CN110435864B

CN110435864B - Pod drive

Info

Publication number: CN110435864B
Application number: CN201810422071.9A
Authority: CN
Inventors: 田中伟; 段瑞春; 王睿男; 杨勇; 刘大为; 马库斯·霍勒斯; 罗兰·比特纳
Original assignee: Siemens Energy Global GmbH and Co KG
Current assignee: Siemens Energy Global GmbH and Co KG
Priority date: 2018-05-04
Filing date: 2018-05-04
Publication date: 2022-08-26
Anticipated expiration: 2038-05-04
Also published as: CN110435864A

Abstract

The invention provides a pod driver. The pod drive includes: a housing; a motor mounted in the housing; a propeller rotatably disposed at the first end of the housing and configured to be connected with a rotor of the motor; a water flow guide member disposed at a second end portion of the housing opposite to the first end portion and configured to guide the water flow flowing through the housing in a direction opposite to a direction of a vortex formed at the second end portion by the water flow flowing through the housing. Thus, the size of the tail separator area can be fixed, thereby suppressing the pulsating lateral hydrodynamic force and thus improving the maneuverability of the nacelle as a driver.

Description

Pod drive

Technical Field

The present invention relates to a pod drive, in particular to an electric pod drive for a vessel.

Background

The pod drive may act as a drive unit for the vessel. In such applications, the pod drives may be external to the hull and located below the water surface, for example, in sea water. The pod drive may comprise an electric motor and a propeller driven by the electric motor to power the vessel. Such POD drives are also referred to as POD drives.

Such pod drives usually have a streamlined housing to reduce as much as possible the resistance to the flow of water through the pod drive.

Furthermore, in such electric pod drives, it is necessary to dissipate heat from the motor in a suitable manner so that the motor operates under acceptable temperature conditions.

Disclosure of Invention

The present invention is directed to solving the above and/or other technical problems and to providing a pod driver.

According to an exemplary embodiment, a pod drive comprises: a housing; a motor installed in the housing; a propeller rotatably provided at the first end of the housing and configured to be connected with a rotor of the motor; a water flow guide member disposed at a second end portion of the housing opposite to the first end portion and configured to guide the water flow flowing through the housing in a direction opposite to a direction of a vortex formed at the second end portion by the water flow flowing through the housing. Thus, the size of the tail separator area can be fixed, thereby suppressing the pulsating lateral hydrodynamic force and thus improving the maneuverability of the nacelle as a driver.

The water flow guide member is configured to have a direction of guiding the water flow opposite to a rotation direction of the propeller. For example, the water flow guide member includes a groove formed in the middle of the second end of the housing. The groove has a star shape and includes a central groove and a plurality of peripheral grooves located around the central groove and communicating with the central groove, wherein each peripheral groove is formed in an equilateral triangle shape or a bar shape inclined at a predetermined angle with respect to the center of the central groove in one direction. The peripheral groove is inclined in the direction opposite to the rotation direction of the propeller. As such, since the water flow guide member can guide the water flow in the direction opposite to the direction of the vortex, it is possible to suppress the rotation of the vortex, and thus to reduce the resistance caused by the vortex and to reduce the noise level.

Further, the water flow guide member includes a vortex generator formed at a middle portion of the second end portion of the housing, wherein a direction of a vortex generated by the vortex generator is opposite to a rotation direction of the propeller.

The housing includes at least one of a heat dissipation pattern formed on an inner surface of the housing for filling a gap between the inner surface of the housing and the motor and a drag reduction pattern formed on an outer surface of the housing for reducing resistance to water flow through the housing. According to an exemplary embodiment, the heat dissipation pattern may be filled in a gap between the inner surface of the case and the motor, thereby transferring heat of the motor to the case to dissipate heat of the motor. In addition, the drag reducing pattern may cause the water flow to form a turbulent boundary layer as it flows through the shell, thereby reducing the drag of the water flow against the shell.

At least one of the drag reducing pattern and the heat dissipating pattern is formed by an additive manufacturing process. The shell is integrally formed with at least one of the drag reducing pattern and the heat dissipating pattern by an additive manufacturing process.

