WO2022059709A1

WO2022059709A1 - Canned motor pump

Info

Publication number: WO2022059709A1
Application number: PCT/JP2021/033947
Authority: WO
Inventors: 銀春曹; 浩忠長野; 優今川; 健太則定; 正和福島
Original assignee: 三相電機株式会社
Priority date: 2020-09-16
Filing date: 2021-09-15
Publication date: 2022-03-24
Also published as: JPWO2022059709A1

Abstract

In order to provide a high-precision canned motor pump which is lightweight and with which efficiency is not liable to deteriorate: a rear bearing (5), which is an insert member, is held by insert molding in a bearing holding portion (10) at the center of a bottom surface provided at the rear end of a back casing (4); a recessed portion (27) provided in the outer circumference of the rear bearing mates with a projecting portion (28) of the inner circumference of the bearing holding portion; an outer cylinder wall (17) is provided extending parallel to the axial direction of a shaft (7) as a cylindrical outer extended portion, on a bottom surface outer circumferential portion of the back casing; a lid (20) mates with and is sealed to a distal end of the outer cylinder wall; an intermediate casing (13, 14) for holding a front bearing (6) is provided between a motor portion (2) and a pump portion (3); the rear bearing and the front bearing support the shaft with freedom to rotate; and the back casing, the cylindrical outer extended portion, the lid, and the outer circumference of a stator are covered and formed as an integrated body by means of a resin molding (29).

Description

Can do motor pump

The present invention relates to a canned motor pump in which a rotor (rotor) of a motor mounted on a shaft is immersed in a liquid to be operated together with an impeller of the pump of the driven portion. In a canned motor pump, the rotor attached to the shaft is liquidtightly separated from the stator (stator) of the motor by a cylindrical back casing (can) having a liquidtight structure that accommodates the rotor. In particular, the present invention relates to a canned motor pump which is also suitable for a vortex pump in which the internal pressure of the can is high.

In a normal pump, the pump part containing the impeller and the motor are sealed with a mechanical seal, but there is a risk that liquid will easily leak from the shaft seal part of the pump part casing. In a canned motor pump, a liquid-tight partition is provided between the rotor attached to the shaft and the stator by a cylindrical back casing (can), and the fluid around the rotor and shaft is operated by an impeller (handling). Since the structure is soaked in liquid), the pump part with the impeller to the rotor part of the motor are integrated, and the handling liquid is handled between the pump part and the motor part while lubricating and cooling the bearings etc. The liquid is kept tight without leaking.

Canned motor pump cans are often made of metal such as stainless steel because they are parts to which pressure is applied in a watertight state, but in consideration of manufacturing costs and weight increase, synthetic resin casings are used instead. Attempts have been made to do so.

However, when synthetic resin is used for a casing such as a can, for example, a bearing holding portion is provided at the center of the bottom of a cylindrical can and molded, and then the bearing is press-fitted into the bearing holding portion to attach a rotor to the shaft. Is rotatably supported. As the synthetic resin used for the can, for example, PPS (Polyphenylene sulfide) fiber-reinforced with glass fiber is used from the viewpoint of heat resistance, strength, and rigidity (see, for example, Patent Document 1). On the other hand, the material of the bearing inserted by press fitting is alumina-based ceramics, SiC, carbon or the like. The material of the synthetic resin of the can and the bearing to be press-fitted are usually different.

For example, the linear expansion coefficient of PPS is 2.6 × 10 ^-5 / ° C, the linear expansion coefficient of alumina ceramics is 7.2 × 10 ^-6 / ° C, and the linear expansion coefficient of SiC is 3.7. The linear expansion coefficient of × 10 ^-6 / ° C. and carbon is 5.0 × 10 ^-6 / ° C.

If the heat generated by the sliding parts of the bearing or the temperature of the liquid used rises during the operation of the pump, the materials of the synthetic resin back casing and the bearing will be different. The bearing inserted by the bearing may protrude in the axial direction from the bearing holding frame. Then, the clearance with the end of the rotor is lost, the shaft is locked, the rotation of the rotor is hindered, and there is a concern that troubles such as the pump stopping may occur. Further, if the thickness of the synthetic resin of the back casing is reduced, it becomes difficult to secure the dimensional accuracy of the parts due to the deformation of the parts due to water pressure, and there is a risk of water leakage due to the resin cracking.

