US3478887A - Combination centrifugal and magnetic separator device - Google Patents

Description

Nov. 18, 1969 c. v. OHRBERG COMBINATION CENTRIFUGAL AND MAGNETIC SEPARATOR DEVICE Filed July 18, 1967 "United States Patent 3,478,887 COMBINATION CENTRIFUGAL AND MAGNETIC SEPARATOR DEVICE Carl V. Ohrberg, N ordborg, Denmark, assignor to Danfoss A/S., Nordborg, Denmark, a company of Denmark Filed July 18, 1967, Ser. No. 654,213 Claims priority, application Germany, July 19, 1966, 1) 50,616 Int. Cl. B03c 1/02 US. Cl. 210223 3 Claims ABSTRACT OF THE DISCLOSURE A separator device for separating solid contaminants from a lubricating fluid in rotary apparatus comprising a centrifugal separator and a magnetic separator internally of a common housing driven rotationally jointly in which centrifugal force and the position of the magnetic separator and the flow of leakage fluid lubricating the working parts of a rotary machine is along at path effective to allow flow of metallic contaminants over the magnetic separator and along a path rendering the centrifugal separator also more effective. The magnetic separator is selfcleaning because of its rotation and the flow path of the lubricating fluid and any contaminants leaving it are then retained by the centrifugal separator. The separator device is particularly applicable to fluid motors and pumps having commutating valves in which a rotary driven slide valve houses the separator device.

This invention relates generally to hydraulic rotary apparatus and more particularly to separators for solid contaminants in the lubricating system of rotary apparatus.

The use of centrifugal separators for separating solid contaminants from oil lubricating working parts of rotary apparatus, is well known. Usually these separators rotate together with a rotary part of the rotary machine, for example an engine, and have a separating chamber spaced a selected radial distance from the axis of rotation thereof. Generally the separating chamber has a greater axial distance from the axis of rotation than the inlet and outlet thereto. However, the efliciency of this type of centrifugal separator is reduced as its speed is reduced and efficiency also varies in dependence upon the size of particles that are to be separated. Fine particles are relatively hard to separate and centrifugal separators are not as effective as they might be in separating the least desirable solid contaminants such as small metallic particles of the rotary apparatus itself abraded during operation of the working parts thereof.

It is also known to use a permanent magnet in lubricating systems which attracts metal particles of any size when these particles enter its effective field. When separation of solid contaminants is taking place magnetically, however, the difficulty is that the whole stream of lubricant must be led past the magnet. Moreover, the magnet has to be cleaned from time to time because its efficiency drops when the metallic contaminants become too thick thereon and there is a risk that the less firmly held or attracted metallic particles or contaminants will be carried away by the force of the oil stream and will thus remain in the apparatus.

It is a principal object of the present invention to provide a separator for solid contaminants which has a highly efficient cleaning or separation effect irrespective of the speed of the rotary apparatus in which it is employed and which is capable of separating particles including attracting metallic particles over a long period of time preferably the whole working life of the rotary apparatus to which the separator is attached.

3,478,887 Patented Nov. 18, 1969 The separator device in accordance With the invention is characterized in that a centrifugal separator and a magnetic separator are combined such that the magnet is arranged coaxially with the separating chamber of the centrifugal separator. In such an arrangement the known effects of centrifugal separation and of magnetic separation operate and supplement one another. At high speeds the centrifugal separator is fully effective and it becomes less important if the magnetic separator is not fully effective due to the high flow velocity of oil. At low speeds the centrifugal separator is less effective while on the other hand the efiiciency of the magnetic separator is not impaired since the flow velocity of the oil is slow and the efficiency of the magnetic separator is likewise unimpaired.

The two separators supplement each other during operation in that they boost each others respective actions. The magnetic separator decelerates metal particles which do not adhere to it in such a way that allows the centrifugal separator to take effect thereon since the centrifugal action is more effective due to the deceleration of the particles. The separating chamber of the centrifugal separator acts as a collecting chamber for solid contaminants held by the magnetic separator and eventually released therefrom during self-cleaning action thereof. If lumps of metallic contaminants are detached from the magnet of the magnetic separator they are not carried along by the lubricant stream but are held in the separating chamber so that rotary apparatus running at higher speeds becomes self-cleaning during such periods. That is the magnet is self-cleaning since a contaminant layer which has grown too thick on the magnet is thrown toward the peripheral wall of the separating chamber which then functions as a collecting chamber for the particles selfcleaned from the magnetic separator.

