JP2003184783A - Canned motor pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a canned motor pump capable of preventing a circulating fluid after cooling a motor and lubricating and cooling bearings. <P>SOLUTION: A pressure liquid chamber A for inside guiding part of a pump handling fluid pumped up after passing through an impeller is provide adjoining the bearing 9a positioning on the impeller 2 side and the fluid in the pressure liquid chamber A is divided into two directions. One part of the fluid is returned to a space on the back surface of the impeller via penetrating holes 14a, 14b of a rotor penetrating from a rotor end on the opposite side of the impeller to the vicinity of a fitting end of the impeller after passing through the bearing 9a on the impeller side, a gap between the motor rotor 10 and a motor stator 3 and the bearing 9b on the opposite side of the impeller while the other part of the fluid is returned to the space on the back surface of the impeller via non-contact throttle mechanisms 4a, 4b. A penetrating hole 2h communicating with an impeller liquid passing passage 2g constituted of an impeller blade 2d and an impeller main plate 2e is formed on a liner part 2c of the impeller main plate. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a canned motor pump and, more particularly, to a canned motor pump which can prevent the evaporation of a circulating fluid after cooling a motor and lubricating / cooling a bearing. It is about. FIG. 11 is a sectional view showing a general structure of a canned motor pump. As shown in FIG. 11, an impeller 2 is disposed inside a pump casing 1 of a pump section, and a casing cover 3 is fixed to an opening on the high-pressure side of the pump casing 1. One end of the rotor 5 is inserted into the casing cover 3, and the distance piece 6, the thrust plate 7 a, the shaft sleeve 8 a, and the impeller 2 fitted to the rotor 5 are connected to one end of the rotor 5 by bolts 21. Has been fixed through. On the other hand, to the other end of the rotor 5, a thrust plate 7b and a shaft sleeve 8b are fixed via bolts 22. By providing an inwardly projecting convex portion 3a on the inner peripheral surface of the casing cover 3, a pressure is applied between the impeller-side bearing 9a, the casing cover 3, the distance piece 6, and the shaft sleeve 8a. A space A as a liquid chamber is formed, and a non-contact throttle mechanism 4a is formed between the inner peripheral surface of the convex portion 3a and the distance piece 6. That is, the convex portion 3a has an inner peripheral portion that is close to the outer peripheral surface of the distance piece 6 with a slight gap, and forms a flow path a here. Further, inside the casing cover 3, there is provided a flow hole 3 b for guiding a part of the pump handling liquid pressurized by the impeller 2 into the space (pressure liquid chamber) A. Further, a bulging portion 3c bulging in a sleeve shape is formed on the end surface of the casing cover 3 on the impeller side, so that the inner peripheral surface of the bulging portion 3c and the boss portion 2a of the impeller 2 are formed.
, A non-contact second throttle mechanism 4b is formed. That is, the inner peripheral surface of the bulging portion 3c is
The flow path b is formed in the vicinity of the outer peripheral surface of the boss portion 2a with a slight gap. At the same time, two spaces B and C are defined between the casing cover 3 and the impeller 2 with the swelling portion 3c sandwiching the second throttle mechanism 4b. Balance hole 2
Through b, it communicates with the suction side of the pump. The rotor 5 has a pair of bearings 9 on both sides thereof.
It is rotatably supported via a and 9b. A rotor 10 of a motor section is fixed to a substantially central portion of the rotor 5, and a space D is provided between the rotor 10 and a bearing 9a on the impeller side, and a bearing on the opposite side of the rotor 10 and the impeller. 9b, and a space F is formed between the end cover 11 and the bearing 9b opposite to the impeller. The flow path c is between the impeller-side bearing 9a and the shaft sleeve 8a, the flow path d is between the end face of the impeller-side bearing 9a and the thrust plate 7a, the can 12a of the rotor 10 and the stator 13 Between the can 12b and the bearing 9b on the side opposite to the impeller.