Therefore, as a countermeasure when the shaft is locked, a means of inserting a flat-blade screwdriver or the like through a through hole in the axial direction to forcibly rotate the shaft and unlocking the shaft has been proposed. This is done by providing a tubular support member attached with screws and a through hole that penetrates the center of the can in the axial direction at the bottom of the can of the canned motor pump using a metal motor case such as aluminum. Is covered with a removable plug, and when locked, the plug is removed and a flat-blade screwdriver is inserted into the through hole in the axial direction to rotate the shaft (see Patent Document 2). However, this proposal is only a countermeasure after the lock has been locked, and the lock itself is not suppressed. Further, since the casing and the tubular support member are made of metal, they are heavier than those made of synthetic resin and have difficulty in processing.

Japanese Unexamined Patent Publication No. 2011-132916 Japanese Unexamined Patent Publication No. 2009-299628

The problem to be solved by the present invention is to reduce the weight of the cylindrical back casing (can) that covers the rotor portion of the motor portion of the canned motor pump by using a synthetic resin that is easy to process and has excellent moldability. In addition to ensuring strength and watertightness, bearings made of a material different from synthetic resin cans are forced to move in the axial direction from the bearing holding frame of the can due to the difference in thermal expansion rate. In order to prevent the rotation of the motor from locking and stopping due to contact with the rotor due to pushing out, a can structure that suppresses locking is provided so that the bearing does not push out and come into contact. It is to provide a canned motor pump.

In particular, when looking at centrifugal pumps with high lift characteristics, the water pressure inside the can tends to increase compared to general centrifugal pumps. Then, since the back casing itself is easily deformed by the water pressure, high component accuracy is required to ensure the watertightness of the back casing. It is also required to prevent the back casing from cracking due to pressure and leaking water.

Furthermore, the inventors have found that the performance tends to decrease as the temperature of the liquid handled by the pump rises. It is considered that this is because the dimensional accuracy deteriorated due to thermal expansion and the shaft core was shaken.

Therefore, a further object of the present invention is to provide a canned motor pump that prevents water leakage due to cracking of the back casing, improves component accuracy, and has improved stability and is resistant to thermal expansion.

The first means for solving the above-mentioned problems is a canned motor unit provided with a cylindrical resin back casing that partitions between a rotor mounted on a shaft and a stator arranged on the outer periphery of the rotor. In a canned motor pump consisting of a pump part in which an impeller attached to the front of the shaft drives the rotation of the motor to operate the liquid.
The rear bearing, which is an insert member, is held by insert molding in the bearing holding portion at the center of the bottom surface provided at the rear end of the back casing.
The recess provided on the outer circumference of the rear bearing is fitted with the protrusion on the inner circumference of the bearing holding portion.
On the outer peripheral portion of the bottom surface of the back casing, there is an outer cylinder wall extending in parallel with the axial direction of the shaft as a tubular outer extension.
The lid is fitted to the tip of the outer cylinder wall and sealed.
An intermediate casing is provided between the motor section and the pump section to hold the front bearing.
The rear and front bearings support the shaft rotatably and
Further, the back casing, the tubular extension portion, the lid body, and the outer periphery of the stator are integrally covered with a resin mold.
It is a canned motor pump characterized by.

The inner surface of the lid may be fitted with an inner cylinder wall facing the outer cylinder wall of the tubular outer extension portion. Further, the shielding property of the back casing may be enhanced by arranging an O-ring in the gap between the outer cylinder wall and the inner cylinder wall.

Further, since the tubular outer extension and the lid are both made of resin, they can be easily sealed by heat welding with ultrasonic waves or the like, and the shielding property of the back casing can be improved.

The rear bearing is not a conventional press-fitting, but an insert molding in which the bearing is inserted in advance and then resin-molded. During insert molding, the protrusions of the bearing holding frame of the back casing are formed in close contact with the rib-shaped or ring-shaped recesses provided on the outer periphery of the bearing, so that the recesses and the protrusions mesh with each other to prevent them from coming off. It is easy to prevent the bearing from moving in the axial direction due to expansion.

The second means is described in the canned motor according to the first means, wherein the outer cylinder wall of the tubular outer extension portion is provided with a recess serving as a relief groove in the circumferential direction on the outer periphery thereof. It is a pump.

The groove of the recess is a groove provided in the circumferential direction on the outer peripheral surface of the outer cylinder wall. For example, a semicircular recess having a depth of about 1 mm is formed all around on the outer peripheral surface. Then, this groove becomes a relief groove, absorbs the distortion of deformation due to heat, and suppresses the amount of deformation in the axial direction of the bearing.

The third means is characterized in that the intermediate casing is composed of a metal main member and a resin reinforcing member, and the main member and the auxiliary member are provided with a free portion. The casing motor pump according to the means.

