Magnetic coupling pump

Abstract

A magnetic coupling pump according to the present invention has a housing including a pump chamber a motor chamber. The rotor includes a plurality of impellers projected from top face of a substantially disc-shaped main body of the rotor to be located in the pump chamber, and a substantially cylindrical magnet section projected from back face of the main body to be located in the motor chamber. The rotor is located in engine coolant, and is driven by a stator located inward of the magnet section in the motor chamber for sucking coolant from an inlet port and exhausting it from an outlet port. The pump is provided along an inner circumference of the stator with a cavity communicating with passages of fluid along an inner circumference of the magnet section and the back face of the main body of the magnet section. The cavity admits the coolant. The pump according to the present invention is able to prevent heat-up in the inner circumferential part of the stator.

Description

[0001] The present application claims priority from Japanese Patent Application No. 2003-142389 of Hatano, filed on May 20, 2003, the entirety of which is hereby incorporated into the present application by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a magnetic coupling pump for pumping fluids such as engine coolant for vehicles, and more particularly, relates to an outer-rotor type magnetic coupling pump in which a stator is located toward a rotation center of a rotor having impellers for feeding fluids, and a substantially cylindrical magnet section of the rotor is located around the stator.

[0004] 2. Description of the Related Art

[0005] In conventional outer-rotor type magnetic coupling pumps for engine coolant for vehicles, a rotor having impellers for feeding coolant is located in a housing, as disclosed in Japanese Laid Open Patent Application No. JP10-311290.

[0006] In this magnetic coupling pump, the housing includes a pump chamber having inlet port and outlet port of coolant, and a motor chamber. The rotor includes impellers which are projected from top face of a disc-shaped body of the rotor to be located in the pump chamber, and a substantially cylindrical magnet section which is projected from back face of the rotor body to be located in the motor chamber. This rotor is located in the coolant, and is driven to rotate by rotating magnetic field generated by a stator located inward of the magnet section in the motor chamber to suck the coolant from the inlet port and exhaust it from the outlet port.

[0007] In the conventional outer-rotor type magnetic coupling pump, however, there is no means of cooling down a part inward of the stator though the outer circumference of the stator can be cooled down by coolant interposed between the stator and the magnet section. Accordingly, heat-up of the stator and burnout of coils of the stator caused by the former has been a concern in a high-load driving condition using a lot of electricity.

SUMMARY OF THE INVENTION

[0008] The present invention contemplates to solve the above mentioned problem, and therefore, has an object to provide a magnetic coupling pump capable of preventing heat-up of an inner circumferential part of the stator.

[0009] A magnetic coupling pump according to the present invention is to suck fluid from an inlet port and exhaust the fluid from an outlet port, and includes a housing and a rotor. The housing includes a pump chamber having the inlet and outlet ports of fluid and a motor chamber. The rotor includes: a plurality of impellers projected from top face of a substantially disc-shaped main body of the rotor to be located in the pump chamber; and a magnet section projected from back face of the main body to be located in the motor chamber and having a substantially cylindrical shape. The rotor is located in the fluid and driven by a rotating magnetic field generated by a stator located inward of the magnet section in the motor chamber. A cavity is located along an inner circumference of the stator so as to communicate with passages of fluid along an inner circumference of the magnet section and the back face of the main body of the magnet section.

[0010] In the magnetic coupling pump according to the present invention, fluid flows into the cavity located inward of the stator from fluid passages along the inner circumference of the magnet section and the back face of the main body of the rotor, and the inner circumferential part of the stator is cooled down by this fluid.

[0011] Therefore, the magnetic coupling pump of the present invention is able to prevent heat -up of the inner circumferential part of the stator and burnout of coils of the stator, whereby becomes durable even under high-load driving which consumes a lot of electricity.

[0012] If the main body of the rotor is provided in the vicinity of an inner circumferential part of the stator with a plurality of through holes, the fluid in the cavity is able to flow into the pump chamber via the through holes of the rotor main body. That is, the fluid forms a cooling stream for cooling the stator that flows from the outer circumferential side to the inner circumferential side of the stator, and further flows from the inner circumferential side of the stator to the pump chamber. Therefore, heat-up of the inner circumferential part of the stator is further prevented, and in addition, heat-up of the outer circumferential side of the stator is properly prevented, too. Consequently, burnout of the coils of the stator and heat deformation of the housing are properly prevented, which further elongates a life span of the pump even under high-load driving which consumes a lot of electricity.