The drag reducing pattern includes a plurality of drag reducing protrusions, wherein the plurality of drag reducing protrusions are located on an outer surface of a middle portion of the casing and configured to rotationally extend around the casing on the outer surface along a length (axial) direction of the casing. The drag reduction pattern is formed such that the middle portion of the shell has a plurality of minimum and maximum radii in the length direction of the shell. Each of the plurality of drag reducing protrusions is formed in a bar shape having a curved outer surface. Each of the plurality of drag reducing protrusions is formed to have a predetermined height protruding from an outer surface of the shell. Thus, the water flow forms a turbulent boundary layer as it flows over the plurality of protrusions and recesses between the plurality of drag reducing protrusions, thereby reducing the drag of the water flow against the outer surface of the shell.

The heat dissipation pattern includes a plurality of heat dissipation protrusions, wherein a heat dissipation protrusion of the plurality of heat dissipation protrusions, which is located at a position where a stator of the motor of the case is located, is formed to have a shape corresponding to a shape of a groove of a lamination sheet of the stator so as to be filled in the groove of the lamination sheet when the motor is mounted in the case. Therefore, the heat dissipation of the motor can be improved by the heat dissipation pattern.

According to another exemplary embodiment, a pod drive includes: a housing; an electric motor mounted in a housing, wherein the housing includes at least one of a heat dissipation pattern formed on an inner surface of the housing for filling a gap between the inner surface of the housing and the electric motor and a drag reduction pattern formed on an outer surface of the housing for reducing a resistance of a water flow flowing through the housing. Accordingly, the heat dissipation pattern may be filled in a gap between the inner surface of the case and the motor, thereby transferring heat of the motor to the case to dissipate heat of the motor. In addition, the drag reducing pattern may cause the water flow to form a turbulent boundary layer as it flows through the shell, thereby reducing the drag of the water flow against the shell.

At least one of the drag reducing pattern and the heat dissipating pattern is formed by an additive manufacturing process. For example, the shell is integrally formed with at least one of the drag reducing pattern and the heat dissipating pattern by an additive manufacturing process.

The drag reduction pattern includes a plurality of drag reduction protrusions, wherein the plurality of drag reduction protrusions are located on an outer surface of a middle portion of the casing and configured to rotatably extend around the casing on the outer surface in a length (axial) direction of the casing. The drag reduction pattern is formed such that the middle portion of the shell has a plurality of minimum and maximum radii in the length direction of the shell. Each of the plurality of drag reducing protrusions is formed in a bar shape having a curved outer surface. Each of the plurality of drag reducing lugs is formed to have a predetermined height projecting from an outer surface of the shell such that water flow forms a turbulent boundary layer when flowing over the plurality of lugs and recesses between the plurality of drag reducing lugs. Thus, the water flow forms a turbulent boundary layer as it flows over the plurality of projections and recesses between the plurality of drag reducing projections, thereby reducing the drag of the water flow against the outer surface of the casing.

Drawings

The drawings are only for purposes of illustrating and explaining the present invention and are not to be construed as limiting the scope of the present invention, wherein,

FIG. 1 is a perspective view showing a pod drive according to an exemplary embodiment;

FIG. 2 is a cross-sectional view showing a pod drive according to an exemplary embodiment;

FIGS. 3 and 4 are diagrams illustrating a water flow directing member of a tail portion of a pod drive according to an exemplary embodiment, respectively;

FIG. 5 is a cross-sectional view illustrating a drag reduction pattern of a housing of a pod drive according to another exemplary embodiment.

Description of the reference numerals

100-casing 300 motor 500 propeller 700 water flow guiding member

113 Heat sink Pattern 115 drag reduction Pattern

Detailed Description

In order to more clearly understand the technical features, objects, and effects of the present invention, embodiments of the present invention will now be described with reference to the accompanying drawings.

Fig. 1 is a perspective view showing a pod drive according to an exemplary embodiment, and fig. 2 is a sectional view showing the pod drive according to the exemplary embodiment. As shown in fig. 1 and 2, the pod drive according to an exemplary embodiment may include a housing 100, a motor 300, a propeller 500, and a water flow guide member 700. The pod drives according to exemplary embodiments may be mounted at the bottom of the hull of the vessel and may be located below the water surface, e.g. may be immersed in seawater.

The housing 100 may have an installation space for installing the motor 300. For example, the housing 100 may include a middle portion 110 and first and

second end portions

130 and 150 located at sides of the middle portion, and an installation space may be defined by the middle portion 110 and the

end portions

130 and 150 together. The housing 100 may be formed of a material such as steel. In an exemplary embodiment, the case 100 may be formed through an Additive Manufacturing (AM) process, which will be described in detail below.

