阅读说明：本技术 具有油润滑真空泵的真空泵系统 (Vacuum pump system with oil-lubricated vacuum pump ) 是由 罗伯托·卡博里 安德莉亚·莱波尔 安德莉亚·伯塔洛特 乔瓦尼·伊恩努奇 于 2019-07-02 设计创作，主要内容包括：本发明涉及具有油润滑真空泵的真空泵系统,所述真空泵送系统(100)包含油润滑的真空泵(20)和马达(30),所述油润滑的真空泵(20)包含固定的泵定子和可旋转的泵转子(23),所述马达(30)包含固定的马达定子(32)和可旋转的马达转子(33),所述固定的马达定子(32)和可旋转的马达转子(33)相互配合用于驱动所述泵转子(23)旋转。马达(30)还包含不透油的单元(50),该单元由金属护套组成,该金属护套包围所述马达转子(33)并形成容器,所述容器用于收集从泵(20)泄漏的任何油并将其保持在马达(30)内部。(The invention relates to a vacuum pump system with an oil-lubricated vacuum pump, the vacuum pump system (100) comprising an oil-lubricated vacuum pump (20) and a motor (30), the oil-lubricated vacuum pump (20) comprising a stationary pump stator and a rotatable pump rotor (23), the motor (30) comprising a stationary motor stator (32) and a rotatable motor rotor (33), the stationary motor stator (32) and the rotatable motor rotor (33) cooperating for driving the pump rotor (23) in rotation. The motor (30) also comprises an oil-tight unit (50) consisting of a metal sheath that surrounds the motor rotor (33) and forms a reservoir for collecting any oil leaking from the pump (20) and keeping it inside the motor (30).)

1, vacuum pumping system (100; 200; 300), comprising:

-a vacuum pump (20), the vacuum pump (20) comprising a pump housing (21) defining a fixed pump stator and housing a rotatable pump rotor (23), the pump stator and the pump rotor (23) cooperating with each other to pump fluid from a pump inlet (27) to a pump outlet (28); and

-a motor (30), the motor (30) comprising a motor housing (31) in which a fixed motor stator (32) and a rotatable motor rotor (33) are received, the motor stator (32) and the motor rotor (33) cooperating with each other to drive the pump rotor (23) in rotation by means of a drive shaft (34);

characterized in that the vacuum pump (20) is an oil-lubricated vacuum pump and the system (100; 200; 300) further comprises an oil-tight unit (50; 150; 250; 60, 70; 80, 90), the oil-tight unit (50; 150; 250; 60, 70; 80, 90) being arranged to enclose at least portions of the motor rotor (33) and to form at least portions of a container for collecting any oil leaking from the pump (20) and retaining it inside the motor (30).

2. Vacuum pumping system (100; 200; 300) according to claim 1, wherein the unit (50; 150; 250; 60, 70; 80, 90) has at least portions (53; 160; 180; 60; 80) sandwiched between the motor housing (31) and the pump housing (21).

3. Vacuum pumping system (100) according to claim 1 or 2, wherein the unit comprises a substantially cylindrical jacket (50; 150; 250), the jacket (50; 150; 250) surrounding the entire motor rotor (33) and forming the container, and wherein the jacket (50; 150; 250):

-having a side wall (51; 151; 251), said side wall (51; 151; 251) being located in an air gap separating said motor rotor (33) from said motor stator (32);

-open at the th end, the sheath being sandwiched between the motor housing (31) and the pump housing (21) at the th end, and

-at a second end opposite to said th end, closed by a base (52; 170; 190) at least partially housed inside said motor casing (31).

4. The vacuum pumping system (100) of claim 3, wherein the open end of the sheath (50) has a rim (53), the rim (53) protruding radially outward and forming a sheath portion sandwiched between the motor housing (31) and the pump housing (21), and wherein a static seal (54) is provided between a surface of the rim (53) facing the pump housing (21) and an opposing surface of the pump housing (21).

