JP2007151210A - Brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brushless improved in the strength of a can through a simple structure without increasing the number of components. <P>SOLUTION: In a brushless motor mounted on a water pump, an extension side rib 33 and a bottom side rib 34 are formed, respectively, at the extension portion 31 and the bottom portion 32 of a can 30 which allows inflow of liquid. These ribs are formed integrally with the can 30 by combining radial shape and annular shape. With these ribs, strength of the can 30 can be enhanced while reducing vibration of the can 30. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a brushless motor mounted on a water pump that assists the flow of liquid.

  Conventionally, in a motor mounted on a water pump, a method in which a space for sealing an armature or the like is formed by combining a plurality of cylindrical covers in order to isolate the armature from an external liquid has been the mainstream. (For example, see Patent Document 1 as an example of a conventional water pump motor in which a sealed space is formed).

Japanese Patent No. 2999843

However, the can of FIG. 1 in Patent Document 1 improves the strength of the can by combining it with a member that also serves as a reinforcement at the bottom surface where the most water pressure is applied inside the can. Furthermore, in the brushless motor in Patent Document 1, rotation control is performed using a Hall element. For this reason, it is necessary to narrow the gap between the Hall element and the driving magnet, and a member serving also as a reinforcement is not disposed in the can in the portion where the Hall element is disposed. As a result, the strength of the can decreases at the portion where the hall element of the can is disposed.
As described above, the conventional structure has the following problems.

  1) By using another member for reinforcing the can, the number of members increases, and the unit price of the brushless motor increases.

  2) Since the strength of the arrangement portion of the hall element of the can is low, the can cannot withstand the water pressure, and there is a possibility that the liquid leaks into the sealed space where the armature and the circuit are arranged.

  3) In order to make the space between the armature and the rotating portion as small as possible, the thickness of the cylindrical portion of the can is made as thin as possible. As a result, the strength of the cylindrical portion of the can may be reduced.

  Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide a brushless motor that improves the strength of a can with a simple structure that does not increase the number of parts.

  According to claim 1 of the present invention, the brushless motor has a bottomed cylindrical outer cover with one end opened, and a bottomed cylindrical shape with at least a portion accommodated in the outer cover and one end opened. A can made of resin having non-conductivity and non-magnetism that allows liquid to flow from the opening to the inner peripheral surface of the cylindrical portion, and abutted and fixed to the inside of the cylindrical portion of the outer cover. An annular armature disposed on the inner peripheral surface of the cylindrical portion of the can with a gap therebetween, and a driving magnet facing the armature in a radial direction and supporting the driving magnet, the center of the armature A rotating body having a shaft disposed on the shaft, and the outer cover and the can are connected via a seal material to form a sealed space for accommodating the armature, and the can The other end of the bottom wall, and a plurality of ribs are formed.

  According to the first aspect of the present invention, the bottom surface portion can be reinforced by providing a rib on the bottom surface portion where the liquid pressure is applied most inside the can. Therefore, a separate member is not required for reinforcing the can as in the conventional case, and the number of parts can be reduced. Furthermore, since the strength can be improved without extremely increasing the thickness of the bottom surface portion, shrinkage cavities and crack cavities are not caused during resin molding of the can. Accordingly, liquid leakage into the sealed space due to these resin molding defects can be prevented, and the reliability of the brushless motor can be improved.

  According to claim 2 of the present invention, according to claim 1, the plurality of ribs are formed by combining annular ribs and radial ribs.

  According to claim 2 of the present invention, by forming the rib on the bottom surface portion of the can by a combination of an annular shape and a radial shape, the strength of the rib itself can be improved. Therefore, the vibration of the rib itself due to the propagation of the vibration of the can can be suppressed. Furthermore, since the plane of the bottom portion is divided, vibration energy radiated from the plane can be reduced. Accordingly, the vibration of the can can be reduced.

  According to a third aspect of the present invention, the can extension according to any one of the first and second aspects, wherein the can has an opening end extending radially outward and connected to the opening of the outer cover. A portion is formed, and radially extending ribs are formed at equal intervals in the circumferential direction in the can extending portion.

  According to claim 3 of the present invention, the radial extension-side rib is formed in the can extension portion of the can, whereby the strength of the can extension portion can be improved. Accordingly, the vibration of the can can be reduced.