[0013] When the rotor includes a shaft section projecting into the cavity, the shaft section is desirably provided in its outer circumference with a plurality of impellers for stirring the fluid. With this arrangement, the impellers are able to stir the fluid in the cavity when the rotor is driving, and therefore, entire area of the inner part of the stator is cooled down quickly and properly.

[0014] When the rotor includes a shaft section projecting into the cavity, moreover, it will also be appreciated that the shaft section internally includes a passage with apertures opening in the cavity and in a top face side of the main body, such that the fluid in the cavity circulates to the top face side of the main body through the passage. With this arrangement, the fluid in the cavity is able to flows out toward the top face side of the rotor main body or into the pump chamber via the passage of the shaft section. Especially, the fluid in a bottom part of the cavity is also able to circulate to the pump chamber via the passage. Therefore, cooling-down effect of the inner circumferential part of the stator is enhanced.

[0015] Furthermore, if the rotor is rotatably supported at two positions of a position proximate to the main body and at a position in the cavity, the rotation of the rotor is stabilized, which reduces the loss of rotation moment of the rotor.

BRIEF DESCRIPTION OF DRAWINGS

[0016] FIG. 1 is a vertical section of an embodiment of the magnetic coupling pump according to the present invention;

[0017] FIG. 2 is a vertical section of the rotor of the pump of FIG. 1;

[0018] FIG. 3 is a transverse section of the rotor of FIG. 2 taken along line III-III of FIG. 2; and

[0019] FIG. 4 is a vertical section of another embodiment of the magnetic coupling pump according to the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0020] Preferred embodiments of the present invention are now described below with reference to the accompanying drawings. However, the invention is not limited to the embodiments disclosed herein. All modifications within the appended claims and equivalents relative thereto are intended to be encompassed in the scope of the claims.

[0021] FIGS. 1 to 3 illustrate an embodiment P1 of the magnetic coupling pump according to the present invention for feeding engine coolant W for vehicles. The pump P1 includes a housing 1 which is made from synthetic resin and has therein a rotor 15 with a plurality of impellers 17 for feeding the coolant W.

[0022] The housing 1 includes a pump chamber 2 in which the impellers 17 of the rotor 15 are located, and a motor chamber 6 located below the pump chamber 2. The pump chamber 2 has a ceiling wall 2a and has a substantially cylindrical shape. An inlet pipe 3 for introducing the coolant W projects upward from the ceiling wall 2a, and an outlet pipe 4 for exhausting the coolant W projects outwardly from a circumferential wall 2b.

[0023] The motor chamber 6 includes a circumferential wall 7 having a substantially cylindrical shape, a bottom wall 8 extending from a lower inner part of the circumferential wall 7, and a stator section 9 protruding upward from the bottom wall 8.

[0024] The stator section 9 is provided along its inner circumference with a cavity 11 to which the coolant W is admissible, and has a substantially cylindrical shape as a whole. The stator section 9 includes therein a stator 10 wound by coils 10a for generating a rotating magnetic field when electrified. A member designated by a reference numeral 12 is a circuit board for rotating the rotor 15 on which power transistors for driving the stator 10, and a Hall element for detecting rotation angle of the stator 10, and so on are located. A member designated by a reference numeral 13 is a terminal for supplying electricity to the circuit board 12.

[0025] The rotor 15 includes a main body 16 having a substantially disc shape and a magnet section 18. The main body 16 has impellers 17 projected upward from its top face 16a. The magnet section 18 has a substantially cylindrical shape, and extends downward from the vicinity of the outer edge of the main body 16, or from a back face 16a of the main body 16 to be located between an outer circumference of the stator 10 and an inner circumference of the circumferential wall 7. The magnet section 18 is driven and rotates by the rotating magnetic field generated by the stator 10. In the foregoing embodiment, the magnet section 18 is made from a material made by mixing magnetic powder into synthetic resin material such as polyamide that forms the rotor 15 except later-described shaft 20 and bearings 25.

