US20090104057A1

US20090104057A1 - Pump having magnetic coupling mechanism

Info

Publication number: US20090104057A1
Application number: US12/346,411
Authority: US
Inventors: Shuichi KISHI
Original assignee: Daito Kogyo Co Ltd
Current assignee: Daito Kogyo Co Ltd
Priority date: 2006-04-24
Filing date: 2008-12-30
Publication date: 2009-04-23
Also published as: JP2009299471A

Abstract

A pump having a magnetic coupling mechanism for driving a drive member of the pump includes a reduction mechanism provided between the drive member of the pump and the magnetic coupling mechanism driven by an external driving source, and in an enclosed housing there are arranged the driving member of the pump, the reduction mechanism and an inner magnet, which constitutes the magnetic coupling mechanism. Due to the reduction mechanism, the pump using a magnetic coupling having a relatively small torque transfer capacity is able to generate a required large torque.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a pump capable of effectively delivering a fluid by means of magnetic coupling action of a pair of magnets without leaking it to the outside when transferring a fluid ranged from high viscosity to low viscosity or a high viscous fluid under a high-pressure, more particularly to a pump having a magnetic coupling mechanism (no shaft sealing mechanism).
2. Description of the Related Art
In recent years, a market need for a pump in which a drive member such as a gear is driven by means of magnetic coupling action, i.e., a pump having a magnetic coupling mechanism tends to further increase. As a recent trend, a high-performance pump is becoming available as distinct from several tens of years ago, since the magnet industry as an essential technology thereof has been developed a high-performance magnet such as a neodymium-based magnet or the like.
In the pump industry, the most popular type of commercially available pump having such a magnetic coupling mechanism is a centrifugal type of pump. The centrifugal type of pump is suitable for transferring a fluid having low head, large volume and low viscosity in comparison to other types of pumps, and the magnetic coupling used in a centrifugal type pump is not required to have a large transferring capacity. It is therefore possible to design a magnetic coupling relatively compact in size with respect to the pump size, which also contributes to reduction in manufacturing cost.
In difference to the centrifugal type pump, it is only recently that, due to enhanced performance of a magnet used for magnetic couplings, gear pumps using a magnetic coupling become commercially practical and are being accepted in the market.
One of gear pumps having such a magnetic coupling mechanism is disclosed, for example, in Japanese Unexamined Patent Application Publication No. 2006-052652.
In this gear pump, it is intended to provide a simplified transmission mechanism for transmitting rotational force to a gear and a sealing construction for preventing the leakage of a liquid to outside of a housing, and to attain size reduction thereof. More specifically, the gear pump includes a plurality of gears engaged with each other, a housing for accommodating the gears in a state of being hermetically sealed in isolation from the outside, a supply passage for feeding a fluid into the housing, and a discharge passage for delivering the fluid from the housing, and is configured such that at least one or more of the gears is a profile shifted spur gear, a magnetic member is attached to at least one or more of the gears, and a driving source is provided outside the housing, and when the driving source is energized, a rotational driving force is applied to the gears each provided with the magnetic member.
In Japanese Unexamined Patent Application Publication No. 2007-285270, a variable displacement pump is proposed in which a loss in power transmission from a drive shaft to a pump driving rotational body (or drive gear) hardly occurs even when the pump is driven at a low rotational speed. This variable displacement pump includes a pump housing, a drive shaft rotationally driven by an external driving source, and a pump driving rotational body rotationably installed in the pump housing, and is configured such that the pump driving rotational body is provided with a shaft hole in its center in order to allow the drive shaft to pass therethrough, and either of an inner peripheral wall portion partitioning the shaft hole or an outer peripheral portion of the drive shaft opposing the inner peripheral wall portion is formed of a permanent magnet, while the other portion is formed of a magnetic material.
Likewise, in Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2007-531844, there is proposed a magnetically driven gear pump that includes a housing and a rotatable annular magnetic drive assembly, which is magnetically connected to an annular driven magnetic rotor assembly, but located spaced apart therefrom and is provided with an annular canister therebetween. The magnetically driven gear pump is configured such that, when the annular magnetic drive assembly starts to rotate, the annular driven magnetic rotor assembly rotates at a first shaft portion of a displaced static shaft, while a rotor gear drives an idler gear rotating at a second shaft portion of the displaced static shaft.

