GB2040739A

GB2040739A - Apparatus for removing entrapped gas and separating out particles from fluid

Info

Publication number: GB2040739A
Application number: GB7936931A
Authority: GB
Original assignee: Technical Development Co
Current assignee: Technical Development Co
Priority date: 1979-02-01
Filing date: 1979-10-24
Publication date: 1980-09-03
Also published as: DE3002183C2; IT7951071A0; JPS55102451A; FR2448100B1; JPS6341621B2; FR2448100A1; DE3002183A1; IT1164094B; GB2040739B

Abstract

In an apparatus (10) for removing entrapped gas and selectively removing and detecting particles above a predetermined mass in an oil lubrication system, the oil enters tangentially at the top of an outer cylinder (12) and is caused to cyclonically work its way down to the bottom of the cylinder. The oil is then forced to reverse its flow and travel up along and out through an inner cylinder (44). The centrifugal force fields created by such flow first cause entrapped gas to coalesce in the centre of the flow pattern so that it can be vented from the system via a tube (24). It also causes heavier particles, which are used by the apparatus to detect impending failure of components of the system, to be thrown out of the flow pattern into a detection chamber (28) which communicates at (32) with the interior of the outer cylinder while lighter particles remain suspended in the oil. A magnetic sensor (30) is provided at the entrance to the chamber to signal to the operator of the system the presence of the heavier particles which are trapped in the chamber for subsequent removal from the system. <IMAGE>

Description

SPECIFICATION Apparatus for use in a fluid system, for removing entrapped gas and separating out particles above a predetermined mass for the fluid This invention relates to apparatus for use in a fluid system, for removing entrapped gas and separating out particles above a predetermined mass from the fluid.

The apparatus may particularly but not exclusively be used in conjunction with hydraulic or lubrication systems for mechanical equipment which utilize a fluid such as oil.

Mechanical power transmission equipment is sub .ject to wear due to abrasion, caused by the contact of moving parts under pressure at high relative speeds.

This results in the release of a quantity of smail particles. Such "wear particles" or "fuzz" are generally 2 to 20 microns in size. Particles of this size, when suspended in a circulating fluid such as heavy lubricating oil generally move with it rather than reacting promptly to gravity and inertial forces.

However, once normal "wear in" occurs the quantity of such particles reduces to a relatively low value which in most systems are readily removed from the system through the use of suitable filters or by strategically placed magnets, if the particles are of a ferrous nature. When the components of the power transmitting system which is being lubricated become overleaded or when localized areas of weak ness occur, the situation changes radically. In such cases much larger and heavier particles of material become loosened, generally at the point of contact between moving parts under high surface pressure.

Furthermore once the surface has been deformed by the breaking off of such particles the rate of deterioration accelerates resulting in the breaking off of additional particles at increasing rates. Additionally, the quantities of wear particles produced are substantially increased. Failure particles generally fall into the 100 to 2000 micron size range. Due to their greater mass they are less subject to being sus pended in the lubricating fluid.

It is well known that the structural failure of drive train components may be predicted in advance of such failure by monitoring the condition of the lubricating oil. Such structural failure is indicated when metallic particles in the size range of failure particles, i.e. greater than 100 microns, are detected or when the quantity of wear particles substantially increases. The apparatus of the present invention may be used to separate out such failure particles so that a signal warning the operator of the situation occurring may be provided.

The prior art is replete with descriptions of various apparatus which will detect the presence of failure particles Some of these apparatus use filters of varying mesh size which are periodically checked so as to determine the presence of failure particles. This approach is not appropriate for aircraft applications as it does not lend itself to inflight monitoring. Other apparatus use electronic devices wherein failure particles are detected by the disturbance of a magnetic or electric field by such particles. A problem associated with such apparatus has been that a collection of wear particles is detected as a failure particle thus resulting in a false indication.

Additionally, such magnetic detectors are highly dependent upon the sensor which is used in determining the overall accuracy and sufficiency of the apparatus. U.S. Patents Specifications Nos.

2,936,890 issued May 1960 and 3,432,750 issued March 1969 to Botstiber are examples of magnetic chip detectors. U.S. Patent Specification No.

3,317,042 issued May 2, 1967 to Botstiber is an example of an apparatus which combines a filter with a circuit completion type sensor.

In addition to generating particulate debris, power applications also tend to create a degree of churning of the lubricating fluid with resultant formation of foams of entrapped gas which are often highly stable. In many systems equal amounts of air, by volume, are mixed with oil. In still other high speed applications such as in the lubrication systems for gas turbines as many as four parts of air may be mixed with one part of oil, by volume. Such dilution of the oil is obviously undesirable since it results in less oil coming in contact with the surfaces requiring lubrication thus diminishing the lubricating effect of the oil. Additionally, the cooling effect of the oil is substantially reduced. This, of course, increases the probabilities of over heating and accelerated wear.

Various means are disclosed by the prior art for removing air from a lubricating fluid. However, none of these "foam breakers" is combined with a device designed to remove debris particles at the same time. As a result separate devices must be used which, of necessity, increases both the weight and complexity of such systems. This is particularly undesirable and detrimental for aircraft applications.

