JPH0631198Y2 - Bearing device for leak-free pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is a leak-free (sealless) pump such as a magnet drive pump or a canned motor type pump used for transferring dangerous chemical liquids, expensive chemical liquids, etc. In particular, the present invention relates to a bearing device that prevents damage to the bearing due to insufficient lubrication and cooling of the bearing or impact load.

[Conventional technology]

As described above, in the leak-free pump, the pump impeller and the driven magnet wheel are attached to the rotary shaft, and the drive magnet wheel that is interlocked with the electric motor via the can that corresponds to the outer periphery of the driven magnet wheel and corresponds to the thin partition wall. The magnet drive pump that rotates the pump impeller by applying magnetic force to the driven magnet wheel and the motor rotor together with the rotating part of the pump are immersed in the pumping liquid to overhang the impeller. The supported motor shaft is supported by two bearings in liquid, and a thin corrosion-resistant cylindrical can is attached inside the motor stator to isolate the rotor and insulate the stator from liquid. There are canned motor type pumps.

FIG. 3 is a longitudinal sectional view showing a conventional example of the above-mentioned magnet drive pump, in which an impeller 2 arranged in a pump casing 1 made of a non-magnetic material is attached to a rotor 4 together with a driven magnet wheel 3. It is rotatably supported by a slide bearing 5 made of carbon or ceramics. The slide bearing has a slight axial gap (end play) between the end surface of the rotary side bearing slide body and the end surface of the stationary side bearing slide body at one end (on the left side on the electric motor side in the figure).
This is provided in order to prevent deviation due to manufacturing error of each component at the time of assembly and escape due to thermal expansion during operation.

On the other hand, the drive magnet wheel 6 is arranged outside a can (can) 7 made of a thin non-magnetic material that separates the chambers containing the magnet wheels 3 and 6 from each other, and via a yoke (frame) 8. It is attached to the rotating shaft 10 of the electric motor 9. In the figure, 11
Is an outer side plate of the electric motor 9, 12 is a cooling fan, 13 is a bracket (arm) for accommodating the drive magnet wheel 6 and for mounting the electric motor 9 on the pump casing 1, and 13a is a cooling hole formed on the peripheral surface of the bracket 13. A ventilation hole, 14 is a casing cover.

When the drive magnet wheel 6 is rotated by the electric motor 9 during pump operation, the magnetic force of the drive magnet wheel 6 causes the driven magnet wheel 3 to rotate, the pump impeller 2 is driven, and as shown by the arrow a, Is designed to inhale and exhale.

A part of the high-pressure liquid discharged from the outer peripheral outlet of the impeller 2 has a hole 14a in the casing cover 14 as shown by an arrow B.
A circulating flow is formed which is guided to the magnet side end of the slide bearing 5, flows between the sliding surfaces toward the impeller side end, and returns to the pump chamber again. After passing through the hole 14a of the casing cover 14 as indicated by the arrow B, a part of the liquid further flows through the gap between the outer peripheral portion of the driven magnet wheel 3 and the inner surface of the can 7 as shown by the arrow C, and rotates. It is designed to be guided to the suction part through the central part of the shaft.

[Problems to be solved by the device]

The above-mentioned conventional magnet drive pump (non-leak pump)
Employs a sliding bearing structure made of carbon or ceramics.However, in the conventional sliding bearing structure pump, when the idle operation, cavitation operation, transfer of the aerated liquid, etc. Since the circulating flow does not flow smoothly, there is a problem in that the bearing is in a state of insufficient lubrication and cooling and is damaged in a short time, so that the original function of sucking and pumping the liquid by the pump impeller cannot be achieved.