The main member of the intermediate casing is a member that holds the front bearing of the intermediate casing, and by making it made of metal, corrosion resistance and strength are ensured while suppressing dimensional deformation. Stainless steel is suitable because it is immersed in liquid. By combining the main metal member and the resin reinforcing member, both weight reduction and strength assurance are achieved, but the main member of the intermediate casing and the resin reinforcing member are not integrally adhered to each other, but both. When a free structure in which a part of the members is separated from each other, the stress due to the difference in thermal expansion of both members can be released, so that it is possible to avoid a decrease in operating efficiency due to deformation.

Further, the can-motor pump may be characterized in that it is provided with a free contact portion in which an O-ring is arranged in the gap between the main member and the auxiliary member.
If the main member of the intermediate casing and the resin reinforcing member are not integrally brought into close contact with each other, but a floating structure in which a part of both members is separated from each other and the two members come into contact with each other via an О ring, both members are used. While releasing the stress due to the difference in thermal expansion, it is possible to suppress the pressure loss from the gap between the two members and secure the shielding property, so that it is possible to avoid a decrease in operating efficiency due to deformation.

The fourth means is the canned motor pump according to any one of the first to third means, characterized in that the pump portion is a vortex pump.

The device of the can motor unit of the present invention can be applied in combination with the type of impeller of the pump unit without any particular limitation, but especially when applied to a vortex pump, the efficiency is reduced when the rotation speed increases. It becomes easier to exhibit the desired performance without. In a vortex pump, a large number of radial vane grooves are provided on the outer periphery of the impeller of the pump section, and the impeller rotates to generate a vortex along the inner wall of the pump and pressurize it repeatedly. A relatively small amount of liquid can be transferred at high pressure. The vortex pump can have a high lift by increasing the rotation speed of the pump. That is, since the vortex pump is a small pump with a high lift, a high pressure is generated in the entire back casing. It is important to be able to maintain efficiency during use because it is generally susceptible to deformation due to the high pressure and is also susceptible to thermal expansion. Therefore, the structure suitable for manufacturing by insert molding in which the rear bearing does not easily come off from the resin back casing and the shielding property is ensured is suitable for the eddy current pump in which high pressure is generated.

In particular, when used as a high-lift pump such as a vortex pump, the pressure around the impeller becomes high, but the pressure escapes from the gap between the main metal member and the resin reinforcing member. If this happens, the capacity of the pump will be reduced.
Therefore, if the watertightness is maintained by arranging an О ring in the gap of the free contact portion, the pressure drop around the impeller is suppressed, and the pump efficiency during use is maintained.

Conventionally, the resin back casing has a U-shaped cross section and has a cylindrical bottom. However, since it is difficult to mold a small one and the dimensional accuracy tends to deteriorate, the rear bearing is press-fitted after molding. When a general manufacturing method such as incorporating the bearing was used, the press-fitted bearing was pushed forward by thermal expansion during the operation of the pump, and it was easy to pull out.

On the other hand, as in the present invention, the bottom of the back casing is opened, and the outer cylinder wall of the tubular outer extension portion provided on the outer periphery of the bottom opening is sealed by ultrasonic welding of the lid. Then, since it becomes easy to mold the rear bearing of the insert member in the open back casing, the rear bearing can be held by insert molding without using the method of press-fitting the rear bearing after molding. Can be done.

It is held in the back casing by resin molding with the rear bearing inserted in advance, and the bearing holding frame of the can protrudes into the rib-shaped or ring-shaped recess provided on the outer circumference of the rear bearing. Since the portions are formed in close contact with each other, the concave portions and the protruding portions are fitted to each other to provide a strong stopper and prevent the bearing from moving in the axial direction. Then, since the rear bearing is difficult to come out in the axial direction (forward), troubles such as the rotor and the bearing coming into contact with each other and locking are suppressed. In addition, since the outer cylinder wall of the tubular outer extension and the lid are sealed, the watertightness is maintained.

In addition, when the cylindrical back casing body made of synthetic resin, the tubular outer extension, and the periphery of the lid and the stator are integrally molded with resin, the whole is integrally held and reinforced. Therefore, water leakage due to cracking of the back casing can be prevented, and since the accuracy of parts is stable, it is resistant to changes due to use such as thermal expansion, and the rotation of the pump is suppressed from being locked, resulting in more stability. It will be improved.