5. Vacuum pumping system (100) according to claim 3 or 4, wherein the sheath (50) is made of sheet metal.

6. The vacuum pumping system (300) of claim 3, wherein the sheath (150; 250) is provided with a base (160, 170; 180, 190) at both the th and second ends, the base (160, 170; 180, 190) being larger in diameter than the sidewall (151, 251) and projecting radially outward from the sidewall (151, 251), and wherein, in the base (160; 180) provided at the th open end of the sheath (150; 250), a surface facing the pump housing (21) is configured to engage in an oil-tight manner a complementarily-shaped axial recess (26) formed in the pump housing (21).

7. A vacuum pumping system (300) according to claim 6, wherein in the radially protruding portion of the base (160, 170; 180, 190) mutually opposing surfaces are shaped so as to define annular circumferential axial recesses (163, 173; 183, 193) for receiving opposite axial ends of the motor stator (32), and wherein each of the circumferential axial recesses (163, 173; 183, 193) is radially delimited towards the outside of the motor (30) by an axially protruding rim (161, 171; 181, 191) located between the motor stator (32) and the motor casing (31) and towards the inside of the motor (30) by a thickened end portion (162, 172; 182, 192) of the side wall (151, 251).

8. The vacuum pumping system (300) of claim 6 or 7, wherein the base (170) disposed at the second end of the sheath (150) is completely received within the motor housing (31).

9. The vacuum pumping system (300) of claim 6 or 7, wherein a surface (194) of the base (190) provided at a second end of the sheath (250) remote from the motor (30) has a tapered profile protruding at least partially outside the motor housing (31), and wherein the surface (194) protruding outside the motor housing (31) is provided with fins (196).

10. The vacuum pumping system (300) of any of of claims 6-10, wherein the jacket (150; 250) is made of an oil resistant, electrically insulating thermoset or thermoplastic resin.

11. Vacuum pumping system (200) according to claim 1 or 2, wherein the unit comprises -th and second disc-shaped assemblies (60, 70; 80, 90), the -th and second disc-shaped assemblies (60, 70; 80, 90) housing opposite axial ends of the motor stator (32) and the motor rotor (33) and forming, together with the motor stator (32) , a reservoir for collecting any oil leaking from the pump (20) and retaining it inside the motor (30), the -th assembly (60; 80) forming part of the unit sandwiched between the motor housing (31) and the pump housing (21) and engaging in an oil-tight manner a complementarily shaped axial recess (26) formed in the pump housing (21).

12. Vacuum pumping system (200) according to claim 11, wherein the and second assemblies (60, 70; 80; 90) have, on their mutually opposite faces, respective circumferential axial recesses (63; 73; 83; 93) for housing opposite axial ends of the motor stator (32), and wherein the circumferential axial recesses (63, 73; 83, 93) are radially defined towards the outside of the motor (30) by respective annular axial projections (61; 81) located between the motor stator (32) and the motor casing (31) and radially towards the inside of the motor (30) by respective second annular axial projections (62; 82) located between the motor stator (32) and the motor rotor (33).

13. Vacuum pumping system (200) according to claim 11 or 12, wherein the second disc assembly (80; 90) is completely received within the motor housing (31).

14. Vacuum pumping system (200) according to claim 11 or 12, wherein a surface (94) of the second disc assembly remote from the motor (30) has a tapered profile protruding at least partially outside the motor housing (31), and wherein the surface (94) of the second disc assembly (90) protruding outside the motor housing (31) is provided with fins (96).

15. The vacuum pumping system (200; 300) of any of of claims 11-14, wherein the and second disc assemblies (60, 70; 80, 90) are made of an oil resistant, electrically insulating thermoset or thermoplastic resin.

Technical Field

The present invention relates to a vacuum pump system, and more particularly, to a vacuum pump system having an oil-lubricated vacuum pump.