And a thrust plate 7b, and a flow path g between the bearing 9b and the shaft sleeve 8b opposite to the impeller. A through hole 14 penetrating in the axial direction is formed inside the rotor 5, and this through hole 14 is open on both sides including bolts 21 and 22 at both ends. And
The space F between the end cover 11 and the bearing 9b on the side opposite to the impeller and the suction side of the pump communicate with each other by the through hole. Both bearings 9a and 9b have
A spiral groove and a groove extending along the axial direction are provided on the inner peripheral surface. The thrust plates 7a, 7b of the bearings 9a, 9b
A groove extending in the radial direction is provided on the sliding surface with the groove b. [0007] In the canned motor pump having the above structure, the pressurized pumping liquid after passing through the impeller is led into the space A constituting the pressure liquid chamber from the circulation hole 3b provided in the casing cover 3, and two liquids are formed therefrom. Reflux in the direction.
The first flow includes the first throttle mechanism 4a, the space B, the second throttle mechanism 4b, the space C, and the balance hole 2b of the impeller 2.
, And is returned to the suction side of the pump. The second flow is from the space A, the flow path c, the flow path d, the space D, the flow path e,
The liquid passes through the space E, the flow path f, the flow path g, the space F, and the through hole 14 in order, and returns to the suction side of the pump. Since both the first flow and the second flow are connected to the suction side of the pump at the end, the pumped liquid that has been pressurized after passing through the impeller flows from the space A into the lower pressure part of the pump. The fluid flows back to the suction side, and the second flow is cooled by the motor unit and the bearings 9a, 9
b. Lubrication and cooling are performed. However, in the conventional canned motor pump as described above, in the second flow, after cooling the motor and lubricating / cooling the bearing, it passes through the shaft through hole, The circulating fluid that has returned to the low-pressure suction side
Since the heat generated by the motor and the bearing is absorbed and the temperature rises, the saturated steam pressure at this temperature increases. And when this saturated steam pressure is higher than the suction pressure,
The circulating liquid is vaporized, and the vapor phase generated by the vaporization flows into the impeller inlet to generate cavitation. An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a canned motor pump capable of preventing the circulating fluid from evaporating after cooling the motor and lubricating and cooling the bearing. [0010] The invention according to claim 1 comprises a rotor having a motor rotor sealed with cans and an impeller fixed thereto, bearings are arranged at both ends of the rotor, and the blades are arranged. In the canned motor pump configured to cool the motor rotor and the can-sealed motor stator with the boosted pump handling liquid after passing through the car and to lubricate and cool the bearings, the impeller side A pressurized liquid chamber is provided adjacent to the located bearing for guiding a part of the pumped liquid which has been pressurized after passing through the impeller, and the liquid in the pressure liquid chamber is divided into two directions. The rotor on the vehicle side passes through the gap between the motor rotor and the motor stator and the bearing on the opposite side of the impeller from the rotor end on the side opposite to the impeller to the vicinity of the impeller mounting end. Through the through hole Then, it is configured to return to the space behind the impeller and the other is returned to the space behind the impeller via a non-contact throttle mechanism, and further, to the liner portion of the impeller main plate, the impeller blades and A canned motor pump characterized in that a through-hole communicating with an impeller liquid passage formed by an impeller main plate is provided. According to the present invention, the circulating fluid is returned to the space behind the impeller, and the liner portion of the impeller main plate is further provided with a through hole communicating with the impeller liquid passage. Thus, the pressure of the circulating fluid at the reflux destination can be constantly maintained at a higher pressure than the saturated vapor pressure of the circulating fluid whose temperature has increased, so that the circulating fluid can be prevented from being vaporized. Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are views showing the structure of a canned motor pump according to a first embodiment of the present invention,
1 is a sectional view of the entire canned motor pump, and FIG.
It is an enlarged view of the back part of the impeller 2 of FIG. The same or corresponding parts as those in the conventional example are denoted by the same reference numerals, and the description thereof will not be repeated. As shown in FIG. 1, an impeller 2 is disposed inside a pump casing 1 of a pump section, and a casing cover 3 is fixed to an opening on the high-pressure side of the pump casing 1. Casing cover 3
One end of the rotor 5 is inserted through the inside of the
The distance piece 6, the thrust plate 7a, the shaft sleeve 8a, and the impeller 2 fitted to the rotor 5
It is fixed via a bolt 21. On the other hand, to the other end of the rotor 5, a thrust plate 7b and a shaft sleeve 8b are fixed via bolts 22. As shown in FIG. 2, inside the rotor 5,
An axial hole 14a of the rotor extending from the rotor end opposite to the impeller 2 to the vicinity of the mounting end of the impeller 2 and a radial through hole 14b from the end of the axial hole 14a are provided. That is, the axial hole 14a and the radial through hole 14b form a through hole penetrating from the end of the rotor 5 to the vicinity of the impeller mounting end. The distance piece 6 has the same position in the radial direction as the radial through hole 14b.