SUMMARY OF THE INVENTION

The above gear pumps are used for a variety of fluids, particularly used as a high-pressure generator in various ranges of rotation speeds in equipment for quantitative transfer or metering transfer of a high viscous fluid and for hydraulic power transfer.
In order to transfer a fluid having high viscosity under a high pressure, however, a large-sized magnetic coupling having a large torque transfer capacity is needed as a matter of course. That is, in the case when a fluid having high viscosity or high pressure is transferred by a gear pump, since a large load is applied to the gear pump, a so-called slipping phenomenon may occur in its magnetic coupling mechanism portion and thereby the torque of the external driving source may not be accurately transferred to the gear pump, which causes a critical problem in the gear pump that is desired to implement quantitative transfer or metering transfer.
Accordingly, when the specification of a gear pump requires the installation of a magnetic coupling having a large torque transfer capacity, the surface area of magnets should be increased to enhance the capacity of the magnetic coupling and as the result the apparatus size becomes large.
On the other hand, there is an attempt to utilize a more effective neodymium magnet, since the performance of a magnetic coupling much depends on the performance of a magnet and a high-performance magnetic coupling contributes to suppress increase in the coupling size. However, a rare metal such as neodymium is extremely expensive and is becoming difficult to obtain in recent years, so there is a need that a gear pump having a small-sized magnetic coupling, while still having a large torque transfer capacity would be provided.
The present invention addresses the above problems with the object of providing a pump having a magnetic coupling mechanism, the pump being able to produce a large transfer torque needed for heavy duty applications using a magnetic coupling having a relatively small transfer torque capacity without a fear of liquid leakage from a pump driving portion, and also having a simple construction and a high cost performance without using expensive material such as a rare metal.
In order to achieve the above object, a first aspect of the invention provides a pump having a magnetic coupling mechanism for driving a drive member of the pump by means of magnetic coupling action of an inner magnet and an outer magnet both constituting the magnetic coupling mechanism, wherein a reduction mechanism is intervened between the drive member of the pump and the magnetic coupling mechanism driven by an external driving source, and the drive member of the pump, the reduction mechanism and at least the inner magnet constituting the magnetic coupling mechanism are arranged in an enclosed housing.
A second aspect of the invention provides the pump having the magnetic coupling mechanism according to the first aspect of the invention, wherein the magnetic coupling mechanism includes a magnet portion having a bottomed cylindrical shape and constituting the enclosed housing, a rotor, on an outer peripheral portion of which the inner magnet is provided and in the central portion of which one end of a drive shaft for driving the reduction mechanism is connected, the rotor being disposed freely rotatably inside the magnet portion, and a cylindrical rotating member, on an inner peripheral portion of which the outer magnet is provided so as to oppose the inner magnet, the rotating member being disposed with keeping a predetermined gap with respect to the outer periphery of the magnet portion.
A third aspect of the invention provides the pump having the magnetic coupling mechanism according to the first aspect of the invention, wherein the pump is a gear pump.
Since a pump having a magnetic coupling mechanism of the present invention includes a reduction mechanism provided between a drive member of the pump and the magnetic coupling mechanism driven by an external driving source, even though the external driving power is small, the pump using a magnetic coupling having a relatively small torque transfer capacity is able to generate a torque required for pumping a fluid having high viscosity or under high pressure without slipping in the magnetic coupling.
Moreover, since the drive member of the pump, the reduction mechanism and an inner magnet, which constitutes the magnetic coupling mechanism, are accommodated in an enclosed housing, there is no fear of leakage of the fluid from the driving portion of the pump to the outside.
Furthermore, the pump having the magnetic coupling mechanism is able to deal with a fluid ranged from high viscosity to low viscosity under a high pressure without upsizing the magnetic coupling by selecting the reduction ratio of the reduction mechanism, and thereby it is possible to obtain a compact and easily manufactured pump.
As the result, it is enabled that a pump is standardized and mass produced, and becomes adaptable to a wide variety of applications. In addition, the pump having the magnetic coupling mechanism is able to be constructed without using an expensive rare metal, which results in resource savings as well as low manufacturing cost.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially cross-sectional side view of a gear pump as an example of a pump having a magnetic coupling mechanism according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A preferable example of a pump having a magnetic coupling mechanism according to the present invention will be described below with reference to the attached drawing. It should be noted that the present invention is not limited to the following embodiment in any way, and may be practiced in various other forms not departing from the spirit and scope of the invention.
