GB2244661A

GB2244661A - Degassing hydraulic fluid

Info

Publication number: GB2244661A
Application number: GB9012707A
Authority: GB
Inventors: David Samuel Paul
Original assignee: AGCO Manufacturing Ltd
Current assignee: AGCO Manufacturing Ltd
Priority date: 1990-06-07
Filing date: 1990-06-07
Publication date: 1991-12-11
Anticipated expiration: 2010-06-07
Also published as: GB2244661B; GB9012707D0

Abstract

The present invention provides an air removal system of particular use for removing air from the oil of an hydraulic system. The invention provides a collection chamber 20 for the storage of oil, a fluid inlet 26 for supplying fluid to the chamber 20 and a deflector member 24 which acts to reduce the kinetic energy of oil entering the chamber 20 and directs the incoming oil substantially parallel with and adjacent to the surface of any oil in the chamber 20. Reducing the kinetic energy of the incoming oil helps prevent any air bubbles contained therein being further broken up. Directing the incoming oil substantially parallel with and adjacent to the surface allows the air bubbles to rise to the surface rather than be drawn back into the hydraulic circuit. Chambers 47, 46 help in condensing oil droplets in the air and baffle plate 36 cuts down splashing brought about by rough movement. <IMAGE>

Description

AN AIR REMOVAL SYSTEM The present invention relates to an air removal system and relates particularly to an air removeal system in which a chamber is used to allow air to separate from a fluid.

One example of an air removal system is shown in US Patent No 4,592,418 in which a narrow passage formed by a tube is used to transfer a water/air mixture into a chamber in which the air is separated from the water. The water/air mixture enters the chamber via the tube at a level above the level of the water in the chamber and is passed under the water before exiting the tube into the chamber. The water/air mixture is directed substantially downwards or substantially upwards as it exits the tube and the air is separated from the water by means of its natural bouyancy which raises it to the surface of the water. Water is withdrawn through an outlet at the bottom of the chamber for circulation around a cooling device such as a radiator.

One of the problems associated with the above mentioned device is that if there is insufficient distance between the exit from the tube and the outlet air may be drawn into the cooling device rather than separated out from the water as desired, thereby reducing cooling efficiency.

Further to the above, it is possible for more air bubbles to be created or any existing air bubbles to be broken up into a series of much smaller bubbles as the water/air mixture enters the chamber from the tube. Small air bubbles have less bouyancy than larger bubbles and are therefore less likely to reach the surface and be released from the water before the water is drawn form the chamber and circulated around the cooling device. This problem is particularly prelevant where more viscous cooling fluids, such as for example oil, are used. Small air bubbles often have insufficient bouyancy to rise to the surface of the oil before the oil is re-circulated for cooling.

Other problems associated with presently known air removal systems reside in the production of air bubbles within the fluid if the system is installed in a vehicle which travels over rough ground for example, or is otherwise disturb ed in operation and in extracting fluid from the fluid/air mist often created within the device before the air is vented to atmosphere.

It is an object of the present invention to provide an air removal system which obviates or mitigates the foregoing problems.

Accordingly, the present invention provides an air removal system comprising: a collection chamber, for the storage of fluid therein; a fluid inlet; for the supply of fluid to said chamber; and means for reducing the kinetic energy of fluid entering the chamber, thereby to reduce the possibility of air bubbles situated within the incoming fluid being broken up.

The means for reducing the kinetic energy at fluid entering the chamber may, for example, comprise a deflector member adapted to deflect the incoming fluid in a predetermined manner. The deflector may be formed by an arcuate extension of the inlet pipe which curves through an arc of a predetermined magnitude. The magnitude of the arc may be greater than 180 degrees and is preferably substantially 250 degrees.

Preferably, there is provided a means for directing the fluid entering the chamber in a direction substantially parallel with the surface of any fluid situated in said chamber, thereby to assist any air bubbles trapped in said fluid to rise to the surface of any fluid situated in the chamber and to reduce the possibility of any airbubbles being drawn out of the chamber and recirculated through a fluid flow system connected thereto.

The means for reducing the kentic engergy of fluid entering the chamber may be the means for directing the fluid entering the chamber in a direction substantially parallel with the surface of any fluid situated in said chamber.

The arcuate extension may conveniently be formed by a piece of material connected at a first portion to a first side of the inlet and at a second portion to a second side of said inlet at a level above the connection point of said first portion, thereby to define a gap between the first and second portion of said extension for the passage of fluid therethrough.