The invention provides apparatus for use in a fluid system, for removing entrapped gas and separating out particles above a predetermined mass from the fluid, comprising means for separating out particles above a predetermined mass from other particles in the fluid, means for coalescing entrapped gas in the fluid, means operatively connected with said coalescing means for removing said coalesced gas from the fluid, and means for receiving said separated particles whereby they are trapped for subsequent removal from the system.

Preferably, the separating and coalescing means comprise a cylindrical housing having a smooth inner wall; a fluid inlet adapted to tangentially inject the fluid into said housing; a gas outlet in the top of said housing; a first cylindrical tube within said housing and concentric with it depending downward from said gas outlet and adapted to cooperate with said fluid inlet such that when the fluid is injected into the annulus between said first tube and said inner wall, a downwardly directed spiral flow pattern is developed, said flow pattern generating a first centrifugal force field which firstly causes the entrapped gases to coalesce substantially in the centre of said flow pattern and secondly selectively propels particles above a predetermined mass to the outer reaches of said pattern for eventual separation, trapping and removal; fluid removal means having an outlet in the bottom of said housing; and a second cylindrical tube within said housing and concentric with it depending upward from said fluid outlet and adapted first to cooperate with said first tube to maintain said downward spiral flow pattern and said first centrifugal force field and then to cooperate with the bottom of the housing to create a second centrifugal force field which causes said particles above a predetermined mass to be propelled to and kept at the bottom of said housing from which location they are trapped for removal.

Accordingly, the embodiment of the invention to be described provides an apparatus which will separate failure particles from wear particles and which will separate entrapped gases in the fluid of a lubricating system for mechanical drive systems.

The embodiment also provides means for separating failure particles from wear particles and entrapped gases in the fluid of lubrication systems, wherein centrifugal force is used to provide such separation.

In order that the invention may be well understood an embodiment thereof will now be described, by way of example only, with reference to the accompanying drawings in which: Figure lisa top view of a particle and gas separator apparatus; Figure 2 is a vertical cross-section side view along line 2 - 2 in Figure 1; Figure 3 is a horizontal cross-section along line 3 3 in Figure 2.

Referring now to Figures 1, 2 and 3 we see several views illustrating the preferred embodiment of a combination particle and gas separation apparatus 10. The preferred embodiment of the apparatus comprises a hollow cylindrical housing 12 having an integral top 14. Built into said top is oil inlet 16, which receives the fluid from the oil hydraulic system (not shown) and is adapted to inject said fluid tangentially to the smooth inner wall 18 of said hollow housing.

Top 14further contains a gas outlet or discharge 20 which is connected through internal channel 22 to a short hollow first cylindrical tube 24, which, in turn, is concentric with housing 12. Tube 24 also cooperate with inner wall 18 to form a cylindrical annulus, which as will be explained below, is critical to the total operation of the apparatus herein described.

Tube 24 has but a single first opening 25 at its tip which acts as an inlet for the separated gas and foam for subsequent discharge from the system.

Also contained in top 24 is an opening 26 leading into chamber 28, which lies alongside the full length of hollow housing 12 and is further adapted to contain a magnetic particle detector 30. At the bottom of chamber 28 is an exit hole 32, through which separated particles are attracted by magnet 34 of detector 30. As shown in Figure 2 maximum particle capture efficiency is achieved by having said magnet positioned at the same reference point along the length of housing 12 as is hole 32. Oil pressure is maintained in chamber 28 by an "0" ring 33 or similar type of sealing device.

Housing 12 is closed at the bottom with plate 36 which in the preferred embodiment is held in place with a plurality of bolts 38 which screw into lugs 40 in housing 12. Built into said plate is fluid outlet 42 to which a second hollow tube 44 is attached and which, like tube 24 is concentric with housing 12 extending up into the hollow interior of said housing. This tube opens into said interior through a plurality of second openings or holes 46 in its side close to the far end which receive the cleansed fluid for subsequent discharge from the apparatus back into the system. The top end of tube 44 is covered with a flat topped cylindrical shroud 48 which is adapted to contain and channel said cleansed fluid into holes 46. Also contained in bottom 36 is a machined channel 50 which acts to channel the separated solid particles into hole 32 and chamber 28 for collection by magnet 34.

In use the apparatus take advantage of the differences in mass between gas, fluid and solid particles.

When a fluid mixture of different massed components is subjected to a rotational flow it creates a centrifugal force field. In such a field the outward centrifugal velocity achieved, all other factors being equal, of the particles being accelerated varies directly with their mass. Thus in such a field the relatively heavy solid particles will move fastest and farthest away from the centre of rotation while the very light gas bubbles in the foam will be the slowest and move outward the least. The construction of the apparatus is designed to create such centrifugal force fields and take advantage of those differences.

