GB2216189A

GB2216189A - Magnetic coupling for pump drive

Info

Publication number: GB2216189A
Application number: GB8903294A
Authority: GB
Inventors: Haruki Nakao; Katsuji Kikuchi
Original assignee: Nikki Co Ltd
Current assignee: Nikki Co Ltd
Priority date: 1988-02-22
Filing date: 1989-02-14
Publication date: 1989-10-04
Also published as: GB8903294D0; IT8919521A0; KR890017784U; IT1228846B; KR910008483Y1; JPH01125888U

Abstract

A rotary pump comprises a pump unit 2 having a pump impeller 12, and a motor unit 1 having a motor 4 for driving the pump. The motor unit drives a cup-shaped non-magnetic member 7 having permanent magnets 10 attached thereto. The magnets 10 when driven by the motor 4, impart drive across a partition 11 to magnets 15 respective to the vanes 13 of the pump impeller 12. Alternative configurations of opposing magnets are disclosed (Figs 2 and 4). The arrangement avoids leakage of the fluid being pumped along the motor drive shaft. <IMAGE>

Description

"ROTARY PUMP" This invention relates to a rotary pump for household use, which comprises a motor unit and a pump unit which are magnetically coupled to each other.

Rotary pumps for household use generally comprise a housing a pump unit and a motor unit. The housing has a partition dividing the interior of the housing into two chambers. The pump unit is set in the first chamber, and the motor unit in the second chamber. The partition has a watertight seal in its center portion.

The shaft of one of these units extends through this watertight seal and is connected to the shaft of the other unit. Hence, the motor unit can drive the pump unit.

The shaft of the pump unit or the motor unit is in sliding contact with the watertight seal. Strictly speaking, the seal is not watertight. There is the possibility that the water flows, first along the shaft of the pump unit and then along that of the motor unit.

Once water flows into the motor unit it may impair the electrical insulation provided in the motor unit inevitably resulting in a malfunction of the motor unit. The user of the rotary pump should therefore, carefully operate the pump to allow no water to flow from the pump unit into the motor unit.

The object of the present invention is to provide a rotary pump, wherein no water flows from the pump unit into the motor unit along the shafts of these units connected to each other.

According to the invention, there is provided a rotary pump which comprises a pump unit having a pump with a shaft; a motor unit having a motor with a shaft for driving the pump; input coupling means connected to the shaft of the pump; output coupling means connected to the shaft of the motor and opposing the input coupling means; and two sets of magnets, the magnets of the first set being attached to the input coupling means, and the magnets of the second set being attached to the output coupling means and opposing the magnets of the first set.

When the motor of the motor unit is turned on, the output coupling means, which is connected to the shaft of the motor, is rotated. Since the output coupling means and the input coupling means are magnetically coupled by virtue of the magnets attached to them, the input coupling unit is also rotated. As a result, the pump is driven though the pump unit is not physically connected to the motor unit. Owing to the non-physical connection between the pump unit and the motor unit no water flows from the pump unit into the motor unit.

Since not water is allowed to flow from the pump unit into the motor unit, the electrical insulation within the motor unit is maintained complete. The motor unit is safe even if applied with the high voltage which is commercially available. It need not be driven by a lowered voltage, unlike its counterpart of the conventional, household-use rotary pump.

This invention can be more fully understood from the following detailed description when taken in conjunction with the accompanying drawings, in which: Fig. 1 is a partially broken-away view of a rotary pump according to the present invention; Fig. 2 is a front view showing the rotary pump shown in Fig. 1; Fig. 3 is a partially sectional view showing a modification of the input coupling means, and also a modification of the output coupling means; and Fig. 4 is a side view showing a modification of the input coupling means.

The embodiments of the present invention will now be described with reference to the accompanying drawings.

