor R rotates while being strongly pressed against the inner surface of the stator S, the stator S made of metal or rubber is liable to be worn, and abrasion powder is mixed into the pumping fluid, which is especially important in the case of pumping food. Had become a problem.

[Means for solving the problem]

In view of the above problems, the present invention provides a stator having an oval cross section and a female screw-shaped inner surface provided in a casing provided with a discharge port and a suction port with a gap provided therein. The rotor is rotatably supported via a bearing provided with a groove communicating with the rotor, and a rotor having a male screw shape in which the center of the circular cross section is eccentric with respect to the rotation axis is mounted on the stator such that the respective axes are eccentric. While rotatably supported via a bearing, at least the rotor, the stator, and the bearing are formed of ceramics to form a leak-free eccentric screw pump, and the rotor is driven to rotate by rotating the stator,
The fluid is fed under pressure, and a part of the fluid is recirculated through a gap formed between the casing and the stator to cool a bearing that supports the stator.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a stator, which has an oblong cross section and has a female screw-shaped inner surface. Reference numeral 2 denotes a rotor having a male screw shape having a circular cross section eccentric with respect to the rotation axis.
They are mounted such that their axes are eccentric by a distance e.
The stator 1 and the rotor 2 are completely sealed by a suction casing 3 having a suction port 5 and a delivery casing 4 having a discharge port 6 to form a leak-free pump. The stator 1 is rotatably supported by bearings 7 and 8. A portion of the stator 1 that contacts the bearing 7 is provided with a sleeve 9 and a thrust washer 10, and a portion of the stator 1 that contacts the bearing 8 is provided with a sleeve 11 and a thrust washer 12. The rotor 2 is also rotatably supported by thrust bearings 13, 15 and radial bearings 14, 16.

Further, a pulley 17 is rotatably provided outside the suction casing 3, and a driving magnet 18 is provided on the pulley 17, and a driven magnet 19 is provided on the stator 1.

The operation of the non-leakage eccentric screw pump constructed as in the above embodiment is as follows. First, when the pulley 17 is rotated by a motor (not shown), the driving magnet 18 and the driven magnet 19 are attracted, and the torque is transmitted to the stator 1. Is done. When the stator 1 rotates, the rotor 2 mounted eccentrically by a distance e from the axis of the stator 1 rotates in a planetary motion, and as a result, a pumping action occurs to transfer fluid from the suction port 5 to the discharge port 6. It can be pumped.

Further, grooves are formed in the bearings 7 and 8, and the high pressure liquid on the discharge port 6 side passes through the groove of the bearing 7 by utilizing a pressure difference from the high pressure discharge port 6 side to the suction port 5 side. Then, it passes through the outer peripheral portion of the stator 1, passes through the groove of the bearing 8, and returns to the suction port 5 side, and the reflux liquid performs lubrication and cooling.

In the above embodiment, the stator 1, the rotor 2, the suction casing 3, the delivery casing 4, the bearings 7, 8, the sleeves 9, 11, the thrust washers 1,
It is more effective if all of the bearings 0, 12, the thrust bearings 13, 15 and the radial bearings 14, 16 are made of ceramic.

Such an eccentric screw pump according to the embodiment of the present invention can be made leak-free with a simple structure, and since there is no joint portion, maintenance is easy and it can be used for a long time. Further, if the wetted parts are made of ceramic, corrosive fluid can be pumped and wear can be reduced.

 Next, another embodiment of the present invention will be described.

The eccentric screw pump shown in FIG. 2 has almost the same structure as that shown in FIG. 1, except that the stator 1 has a motor unit rotor 21 and the motor unit stator 20 is provided outside the casing.
Are arranged to form a canned motor, and the stator 1 is rotated.

In these eccentric screw pumps, the rotor 2
Is strongly pressed against the inner surface of the stator 1 and rotates. However, if the stator 1 is made of ceramic as described above, wear is small, and there is little possibility that abrasion powder is mixed into the pumping fluid.

The stator 1 has an oval cross section, and has an inner surface formed in a female screw shape so as to rotate the oval,
In order to form the stator 1 from ceramic, it is molded by a rubber press method or a casting method using a male screw-shaped middle mold having a smooth outer surface having the same shape as the inner surface. What is necessary is just to pull out while twisting a metal mold. After firing, the thus formed stator 1 is polished on the inner surface to finish it into a smooth surface before use.

Alumina, zirconia, silicon carbide, silicon nitride, sialon, and the like are used as the ceramics forming the other liquid-contacting parts of the stator 1. Among them, silicon carbide and silicon nitride are most preferred in terms of wear resistance and corrosion resistance. It was excellent.

〔The invention's effect〕

As described above, according to the present invention, a stator having an elliptical cross section and an internal thread-shaped inner surface is provided in a casing provided with a discharge port and a suction port with a gap, and the gap is provided. The rotor is rotatably supported via a bearing provided with a groove communicating with the rotor, and a rotor having a male screw shape in which the center of the circular cross section is eccentric with respect to the rotation axis is mounted on the stator such that the respective axes are eccentric. While rotatably supported via a bearing, at least the rotor, the stator, and the bearing are formed of ceramics. By rotating the stator, the rotor is driven to rotate, and the fluid is pumped, and a part of the fluid is pumped. Since the leakage eccentric screw pump is configured to cool the bearing that supports the stator by refluxing through the gap formed between the casing and the stator, the structure is simple and small. Be a leakage pump can be maintained excellent performance without causing failure over time because there is no joint portion. Further, among the liquid contact parts, the rotor, the stator and the bearing are formed of ceramics, so that even a corrosive fluid can be pumped, and the wear resistance accompanying sliding of each part can be enhanced. In particular, since the bearing that supports the rotation of the stator is cooled by recirculating a part of the pressurized fluid to the gap between the casing and the stator, wear can be further suppressed, and there is no leakage eccentricity that can be used for a long time. It can be a screw pump.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an eccentric screw pump according to an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view showing another embodiment of the present invention. FIG. 3 is a longitudinal sectional view showing a conventional eccentric screw pump. 1: Stator, 2: Rotor 3: Suction casing 4: Delivery casing 5: Suction port 6: Discharge port

Claims (1)

(57) [Claims] 1. A stator having an elliptical cross section and a female screw-shaped inner surface provided in a casing provided with a discharge port and a suction port with a gap provided therein, and having a groove communicating with the gap. On the other hand, a male screw-shaped rotor whose center of a circular cross section is eccentric with respect to the rotation axis is mounted on the stator so that the respective axes are eccentric, and is rotated via the bearing. While freely supporting, at least the rotor, stator, and bearing are formed of ceramics,
By rotating the stator, the rotor is driven to rotate, the fluid is pumped, and a part of the fluid is returned through a gap formed between the casing and the stator to cool a bearing that supports the stator. Eccentric screw pump.