Background

Vacuum pumps are used to achieve vacuum conditions, i.e. to evacuate a chamber (the so-called "vacuum chamber") and establish sub-atmospheric conditions in said chamber. Many different types of vacuum pumps are known, having different structures and operating principles, each time a specific vacuum pump is selected according to the needs of a specific application, i.e. according to the vacuum level to be reached in the respective vacuum chamber.

Typically, a vacuum pump comprises a pump housing in which are disposed or more pump inlets and or more pump outlets, and pumping elements arranged in the pump housing and configured for pumping gas from the pump inlets to the pump outlets, the vacuum pump allowing gas in the vacuum chamber to be evacuated by connecting the pump inlets to the vacuum chamber, thereby creating a vacuum condition in the chamber.

More specifically, in vacuum pumps, the pumping elements comprise a stator defining a pumping chamber and a rotor rotatable in said pumping chamber, and the stator and rotor cooperate with each other to pump gas from the pump inlet to the pump outlet.

Even more specifically, vacuum pumping systems are known in which a vacuum pump is connected to an oil tank, whereby oil can be transferred from the oil tank to the vacuum pump, in particular to a pumping chamber, for use as a coolant and lubricating liquid, and for sealing the chamber. Among these systems, mention may be made of those using a rotary-vane vacuum pump, to which the following description will refer.

A conventional vacuum pumping system using a rotary vane vacuum pump is shown in fig. 1 and generally designated 10.

The pumping system 10 basically comprises a rotary vane vacuum pump 20 and an electric motor 30 for driving the pump 20.

Pump 20 includes a pump housing 21 in which are defined or more pump inlets and or more pump outlets (not shown in the figures). The pump housing 21, modified to also serve as a pump stator, defines internally a pump chamber in which a pump rotor 23 rotates eccentrically.A rotor 23 is fixed to or in -piece with a pump shaft 24 that is driven to rotate by a motor 30 and is provided with or more radially slidable vanes 25 (only can be seen in the figures) that move in contact with the inner walls of the pumping chamber during rotation of the rotor.

The motor 30, in turn, includes a housing 31, the housing 31 being secured to the pump housing 21 and enclosing a motor stator 32 and a motor rotor 33, the motor stator 32 and the motor rotor 33 cooperating to drive the pump rotor 23 for rotation by a drive shaft 34 associated with the motor rotor 33, the drive shaft 34 may be connected to the pump shaft 24, or it may be formed with the pump shaft 24 and the pump rotor 23 , as shown, end walls 35, 36 enclose a chamber housing the motor rotor 33 and rotatably support the ends of the shaft 34 in association with suitable rolling bearings.

In order to prevent oil and possibly toxic gases present in the pumping chamber from passing the motor 30 and escaping in the environment through the motor housing, a dynamic seal 40, typically a lip seal, is provided around the shaft 34 between the motor housing 31 and the pump housing 21. The dynamic seal also serves to prevent dust from entering the pumping chamber.

Further, the prior art relates to dry vacuum pumps, particularly dual rotor pumps, having two parallel rotors coupled by a gear assembly located in a housing containing oil, and the oil-containing chamber is not a pumping chamber but a housing containing the gear assembly.

Dynamic seals are quite expensive. Furthermore, in the case of vacuum pumping systems comprising rotary vane vacuum pumps, these dynamic seals are the main cause of oil leakage during pump operation.

Disclosure of Invention

It is an object of the present invention to provide pumping systems using oil lubricated vacuum pumps with a more effective sealing system for preventing oil leakage from the pumping chamber.

It is a further object of the invention to provide a pumping system using an oil lubricated vacuum pump that does not require a dynamic seal between the vacuum pump and the motor and therefore can be manufactured in a more cost effective manner than prior art systems.

These objects are achieved by a pumping system as claimed in the appended claims.

More specifically, the invention provides vacuum pumping systems comprising an oil lubricated vacuum pump and an electric motor driving the pump, wherein the system further comprises an oil tight unit arranged to enclose at least part of the motor rotor and to form at least part of a container intended to collect and retain inside the motor any oil leaking from the pump.