Another feature of the centrifugal and magnetic separator in accordance with the invention is that it is constructed to have a space saving construction. It comprises a cylindrical casing with inlet and outlet orifices at end faces thereof with an axis of rotation about which is mounted an annular magnet. The radial distance from the axis of rotation of the periphery of the magnet is greater than the inlet and outlet orifice radii. The lubricant fluid entering the separating chamber is deflected around the obstructing magnet, which is axially closer to the outlet than the inlet, so that the lubricant fluid must pass a large part of the effective surface of the magnet. Since the magnet is axially closer to the inlet the lubricating fluid is allowed to have a steadier or less turbulent flow in the separating chamber downstream of the magnet which will enhance the centrifugal separating action.

The separator device for separating solid contaminants from fluid lubricating working parts of a rotary machine in accordance with the invention has a cylindrical housing inserted in a bore of a rotary driven slide valve through which the lubricant fluid flows. The invention is applicable to rotary apparatus, for example gear type fluid motors and pumps, in which working fluid leakage is used for lubricating and cooling the bearings and working parts. In such apparatus the leakage fluid flows over moving parts of the apparatus and will become contaminated due to the abraded metallic particles. These metallic particles may do considerable damage to the lubricated areas if not removed. The use of the separator device of the present invention eliminates the solid contaminants resulting from abrading of the rotary apparatus itself.

Another feature of a separator device in accordance with the invention is that if the apparatus in which the separator is used, is provided with a hollow or tubular rotary driven slide valve or comm-utating valve arrangement it can house the separator device. A first advantage of such an arrangement is that no additional space is required since the separator can be housed in an axial cavity Within the rotary driven slide valve itself. A second advantage is that the whole of the leakage fluid to be treated by the separator device can be collected in the cavity of the rotary slide valve without any difficulty. A third advantage is that the axial cavity of the rotary slide valve may in many cases have a diameter much larger than a corresponding bore in the shafts that it couplesso that the centrifugal separation action can be improved.

Other features and advantages of the separator device in accordance with the present invention will be better understood as described in the following specification and appended claims in conjunction with the following drawings in which:

FIG. 1 is a longitudinal section view of a fluid pressure rotary apparatus provided with a separator device according to the invention;

FIG. 2 is a fragmentary cross section view taken on section line 22 of FIG. 1; and

FIG. 3 is an enlarged view of a separator device of FIG. 1 according to the invention.

While the separator device according to the invention will be described as applied to rotary apparatus or a pressure fluid device constituting a fluid motor it is equally applicable to fluid pumps and other types of fluid pressure devices constructed differently than the apparatus, to which the invention is applied, illustrated herein. Moreover, the fluid motor illustrated may likewise operate as a pum and may be operable in one direction only or fully reversible.

The terms orifice and port used herein are used as equivalents meaning an opening for inlet or outlet of a fluid. valents meaning an opening for inlet or outlet of a fluid. Moreover, the term port means a passageway having length thereto. The term passage is used to mean the act of passing or transit from one place to another and may also be used to mean passageway or port depending upon the context in which it is used.

As illustrated in FIG. 1 the rotary apparatus, to which the invention is applied, has a stator comprising a casing or housing 1 closed at one end with an end cover or plate 3 secured by circumferentially spaced screws 2 and provided with an intermediate plate mounted by screws 4 likewise mounting an end cover or plate 7 at the opposite end of the stator. Intermediate the end cover 7 and the plate 5 is disposed as part of the stator, a gear ring 6 having internal gear teeth or lobes which are stationary. The stationary gear defines the outer walls of a chamber formed therein. The housing 1 is provided with an inlet 7 8 for supplying a flow of hydraulic fluid illustrated by an arrow 9 and is provided with an outlet, not shown, for the discharge or return flow illustrated by an. arrow 10'.

An inner gear 11, as part of a rotor of the machine, is mounted in the chamber formed by the outer gear coaxial with the stator outer ring gear 6 and has its teeth or lobes meshing with the teeth or lobes of the gear ring 6. The inner gear 11 has one tooth or lobe less than the outer gear ring and has superimposed thereon its own rotary movement an orbital movement within the outer gear. That is to say the inner gear rolls in the outer gear and has its center of gravity moving in a closed circular or orbital path about the axis of the outer gear while it rotates in order for the two gears to cooperate in developing therebetween chamber or spaces between the teeth or lobes so that the apparatus can function either as a motor or as a pump. An output shaft 12 is operably con nected to a shaft 13 connected to the inner gear 11. The two shafts are coupled by a multiported rotary driven slide valve 14 having a circumferential groove 15 constantly in communication with the inlet 8 for receiving fluid from a source of fluid under pressure, not shown.