A through hole 6a communicating the radial through hole 14b with the space B is provided. Further, the liner portion 2c of the impeller 2 is provided with a through hole 2h communicating with an impeller passage liquid passage 2g composed of an impeller blade 2d, an impeller main plate 2e and an impeller side plate 2f. In the canned motor pump having the above-described structure, the pumped liquid that has been pressurized after passing through the impeller is guided into the space A that forms the pressure liquid chamber from the circulation hole 3b provided in the casing cover 3, and two liquids are formed therefrom. Reflux in the direction.
The first flow passes through the first throttle mechanism 4a, the space B, the second throttle mechanism 4b, the space C, and the through hole 2h in order, and is returned to the impeller liquid passage 2g. The second flow is from the space A, the flow path c, the flow path d, the space D, the flow path e, the space E, the flow path f, the flow path g, the space F, the axial hole 14a, the radial through hole 14b, It passes through the through-holes 6a in order and returns to the space B,
From there, it merges with the first flow and the second throttle mechanism 4
b, the space C and the through hole 2h pass in order, and return to the impeller liquid passage 2g. Since the first flow and the second flow both communicate with the inlet and the outlet of the impeller liquid passage 2g at the end, the pressurized pump handling liquid after passing through the impeller flows from the space A. , 2g of impeller liquid passage which is a lower pressure part
And the second flow performs cooling of the motor unit and lubrication and cooling of the bearing. FIGS. 3 (a) and 3 (b) show the pressure change from the inlet to the outlet of the impeller liquid passage 2g. FIG.
3A shows a cross section of the impeller 2, and FIG. 3B shows a pressure change corresponding to the impeller liquid passage 2g. This pressure increases as the impeller liquid passage 2g moves toward the outer periphery, but there is a difference between the main plate 2e side and the side plate 2f side.
There is a difference between the impeller blade front surface 2i side and the impeller blade back surface 2j side illustrated in FIG. Therefore, as shown in FIG. 3b, the pressure change is on the main plate 2e side, on the blade surface 2i side, on the curve 15a, on the main plate 2e side, on the blade back 2j side, on the curve 15b, on the side plate 2f side, on the blade surface 2i side. Then, the curve 15c is on the side plate 2f side, and on the wing back 2j side, the curve is like curve 15d. The through hole 2 in the liner portion 2c of the impeller main plate 2e
The circulating liquid that has passed through h returns to the reflux destination pressure Pr section shown in FIG. Here, after cooling of the motor portion and lubrication and cooling of the bearing, the cooling portion passes through the through hole 2h of the liner portion 2c,
Assuming that the saturated vapor pressure of the circulating fluid whose temperature has risen is P1, P
When r> P1, the vaporization of the circulating liquid can be prevented. The example shown in FIG. 3A and FIG.
Since P1 is established, the circulating liquid does not evaporate.
No cavitation occurs. However, in the case of a pump handling liquid in which the change in the saturated vapor pressure P1 is large with respect to the change in the liquid temperature, Pr <P1 may be satisfied. FIG.
FIGS. 5A and 5B show this example, and FIG.
5A shows a cross section of the impeller 2, and FIG. 5B shows a pressure change corresponding to the impeller liquid passage 2g. As in the example shown in FIGS. 5A and 5B, Pr <P1 may be satisfied. In this case, the circulating liquid evaporates and cavitation occurs. FIGS. 6, 7A and 7B show the structure of a canned motor pump according to a second embodiment of the present invention. FIG. 7 (a) is an enlarged view of the back part of the impeller 2 of FIG. 6, and FIG. 7 (b) is a view showing a pressure change corresponding to the impeller liquid passage 2g. As shown in FIG. 7A, a ring 16 is fixed to the outer peripheral portion of the liner portion 2c, and a through hole 2h is formed in the ring 16.