Advantageously, the oil-tight cell has at least a portion sandwiched between the motor housing and the pump housing.

In an th embodiment of the invention, the unit comprises a substantially cylindrical sheath made of sheet metal enclosing the entire rotor and forming the container.

According to a preferred feature of an embodiment of the invention, the sheath has a side wall located in the air gap separating the motor rotor from the motor stator, open at the end, sandwiched between the motor and pump housings at the end, and closed at a second end opposite the end by a bottom wall housed within the motor housing.

According to another preferred features of this embodiment, the open end of the sheath has a rim that projects radially outwardly and forms part of the sheath that is sandwiched between the motor casing and the pump casing.

in the embodiment, the sheath surrounds the entire rotor, has a side wall in the air gap separating the motor rotor from the motor stator, and is open at the end, and is sandwiched between the motor and pump housings at the end.

According to a preferred feature of the second embodiment of the invention the sheath is provided at both ends with a base portion of larger diameter than the side wall and projecting radially outwardly therefrom, and the base portion provided at the open end engages in an oil-tight manner a complementarily shaped axial recess formed in the pump casing.

According to another preferred features of this embodiment, in the radially projecting portion of the base, the mutually opposed surfaces are shaped so as to define annular circumferential axial recesses which receive the opposed axial ends of the motor stator.

Advantageously, the circumferential axial recess is radially delimited towards the outside of the motor by a respective annular axial projection located between the motor stator and the motor casing and towards the inside of the motor by a thickened end portion of the side wall of the jacket.

Since the sheath made of resin and having a very thin side wall is used, there is no need to increase the air gap between the rotor and the stator of the motor in order to accommodate the metal sheath as used in the embodiment and to take account of the thermal expansion thereof.

In a third embodiment of the invention, the unit includes th and second disc assemblies which th and second disc assemblies receive the opposite axial ends of the motor rotor and motor stator and together with the motor stator form a reservoir for collecting any oil leaking from the pump and retaining it inside the motor th assembly forms part of the unit sandwiched between the motor and pump housings and engages in an oil tight manner a complementary shaped axial recess formed in the pump housing.

The two components are made of a non-metallic material, preferably an oil resistant, electrically insulating thermoset or thermoplastic resin.

According to a preferred feature of this second embodiment, the th and second modules have circumferential axial recesses on their surfaces facing the other module for receiving respective axial ends of the motor stator.

Advantageously, the circumferential axial recess is radially delimited towards the outside of the motor by a respective th annular axial projection located between the motor stator and the motor casing and towards the inside of the motor by a respective second annular axial projection located between the motor stator and the motor casing.

Having a "reservoir" located between the motor stator and the motor housing solves the problem of noise and vibration that may affect the pumping system with a metal sheath located in the air gap between the motor stator and the rotor during operation. Furthermore, there is no need to increase the radial dimension of the air gap to allow insertion of the sheath and account for its thermal expansion.

In the second and third embodiments, the base of the sheath opposite the open end and the second disc assembly may be fully housed within the motor housing, respectively. In the alternative, their surfaces remote from the motor may have a tapered profile projecting at least partially outside the motor housing. Such a tapered surface may then be provided with fins.

Embodiments in which the sheath base or second component partially exits the motor housing have better heat dissipation than embodiments in which the elements are completely contained within the motor housing, because the sheath base or second component can directly receive the airflow generated by the external cooling system of the pumping system. Furthermore, providing fins allows for an increased cooling surface and more efficient circulation of the external flow of cooling air.

Drawings

preferred embodiments of the invention, given by way of non-limiting example, will be described hereinafter with reference to the accompanying drawings, in which:

figure 1 is a longitudinal section of the part of a pumping system of the prior art;

FIG. 2 is a longitudinal cross-sectional view, similar to FIG. 1, of portion of a pumping system according to embodiment of the invention;

figure 3 is a longitudinal section of a pumping system according to a second embodiment of the invention;

figure 4 is a longitudinal section similar to figure 2 of the part of the pumping system according to a variant of the embodiment shown in figure 3;

figure 5 is a longitudinal section similar to figure 3 of a pumping system according to a third embodiment of the invention; and is

Fig. 6 is a longitudinal section similar to fig. 4 of the part of the pumping system according to a variant of the embodiment shown in fig. 5.