  According to a fourth aspect of the present invention, in accordance with the third aspect, an outer annular rib continuous with the extended rib is formed on the radially outer side of the can extending portion.

  According to claim 4 of the present invention, the outer annular rib is further formed on the radially outer side of the radially extending rib, so that the vibration of the radial rib itself can be reduced, and the can The strength of the extension can be improved. Therefore, the vibration of the can can be further reduced.

  According to a fifth aspect of the present invention, in accordance with the fourth aspect, the outer cover is formed with a stepped portion having a different inner diameter in the axial direction in the cylindrical portion, and the armature is disposed in the outer axial direction. An end portion is in contact with the stepped portion, and at least one of the extension side rib and the outer annular rib in the can is in contact with the armature in the axial direction.

  According to claim 5 of the present invention, at least one of the radial extending side rib and the outer annular rib formed in the can extending portion comes into contact with the armature, so that the armature Since the structure is fixed by being sandwiched between the stepped portion and the rib in the axial direction, the fixing strength of the armature can be improved. Therefore, vibration generated from the armature itself can be reduced.

According to a sixth aspect of the present invention, in accordance with any one of the first to fifth aspects, the armature includes a core back portion formed in an annular shape, and a plurality of armatures extending from the core back portion toward the central axis. The teeth part and
The adjacent teeth portions have a gap in the circumferential direction,
The cylindrical portion of the can corresponding to the gap and the radial direction is formed with a cylindrical portion rib.

  According to the sixth aspect of the present invention, the strength of the cylindrical portion can be improved by forming the rib in the cylindrical portion of the can. As a result, it is possible to provide a highly reliable brushless motor that does not crack with respect to the water pressure flowing into the can. Further, since the cylindrical portion of the can is formed with a small thickness, there is a possibility that the hot water flow in the cylindrical portion is poor and poor molding occurs. However, by providing the cylindrical portion rib, the hot water flow in the cylindrical portion rib portion is improved, so that molding defects can be prevented.

  According to claim 7 of the present invention, according to claim 6, the cylindrical portion rib and the radial rib are connected to each other.

  According to claim 7 of the present invention, the hot water flow of the resin can be further improved by connecting the radial rib and the cylindrical portion rib. Therefore, the moldability of the can can be improved.

  According to an eighth aspect of the present invention, according to any one of the sixth and seventh aspects, the cylindrical portion rib and the extending side rib are connected to each other.

  According to claim 8 of the present invention, the hot water flow of the resin can be improved by connecting the cylindrical portion rib and the extending side rib. Furthermore, if it connects with a radial shape rib, the hot water flow of resin can be improved further. Therefore, the moldability of the can can be further improved.

  According to a ninth aspect of the present invention, in any one of the first to fifth aspects, a circuit in which an electronic circuit component for supplying a driving current to the armature in a sensorless manner is mounted in the sealed space. A substrate is arranged.

  According to claim 9 of the present invention, since it is a sensorless system, position detecting electronic components such as a hall element generally required for a brushless motor can be eliminated. Therefore, since it is not necessary to consider the gap between the driving magnet and the position detecting electronic component, it is possible to increase the thickness of the bottom surface portion of the can disposed between the driving magnet and the position detecting electronic component. it can. As a result, the degree of freedom in designing the rib formed on the bottom surface of the can can be improved.

  According to the present invention, it is possible to provide a brushless motor that improves the strength of a can with a simple structure that does not increase the number of parts.

<Overall structure of brushless motor>
An embodiment of a brushless motor according to the present invention will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view in the axial direction of a brushless motor.

  Referring to FIG. 1, a substantially cylindrical outer cover 10 that opens downward is formed by plastic working such as pressing a steel plate. An extending portion 11 extending outward in the radial direction is integrally formed at the lower end portion of the outer cover 10. The cylindrical portion 12 of the outer cover 10 is formed with an upper step portion 13 and a lower step portion 14 that are spaced apart in the axial direction. The upper step 13 is formed at the axial center of the cylindrical portion 12 of the outer cover 10 and performs axial positioning and holding of an armature 20 described later. The lower step 14 is formed on the lower end side of the outer cover 10, and the sealing member 40 described later is positioned and held in the axial direction and the radial direction by the lower step 14 and a can 30 described later.