Fig. 1 shows a rotary pump according to a first embodiment of the present invention. As is shown in this figure, the rotary pump comprises a motor unit 1 and a pump unit 2. The motor unit 1 comprises a watertight housing 3 and a motor 4 placed within the housing 3. The housing 3 is made of electrically insulative material such as plastics, and is a hollow cylinder having two end walls 3a and 3b. Two recesses 9 are made in the inner surface of the end walls 3a and 3b, respectively. Two bearings 5 are set in these recesses 9, and supports the end portions of the shaft 6 of the motor 4. One end portion of the shaft 6 extends through the end wall 3b. A cup-shaped holder 7 is fastened to this end portion of shaft 6. The shaft 6 and the holder 7 constitute the output coupling unit of the motor unit 1.

A plurality of yokes 8 is attached to the inner circumferential surface of the holder 7, set apart from one another at regular intervals along the circumference of the holder 7.

The pump unit 2 comprises a watertight casing 11 defining a pump chamber, and an impeller 12 rotatably provided within the casing 11. The impeller 12 has a number of vanes 13. Non-magnetic supports plates 14 are fastened to the vanes 13. Yokes 15 are connected at one end to the support plates 14, and extend substantially parallel to the shaft 16 of the impeller 12. Permanent magnets 17 are fastened to the outer circumferential surfaces of the yoke 15, respectively. The front portion of the pump unit 2 is fitted in the housing 3 of the motor unit 1. The casing 11 is fastened to the housing 3 in watertight fashion by means of a packing 18 and screws 20.

Once the motor unit 1 and the pump unit 2 have been assembled together, the magnets 10 oppose the magnets 17, with the circumferential wall of the casing 11 located in the gap between the magnets 10, on the one hand, and the magnets 17, on the other. The magnets 10 and 17 are located such that those of one set are attracted to those of the other set. As a result, copshaped holder 7 is magnetically coupled to the impeller 12; hence, the motor 4 is magnetically connected to the impeller 12.

Therefore, when the motor 4 is turned on, the impeller 12 is rotated, whereby the pump unit 2 performs its function. More specifically, the unit 2 can take in water via its inlet port 19 and discharge the water through its outlet port 21 (Fig. 2). For instance, a hose is attached at one end to the inlet port 19, with other end put in the water in a bathtub, another hose is connected at one end to the outlet port 21, and a shower nozzle is attached at the other end to a shower nozzle.

In this cause, the water is pumped up from the bathtub and applied from the shower nozzle.

The present invention is not limited to the embodiment described above. Various changes and modifications can be mode. For instance, the pump can be any other type of a rotary pump, instead of one having an impeller.

In the above embodiment the permanent magnets 10 are arranged on the inner circumferential surface of the holder 7. Instead they can be attached to the end surface of the holder 7 as is shown in Fig. 3. If such is the case, the permanent magnets 17 must be attached to the ends of the support plates 14, so that they oppose the permanent magnets 10.

Further, as is illustrated in Fig. 4, the shaft 16 can be projected outside the casing, a drum can be attached to this shaft 16, and permanent magnets 17 can be fastened to this drum, either on the end surface of the circumferential surface thereof. Moreover, the motor unit 1 and the pump unit 2 need not be located within the same housing. The motor unit 1 and the pump unit 2 can be provided outside and inside a bathroom or a bathtub, respectively, opposing each other, with the wall of the bathroom or bathtub interposed between these units 1 and 2.

Claims

Claims:

1. A rotary pump comprising: a pump unit having a pump with a shaft; a motor unit having a motor with a shaft for driving the pump; input coupling means connected to the shaft of the pump; output coupling means connected to the shaft of the motor and opposing the input coupling means; and two sets of magnets, the magnets of the first set being attached to the input coupling means, and the magnets of the second set being attached to the output coupling means and opposing the magnets of the first set.

2. The rotary pump according to claim 1, wherein said pump has an impeller with a plurality of vanes, and the magnets of the first set are attached to the vanes of the impeller, respectively.

3. The rotary pump according to claim 1, wherein said output coupling means has a coup-shaped holder made of non-magnetic material and attached to the shaft of said motor, and the magnets of the second set are attached to the holder.

4. The rotary pump according to claim 1, wherein said magnets of both sets are permanent magnets.

5. A rotary pump, substantially as hereinbefore described with reference to the accompanying drawings.