It is an object of the present invention to provide a leak-free pump capable of sucking and pumping liquid, which is the original function of the pump, without damaging the bearing even in the above operating state.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention rotatably supports a rotor by a radial bearing and a thrust bearing, and a part of the liquid is attached to the outer circumference of an impeller of the rotating rotor. In a non-leakage pump for flowing from a high-pressure part to a low-pressure part formed between the rotor and a casing surrounding the rotor, lubricating and cooling a bearing with the liquid, and sucking and pumping the liquid by the impeller. A ball bearing or a cylindrical roller is provided in the bearing, a back blade is provided in the impeller, and a radially inner end portion of the back blade is provided close to one end portion of the bearing portion,
It is characterized in that a forced circulation path is formed through the gap between the outside of the bearing and the inside of the bearing by the differential pressure generating function of the back blade.

[Action]

Since the present invention is configured as described above, when the electric motor is operated during pump operation, the driven rotor separated from the driving rotor by a thin partition (can) is rotated by magnetic force or electromagnetic force, A pump impeller integrated with the driven rotor is driven to pump the liquid.

Due to the above pump action, a part of the high-pressure liquid discharged from the outer peripheral outlet of the impeller is guided to the back side of the casing cover supporting the ball bearing or the cylindrical roller bearing (that is, rolling bearing), and then from the electric motor side. It is returned to the suction low-pressure part of the back blade of the pump impeller through the gap of the rolling bearing toward the impeller side, merges with the liquid in the pump chamber from here, and a part is again discharged from the outlet on the outer circumference of the impeller. With the high pressure liquid
A forced circulation path that flows through the bearing is formed.

In the above case, generally, the ball bearing or the cylindrical roller bearing has a gap several times larger than that of the conventional slide bearing, so that the liquid passing through the bearing easily flows sufficiently. Therefore,
Since the lubrication and cooling action of the bearing is positively performed by the liquid sucked and pumped by the pump itself, the bearing sliding heat or the cylindrical roller bearing reduces the bearing sliding heat generation.

Further, since the ball bearing and the cylindrical roller bearing themselves have a slight gap, they do not have an end play in the bearing portion unlike the conventional slide bearing. Therefore, vibration in the axial direction of the rotor due to cavitation operation or aeration operation is eliminated, and as a result, bearing damage due to impact load is also eliminated.

On the other hand, when the back blade is attached to the pump impeller, a negative pressure is generated at the inner portion in the radial direction of the back blade, that is, the center of the back surface (bearing side) of the impeller during pump operation. That is, since the difference in pressure between the electric motor side and the impeller side becomes large, the lubricating liquid flows more easily, and the above-described operational effects are further promoted.

〔Example〕

 Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a vertical cross-sectional view of a magnet drive pump provided with a ball bearing according to an embodiment of the present invention, in which the same reference numerals as those shown in FIG. 3 denote the same or like parts. And

In the figure, an impeller 2 housed in a pump casing 1 made of a non-magnetic material is attached to a rotor 4 together with a driven magnet wheel 3 and a ball bearing attached to a casing cover 14.
It is rotatably supported by 25. On the other hand, the drive magnet wheel 6 is arranged outside the can 7, and is attached to the rotating shaft 10 of the electric motor 9 via the yoke 8. The fan 12 is attached to the outside of the outer side plate 11 of the electric motor 9. It is installed at the end of 10 opposite output shafts. In the figure, 13 is a bracket.

Further, as shown in an enlarged manner in FIG. 2, a back blade 22 is provided on the back surface of the impeller 2 and a gap s in the axial direction from the casing cover 14
Is mounted so that it is as small as possible.
Therefore, while the pump is operating, the main flow of the high-pressure liquid discharged from the outer peripheral outlet of the impeller 2 is discharged from the discharge port as indicated by arrow A, but a part of the high-pressure liquid is indicated by arrow B. The hole 14 in the casing cover 14 located outside the bearing.
After passing through a, it flows into the back side, that is, the driven magnet wheel 3 side, then changes direction and is guided through the gap of the ball bearing 25 to the back surface center portion 22a of the impeller 2 where negative pressure is generated by the back blade 22. Form a forced circulation path. In this way, the pressure difference between both sides of the main bearing 25 is increased by the back blade 22, so that the lubricating liquid can flow more easily.