The rotary slide valve 14 is a tubular valve element housed within a bore of the stator for rotataion and acts .4 as an coupling or link between the shafts. It is provided with an axial recess in which the shaft 12 is received and positively connected thereto, for example by welding. The shaft 13 extends axially internally of the tubular rotary slide valve 14 and is coupled to the inner gear 6 and the sleeve slide valve 14 by crowned involute splines or teeth longitudinally arcuate as shown to permit rocking or tilting movement so that the shaft 13 is able to allow for or compensate for the orbital movement of the inner gear. The inner gear rolls in the outer gear and this type of compensating connection and gear operation is of the type shown in United States Patent 2,821,171 granted to Charlson on Jan. 28, 1958.

The rotary slide valve 14 is provided with two circumferential grooves 15, 16 axially spaced from each other and in communication with the inlet 8 and outlet respectively of the housing 1. These circumferential grooves 15, 16 are constantly in communication with the fluid inlet and the outlet.

The slide valve 14 is provided circumferentially thereof with axially extending ports or passageways formed as concavities or grooves 17 which are spaced angularly or circumferentially relative to each other and have one end open and communicating with the circumferential groove 15. These axial grooves are arcuately constructed as illustrated in the drawing and are open to the periphery of the slide valve 14 and closed at the end opposite to the closed end. A second plurality of ports formed as concavities or arcuate grooves 18 alternating with the grooves 17 are disposed circumferentially angularly spaced on the rotary slide. The grooves 18- communicate with the circumferential groove 16 and likewise have one end closed. The number of grooves 17, 18 in each plurality of grooves correspond to the number of teeth of the inner gear 11.

The casing or stator 1 is disposed circumferentially of the slide valve 14 and defines a multiported valve plate provided with orifices or openings 19 which communicate with ports or passageways 20 extending axially of the casing generally in the same axial direction as the grooves. These axial passages 20 communicate with the spaces 21 formed between the adjacent teeth of the gear rings that define the activating cells or chambers subjected to pressure fluid. Half of these spaces are subjected to fluid pressure and the opposed half is connected to a return line or outlet under control of the commutating valve, ie the slide valve 14 and the valve plate or stator 1. The positive displacement chambers or spaces 21 formed between the teeth of the stationary outer gear ring 6 and those of the inner orbital gear 11 are alternately connected to the inlet 8 and the outlet 10' through the passageways 20 and the two pluralities of axial grooves defining the orifices or ports of the commutating valve arrangement.

It will be seen that if fluid under pressure is provided at the inlet 8 the inner gear 11 is driven rotationally and the apparatus operates as a motor delivering an output torque through shaft 12. Conversely if the shaft 12 is rotatably driven as an input shaft the apparatus can take a suction through the discharge opening, not shown, so that the apparatus will function as a pump discharging through the inlet 8. In which case the second plurality of orifices are the high pressure orifices and the first plurality are at a lower pressure and function as the discharges orifices.

In the present embodiment illustrated the apparatus is functioning as a motor and the axial grooves 17 are high pressure orifices and the axial grooves 18 are low pressure orifices. These ports or orifices coincide or are in registry alternately with the distribution ports 19 formed in the casing 1. As relative rotation takes place between the rotary slide valve and the housing or stator the high and low pressure ports are brought into opposed positions of registry with the distribution ports 19 so that flow takes place between the inlet, the driven gear and the discharge outlet. It being understood, of course, that rotation of the inner gear is effected by the pressure fluid delivered to the open spaces between the gear teeth causing the apparatus to function as a motor. The pressure chambers or spaces become return chambers which close for returning or discharging the fluid as the inner gear rotates.

As illustrated in FIG. 2 assuming that the sense of rotation of the rotary slide valve 14 is counterclockwise as indicated in the drawing by the arrow the high pressure orifices or ports 17 are illustrated in communication with the stator ports 19 and with one of them interrupting communication therewith and a third is closed off by the inner bore of the casing 1. As rotation continues the port or groove 17 shown in a closed condition begins to communicate with a distribution port 19. The individual rotor ports are successively placed in communication with the rotator parts and flow is established between the ports in a sequence to provide continuous rotation of the rotor as half the spaces formed between the gear teeth are subjected to fluid pressure and the opposed half are connected to the return discharge outlet through the ports.