The motor 300 may be installed in the installation space of the housing 100. The motor 300 may include a stator 310 and a rotor 330. The stator 310 of the motor 300 may be installed in the middle of the housing 100. In addition, the stator 310 may include a lamination sheet 311.

The propeller 500 may be rotatably disposed at the first end 130 of the housing and may be connected with the rotor 330 of the motor 300. Thus, when the pod drive according to an exemplary embodiment is immersed in water (e.g., seawater), the electric motor 330 may drive the propeller 500 to rotate, thereby providing power. However, exemplary embodiments are not limited thereto, and the pod driver according to exemplary embodiments may include a plurality of (e.g., two) propellers, each of which may be respectively provided at first and second ends of the housing and connected with the rotor 330 of the motor 300 so as to be driven to rotate by the motor 300 and thus provide power.

When the pod drive according to an exemplary embodiment travels in water, a flow of water may flow through the housing 100 in a direction from the first end 130 to the second end 150. Therefore, hereinafter, the second end portion 150 is also referred to as a tail portion 150. The water flow guide member 700 may be provided at the second end 150 of the housing 100, and may guide the water flow flowing through the housing in a direction opposite to a direction of a vortex formed at the second end 150 by the water flow flowing through the housing 100, so that the strength of the vortex is suppressed, and thus the influence of the vortex on the pod driver may be reduced. For example, the water flow guiding member 700 may be configured to have a direction of guiding the water flow opposite to the rotation direction of the propeller 500.

In particular, vortices may form on the outside of the nacelle drive under the influence of the propeller slipstream. The vortex formed at the tail can change the streamline shape near the nacelle drive, resulting in additional drag increments. From an energy point of view, the kinetic energy taken away by the vortex requires the nacelle drive to generate additional thrust to balance, i.e. equivalent to an increase in flow resistance. Furthermore, the position of the separation zone at the rear of the pod drive changes from time to time due to the influence of unsteady flow, thereby giving the rear end of the pod propeller a constantly pulsating lateral force, while also requiring the motor system in the control direction of the hull to provide additional torque to balance. In addition, the vortex in the wake may contain cavitation from the propeller tip, may be stably propagated far downstream, and may cause significant noise problems after interference with transmission and the like.

The water flow directing member of the pod drive according to exemplary embodiments, disposed at the end of the housing downstream of the water flow (i.e., the tail), may fix the size of the tail separation region, thereby suppressing the pulsating lateral hydrodynamic force and thus improving the maneuverability of the pod as a drive.

Further, since the water flow guide member can guide the water flow in the direction opposite to the direction of the vortex, it is possible to suppress the rotation of the vortex, and thus to reduce the resistance caused by the vortex and to reduce the noise level.

Fig. 3 and 4 are diagrams illustrating a water flow guiding member of a tail portion of a pod drive according to an exemplary embodiment, respectively. The water flow guide member 700 may include or be configured as a groove formed in the middle of the second end 150 of the housing 100. Here, the groove 700 may have a star shape. The star-shaped recess 700 may include a central slot 710 and a plurality of peripheral slots 730 positioned around the central slot 710. The middle groove 710 may have a circular shape and communicate with the outer groove 730. In other words, the middle groove 710 may be integrated with the outer groove 730. Each of the peripheral grooves 730 may have an equilateral triangle shape as shown in fig. 3, or may have a bar shape as shown in fig. 4, and such equilateral triangle shape or bar shape of the peripheral grooves 730 may be inclined at a predetermined angle in a direction with respect to the center of the central groove. Here, the inclination direction of the peripheral groove 730 may be opposite to the direction of the propeller. For example, when the propeller rotates in a clockwise direction, the direction of inclination of the peripheral groove 730 may be a clockwise direction as shown in fig. 3 and 4, or vice versa.

In an exemplary embodiment in which the water flow guide member 700 is formed in the form of a groove, the groove may be formed in the outer surface of the housing 100 of the pod driver formed of, for example, steel by a process of cutting, milling, or the like. The thickness of the steel material generally used to form the case 100 may be about 80mm, and thus, the depth of the groove formed in such a case 100 may be 1/3 to 1/2 of the thickness of the case 100.