In fig. 2 to 6, the same reference numerals as in fig. 1 are used to designate the components of the pump and the motor.

Detailed Description

Fig. 2 shows an th embodiment of a pumping system 100 according to the invention to more effectively seal the motor 30 against leakage of oil from the pumping chamber, a sheet metal sheath 50 is provided which surrounds the motor rotor 32 and is sandwiched between the motor housing 31 and the pump housing 21 at end .

The sheath 50 is a substantially glass-shaped member, i.e., a substantially cylindrical member that is open at the end (the end sandwiched between the motor housing 31 and the pump housing 21), and has a side wall 51 that is located in the air gap between the stator 32 and the rotor 33 of the motor 30, the open end surrounds the corresponding end wall 35 of the rotor chamber, and a bottom wall (or base) 52 opposite the open end is disposed inside the motor housing 31, the open end of the sheath 50 has a rim 53 that projects radially outward, the rim 53 being the portion of the sheath 50 sandwiched between the motor housing 31 and the pump housing 21, a sealing gasket 54, in particular an O-ring, is provided between the rim 53 and the opposite surface of the pump housing 21 in order to ensure oil tightness between the pump 20 and the motor 30.

The provision of the jacket 50 and O-ring 54 results in any oil leaking from the pump environment being collected within the sheath 50. As can be readily appreciated by those skilled in the art, static seals such as O-rings 54 are less likely to fail than prior art dynamic seals 40. Furthermore, the provision of a jacket that collects any possible oil leaks prevents the escape of oil (or any other unwanted substances, such as gases generated or present in the pump for some reason, etc.) and its dispersion in the environment.

The provision of the sheet metal sheath 50 and associated O-ring 54 overcomes the problems associated with the use of lip seals, but in some respects remains to be improved, particularly:

since the metal sheath 50 is located between the stator 32 and the rotor 33 of the motor 30, it can generate noise and vibrations during operation of the pumping system 100.

It may be necessary to increase the radial dimension of the air gap to allow insertion of the sheath 50 itself and to take account of its thermal expansion, thus requiring an increase in the radial dimension of the entire pumping system 100.

This improvement is achieved by the system 200 shown in fig. 3 and 4.

More specifically, in the embodiment of FIG. 3, pairs of disc assemblies 60, 70 are provided, which are made of non-metallic materials, particularly leak-proof, oil-resistant, and electrically insulating thermoplastic or thermoset resins, and are configured to receive opposite axial ends of motor stator 32 and motor rotor 33. with this arrangement, assemblies 60, 70 form, together with motor stator 32 , -type "containers" that collect any oil that leaks from pump 20 and retain such oil within motor 30.

The assembly 60 is sandwiched between the pump housing 21 and the motor housing 31 and is fitted in an oil-tight manner in a complementary shaped recess 26 provided in the opposite surface of the pump housing 21. a central opening 65 in the assembly 60 receives the end wall 35 of the rotor chamber on its surface facing the assembly 70, the assembly 60 has two substantially parallel annular axial projections 61, 62 defining an annular axial recess 63 for receiving the end of the stator 32. the outer annular projection 61 is sandwiched between the motor stator 32 and the motor housing 31, and the inner annular projection 62 is sandwiched between the motor stator 32 on the side of and the motor rotor 33 and end wall 35 on the side of 35 .