A gear pump 1, which is a preferable embodiment of the present invention, includes an enclosed-type casing 2, a gear mechanism 3 installed in the casing 2 as pumping members, a reduction mechanism 4 for driving the gear mechanism 3, and a magnetic coupling mechanism for driving the reduction mechanism 4, the magnetic coupling mechanism being constituted of an inner magnet 5 and an outer magnet 6.
The enclosed-type casing 2, which is a principal housing of the gear pump 1, has at least one suction port 1A and at least one delivery port (not shown). In this embodiment, the enclosed-type casing 2 is constructed of a head portion 21, a pumping-member holding portion 22, a base portion 23, and a magnet portion 24.
The head portion 21 is a substantially cylindrical body having a connection flange formed integrally in one end thereof, and is provided with a bearing portion 21 a for supporting one side of a drive gear shaft 32 of a drive gear 31 constituting the pumping members of the gear pump 1, the bearing portion 21 a being formed to one-side and in the axial direction.
The pumping-member holding portion 22 is a substantially cylindrical body having a space portion for accommodating the drive gear 31 and a driven gear 33 therein, and the head portion 21 and the base portion 23 are connected to the pumping-member holding portion 22 at its openings on both sides thereof using bolts, respectively, so as to be united therewith. In the pumping-member holding portion 22, the drive gear 31 and the driven gear 33 both constituting the gear mechanism 3 are held in a state of being engaged with each other. At this time, one side of the drive gear shaft 32 is freely rotatably held in the bearing portion 21 a, which is formed to one-side in the head portion 21, through the intermediary of a tubular bearing member B.
The base portion 23 is an irregular-shaped cylindrical body, in a specified part of which a space portion S having a diameter and a width required for installing the reduction mechanism 4 is formed in a direction orthogonal to the axial direction. From the end face of the base portion 23 on the side of pumping-member holding portion 22 to the space portion S, there is formed an insertion hole H for passing through the other side of the drive gear shaft 32 in a direction parallel to the axial direction, and from the other end face of the base portion 23 to the space portion S, there is formed the other insertion hole H for passing through a drive shaft 41 of a gear g constituting the reduction mechanism 4.
In addition, in one end of the base portion 23 on the side of the pumping-member holding portion 22, a bearing portion 35 is formed to one-side in a direction parallel to the axial direction, the bearing portion 35 serving for freely rotatably supporting a driven gear shaft 34 of the driven gear 33 through the intermediary of a tubular bearing member B.
The reduction mechanism 4 installed in the space portion S is constituted of a pair of gears g, G having different diameters with each other and being provided with a desirable reduction ratio. An end portion of the drive gear shaft 32 of the drive gear 31 is coupled to the gear G in its central portion by means of a key and a key groove so as to be rotated as one piece. Incidentally, although the reduction ratio to be set varies depending on a liquid to be used, a preferable practical range of the reduction ratio may be the order of 1:3-40.
It should be understood that, although a general gear reducer using spur gears is used as the reduction mechanism 4 in this embodiment shown in the attached drawing, it can be changed to other appropriate type of reducer depending on the application of the pump, and the type of gears is not particularly limited. Moreover, a reduction mechanism having a peculiar configuration such as, for example, a Cyclo-Speed Reducer (a trade name of Sumitomo Heavy Industries, Ltd.), which is constructed from an inscribed planetary gear and an arc-shaped gear, or the like can also be employed and the type of reduction mechanism is not particularly limited.
The magnet portion 24 is constituted of a cylindrical member having a flange surrounding the opening portion thereof, and in its inside a rotor 51 is freely rotatably disposed, the rotor 51 being mounted to the other end of the drive shaft 41 of the gear g.
The rotor 51 is constituted of a cylindrical rotating body having a pass-through hole for allowing the drive shaft 41 of the gear g to pass through in its central portion and also having a recessed portion having a predetermined width formed in a ring shape on its outer periphery. The drive shaft 41 of the gear g is fixed to the pass-through hole by means of a key and a key groove, and the inner magnet 5 constituting the magnetic coupling mechanism together with the outer magnet 6 is fixed in the recessed portion.