In a preferred arrangement, the width of the arcuate extension is substantially greater than the width of the inlet and the arcuate extension is formed substantially without sidewalls, thereby allowing any incoming fluid to interact with any fluid situated in the chamber to help reduce the kinetic energy of the incoming fluid as it passes around the arcuate portion.

In a simple arrangement, the means for directing the flow of fluid leaving the inlet pipe comprises the second portion of the arcuate extension the tangent of which extends substantially parallel with the surface of any fluid situated in said chamber.

In an advantageous arrangement, the width of the gap increases as the distance from the inlet increases, thereby reducing the possibility of the edges of the gap interfering with the flow of incoming fluid.

In another aspect of the present invention a means for reducing the movement of any fluid situated in the chamber is provided thereby to reduce and possibly eliminate the production of air bubbles in said fluid if the air removal system is installed in, for example, a vehicle which travels over rough ground, or is otherswise disturbed in operation.

The means may comprise a baffle which extends across the surface of any fluid situated in the chamber. The baffle may be provided with one or more gaps between itself and the chamber or one or more holes within itself for the passage of air therethrough.

In a still further aspect of the present invention, there is provided a means for removing any fluid from the fluid/air mist often created within a degassing device. The means may comprise a filtering device which allows any fluid situated within said fluid/air mixture to be returned to the collection chamber. Preferably the means comprises at least one separation chamber into which the fluid/air mixture is introduced via a plurality of holes provided around the upper periphery thereof and a drain hole provided in the base thereof through which any separated fluid is returned to the collection chamber. Fluid is deposited on the walls of the separation chamber before the air and any remaining fluid is drawn from the chamber via an air hole provided therein. The air and any remaining fluid may be passed through a second separation container before the air is vented to atmosphere.

The present invention will now be more particularly described by way of example only with reference to the accompanying drawings, in which: Figure 1 is a side elevation of an earth moving vehicle incorporating an oil tank having a degassing device according to the present invention.

Figure 2 is a cross sectional view of the oil tank provided in the vehicle illustrated in figure 1.

Figure 3 is a view in the direction of arrow A in figure 2.

Referring to the drawings in general but particularly to figures 1 and 2, a vehicle, such as an industrial tractor loader 10, is provided with an oil tank 12 for the collection of oil 14 used in, for example, the hydraulic system (not shown) for the operation of the lift and bukcet cylinders 16 and 17 respectively of the loader. The air removal system shown generally at 12 comprises an oil inlet 18, a collecting chamber 20 for the storage of oil therein an oil outlet 22, a means 24 for reducing the kinetic energy of oil entering the chamber and for directing oil leaving the inlet in a direction substantially parallel with the surface of any oil situated in the chamber 20.

Turning now more particularly to figure 2, the inlet 22 is situated towards the top of the chamber 20 and includes a pipe 26 which acts to direct any oil/air mixture entering the tank 12 downwardly and under the surfacets) of any oil situated within the chamber 20. A deflector in the form of an arcuate extension 24 to the outlet 28 of the pipe 26 is formed by a piece of a sheet material connected at a first portion 24a to a first side 26 of the pipe and at a second portion 24b to a second side 26b of the pipe at a level above the connection point of the first end 24a. A gap G (best seen in Figure 3) is defined between the first and second ends of said extension 24 for the passage of oil therethrough. The arcuate extension 24 curves through an angle of at least 180 degrees and is preferably curved through as large an angle as possible whilst still maintaining an adequate gap G.In the arrangement shown, an angle of substantially 250 degrees has been found to be particularly suitable as this allows the oil/air mixture to be directed in the required direction. It will, however, be appreciated that the angle may be varied depending upon the installation, the important factor being that the oil/air mixture should leave the inlet in a direction substantially parallel with the surface of any oil situated in the chamber 20.

The width W of the arcuate extension 24 is preferably substantially greater than the width w of the inlet pipe 26 and the extension is formed substantially without sidewalls thereby to allow the incoming oil/air mixture to interact with any oil situated in the chamber 20. The width of the gap G may increase as the distance from the inlet increases thereby to reduce any obstruction to the flow of oil therethrough.

The oil outlet 22 is positioned remove from the arcuate portion 24 and at a level below the level of the gap G.