In the preferred embodiment, as noted above, the fluid being cleaned is injected tangentially through inlet 16 into the interior of chamber 12. Inlet 16 is designed to cooperate with top 14 and hollow tubes 24 and 44 to create a downwardly directed cyclonic spiral flow pattern in the annulus which lies between smooth inner wall 18 and said hollow tubes. This cyclonic flow creates the first centrifugal force field needed to quickly force the heavy solid particles to the outer reaches of said flow pattern while, at the same time allowing the gas bubbles to coalesce in the centre of the pattern. As shown in Figure 2 in the flat top surface 54 of shroud 48 extends far enough out into the interior of housing 12 so that said coalesced bubbles cannot travel very far down the length of said housing with the spiralling fluid. This forces them into opening 25 of tube 24 for ultimate discharge out of the system through channel 22 and gas outlet 20. To maintain system pressure, outlet 20 leads to a pressure valve (not shown) which only opens when the gas pressure exceeds system pressure. By so doing any quantity of oil which might have been inadvertantly swept out with the collected foam and gases can be separated and drained out, as the foam breaks, for subsequent recovery and reuse.

The spirally rotating fluid will not be affected by the shroud extension and will continue in its downward pattern along with the metal chips. When the flow pattern reaches bottom plate 36 it reverses itself and flows in a generally upward path alongside tube 44 into shroud 48. This, as noted channels the flow through holes 46 into hollow tube 44, fluid discharge 42 and back into the system (not shown). As the flow pattern reverses itself it creates a second centrifugal force field which propels the separated particles down to the bottom 36 of housing 12 and keeps them there. The rotation of the cyclonic flow pattern tends to drag the particles around bottom plate 36 until they fail into machined channel 50 which directs them through hole 32 for collection by magnet 34. The design of the preferred embodiment is such that essentially all particles having a mass of 2.26 x 105g (equal to a steel sphere with a diameter of 200 microns) or greater will be effectively removed from the fluid being treated. Smaller "fuzz" particles are not as greatly affected by the two centrifugal force fields and most of these relatively innocuous particles are swept out of the treatment apparatus thus allowing for an effective means of sorting and segregating failure particles from the general non-critical mass of particulate material in the fluid. Detector 30 can be of any conventional design. In the preferred embodiment it is of the type which has a gap 56 which when bridged by one or more particles will send out an electrical signal through connector 58, thus warning the operator of a possibly critical problem developing somewhere in the system. Such a warning will permit effective maintenance and repair before a catastrophic failure will develop.

Claims

1. Apparatus for use in a fluid system, for removing entrapped gas and separating out particles above a predetermined mass from the fluid, comprising means for separating out particles above a predetermined mass from other particles in the fluid, means for coalescing entrapped gas in the fluid, means operatively connected with said coalescing means for removing said coalesced gas from the fluid, and means for receiving said separated particles whereby they are trapped for subsequent removal from the system.

2. An apparatus as claimed in claim 1, wherein said separating and coalescing means comprise a cylindrical housing having a smooth inner wall; a fluid inlet adapted to tangentially inject the fluid into said housing; a gas outlet in the top of said housing; a first cylindrical tube within said housing and concentric with it depending downward from said gas outlet and adapted to cooperate with said fluid inlet such that when the fluid is injected into the annulus between said first tube and said inner wall, a downwardly directed spiral flow pattern is developed, said flow pattern generating a first centrifugal force field which firstly causes the entrapped gases to coalesce substantially in the centre of said flow pattern and secondly selectively propels particles above a predetermined mass to the outer reaches of said pattern for eventual separation, trapping and removal; fluid removal means having an outlet in the bottom of said housing; and a second cylindrical tube within said housing and concentric with it depending upward from said fluid outlet and adapted first to cooperate with said first tube to maintain said downward spiral flow pattern and said first centrifugal force field and then to cooperate with the bottom of the housing to create a second centrifugal force field which causes said particles above a predetermined mass to be propelled to and kept at the bottom of said housing from which location they are trapped for removal.

3. An apparatus as claimed in claim 2, wherein said gas removing means comprises said first tube, having a first opening at one end thereof disposed within the housing to receive said coalesced gases; an internal channel connecting said first tube to said gas outlet; and wherein said second tube is provided with a flat topped cylindrical shroud at the end thereof disposed within the housing, said shroud being adapted to intercept said coalesced gases and prevent them from travelling further downward toward the bottom of said housing and then to direct them into said first opening in said first tube for discharge from the system.

4. An apparatus as claimed in claim 3, wherein said fluid removal means comprises said second tube adapted to cooperate with the bottom of said housing to reverse the spiral flow pattern and force the fluid to flow back alongside said second tube upwardly into said shroud, said shroud being adapted to contain and direct said flowing fluid into a plurality of second openings in the side of said second tube whereby said fluid is admitted to said fluid outlet for discharge from the apparatus back into the system.

5. An apparatus as claimed in claim 2,3 or 4, wherein said receiving means comprises a channel in the bottom of said housing adapted to receive said particles above a predetermined mass after they have been propelled out of said flow pattern by said second force field and further adapted to conduct said particles through a hole in the side of said housing into a chamber alongside said housing which acts to trap said particles above a predetermined mass, said chamber further containing a magnetic particle detector positioned with the magnet thereof across said hole from said channel and adapted to signal the presence of trapped particles above a predetermined size.

6. An apparatus for use in a fluid system for removing entrapped gas and separating out particles above a predetermined mass from the fluid substantially as herein described with reference to the accompanying drawings.