  The armature 20 held by the upper step portion 13 in the cylindrical portion 12 of the outer cover 10 is a laminate composed of a core back portion 21 formed in an annular shape and a plurality of teeth portions 22 extending radially inward. The core 23, the insulator 24 which fixes this laminated core 23 so that it may be pinched | interposed from an up-down direction, and the conducting wire 25 wound around the teeth part 22 from the outer side of the insulator 24 are provided. The outer peripheral edge of the core back portion 21 has a non-covered portion 21a that is not covered by the insulator 24. The non-covered portion 21a and the upper step portion 13 of the outer cover 10 come into contact with each other, so that the armature 20 Axial positioning and holding are performed.

  The can 30 is formed in a substantially cylindrical shape that opens downward, and is formed by, for example, injection molding using a resin having non-conductivity and non-magnetism. A can extension 31 is formed at the lower end of the can 30 and extends radially outward. The can extension portion 31 is in contact with the cylindrical portion 12a formed below the lower step portion 14 of the outer cover 10 in the radial direction. A sealing member 40 is fixedly disposed between the can extending portion 31 and the lower step portion 14 of the outer cover 10.

  A bus bar 50 is formed on the upper side of the cylindrical portion 12 of the outer cover 10 so as to be in contact with and fixed to the inner peripheral surface of the cylindrical portion 12. An opening hole is formed in the bottom surface portion 15 of the outer cover 10, and a connector portion 51 that is supplied with an electric current from an external power source is formed integrally with the bus bar 50 so as to be inserted into the opening hole. Further, on the lower surface of the bus bar 50, a circuit board 60 that controls rotation by controlling the timing of energizing the armature 20 is fixed.

  A rotation provided with a cylindrical shaft 70 formed along the central axis of the armature 20 and a driving magnet 80 arranged with a gap in the radial direction on the radially inner side of the can 30. A body 90 is formed. The rotating body 90 further includes a magnetic yoke 100 and a shaft 70 disposed in contact with the driving magnet 80 in the radial direction, a driving magnet 80, and a holding member 110 for fixing and holding the yoke 100. The holding member 110 is formed by a resin mold and has a substantially H shape.

  When a current is supplied from an external power source (not shown) to the armature 20 at an appropriate energization timing, a magnetic field is generated in the armature 20, and due to the interaction between the magnetic field and the driving magnet 80, the rotating body 90 is Rotating drive.

<Main part>
With reference to FIG. 2 and FIG. 3, the detail of the shape of the can 30 which is the principal part of this invention is demonstrated. FIG. 2 is a schematic cross-sectional view in the axial direction of the can 30, and FIG. 3 is a top view of the can 30. FIG. 4 is a top view when the armature 20 and the can 30 are combined.

  Referring to FIG. 2, the can 30 formed in a substantially cylindrical shape is formed so that the thickness of the cylindrical portion 35 is the thinnest. As a result, the radial gap between the armature 20 and the driving magnet 80 can be reduced, and the magnetic loss generated by this gap can be reduced. As a result, a highly efficient brushless motor can be provided. An extension side rib 33 and a bottom side rib 34 are formed on the can extension part 31 and the bottom part 32 of the can 30, respectively.

  Next, the extension side rib 33 and the bottom side rib 34 will be described with reference to FIG.

  The extension ribs 33 are integrally formed in a plurality of radial shapes so as to extend radially outward from the cylindrical portion 35 of the can 30. Further, an annular outer ring rib 33 a formed on the radially outer side of the can extending part 31 is formed integrally with the can extending part 31 and the extending side rib 33. Thereby, the intensity | strength of the can extension part 31 can be improved. Further, the extension-side rib 33 is formed integrally with the cylindrical portion 35, whereby the strength of the extension-side rib 33 itself can be improved, and further, the extension-side rib 33a is also formed integrally with the outer annular rib 33a. Thus, the extension-side rib 33 can further improve the strength. At the same time, the outer annular rib 33a is also formed integrally with the extended rib 33, whereby the strength of the outer annular rib 33a itself can be improved. As a result, the can 30 can reduce vibration caused by the liquid allowed to flow into the inner peripheral side of the can 30.