On the outer periphery of the magnet portion 24, a rotating member 61 having a bottomed cylindrical shape is freely rotatably provided so as to cover the magnet portion 24 with a predetermined gap. There is formed a recessed portion having a predetermined width on its inner periphery of the rotating member 61, as opposed to the inner magnet 5 fixed to the rotor 51, the recessed portion being provided with the outer magnet 6 fixed thereto, which constitutes the magnetic coupling mechanism. In the center bottom portion of the rotating member 61, a base end portion of a drive shaft 26, a top end portion of which is connected to an external driving source such as a motor, is inserted and fixed.
The drive shaft 26 is freely rotatably supported on the base end portion side thereof by bearings in a bearing portion 27, which is connected to a cylindrical cover member 25 provided next to the base portion 23 constituting the casing 2.
Adjacent ones of these head portion 21, pumping member holding portion 22, base portion 23 and magnet portion 24 are connected to each other via an O-ring, and are constructed so that a fluid flowing into and out from the gear pump 1 is prevented from leaking outside therefrom.
Upon activation of an external driving source such as a motor, the drive shaft 26 of the gear pump 1 constructed as described above starts to be rotated, and then the rotating member 61 integrally connected to the drive shaft 26 is concurrently rotated. Since the rotating member 61 is provided with the outer magnet 6 on its inner periphery, the outer magnet 6 is also concurrently rotated.
Due to magnetic coupling action, the rotation of the outer magnets 6 brings about rotation of the inner magnet 5 disposed as opposed to the outer magnet 6 through the intermediary of the magnet portion 24 having a bottomed cylindrical shape, and then the rotor 51 starts to be rotated. The rotation of the rotor 51 is transmitted to the gear g constituting the reduction mechanism 4 via the drive shaft 41.
The rotation of the gear g brings about rotation of the gear G and then rotation of the drive gear shaft 32 of the gear mechanism 3 connected to the gear G is concurrently rotated, which causes both the drive gear 31 and the driven gear 33 to be rotated; thereby a fluid is sucked from the suction port 1A into the inside of the gear pump 1 and is delivered from the delivery port at a constant quantity.
Accordingly, the gear mechanism 3 is able to smoothly deal with the fluid without occurrence of a slipping phenomenon between the inner magnet 5 and the outer magnet 6 even when being applied with a large load due to resistance of the fluid flowing into the gear pump 1, as long as a predetermined reduction ratio is capable to manage the applied load.
Since the gear mechanism 3 is configured to be driven not by direct magnetic coupling action but by indirect action through the reduction mechanism 4, it is possible to effectively deal with a fluid ranged from high viscosity to low viscosity by utilizing the characteristics of a gear pump, while keeping the size of an external drive motor compact and avoiding both the inner magnet 5 and the outer magnet 6 constituting a magnetic coupling to become upsized.
Although the gear pump is exemplarily employed as an inventive pump in the above embodiment, the invention is applicable to a variety of pumps such as a volute pump, a screw pump, a vane pump, a rotary pump, a piston pump, and the like. These pumps each have a basic mechanism to be used for converting driving power to mechanical work (energy), but the present invention is also able to be used for converting mechanical work to driving power.
The system of this pump having the magnetic coupling mechanism of the present invention is able to be utilized by other pumps since a drive member of the pump can be effectively driven by a relatively small external power and also an expensive material such as a neodymium-based magnet or the like is not necessary to be used for construction of the magnetic coupling mechanism.

Claims

1. A pump having a magnetic coupling mechanism for driving a drive member of the pump by means of magnetic coupling action of an inner magnet and an outer magnet both constituting the magnetic coupling mechanism,

wherein a reduction mechanism is intervened between the drive member of the pump and the magnetic coupling mechanism driven by an external driving source, and

the drive member of the pump, the reduction mechanism and at least the inner magnet constituting the magnetic coupling mechanism are arranged inside an enclosed housing.

2. The pump having the magnetic coupling mechanism according to claim 1,

wherein the magnetic coupling mechanism comprising:

a magnet portion having a bottomed cylindrical shape and constituting the enclosed housing,

a rotor, on an outer peripheral portion of which the inner magnet is provided and in the central portion of which one end of a drive shaft for driving the reduction mechanism is connected, the rotor being disposed freely rotatably inside the magnet portion, and

a cylindrical rotating member, on an inner peripheral portion of which the outer magnet is provided so as to oppose the inner magnet, the rotating member being disposed with keeping a predetermined gap with respect to the outer periphery of the magnet portion.

3. The pump having the magnetic coupling mechanism according to claim 1, wherein the pump is a gear pump.