[0026] The main body 16 is provided near the inner circumference of the stator 10 with a plurality of through holes 16c through from the top to the back. Located vertically in the center of the main body 16 is a shaft section 19, which includes a shaft 20 and a sliding boss section 26. The shaft 20 is made of metal pipe, and penetrates the base 16. A lower end 20b of the shaft 20 is fixed to the center of the bottom wall 8 of the motor chamber 6 in the housing 1. This pipe-shaped shaft 20 is open at its upper end, and is provided in a part submerged in the coolant W near the lower end 20b, or in a part near a bottom 11a of the cavity 11 with a plurality of holes 22 communicating in and outsides of the shaft 20. These holes 22 serve as inlet ports for inletting the coolant W such that the coolant W flows through an inner passage 21 of the shaft 20 and flows out of the upper end of the shaft 20 serving as an outlet port 23.

[0027] The sliding boss section 26 has a cylindrical shape, and is integrally formed with the main body 16 in the center of the main body 16. Bearings 25 are fixed to upper and lower parts of an inner circumference of the sliding boss section 26 such that the shaft 20 rotatably supports the sliding boss section 26. The bearings 25 are made of resin or metal capable of reducing friction force. An E-ring 24 is located proximate to the top end 20a of the shaft 20 to prevent the sliding boss section 26 from coming off from the shaft 20.

[0028] The E-ring 24 is required since the rotor 15 is prone to float up when rotating because of negative pressure generated near the inlet pipe 3. When the pump P1 is in service, the rotor 15 rotates at 3000 to 3800 rpm.

[0029] The rotor 15 is submerged in the coolant W except the lower end 20b of the shaft 20 fixed to the housing 1. The sliding boss section 26, which is located in the cavity 11 or inward of the stator section 9, is provided on the outer circumference in its lower part with a plurality of stirring impellers 27 for stirring the coolant W in the cavity 11.

[0030] In the magnetic coupling pump P1, the coolant W flows into the cavity 11 positioned inward of the stator 10 from fluid passages along the inner circumference 18a of the magnet section 18 and the back face 16b of the main body 16 of the rotor 15, whereby the inner side of the stator 10 is cooled down.

[0031] Therefore, the magnetic coupling pump P1 is able to prevent heat-up of an inner circumferential part of the stator 10 and burnout of the coils 10a of the stator 10, where by becomes durable even under high-load driving which consumes a lot of electricity.

[0032] In the preferred embodiment, the through holes 16c pierced through vertically are located near the inner circumference of the stator 10 of the main body 16. When the rotor 15 is driven and rotates, negative pressure occurs toward the inlet pipe 3, and the coolant W in the cavity 11 flows toward the pump chamber 2 via the through holes 16c of the main body 16. In other words, the coolant W forms a cooling stream F0 for the stator 10 that flows from the outer circumferential side to the inner circumferential side of the stator 10, and further flows from the inner circumferential side of the stator 10 to the pump chamber 2. Therefore, heat-up of the inner circumferential part of the stator 10 is further prevented, and in addition, heat-up of the outer circumferential side of the stator 10 is properly prevented. Consequently, burnout of the coils 10a of the stator 10 and heat deformation of the stator section 9 in the housing 1 are properly prevented, which further elongates a life span of the pump P1 even under high-load driving which consumes a lot of electricity.

[0033] In the preferred embodiment, moreover, the rotor 15 includes the shaft section 19 projecting into the cavity 11, and the sliding boss section 26 of the shaft section 19 is provided on its outer circumference with the stirring impellers 27 for stirring the coolant W. Accordingly, the impellers 27 are able to stir the coolant W in the cavity 11 when the rotor 15 is driving, and therefore, entire area of the inner part of the stator 10 is cooled down quickly and properly.

[0034] Furthermore, the rotor 15 includes the shaft section 19 projecting into the cavity 11, and the shaft 20 of the shaft section 19 internally has the passage 21 provided with apertures open into the bottom part 11a of the cavity 11 and in the surface 16a of the main body 16 such that the coolant W in the bottom part 11a of the cavity 11 circulates to the pump chamber 2 above the rotor main body 16. When the rotor 15 is driven and rotates, negative pressure occurs toward the inlet pipe 3, and the coolant W in the bottom part 11a of the cavity 11 flows into the passage 21 of the shaft 20 from the inlet ports 22, and then flows out of the outlet port 23 or the top end 20a of the shaft 20 into the pump chamber 2 above the main body 16, via the passage 21. That is, the coolant W forms a cooling stream F1 for the stator 10 that flows from the outer circumferential side to the inner circumferential side of the stator 10, and flows from a bottom part of the inner circumferential side of the stator 10 to the pump chamber 2 via the passage 21. Thus, cooling-down effect of the inner part of the stator 10 is enhanced.