  Further, referring to FIG. 1, the extension-side rib 33 and the outer annular rib 33 a are positioned in the axial direction by contacting the lower surface of the armature 20. Thereby, the armature 20 is clamped in the axial direction by abutting the upper surface with the upper step portion 13 of the outer cover 10 and abutting the lower surface with the extending-side rib 33 and the outer annular rib 33a. As a result, the armature 20 is firmly held, so that vibration due to the armature 20 can be greatly reduced. Furthermore, by forming the extension-side ribs 33 between the conductors 24 of the armature 20, the conductors 24 and the extension-side ribs 33 can be overlapped in the axial direction, so the axial height of the brushless motor is made low. (The dotted line portion of the armature 20 in the figure).

  Referring to FIG. 3 again, the bottom surface side rib 34 formed on the bottom surface portion 32 is formed in a radial shape with the three annular ribs 34 a formed concentrically and in an annular shape with respect to the center of the can 30. And a radially shaped rib 34b. The annular rib 34a and the radial rib 34b are integrally formed. Thereby, the intensity | strength of the annular rib 34a and the radial shape rib 34b can each be improved. Furthermore, the radial end of the radial rib 34b is formed integrally with the inner annular rib 34a1 formed on the innermost side of the annular rib 34a, thereby further improving the strength of the radial rib 34b. it can. Further, as compared with the bottom surface portion configured by a conventional flat surface, the bottom surface portion 32 having a shape in which a plurality of annular ribs 34a and radial ribs 34b are integrally combined as shown in the figure is provided on the bottom surface. The vibration energy radiated from the portion 32 can be dispersed. As a result, the vibration of the can 30 can be reduced.

  Further, it is possible to improve the strength by increasing the thickness of the can extension part 31 and the bottom part 32 instead of the extension side rib 33 and the bottom face side rib 34, but in the resin molding, the can extension part 31 can be improved. Increasing the thickness of the bottom surface portion 32 causes the problem of shrinkage nests and cracks. As a result, the dimensional accuracy of the can 30 is lowered and the strength of the can 30 is lowered. Therefore, it is effective to form the extending-side rib 33 and the bottom-side rib 34 that can be resin-molded with approximately the same thickness of the can 30.

  Further, by forming the extension side rib 33 and the bottom side rib 34 to improve the strength of the can 30, it becomes unnecessary to separately attach a reinforcing member to the can 30 as in the prior art, so that the number of parts can be reduced. be able to. Further, if a separate reinforcing member is used, a portion for positioning and fixing the reinforcing member must be formed, and the internal structure of the brushless motor becomes complicated. In the present invention, however, the extending rib 33 and the bottom rib 34 are formed. Since it corresponds only by this, since there is no influence on other components at all, the internal structure of a brushless motor can be simplified.

  Next, referring to FIG. 4, circumferentially extending portions 22 a extending in the circumferential direction are formed at both ends in the circumferential direction of the inner circumferential side tip portion of the tooth portion 22 of the armature 20. A gap 22b is formed between adjacent circumferentially extending portions 22a.

  Cylindrical ribs 35a are formed at portions of the cylindrical portion 35 of the can 30 that are opposed to the gap 22b in the radial direction so as to extend radially outward. As a result, the cylindrical portion rib 35a is inserted into the gap 22b.

  Conventionally, the smaller the radial gap between the armature 20 and the driving magnet 80, the better the magnetic efficiency. Therefore, it is desirable to make the radial gap as narrow as possible. However, when the radial gap is narrowed, the thickness in the radial direction of the cylindrical portion 35 of the can 30 disposed in the radial gap must be formed as thin as possible. Therefore, the hot water flow of the resin in the cylindrical portion 35 is deteriorated. Therefore, it has become a cause of forming defects of the can 30.

  However, by forming the cylindrical portion rib 35a, even if the cylindrical portion 35 is formed to an extremely thin thickness that can be molded, the passage when the resin flows is increased because of the cylindrical portion rib 35a. Therefore, the hot water flow is improved by the cylindrical portion rib 35a, and the moldability of the resin molding can be improved. As a result, the can 30 can be manufactured stably. Furthermore, the cylindrical part rib 35a is connected to the radial rib 34b formed on the bottom face part 32 of the can 30 and is integrally formed, whereby the hot water flow can be further improved. As a result, the moldability of the can 30 can be further improved. Furthermore, the cylindrical part rib 35a can further improve the moldability by being connected to the extending side rib. Further, the strength of the can 30 can be improved by connecting the cylindrical ribs 35a, the radial ribs 34b, and the extending ribs. As a result, it is possible to maintain rigidity against the water pressure of water allowed to flow into the inner peripheral side of the cylindrical portion 35 of the can 30. Therefore, vibration generated by water pressure can be suppressed.