It can be seen that if the external connections to the apparatus are interchanged, i.e. the fluid is supplied at the discharge and discharged at the outlet 9, then the axial grooves or ports 18 will become the high pressure orifices and the rotary slide valve will revolve in the opposite direction. In this case the bypass ducts 22 provided on the axial grooves 18 will be provided at a leading edge thereof and will function as heretofore described.

The motor is provided with a thrust bearing 22 absorbing thrust developed by the rotor. The slide valve 14 has a longitudinal bore 24 within which the drive shaft 13 extends axially. At one end in a reduced diameter portion thereof is disposed a separator device 24 embodying the invention.

The separator device 24 is mounted at one end of the internal bore or cavity 23 of the rotary slide 14. Fluid leakage from the working fluid, lubricating the working parts, flows into the cavity or bore 23 in which the pressure is somewhat higher than the discharge pressure of the apparatus. Leakage working fluid may reach this cavity 23, for example from the positive displacement chambers 21, to which working fluid at supply pressure is applied, along the surface on which the gear 11 and the cover 7 or the intermediate plate 5 are in contact. The same applies to the fluid flowing from the groove 15 along the circumference of the slide valve in a direction towards the gear 11 and is then deflected at the intermediate plate 5 towards the interior of the slide valve bore. Thus any leakage fluid will flow through the inner bore of the rotary slide 14 and at the left end of this bore or cavity 23 is disposed the separator coaxial with the cavity.

Leakage fluid flows through the separator 24, where solid contaminants are removed from the lubricating fluid as later explained, and outwardly thereof through passageways which lead to and supply the thrust bearing 22. The leakage fluid returns from the outer circumference of the thrust hearing by way of the circumference of the rotary slide valve 14 to the circumferential groove 16 which is at discharge pressure. Even if the leakage fluid has absorbed abraded particles in the positive displacernent cells 21 or during its travel along the sliding surfaces of the working parts the bearing 22 is lubricated by the fluid which is free of abraded particles since they are removed from the leakage fluid by the separator 24.

The separator device 24 comprises two telcscoped parts 26 and 27 defining a cylindrical housing thereof mounted in the slide valve for rotation therewith. Both housing parts 26, 27 are provided with end faces 28, 29 with inlet apertures 30 and outlet apertures 31 disposed as a plurality of openings angularly spaced on a circle circumferentially of the axis of rotation of the separator device. Each of the housing parts has a respective inwardly directed axial pin portion 32, 33 between which an annular magnet is disposed circumferentially thereof projecting into a contaminant separating chamber 35 defined by the housing.

The inner diameter of the separating chamber 35 is larger than the circle on which the inlet and outlet apertures 30, 31 are disposed. The radial distance from the axis of rotation defined by the pins is less for these apertures than the outer radius of the magnet 34 so that oil passing through the separator 24 is deflected in the manner illustrated by the arrows in FIG. 3 of the drawing. The deflection is more pronounced on the inlet side of the separator than on the exit since the axial distance of the magnet 30 from the point of entry or inlet apertures is less than the axial distance from the outlet apertures. In this way the oil must flow closely past the magnet and is subjected to a deflection in a centrifugal direction so that both the magnetic separator and the centrifugal separator are coactive and more effective. Moreover, as indicated heretofore the fluid is also allowed to assume a more stable flow downstream of the magnet so that the centrifugal separator is also rendered more effective because of this greater flow stability. The relatively quiet zone formed downstream of the magnet allows the centrifugal action of the centrifugal separator to be more effective even as to fine particles of contaminants. It will be noted that as metallic particles move past the magnet they are attracted thereto and if not they are slowed down, as well as other particles so that the action of the centrifugal separator is more effective thereon.

During operation metallic particles 36 separated from the fluid flow by the magnet collect on the surface of the magnet while other solid contaminants which are not magnetic are separated by centrifugal action and are illustrated at 37. These contaminants collect on the inner wall of the housing defining the outer circumference of the separating chamber 35. When an excessive amount of metallic contaminant particles have collected on the magnet 36 so that it can no longer arrest or attract them the excessive particles are detached from the magnet and will move outwardly and join the other contaminant particles 37 in the separating chamber. Thus as the centrifugal force becomes larger and more effective than the force of magnetic attraction the magnet becomes selfcleaning so that the magnetic separator is a self-cleaning magnetic separator.