Furthermore, by denting a part of the outer circumference of the outer cylinder wall of the tubular outer extension portion in a groove shape to form an escape groove, it is possible to eliminate the distortion of deformation due to heat or the like and escape. Therefore, since the amount of deformation of the bearing in the axial direction can be further suppressed, the pump can be operated more smoothly and stably.

In addition, if a metal member is used for the intermediate casing, corrosion resistance can be ensured while suppressing dimensional deformation. Therefore, even when the temperature of the liquid handled by the pump rises, dimensional deformation is small, so that the bearing is axially oriented. The amount of deformation of the bearing can be suppressed, and problems such as locking of rotation are suppressed. That is, if the material of the main member of the intermediate casing that holds the front bearing is made of metal such as stainless steel, it is useful for maintaining strict dimensions because it has high strength and can suppress deformation, and efficiency is reduced due to deformation. Can be avoided, and corrosion resistance can be ensured because it is immersed in liquid.

Furthermore, by combining the main metal member and the resin reinforcing member, the part facing the blade can be easily processed into a desired shape by resin. Therefore, as compared with the case of using only metal, the space around the blades can be easily made into an optimum shape, and the efficiency of the pump can be more easily exhibited. In addition, when the impeller rotation starts up, the impeller may come into contact with the surrounding wall because it tends to shake in the axial direction, but the resin reinforcing member can be positioned near the impeller. Therefore, even if the impellers come into contact with each other, the wear of the impellers can be reduced as compared with the metal if the resin is used, so that failure can be easily avoided and the decrease in pump capacity can be suppressed.

In addition, the main member of the intermediate casing and the resin reinforcing member are not integrally brought into close contact with each other, but a part of both members is separated from each other to form a free structure, so that the stress due to the difference in thermal expansion of both members is released. Therefore, it is possible to avoid a decrease in operating efficiency due to deformation.

Furthermore, since the water pressure is high, the overall shape of the resin back casing tends to change when the internal pressure of the can increases. Therefore, by integrally covering the entire motor portion with a mold, the shape is stably maintained and the dimensions are less likely to be out of order, so that the watertightness can be easily maintained. In particular, in a small, high-pressure vortex pump, if changes in dimensional accuracy are suppressed and deviations are reduced, it will be easier to maintain more stable and smooth operation during operation.

Since the vortex pump is a high-lift pump, the water pressure inside the can tends to be high and leakage is likely to occur, and the dimensional accuracy required when the liquid temperature rises is more severe. When deviations occur, the loss from the desired characteristics is more noticeable than with other pumps. When the canned motor unit of the present invention is applied in combination with the impeller of a vortex pump, the accuracy can be easily maintained, so that a small and high-lift pump with little loss can be obtained. In other words, by opening the bottom of the back casing and sealing it with the tubular outer extension and the lid, it is possible to hold the bearing that is more difficult to pull out forward, and the whole is integrally molded with resin. Therefore, the dimensional change is suppressed, so that the dimensional accuracy is maintained. Therefore, it is possible to provide a stable vortex pump that is watertight and difficult to lock. Then, the characteristics of the highly efficient high-lift vortex pump are less likely to be attenuated, so that high performance as expected can be exhibited.

Further, in addition to the present invention, if an O-ring is arranged in the gap between the free portion of the main member of the intermediate case and the auxiliary member and is brought into contact with the O-ring, the stress due to the difference in thermal expansion of both members is generated. In addition to being able to escape, it can be kept watertight, so it is possible to avoid a decrease in operating efficiency due to deformation, and it is possible to suppress pressure loss from the gap between the main member and the resin reinforcing member. It is possible to avoid a decrease in pressure and a decrease in pump capacity.

Further, in addition to the present invention, if an inner cylinder wall facing the outer cylinder wall of the tubular outer extension portion is provided on the inner surface of the lid body at the bottom of the back casing and an O-ring is arranged between both walls, the lid body and the cylinder The watertightness of the extension part becomes higher and more stable. The lid located at the bottom of the resin back casing has a structure that is easy to apply to small pumps whose accuracy is difficult to secure by press-fitting bearings, and while it has manufacturing advantages, it is sealed by welding, although it is sealed. It is not easy to secure watertightness compared to the integrated back casing. Not only is the hydraulic fluid filled inside, but high pressure is applied inside the pump, so arranging the О ring contributes to a watertight shield.