[0035] In addition, in the magnetic coupling pump P1, the rotor 15, when rotating, is supported by two bearings 25 which are located near the upper and lower end of the rotor 15, i.e., at a position near the main body 16 and a position in the cavity 11. Therefore, the rotation of the rotor 15 is stabilized, which reduces the loss of the rotation moment of the rotor 15.

[0036] Although the preferred embodiment shows the shaft section 19 of the rotor 15 having the sliding boss section 26 with the stirring impellers 27, the shaft section does not necessarily have to be provided with the impellers 27.

[0037] Although preferred embodiment shows the shaft section 19 of the rotor 15 having the pipe-shaped shaft 20 which serves as the fluid passage 21, the magnetic coupling pump may include a shaft section 19A which has a sliding boss section 26 with the stirring impellers 27 and a shaft 20A without the passage 21, as in a magnetic coupling pump P2 shown in FIG. 4.

[0038] Although the preferred embodiment shows the main body 16 of the rotor 15 with a plurality of though holes 16c through from top to bottom, the rotor 15 may include no through holes 16c.

Claims

1. A magnetic coupling pump for sucking fluid from an inlet port and exhausting the fluid from an outlet port, the pump comprising a housing and a rotor, the housing including a pump chamber having the inlet and outlet ports of fluid and a motor chamber, the rotor including: a plurality of impellers projected from top face of a substantially disc-shaped main body of the rotor to be located in the pump chamber; and a magnet section projected from back face of the main body to be located in the motor chamber, the magnet section having a substantially cylindrical shape, the rotor being located in the fluid and driven by a rotating magnetic field generated by a stator located inward of the magnet section in the motor chamber, wherein a cavity is located along an inner circumference of the stator, the cavity communicating with passages of fluid along an inner circumference of the magnet section and the back face of the main body of the magnet section.

2. The magnetic coupling pump according to claim 1, wherein: the main body of the rotor includes a plurality of through holes in the vicinity of an inner circumferential part of the stator, the through holes being through from the top face to the back of the main body.

3. The magnetic coupling pump according to claim 1, wherein: the rotor includes a shaft section projecting into the cavity; and the shaft section is provided in the outer circumference thereof with a plurality of impellers for stirring the fluid.

4. The magnetic coupling pump according to claim 2, wherein: the rotor includes a shaft section projecting into the cavity; and the shaft section is provided in the outer circumference thereof with a plurality of impellers for stirring the fluid.

5. The magnetic coupling pump according to claim 1, wherein: the rotor includes a shaft section projecting into the cavity; and the shaft section internally includes a passage with apertures opening in the cavity and in a top face of the main body, whereby the fluid in the cavity circulates to the top face side of the main body through the passage.

6. The magnetic coupling pump according to claim 2, wherein: the rotor includes a shaft section projecting into the cavity; and the shaft section internally includes a passage with apertures opening in the cavity and in a top face of the main body, whereby the fluid in the cavity circulates to the top face side of the main body through the passage.

7. The magnetic coupling pump according to claim 3, wherein: the shaft section internally includes a passage with apertures opening in the cavity and in a top face of the main body, whereby the fluid in the cavity circulates to the top face side of the main body through the passage.

8. The magnetic coupling pump according to claim 1, wherein the rotor is rotatably supported at two positions of a position proximate to the main body and at a position in the cavity.

9. The magnetic coupling pump according to claim 2, wherein the rotor is rotatably supported at two positions of a position proximate to the main body and at a position in the cavity.

10. The magnetic coupling pump according to claim 3, wherein the rotor is rotatably supported at two positions of a position proximate to the main body and at a position in the cavity.

11. The magnetic coupling pump according to claim 4, wherein the rotor is rotatably supported at two positions of a position proximate to the main body and at a position in the cavity.