  Referring to FIG. 1, the driving method of the brushless motor according to the present embodiment is a sensorless system that does not use position detection electronic components such as a Hall element. In particular, the sensorless system of the present invention is a method of acquiring and using position information from the back electromotive force waveform generated in the conductor 24. As a result, when using position detection electronic components such as conventional Hall elements, the axial gap between the driving magnet and the circuit board on which the position detection electronic components are mounted is reduced in order to improve position detection accuracy. There is a need. Therefore, it is essential that the thickness of the bottom surface portion of the can disposed between the position detection electronic component and the driving magnet is thin. However, when the driving method is sensorless driving as in the present invention, the position detection electronic component is not necessary, and the thickness of the bottom surface portion 32 of the can 30 can be freely set. Therefore, in order to form the bottom surface side rib 34 on the bottom surface part 32, the sensorless method is suitable.

  As mentioned above, although one form of the Example of this invention was described, this invention is not limited to said Example, A deformation | transformation is possible within a claim.

For example, in FIG. 3 of the embodiment, each rib is formed, but the number of these ribs is not limited to the number in the drawing, and if at least one rib is formed, the effect can be exhibited.

It is an axial direction schematic sectional view showing one form of an embodiment of a brushless motor of the present invention. It is an axial direction schematic sectional view showing one form of the can of the present invention. It is a top view which shows one form of the can of this invention. It is a top view which shows one form of the can and armature of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Outer cover 20 Armature 30 Can 31 Can extension part 32 Bottom part 33 Extension side rib 33a Outer ring rib 34 Bottom face side rib 34a Ring-shaped rib 34a1 Inner ring rib 34b Radial shape rib 35 Cylindrical part 40 Sealing Member 50 Bus bar 60 Circuit board 70 Shaft 80 Driving magnet 90 Rotating body 100 Yoke 110 Holding member

Claims (9)

A brushless motor,
A bottomed cylindrical outer cover with one end open;
A non-conductive and non-magnetic resin that has a bottomed cylindrical shape that is at least partially accommodated in the outer cover and that has an open end, and allows liquid to flow from the opening to the inner peripheral surface of the cylindrical portion. With molded cans,
An annular armature that is abutted and fixed to the inside of the cylindrical portion of the outer cover and is arranged outside the can;
Rotation provided with a drive magnet disposed radially on the inner circumferential surface of the cylindrical portion of the can and opposed to the armature in a radial direction, and a shaft disposed on the central axis of the armature that supports the drive magnet Body,
With
A brushless motor, wherein a plurality of ribs are formed on the other end side of the bottom wall of the can. The brushless motor according to claim 1, wherein the plurality of ribs are formed by combining annular ribs and radial ribs. At the opening end of the can, a can extension is formed that extends radially outward and is connected to the opening of the outer cover,
3. The brushless motor according to claim 1, wherein radially extending ribs are formed at equal intervals in the circumferential direction in the can extending portion. 4. The brushless motor according to claim 3, wherein an outer annular rib that is continuous with the extension-side rib is formed on an outer side in the radial direction of the can extension portion. In the outer cover, a step portion is formed in the cylindrical portion so that the inner diameter is different in the axial direction,
The armature has an outer axial end abutting against the stepped portion,
5. The brushless motor according to claim 4, wherein at least one of the extension-side rib and the outer annular rib of the can abuts against the armature in an axial direction. The armature includes a core back portion formed in an annular shape and a plurality of teeth portions extending from the core back portion toward the central axis,
The adjacent teeth portions have a gap in the circumferential direction,
The brushless motor according to any one of claims 1 to 5, wherein a cylindrical portion rib is formed in a cylindrical portion of the can corresponding to the gap and the radial direction. The brushless motor according to claim 6, wherein the cylindrical rib and the radial rib are connected to each other. The brushless motor according to claim 6, wherein the cylindrical portion rib and the extension side rib are connected to each other. 7. The circuit board according to claim 1, wherein a circuit board on which an electronic circuit component for supplying a driving current to the armature in a sensorless manner is mounted is disposed in the sealed space. Brushless motor.

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