It is sectional drawing of the back casing of the back casing of one Embodiment of this invention. It is an exploded view of the back casing of the can motor part of one embodiment of this invention. FIG. 3 is a partial cross-sectional view of a can do motor pump according to an embodiment of the present invention. FIG. 3 is a diagram schematically showing how a liquid flows in the back casing in the embodiment of FIG. 3 with arrows. It is a side view of the can motor pump of FIG. 3 as seen from the pump chamber side. It is a cross section of the back casing of the can motor part of another embodiment of the present invention, and is an example of the embodiment not provided with a relief groove. FIG. 3 is a performance curve diagram of the vortex type can do motor pump according to the embodiment shown in FIG. 3 at a speed of 3960 rpm. It is a figure which showed the difference of the power consumption of a motor by the difference of the structure of an intermediate casing. The solid line is for a canned motor pump as shown in FIG. 8, and the intermediate casing is a canned motor pump having a structure in which a metal main member and a resin reinforcing member are combined and the gap is shielded by an О ring, and the dotted line is an intermediate as shown in FIG. This is the case where the casing uses an integrated structure of a resin casing. This is a case where a liquid at 60 ° C. is conveyed with a total head of 50 m and a flow rate of 13 L / min. It is explanatory drawing of the structure of the intermediate casing using the metal main member and the resin reinforcing member of the embodiment of this invention. It is sectional drawing of the back casing of the conventional cand motor part. It is explanatory drawing of the conventional can do motor pump. It is explanatory drawing of the intermediate casing made of resin of an existing shape.

An embodiment of the present invention will be described with reference to the drawings as appropriate. In the example of the embodiment, a case of combining with a vortex pump will be described as an example. Since the structure of the canned motor portion of the present invention is not limited to the type of impeller only for the centrifugal pump, it can be combined with other pump structures such as a centrifugal pump, and is applicable to all canned motor pumps. It is possible. The vortex pump used in the description in the examples is one embodiment of the present invention which can be preferably applied. Since the vortex pump has a high lift as the number of revolutions increases, the shield and dimensional stability of the canned motor section are severely required, such as the internal pressure becoming high, so we implemented a vortex pump that requires strict operation. As a typical example of the above-mentioned form, the canned motor pump will be described below.

The canned motor pump (1) of the present invention includes a pump portion (3) in front of the shaft and a motor portion (canned motor portion (2)) behind the shaft. In FIG. 3, the right side of the drawing is the front part (3), and the left side of the drawing is the rear part (2). Since the eddy current pump of the embodiment is a small and highly efficient pump, the total length of the pump in FIG. 3 is about 16 cm, the pump part is about 5 cm, and the canned motor part is about 11 cm. The width of the pump is about 15 cm, and the height excluding the discharge part is about 11 cm. The motor unit (2) is a drive unit in which the shaft (7) to which the rotor (8) is attached is rotated by the magnetic force generated by the stator (9) which is arranged around the rotor (8) at a distance from the rotor (8). Is.

In the present invention, the rotor (8) attached to the shaft (7) and the stator (9) are partitioned by a cylindrical synthetic resin back casing (can) (4) so as to be watertight. The rear part of (7) is rotatably supported by a rear bearing (5) held by a bearing holding frame (10) provided in the rear center of the back casing (4). In the back casing (4) of FIG. 3, the outer diameter of the cylinder is about 5 cm, the thickness of the resin in the cylinder portion is, for example, about 1 mm, and the length of the shaft is about 12 cm.

The synthetic resin used for the can and the like in the following examples is PPS (Polyphenylene sulfide) fiber-reinforced with glass fiber. The metal member is stainless steel (SUS304) or the like. The bearing is made of alumina-based ceramics, SiC, carbon, etc., and has a coefficient of thermal expansion different from that of PPS made of synthetic resin.

An impeller (12) driven by the rotation of the motor unit (2) is attached to the front portion of the shaft (7), and the shaft is rotated by the motor unit (2) to be taken in from the suction port (23). The liquid (22) is operated and discharged to the discharge port (24).

The shaft (7) is rotatably supported by a rear bearing (5) and a front bearing (6) held in an intermediate casing (11) between the motor portion and the pump portion, and is supported from the pump portion (3). The inside of the back casing (can) (4) is filled with the same liquid (22) as the liquid (22) conveyed by the rotation of the impeller (12).

As schematically shown by arrows in FIG. 4, the liquid (22) enters from the vicinity of the impeller (12) through the intermediate casing (11) to the vicinity of the rotor and passes through the gap between the front and rear bearings and the shaft. This will fill the inside of the back casing (4).

On the other hand, since the outside of the back casing is watertightly shielded, this liquid (22) does not leak to the outside from the cylindrical portion of the back casing (4), and the inside of the back casing (4) is watertight. It is kept in.