The assembly 70 has a central cavity 75 (or possibly a central opening, as in the assembly 60) which receives the end wall 36 of the rotor chamber on its face facing the assembly 60, the assembly 70 has two substantially parallel annular axial projections 71, 72 defining an axial annular recess 73 for receiving the other end of the stator 31, the outer annular projection 71 is sandwiched between the motor stator 32 and the motor housing 31, the inner annular projection 72 is sandwiched between the motor stator 32 on the side and the motor rotor 33 and end wall 36 on the other side, similarly to projections 61, 62, reference numeral 74 denotes the outer face (i.e. the face remote from the motor) or base of the assembly 70, which in the embodiment shown in figure 3 is flat, so that the assembly 70 is fully received within the motor housing 31.

The figure also shows details of the gas inlet and outlet 27, 28, and the outer body of the pumping system 200.

The shape of the components 60 and 70 and the engagement of the component 60 within the recess 26 in the pump housing 21 ensure oil tightness without the use of a sealing gasket such as an O-ring 54. Further, the assembly is sandwiched between the stator 32 and the housing 31 of the motor 30, and thus, problems of vibration and noise do not occur due to the rotation of the rotor 33. At the same time, there is no need to increase the air gap between the stator 32 and the rotor 33 of the motor 30, as required in the embodiment shown in fig. 2, to accommodate the metal sheath 50 and take into account its thermal expansion. The proper choice of resin also makes it possible to improve not only the heat dissipation characteristics with respect to the prior art, but also with respect to the solution of the metal sheath shown in fig. 2.

An improvement is obtained by the configuration of the system 200 shown in FIG. 4 similar to the embodiment of FIG. 3, there is provided pairs of disc assemblies 80, 90 made of non-metallic materials, particularly leak-proof, oil-resistant and electrically insulating thermoplastic or thermoset resins, and formulated to receive opposite axial ends of the motor stator 32 and motor rotor 33. accordingly, the assemblies 80, 90 also form, in conjunction with the motor stator 32 , containers that collect any oil that leaks from the pump 20 and retain such oil within the motor 30.

A disc-shaped assembly 80 is identical to the assembly 60 shown in FIG. 3, and its elements are indicated by numerals corresponding to those used in FIG. 3, but beginning with numeral 8 instead of numeral 6A second disc-shaped assembly 90 differs from the assembly 70 shown in FIG. 3 only in the configuration of its base 94, the base 94 being not flat as the base 74 of the assembly 70, but having a tapered contoured surface (more specifically, frustoconical in shape) on its side facing away from the motor 30, such that the base 94 projects outside the motor housing 31, fins 96 are formed on the portion of the base 94 that is outside the housing 31, the remaining elements of the assembly 90 are identical to those of the assembly 70, which are indicated by numerals corresponding to those used in FIG. 3, but beginning with numeral 9 instead of numeral 7.

The assembly 90 having the base 94 partially out of the motor housing 31 has better heat dissipation than the assembly 70 housed entirely within the motor housing 31 because the base 94 can directly receive the airflow generated by the external cooling system (not shown) of the pumping system 200. Providing the heat sink 96 in the portion of the base 94 that protrudes outside the motor case 31 allows for an increase in cooling surface and a more efficient circulation of the external cooling air flow.

Fig. 5 and 6 show a pumping system 300 according to a third embodiment of the present invention. In fig. 5 and 6, elements that correspond to or are functionally equivalent to elements shown in fig. 3 and 4, respectively, are indicated by the same reference numerals but preceded by the numeral 1.

More specifically, in the embodiment of fig. 5, the container for collecting and retaining any oil leaking from the pump 20 inside the motor 30 comprises a glass-shaped sheath 150 configured to house the axial ends of the stator 32 and the rotor 33 of the motor 30 and, as with the components of the system 200, made of non-metallic materials, in particular of leak-proof, oil-resistant and electrically insulating thermoplastic or thermosetting resins.

The sheath 150 has a side wall 151 consisting of a thin layer of resin in the air gap between the stator 31 and rotor 32 of the motor 30 and two bases 160, 170, the two bases 160, 170 being of larger diameter than the side wall 151 so that they project radially outwardly from the side wall 151 the base 160 at the open end of the sheath 150 has a central opening 165 for receiving the respective closure wall 35 of the rotor chamber, being sandwiched between the pump housing 21 and the motor housing 31 and its surface facing the pump housing 21 being configured to fit in an oil-tight manner in a complementary shaped recess 26 provided in the opposite surface of the pump housing 21. the other bases 170 have a central cavity 175 (or possibly a central opening, such as the base 160) which receives the end wall 36 of the rotor chamber.