Although the water flow guide member formed as the groove having a specific shape is described above with reference to fig. 3 and 4, exemplary embodiments are not limited thereto, and the water flow guide member may be formed as the groove or the protrusion having various shapes according to design or actual needs to guide the water flow flowing through the housing in a direction opposite to the direction of the vortex formed at the tail. For example, in one exemplary embodiment, the water flow directing member may be formed as a vortex generator. In such a case, the direction of the vortex generators generating the vortex may be opposite to the direction of rotation of the propeller.

A pod drive according to another exemplary embodiment will be described below with reference to fig. 2 and 5, and a repetitive description of the same or similar elements will be omitted for the sake of brevity. Here, the pod drive according to another exemplary embodiment may include a housing 100 and a motor 300 installed in the housing 100. The pod drive according to the present exemplary embodiment may be mounted at the bottom of the hull of the vessel and may be located below the water surface, e.g. may be immersed in seawater. The pod drive according to the present exemplary embodiment may further include a propeller (not shown) provided at one or both ends of the housing 100 and connected to the rotor of the motor 300, and a water flow guide member provided at the tail of the housing 100. Furthermore, the pod drive according to the present exemplary embodiment may also not comprise a water flow guiding member.

second end portions

end portions

The motor 300 may be installed in the installation space of the housing 100. The motor 300 may include a stator 310 and a rotor 330. The stator 310 of the motor 300 may be installed in the middle portion 110 of the housing 100. In addition, the stator 310 may include a lamination sheet 311.

In order to better dissipate heat of the stator 310 of the motor 300, the case 100 may further include a heat dissipation pattern 113 formed on an inner surface of the case 100.

As shown in fig. 2, the heat dissipation pattern 113 may include a plurality of heat dissipation protrusions. Such a heat dissipation pattern 113 including a plurality of heat dissipation protrusions may be formed through an additive manufacturing process, for example, may be formed of a material such as steel. In one exemplary embodiment, when the case 100 is formed of, for example, steel through an additive manufacturing process, the heat dissipation pattern 113 may be integrally formed with the case 100 through the same additive manufacturing process.

The heat dissipation pattern 113 may include heat dissipation protrusions on an inner surface of the case 100 at the middle portion 110 where the stator 310 of the motor is located, which may correspond in shape and position to the shape and position of the grooves of the lamination sheet 311 of the stator 310, respectively. Accordingly, when the motor 300 is mounted in the case 100, the stator 310 of the motor 300 may be mounted in the middle portion 110 of the case 100, and at this time, the heat dissipation protrusions at the corresponding positions may be filled in the corresponding grooves of the lamination sheets 311 of the stator 310. In this way, the heat of the motor 300 can be transferred through the heat dissipation pattern 113 filled in the groove of the lamination sheet 311, thereby dissipating the heat of the motor 300.

Further, the heat dissipation pattern 113 may further include heat dissipation protrusions on the inner surface of the case 100 at the middle portion 110 where the stator 310 of the motor 300 is located, the positions and shapes of which correspond to those of the winding heads of the motor 300. Accordingly, when the motor 300 is mounted in the case 100, the heat dissipation protrusions located at the corresponding positions may be filled in the gap between the winding head and the inner surface of the middle portion 110 of the case 100. As such, the heat of the motor 300 may be transferred through the heat dissipation pattern 113 filled into the gap between the inner surface of the case 100 and the winding head, thereby dissipating the heat of the motor 300.

However, exemplary embodiments are not limited thereto, and the heat dissipation pattern 113 may further include heat dissipation protrusions located at other positions of the inner surface of the case 100 and between the case 100 and the motor 300, and the heat dissipation protrusions may be filled between the inner surface of the case 100 and the motor 300 when the motor 300 is mounted in the case 100, so that heat of the motor 300 is transferred through the heat dissipation protrusions to improve heat dissipation of the motor 300.

Referring to fig. 2, the casing 100 may further include a drag reduction pattern 115 formed on an outer surface of the casing 100.

The drag reducing pattern 115 may be located on an outer surface of the middle portion 110 of the shell 100 and may include a plurality of drag reducing protrusions. Such a drag reducing pattern 115 comprising a plurality of drag reducing protrusions may be formed by an additive manufacturing process, for example, may be formed of a material such as steel. In one exemplary embodiment, when the casing 100 is formed of, for example, steel by an additive manufacturing process, the drag reducing pattern 115 may be integrally formed with the casing 100 by the same additive manufacturing process.