In the example of this embodiment, the intermediate casing (11) is formed by combining a main member (13) made of stainless steel and an auxiliary member (14) made of PPS reinforced with glass fiber so as to face each other. It is fixed to the front end of the steel to hold the front bearing (6). Since the resin auxiliary member (14) of the intermediate casing (11) is arranged close to the rear surface of the impeller and combined to form the intermediate casing (11), it rotates when the adjacent impeller (12) starts. As the number increases, the shaft may shake in the axial direction and come into contact with the auxiliary member (14), but since the auxiliary member (14) is made of resin, the blades are compared to the case where they come into contact with a metal member. The car is less likely to wear.

The intermediate casing (11) provided between the front end of the back casing (4) of the motor portion (2) and the impeller (12) of the pump portion includes the front end of the back casing (4) and the front bearing (6). The main member (13) made of stainless steel and the resin reinforcing member (14) are fitted so as to face each other, and the front end of the can (4), the main member (13), and the resin are made of resin. The front end of the back casing (4) stacked in the order of the reinforcing member (14) is screwed, and the front bearing (5) is fitted in the center of the main member (13) and fastened and held by the screw. .. An O-ring (32) is arranged in the gap between the main member (13) and the reinforcing member (14) that are combined facing each other, and the O-ring is in contact with the gap so as to close the gap. The gap between the main member (13) and the reinforcing member (14) does not come into close contact with each other, and even if the hydraulic fluid of the pump is at a high temperature or materials having different coefficients of thermal expansion are combined, O-ring is performed. The structure is shielded via a ring (32). Although it has a floating structure with a degree of freedom, it is maintained watertight by the O-ring (32), so the high pressure around the impeller does not escape from the gap, and the deviation itself due to thermal expansion around the shaft itself. Can be released without loss by buffering the O-ring, so even a pump that operates a high temperature fluid can be applied without loss.

The intermediate casing (11) may be entirely made of synthetic resin. However, as shown by the dotted line in FIG. 8, in the case of the intermediate casing of the embodiment of FIG. 12, the efficiency tends to decrease during high temperature operation as compared with the case where the main member (13) and the auxiliary member (14) are combined.
On the other hand, in the case of the aspect of the present invention of FIG. 9 in which the main member (13) and the auxiliary member (14) are combined, the two types of parts are not simply brought into close contact with each other, but are shielded by an O-ring (32), so that they are shielded from each other. It is not necessary to make the gaps in close contact with each other, and even if you are not aware of the difference in thermal expansion, the pressure that increases due to the rotation of the impeller does not escape from the gaps, and the efficiency of the pump decreases as shown by the solid line in FIG. It will be difficult.

Since the intermediate casing (11) holds the front bearing (6), if the dimensions are deviated due to changes in heat or pressure, the shaft rotation tends to be shaken or lost, so that the temperature and the rotation speed are increased. Sometimes it tends to appear as a difference in pump performance. Therefore, if at least a part of the intermediate casing (11) is made of stainless steel to stabilize the circumference of the front bearing (6), the present invention is applied to a vortex pump that operates at a high speed. Even so, the desired ability and high lift characteristics can be sufficiently obtained.

In the back casing (4) shown in FIGS. 1 and 2, a cylindrical outer cylinder wall (17) of the cylindrical outer extension portion (16) is extended on the outer periphery of the opening at the center of the rear end, for example, by about 5 to 8 mm. A circular lid (20) made of synthetic resin having a diameter that matches the diameter of the opening is fitted and sealed by ultrasonic welding. It was

An inner cylinder wall (18) having a diameter slightly smaller than that of the outer cylinder wall (17) is provided on the inner surface of the lid (20) so as to face the outer cylinder wall (17). An O-ring (19) is placed between the outer cylinder wall (17) to improve the shielding property, and then the lid (20) and the outer cylinder wall (17) are welded and sealed. May be good. In the embodiment shown in FIGS. 1 and 2, the lid body (20) is provided with an inner cylinder wall (18) and an O-ring (19). The lid is made of synthetic resin and can be welded, but in order to increase the strength of the lid, ribs are appropriately provided between the inner cylinder wall (18) and the inner surface (25) of the lid (20). It may be reinforced by providing it. Further, if ribs are appropriately provided on the outer surface of the lid (20), deformation can be suppressed. That is, as a countermeasure against the deformation of the back casing due to the rotational torque coming from the sliding part of the bearing and the pump shaft when the pump is started, the deformation is caused by covering the rib of the lid (20) with a mold resin and fixing it. It can be suppressed.