The present separator device is constructed into the fluid motor or pump described so as to remain therein permanently. Those skilled in the art will understand that in other applications the separator device of the present invention may be made removable and can be made in any desired dimensions.

While a preferred embodiment of the invention has been shown and described it will be understood that many modifications and changes can be made within the true spirit and scope of the invention.

What I claim and desire to be secured by Letters Patent is:

1. In a fluid pressure operated motor, an internally toothed member defining the outer wall of a chamber, a cooperating externally toothed member having a less number of teeth than the internally toothed member and disposed eccentric thereof in said chamber in meshing engagement therewith, one of said members being movable in an orbit about the axis of the other thereof to produce relative rotation between said members, a pair of cooperating relatively movable valve elements one of which is coupled to said internally toothed member and which defines fluid passages communicating with said chamber, the other of said valve elements defining fluid passages communicating with different ones of the fluid passages in said one of the valve elements upon relative movement therebetween, one of said valve elements further defining inlet and outlet ports communicating with the fluid passages therein and adapted to be coupled to a source of fluid pressure, means operatively coupling said externally toothed member to a cooperating one of said valve elements to cause relative rotation between said valve elements responsive to said relative orbital movement between said toothed members, and a separator device, means coupling said separator device to said one of the valve elements for movement rotationally, said separator device comprising a centrifugal separator and a magnetic separator internally of said centrifugal separator and coactive therewith, to separate solid contaminants from a liquid flow through said separator device, said magnetic separator comprising a magnet developing a magnetic field in said centrifugal separator, and said centrifugal separator having a housing defining a chamber having walls having residual magnetism from said magnetic field.

2. In a fluid pressure operated motor, an internally toothed member defining the outer wall of a chamber, a cooperating externally toothed member having a less number of teeth than the internally toothed member and disposed eccentric thereof in said chamber in meshing engagement therewith, one of said members being relatively stationary, the other thereof being relatively movable in an orbit about the axis of said one thereof to produce relative rotation between said members, a relatively stationary valve element and a relatively movable valve element one of which is coupled to said internally toothed member and which defines fluid passages communicating with said chamber, the other of said valve elements defining fluid passages communicating with different ones of the fluid passages in said one of the valve elements upon relative movement therebetween, one of said valve elements further defining inlet and outlet ports communicating with the fluid passages therein and adapted to be coupled to a source of fluid pressure, means operatively coupling said externally toothed member to a cooperating one of said valve elements to cause relative rotation between said valve elements responsive to said orbital movement of one of said toothed members, and a separator device, means coupling said separator to said one of the valve elements for movement rotationally, said separator device comprising a centrifugal separator and a magnetic separator coactive to separate solid contaminants from a liquid flow through said separator device said magnetic separator comprising a magnet developing a magnetic field in said centrifugal separator, and said centrifugal separator having a housing defining a chamber having Walls having residual magnetism from said magnetic field.

3. In a fluid pressure device, an internally toothed member defining the outer wall of a chamber, a cooperating externally toothed member having a less number of teeth than the internally toothed member and disposed eccentric thereof in said chamber in meshing engagement therewith, one of said members moving in an orbit about the axis of the other thereof during relative rotation between said members, valve means including cooperating relatively movable valve elements one of which is operatively coupled to said internally toothed member and which defines fluid passages in communication with said chamber, another of said valve elements defining fluid passages communicating with different ones of the fluid passages in said one of the valve elements upon relative rotation therebetween, said valve means defining inlet and outlet ports communicating with different ones of said fluid passages and adapted to be coupled to a source of fluid, means operatively coupling said externally toothed member to a cooperating one of said valve elements to cause relative movement between said valve elements responsive to said relative orbital movement between said toothed members, and a separator device, means coupling said separator to said one of the valve elements for movement rotationally, said separator device comprising a centrifugal separator and a magnetic separator coactive to separate solid contaminants from a liquid flow through said separator device said magnetic separator comprising a magnet developing a magnetic field in said centrifugal separator, and said centrifugal separator having a housing defining a chamber having walls having residual magnetism from said magnetic field.

References Cited UNITED STATES PATENTS 4/1941 Armbruster 209-232 X 11/1966 Monroe et al 103-l30 US. Cl. X.R.

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