According to this embodiment, since the ball bearing 25 itself has a slight gap, the end play 5a is not provided unlike the conventional slide bearing (Fig. 3). Therefore, the vibration in the axial direction due to the cavitation operation or the air mixing operation is eliminated, and as a result, the bearing is not damaged by the impact load.

Further, since the ball bearing 25 is adopted, the bearing sliding heat is reduced, and in this embodiment, since the open type ball bearing is used, the bearing itself is lubricated and cooled by the liquid sucked and pumped by the pump itself. However, at this time, the clearance through which the lubricating liquid of the ball bearing passes is several times larger than that of the conventional slide bearing, and the lubricating liquid easily flows sufficiently. Therefore, since the lubrication and cooling action of the bearing is positively performed by the liquid sucked and pumped by the pump itself, the bearing sliding heat generation is reduced by adopting the ball bearing or the cylindrical roller bearing.

Further, since the back blade 22 is provided on the back side of the impeller 2, the pressure on the impeller side of the bearing 25 becomes negative pressure, and the pressure difference from the pressure on the driven magnet wheel 3 side of the bearing 25 becomes large. The lubricating liquid will flow more easily. As a result, it is possible to prevent air from collecting around the bearing during cavitation operation or air-mixed operation, and to sufficiently lubricate the bearing.

Although the magnet drive pump has been described as the non-leakage pump in the above-described embodiments, the present invention can be similarly applied to the canned motor type pump.

Further, the structure in which the ball bearing is provided as the bearing device has been described, but a cylindrical roller bearing can also be used. These have the same function as a rolling bearing.

[Effect of device]

As described above, according to the present invention, in the leak-free pump, the ball bearing or the cylindrical roller bearing having a slight clearance is provided in the bearing, so that the bearing is not damaged in a short time during idle operation, and Vibrations in the rotor axis direction due to cavitation operation and aeration operation are eliminated. Therefore, as a result, bearing damage due to impact load can be eliminated.

Furthermore, a ball bearing or a cylindrical roller bearing usually has a gap several times larger than that of a conventional slide bearing, so that the liquid passing through the bearing easily flows easily, and a radial direction is provided on the back side of the impeller. In combination with the function of generating a differential pressure by the back blades provided with the inner end portion close to one side end portion of the bearing portion, the forced circulation passage that passes through the gap portion inside the bearing from the outer side of the bearing portion Is more easily flown, the lubrication and cooling action of the bearing, which is positively performed by the liquid sucked and pumped by the pump itself, is further promoted, heat generation of the bearing sliding is reduced, and cavitation operation is performed. It is possible to prevent air from gathering around the bearing during the air-mixed operation and to sufficiently lubricate the bearing.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a magnet drive pump provided with a bearing device showing an embodiment of the present invention, FIG. 2 is an enlarged sectional view of an essential part of FIG. 1, and FIG. 3 is a longitudinal sectional view showing a conventional example. Is. 1 ... Pump casing, 2 ... Impeller, 3 ... Driven magnet wheel, 6 ... Drive magnet wheel, 7 ... Can, 8 ... Yoke, 9 ... Electric motor, 13 ... Bracket, 14 ... Casing Cover, 14a …… Opening, 22 …… Back blade, 25 …… Ball bearing.

Claims (1)

[Scope of utility model registration request] 1. A low pressure formed by rotatably supporting a rotor by means of a radial bearing and a thrust bearing, and a part of liquid being formed between a high pressure portion on the outer circumference of an impeller of a rotating rotor and a casing surrounding the rotor. In a leak-free pump in which the bearing is lubricated and cooled by the liquid, and the liquid is sucked and pressure-fed by the impeller, a ball bearing or a cylindrical roller is provided in the bearing, and the impeller is provided. A back blade is provided such that a radially inner end portion of the back blade is close to one end portion of the bearing portion, and the back blade passes through a gap portion inside the bearing from the outside of the bearing portion due to a differential pressure generating function of the back blade. A bearing device for a leak-free pump, characterized in that a forced circulation path is formed.