The rear bearing (5) is held by a rear bearing holding frame (10) in the rear center of the back casing (4).
By the way, conventionally, a bearing has been mounted in a form in which a back casing made of synthetic resin is molded and then press-fitted into a cavity of a bearing holding frame. However, when it is also used for a eddy current pump as in the present invention, the pressure tends to increase and the required dimensional accuracy becomes more severe. Therefore, the rear bottom remains closed in a U-shaped cross section. There is a problem that it is easy to lock because it comes off just by press-fitting the bearing.
On the other hand, if the press-fitting is simply replaced with insert molding without securing a large bottom of the can of the back casing, it is slightly inflated in the center of the bottom to fit the rear end of the shaft, as shown in the conventional example of FIG. However, the diameter around the rear end of the shaft tends to narrow during molding, so there is no room around the rear end of the shaft due to burrs and excess resin deposits, and the shaft is inserted deeply. Trouble such as difficulty becomes easy to occur.

Therefore, in the present invention, in order to hold the rear bearing in advance by insert molding, resin molding is performed with the center of the bottom surface of the back casing opened by providing the lid (20), and the rear bearing (5) Will be incorporated in advance by insert molding. As a result, measures are taken to avoid inconvenience during insert molding.

Further, the bearing used in the present invention is made of alumina, SiC, carbon, etc., but its coefficient of thermal expansion is significantly different from that of the synthetic resin of the back casing. Therefore, when the synthetic resin expands due to heat, the diameter of the cavity of the rear bearing holding frame of the back casing expands, and the bearing press-fitted inside comes out and moves in the axial direction. Then, the rotor and the bearing come into contact with each other and the rotation is locked, so that troubles are likely to occur.

Therefore, in the present invention, the rear bearing (5) is press-fitted into the rear bearing holding frame (10) by opening the bottom of the cylindrical back casing (4) and sealing it with the lid (20). Other manufacturing methods are used to make it difficult to slip out. That is, by adopting insert molding in which the rear bearing (5) is inserted at the center position of the rear bearing holding frame (10) at the molding stage of the back casing (4), the bearing is integrated with the casing. The movement in the axial direction is suppressed.

Specifically, the rear bearing (5) is provided with a rib or groove-shaped recess (27), and a protrusion (28) is provided in the hollow portion in the center of the rear bearing holding frame (10) so as to fit the recess (27). ), And by fitting each other, it was decided to prevent slipping out. By devising manufacturing by insert molding in this way, it is possible to obtain a fitting shape that can be easily prevented from coming off.

As the synthetic resin used for the back casing and the can, for example, PPS (Polyphenylene sulfide) fiber-reinforced with glass fiber is suitable from the viewpoint of heat resistance, strength, and rigidity. These synthetic resins are molded to obtain the desired shape. In the case of a vortex pump, it is desirable to improve the dimensional accuracy as much as possible.

In addition, near the rear end of the back casing (4), around the lid body (20) and the outer cylinder wall (17), there are factors of deformation and distortion due to the pressure of the liquid to be handled and the thermal expansion of the synthetic resin due to the rise in liquid temperature. Therefore, the dimensional accuracy is likely to be out of order, and the rotation of the shaft is likely to cause blurring. Therefore, in order to eliminate the distortion behind the back casing (4), a relief groove (21) consisting of a recess having a radius of about 1 mm is formed on a part of the outer peripheral surface of the outer surface of the outer cylinder wall (17) to prevent distortion due to deformation. It is preferable to absorb it because the deviation of the dimensional accuracy is suppressed. The one provided with the relief groove (21) as shown in FIG. 3 exhibits more stable characteristics than the embodiment without the relief groove shown in FIG.

In addition, maintaining watertightness and maintaining dimensional accuracy is important for proper operation of the pump under high pressure conditions and high liquid temperature conditions to obtain high efficiency. Therefore, when the back casing (4) is made of synthetic resin from the viewpoint of weight reduction and cost, the circumference of the can and the circumference of the stator are to suppress the vibration and rotational shake of the shaft and to secure stable rotation. It is good to mold with resin and harden it integrally. Therefore, in the embodiment of the present invention, as shown in FIG. 3, the periphery of the back casing (4) and the stator (9) is integrally solidified with the mold resin (29).

The mold resin that integrally covers the periphery of the stator of the motor and the back casing (can) suppresses vibration by covering the circumference of the iron core of the stator and the circumference of the winding with the mold resin, and also achieves quietness and heat conduction. It is also possible to reduce the winding temperature by using a highly resistant resin.