Is provided. Other configurations are the same as those of the first embodiment shown in FIG. With this configuration, FIG.
As shown in (b), even in the case of a pump handling liquid in which the change in the saturated steam pressure P1 is large with respect to the change in the liquid temperature, Pr> P1 is satisfied, and the circulating liquid can be increased. Can be prevented from evaporating. FIG. 8 is a view showing a modified example of the rear part of the impeller shown in FIG. As shown in FIG. 8, the same effect can be obtained even if the ring 16 is not formed as a separate component but is integrated with the liner portion 2c of the impeller 2. FIGS. 9 and 10 are views showing the structure of a canned motor pump according to a third embodiment of the present invention. FIG. 9 is a cross-sectional view of the entire canned motor pump, and FIG. It is an enlarged view of a back part. As shown in FIG. 10, the impeller 2 has a main plate 2e but no side plate 2f. In other respects, the structure is the same as that of the canned motor pump of the first embodiment shown in FIG. With this configuration, after cooling the motor and lubricating and cooling the bearings,
Since the recirculation pressure Pr can always be maintained at a higher pressure than the saturated vapor pressure P1 of the circulating fluid that has passed through the through hole 2h of the liner 2c and thus increased in temperature, vaporization of the circulating fluid can be prevented. As described above, according to the present invention,
The circulating fluid is returned to the space behind the impeller, and a through hole communicating with the impeller liquid passage is provided in the liner portion of the impeller main plate or the ring fixed to the outer peripheral portion of the liner portion. Thereby, the pressure of the circulating liquid at the reflux destination can be constantly maintained at a higher pressure than the saturated vapor pressure, so that vaporization of the circulating liquid can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing a canned motor pump according to a first embodiment of the present invention. FIG. 2 is an enlarged view showing the back of the impeller of FIG. 1 in an enlarged manner. FIG. 3 is a diagram showing a correlation between impeller liquid passages and pressures in FIG. 1; FIG. 4 is a front view of the impeller of FIG. 1; FIG. 5 is a diagram showing another correlation between the impeller liquid passage and the pressure in FIG. 1; FIG. 6 is a sectional view showing a canned motor pump according to a second embodiment of the present invention. FIG. 7 is a diagram showing a mutual relationship between impeller liquid passages and pressures in FIG. 6; FIG. 8 is a sectional view showing another structure of the impeller of FIG. 6; FIG. 9 is a sectional view showing a canned motor pump according to a third embodiment of the present invention. FIG. 10 is an enlarged view showing the impeller rear part of FIG. 9 in an enlarged manner. FIG. 11 is a sectional view showing a conventional canned motor pump. [Description of Signs] 1 Pump casing 2 Impeller 3 Casing cover 5 Rotor 6 Distance pieces 7a, 7b Thrust plates 8a, 8b Shaft sleeves 9a, 9b Bearing 10 Rotor 11 End covers 12a, 12b Can 13 Stator 14a Axial hole 14b Radial through hole 15 Pressure 16 Ring 21, 22 bolt

Claims (1)

Claims 1. A rotor having a motor rotor sealed with a canister and an impeller fixed thereto, bearings disposed at both ends of the rotor, and a pump handling liquid pressurized after passing through the impeller. A canned motor pump configured to cool the motor rotor and the can-sealed motor stator and to lubricate and cool the bearings, wherein the impeller is disposed adjacent to the bearing located on the impeller side. A pressure liquid chamber that guides a part of the pumped liquid that has been pressurized after passing therethrough is provided, and the liquid in the pressure liquid chamber is divided into two directions, one of which is the impeller-side bearing and the motor rotor. After passing through the gap of the motor stator and the bearing on the opposite side of the impeller, from the rotor end on the opposite side to the impeller, through the through hole of the rotor penetrating to the vicinity of the impeller mounting end, Reflux to the space, To the space behind the impeller through a non-contact throttle mechanism, and further into the liner portion of the impeller main plate, to the impeller fluid passage formed by the impeller blades and the impeller main plate. A canned motor pump having a communicating through hole.