As shown in fig. 2 and 5, the plurality of drag reducing protrusions may have a shape extending rotatably around the casing on the outer surface of the middle portion 110 of the casing 100 along the length direction (axial direction) of the casing 100. A cross section of the drag reducing protrusion is shown in fig. 5, and it can be seen from the cross section of fig. 5 that the curved surface shape of the drag reducing protrusion may have a shape of a quadratic curve. In other words, the outer surface of the strip-shaped drag reducing projection may have the shape of a quadric surface. For example, the drag reduction pattern is formed such that the middle portion of the shell has a plurality of minimum and maximum radii Dx + Dy in the length direction of the shell. Here, the curved shape of the drag reducing projection may be, for example, an elliptic curve having a minimum radius Dx and a maximum radius Dx + Dy. Further, each of the drag reducing protrusions may have a bar shape of which an outer surface is a curved surface shape. For example, the casing 100 having the drag reducing pattern including the plurality of drag reducing protrusions extending in a strip shape rotationally around the casing may have an appearance similar to that of a rope formed by a knot of a plurality of strands. Here, Dx may be, for example, a radius of one meter of a housing of an existing pod drive, and Dy may be a size of several centimeters or ten and several centimeters.

Although an exemplary embodiment including 6 drag reducing protrusions is shown in fig. 5, exemplary embodiments are not so limited and different numbers of drag reducing protrusions may be provided as needed or designed (e.g., the size of the pod drive, the conditions of the water flow environment in which it operates, etc.). In addition, the drag reduction protrusion may be formed to have a predetermined height Dy protruding from the outer surface of the case 100. The height Dy of the drag reducing projections may be determined according to the size of the pod drive, the conditions of the water flow environment in which it operates, etc., so that the water flow forms a turbulent boundary layer when flowing over the plurality of projections and recesses between the plurality of drag reducing projections, thereby reducing the drag of the water flow against the outer surface of the pod drive.

The water flow directing member of the pod drive according to exemplary embodiments, disposed at the end of the housing downstream of the water flow (i.e., the tail), may fix the size of the tail separation region, thereby suppressing the pulsating lateral hydrodynamic force and thus improving the maneuverability of the pod as a drive. Further, since the water flow guide member can guide the water flow in the direction opposite to the direction of the vortex, it is possible to suppress the rotation of the vortex, and thus to reduce the resistance caused by the vortex and to reduce the noise level.

The heat dissipation pattern of the pod drive according to the exemplary embodiment may be filled in a gap between the inner surface of the housing and the motor, thereby transferring heat of the motor to the housing to dissipate heat of the motor. Such a heat dissipation pattern may be formed by an additive manufacturing process, for example, integrally formed with the housing.

The drag reduction pattern of the pod drive according to exemplary embodiments may cause the water flow to form a turbulent boundary layer as it flows through the housing, thereby reducing the drag of the water flow against the housing.

It should be understood that although the specification has been described in terms of various embodiments, not every embodiment includes every single embodiment, and such description is for clarity purposes only, and it will be appreciated by those skilled in the art that the specification as a whole can be combined as appropriate to form additional embodiments as will be apparent to those skilled in the art.

The above description is only an exemplary embodiment of the present invention, and is not intended to limit the scope of the present invention. Any equivalent alterations, modifications and combinations can be made by those skilled in the art without departing from the spirit and principles of the invention.

Claims

1. A pod drive, characterized in that the pod drive comprises:

a housing (100);

a motor (300) mounted within the housing;

a propeller (500) rotatably disposed at the first end (130) of the housing and configured to be connected with a rotor of the motor;

a water flow guide member (700) disposed at a second end (150) of the housing opposite the first end (130) and configured to guide the water flow passing through the housing in a direction opposite to a direction of a vortex formed at the second end by the water flow passing through the housing,

wherein the water flow guide member includes a vortex generator formed at a middle portion of the second end portion of the housing, wherein a direction of a vortex generated by the vortex generator is opposite to a rotation direction of the propeller.

2. The pod drive of claim 1, wherein the water flow directing member is configured to have a direction directing water flow opposite to a direction of rotation of the propeller.