As the resin for molding in the present invention, for example, BMC containing an unsaturated polyester resin as a main component can be preferably used. BMC is a heat using fiber (mainly glass fiber) as a reinforcing material in a matrix in which a thermoplastic polymer as a low shrinkage agent, a curing agent, a filler, and a mold release agent are uniformly mixed with an unsaturated polyester resin as a main component. It is a curable molding material. As shown in FIG. 3, the periphery of the can and the stator is thickly solidified with the mold resin (29). Considering the cooling of the stator, any resin having high thermal conductivity can be suitably used, not limited to BMC, and therefore any resin used for a general mold motor can be applied.

In the pump section, the impeller (12) is arranged in front of the shaft (7) and in front of the front bearing. The impeller of a vortex pump is provided with a large number of vane grooves radially.

As shown in FIG. 3, the entire resin-molded can motor unit and pump unit are surrounded by an outer casing and tightened with bolts or the like to be integrated into a can do motor pump (1) having an exterior.

In the vortex pump shown in the embodiment, the pump portion can be miniaturized, so that it is easy to make it compact and highly efficient. FIG. 7 shows a performance curve diagram of the vortex pump shown in the embodiment of the present invention shown in FIG. 3 at a speed of 3960 rpm as an example of its characteristics.

FIG. 8 shows the power consumption of the motor in the case of the intermediate casing made of resin having an existing shape and the case of using the intermediate casing having a floating structure via an O-ring composed of the main metal member and the auxiliary resin member of the present invention. Show the difference. In the conventional one shown by the dotted line, there was no difference in the fluid at 20 ° C, but when the fluid at 60 ° C was conveyed, the motor power consumption fluctuated during use. That is, in order to secure a total head of 50 m and a flow rate of 13 L / min, extra power consumption was occasionally observed in the conventional example, and it was confirmed that a loss occurred when operating the high temperature liquid. On the other hand, in the case of the present invention, such a loss was not observed, and it was confirmed that high performance without deterioration of efficiency could be obtained. When the power consumption increases, it is considered that abnormal wear of the bearing sliding portion occurs.

Similarly, when the liquid temperature to be conveyed is 70 ° C. and 80 ° C., the motor power consumption is fluctuated in the case of the conventional structure, and the efficiency of the motor is lowered. However, in the present invention, the efficiency is improved. There was no reduction and the desired efficiency was maintained.

1 Canned motor pump 2 Canned motor section 3 Pump section 4 Back casing (can)
5 Rear bearing 6 Front bearing 7 Shaft 8 Rotor 9 Stator 10 Rear bearing holding frame 11 Intermediate casing 12 Impeller 13 Metal main member 14 Resin auxiliary member 15 Opening 16 Cylindrical outer extension 17 Outer tubular wall 18 Inner tubular wall 19 O-ring 20 Lid 21 Relief groove 22 Liquid 23 Suction port 24 Discharge port 25 Inner surface 26 Ribs 27 Recesses 28 Protrusions 29 Molded resin 30 Bottom 31 Screws 32 O-rings

Claims

A canned motor unit equipped with a cylindrical resin back casing that separates the rotor mounted on the shaft from the stator arranged on the outer periphery of the rotor, and an impeller mounted on the front of the shaft drive the rotation of the motor. In a canned motor pump consisting of a pump unit that operates the liquid
The rear bearing, which is an insert member, is held by insert molding in the bearing holding portion at the center of the bottom surface provided at the rear end of the back casing.
The recess provided on the outer circumference of the rear bearing is fitted with the protrusion on the inner circumference of the bearing holding portion.
On the outer peripheral portion of the bottom surface of the back casing, there is an outer cylinder wall extending in parallel with the axial direction of the shaft as a tubular outer extension.
The lid is fitted to the tip of the outer cylinder wall and sealed.
An intermediate casing is provided between the motor section and the pump section to hold the front bearing.
The rear and front bearings support the shaft rotatably and
Further, the back casing, the tubular extension portion, the lid body, and the outer periphery of the stator are integrally covered with a resin mold.
A canned motor pump featuring.
The canned motor pump according to claim 1, wherein the outer cylinder wall of the tubular outer extension portion is provided with a recess that serves as an escape groove in the circumferential direction on the outer periphery thereof.
The canned motor pump according to claim 1 or 2, wherein the intermediate casing is composed of a metal main member and a resin reinforcing member, and the main member and the auxiliary member are provided with a free contact portion.
The canned motor pump according to any one of claims 1 to 3, wherein the pump unit is a vortex pump.