In the radially projecting portions of the bases 160, 170, the mutually opposed surfaces are shaped so as to define annular axial recesses 163, 173, respectively, for receiving the opposite axial ends of the motor stator 32. More specifically, the recess 163 is defined between the rim 161 of the base 160 and the thickened end 162 of the side wall 161, the rim 161 projecting axially towards the base 170 and being sandwiched between the motor stator 32 and the motor casing 31. Similarly, a recess 173 is defined between a rim 171 of the base 170 and a thickened end 172 of the side wall 151, the rim 171 projecting axially towards the base 160 and being sandwiched between the motor stator 32 and the motor casing 31. Reference numeral 174 denotes an outer surface of the base 170 (i.e., a surface away from the motor). In the embodiment shown in fig. 5, the surface 174 is flat and the base 170 is completely contained within the motor housing 31.

The shape of the collet 150, with the base 160 engaging the recess 26 in the pump housing 21, ensures oil-tightness without the use of a sealing gasket such as an O-ring 54. Further, since the sheath 150 is made of resin and the side wall 151 thereof is very thin, it is not necessary to increase the air gap between the stator 31 and the rotor 32 of the motor 30 to accommodate a metal sheath such as the sheath 50 (fig. 2) and to take account of thermal expansion thereof. Moreover, there is no vibration and noise problem. Meanwhile, as in the embodiment shown in fig. 3 and 4, appropriate selection of the resin may also improve not only the heat dissipation characteristics with respect to the prior art, but also the heat dissipation characteristics with respect to the solution of the metal sheath shown in fig. 2.

Referring now to fig. 6, the vessel for collecting and holding any oil leaking from the pump 20 inside the motor 30 includes a glass-shaped jacket 250, which is similar to the jacket 150 and is intended to provide the same improvement over the jacket 150 shown in fig. 5 as provided by the use of the assembly 90 in the pumping system 200 shown in fig. 4.

As with the jacket 150 , the jacket 250 has a side wall 251 constructed of a thin resin layer in the air gap between the stator 31 and the rotor 32 of the motor 30 and two bases 180, 190 having a larger diameter than the side wall 251 so that the bases project radially outward from the side wall 251 the jacket 250 differs from the jacket 150 shown in FIG. 5 only in the configuration of the base 190, the base 190 not having a flat outer surface like the base 170 of the jacket 150, but rather having a surface of tapered profile (more specifically, being frustoconical in shape) so that the surface 94 projects outside the motor housing 31. in addition, heat sinks 196 are formed on portions of the surface 194 outside the housing 31.

The base 190 having a surface 194 that partially exits the motor housing 31 has better heat dissipation than the base 170 that is completely contained within the motor housing 31 because the base 190 can directly receive the airflow generated by the external cooling system (not shown) of the pumping system. Providing the heat sink 196 in the portion of the surface 194 outside the motor case 31 allows for an increased cooling surface and more efficient circulation of the external cooling air flow.

It should be understood that resin may be incorporated between the magnets of the motor stator 32 when resin is poured to form the th and second components 60, 70 and 80, 90 of fig. 3 and 4 or the jackets 150 and 250 of fig. 5 and 6 in view of this fact, the embodiment shown in fig. 3 and 4 may even be construed as a limit case of the embodiment shown in fig. 5 and 6, wherein the resin layer forming the side walls 151, 251 of the jackets 150, 250 has a substantially zero thickness.

Naturally, without altering the principle of the invention, the embodiments and the construction details may be widely varied in the aspects described and illustrated purely by way of non-limiting example, without thereby departing from the scope of the invention as defined in the following claims.