3. The pod drive of claim 1, wherein the water flow directing member comprises a groove formed in a middle of the second end of the housing.

4. The pod driver as set forth in claim 3, wherein the recess has a star shape and comprises a central groove and a plurality of peripheral grooves around the central groove and communicating with the central groove, wherein each of the peripheral grooves is formed in an equilateral triangle shape or a strip shape inclined at a predetermined angle in a direction with respect to a center of the central groove.

5. The pod drive of claim 4, wherein the peripheral channel is angled in a direction opposite to a direction of rotation of the propeller.

6. The pod drive of claim 1, wherein the housing comprises at least one of a heat dissipation pattern (113) formed on an inner surface of the housing for filling in a gap between the inner surface of the housing and the motor and a drag reduction pattern (115) formed on an outer surface of the housing for reducing drag of water flow through the housing.

7. The pod drive of claim 6, wherein at least one of the drag reduction pattern and the heat dissipation pattern is formed by an additive manufacturing process.

8. The pod drive of claim 7, wherein the housing is integrally formed with at least one of the drag reducing pattern and the heat dissipating pattern by an additive manufacturing process.

9. The pod drive of claim 6, wherein the drag reducing pattern comprises a plurality of drag reducing protrusions, wherein the plurality of drag reducing protrusions are located on an outer surface of the middle portion of the housing and are configured to extend rotationally about the housing on the outer surface along a length of the housing.

10. The pod drive of claim 6, wherein the drag reducing pattern is formed such that a middle portion of the housing has a plurality of minimum and maximum radii along a length of the housing.

11. The pod drive of claim 9, wherein each of the plurality of drag reducing protrusions is formed as a strip having an outer surface in a curved shape.

12. The pod drive of claim 11 wherein each of the plurality of drag reducing projections is formed to have a predetermined height projecting from an outer surface of the housing to cause a turbulent boundary layer to be formed by the water flow as it passes along the housing.

13. The pod drive of claim 6, wherein the heat dissipation pattern comprises a plurality of heat dissipation protrusions, wherein a heat dissipation protrusion of the plurality of heat dissipation protrusions at a position where a stator of the motor of the housing is located is formed to have a shape corresponding to a shape of a groove of a lamination sheet of the stator so as to fill in the groove of the lamination sheet when the motor is mounted in the housing.

14. A pod drive, characterized in that the pod drive comprises:

a housing (100);

a motor (300) mounted within the housing,

wherein the water flow guide member includes a vortex generator formed at a middle portion of the second end portion of the housing, wherein a direction of a vortex generated by the vortex generator is opposite to a rotation direction of the propeller,

wherein the case includes at least one of a heat dissipation pattern (113) formed on an inner surface of the case to fill in a gap between the inner surface of the case and the motor and a drag reduction pattern (115) formed on an outer surface of the case to reduce resistance to water flow through the case,

the drag reducing pattern includes a plurality of drag reducing protrusions, wherein the plurality of drag reducing protrusions are located on an outer surface of a middle portion of the casing and configured to rotatably extend around the casing on the outer surface along a length direction of the casing.

15. The pod drive of claim 14, wherein at least one of the drag reducing pattern and the heat dissipating pattern is formed by an additive manufacturing process.

16. The pod drive of claim 15, wherein the housing is integrally formed with at least one of the drag reducing pattern and the heat dissipating pattern by an additive manufacturing process.

17. The pod drive of claim 14, wherein the drag reducing pattern is formed such that a middle portion of the housing has a plurality of minimum and maximum radii along a length of the housing.

18. The pod drive of claim 14, wherein each of the plurality of drag reducing protrusions is formed as a strip having an outer surface in the shape of a curved surface.

19. The pod drive of claim 18 wherein each of the plurality of drag reducing lugs is formed to have a predetermined height projecting from an outer surface of the housing such that a turbulent boundary layer is formed by water flow as it flows over the plurality of lugs and recesses between the plurality of drag reducing lugs.

20. The pod drive of claim 19, wherein the heat dissipation pattern comprises a plurality of heat dissipation protrusions, wherein a heat dissipation protrusion of the plurality of heat dissipation protrusions at a position where a stator of the motor of the housing is located is formed to have a shape corresponding to a shape of a groove of a lamination sheet of the stator so as to fill in the groove of the lamination sheet when the motor is mounted in the housing.