In operation an oil/air mixture is returned to the chamber 20 via the inlet 18 after having been circulated around the vehicles hydraulic system. The mixture is directed under the surface of any oil situated within the chamber 20 by pipe 26. The arcuate extension 24 acts to turn the incoming mixture through a substantial angle thereby dissipating a large portion of the mixtures kinetic energy and reducing the speed of the incoming mixture. As the incoming oil/air mixture passes over the surface of the arcuate extension 24 it fans out thereby exposing a greater portion of the mixture to the surface of the extension 24 and the energy dissipating effect thereof.By reducing the kinetic energy and the speed of the incoming mixture it is possible to significantly reduce the possibility that air bubbles will be formed by the churning of oil as the mixture enters the mass of the oil situated in the chamber 20.

It will be appreciated that in operation the level of oil in the chamber (20) may vary significantly depending upon the number or type of oil driven implements in use. It has been found that the oil level may be reduced to as little as 25 mm above the level of the uppermost portion of the arcuate extension (24) without the incoming oil/air mixture breaking the surface of the oil in the chamber (20) or causing churning of the oil at the surface which may lead to the formation of air bubbles.

The arcuate extension 24 may be formed without sides thereby providing only a partial shield between the incoming mixture and any oil within the chamber 20. By adopting a partial shield it is possible to utilise the mass of the oil already situated within the chamber to help reduce the kinetic energy and speed of the incoming mixture even further without the formation of undesirable air bubbles. The arcuate extension 24 effectively acts to reduce the kinetic energy and speed of the incoming mixture below a level at which it can interact with the oil situated within the chamber without producing bubbles.Interaction between the oil in the chamber 20 and the incoming mixture, after the kinetic energy and speed have been reduced sufficiently by the arcuate extension 24, will further reduce the kinetic energy and speed of the incoming mixture as the incoming mixture mixes with the oil already within the chamber 20.

The majority of the oil/air mixture entering the chamber 20 is directed around the arcuate extension 24 and is passed out therefrom via gap G. The position of the gap G is selected such that the mixture exiting therefrom is directed substantially parallel with the surface of any oil situated within the chamber thereby increasing the probability of any air bubbles trapped in the incoming mixture rising to the surface and reducing the possibility of the bubbles being re-circulated into the hydraulic system.

It will be appreciated that whilst the above mentioned degassing device has been described with reference to relatively high viscosity hydraulic fluid, it may be used to separate air from fluid of high or low viscosity.

In another aspect of the present invention a baffle member 30 is provided which extends across but slightly above the surface(s) of any oil situated in the chamber 20. The baffle 30 may be provided with one or more gaps 32 between itself and the chamber sidewalls 34 or one or more holes (not shown) within itself for the passage of air/oil therethrough. The baffle member 30 may be formed from, for example, 2mm thick sheet material secured at at least one edge 36 to one of the chamber walls 38 although it will be appreciated that other forms and shapes of baffle member 30 may be employed without departing from the spirit of the present invention.

In operation, the baffle member 30 acts to damp down any oil splash in the chamber 20 when the air removal system 12 is disturbed by, for example, driving a vehicle in which the device is installed over rough ground. The gaps 32 or holes (not shown) in the baffle member act to allow air in the chamber 20 to pass by the baffle and exit the chamber 20 via a means for removing any oil from the oil/air mist provided at the top of the chamber 20 and discussed in detail below.

It has been found that a gap of approximately 15mm between either end of the baffle member 30 and the sidewall 34 adjacent thereto is sufficient to allow air to pass to the brether pipe 40 whilst preventing excessive oil passage therethrough. Any oil which does pass through the gaps or holes is quickly drained back into the main body of oil in the chamber.

In a still further aspect of the present invention there is provided a means for removing any fluid from the fluid/air mist created within the air removal system 12. The means may comprise a filtering device comprising at least one separation chamber 42, into which the fluid/air mixture is introduced via a plurality of holes 44 provided around the upper periphery thereof, and a drain hole 46 provided in the base 48 thereof through which any separated fluid is returned to the collection chamber 20. The droplets of oil being heavier than the air in which they are suspended separate out therefrom and are deposited on the sidewalls 50 and the base 48 before the air is drawn from the separation chamber via an outlet 52 provided in the upper surface 54.

It will be appreciated that a filter element (not shown) may be provided within the separation chamber 42 to further assist in the separation of oil from air, although the addition of such a filter is not necessary for the effective performance of the present invention.

The air an any remaining oil droplets may be passed through a second separation chamber 56 before the air is finally vented to the atmosphere. The second separation chamber 56 comprises an inlet 57 again situated towards the upper portion of the chamber, and oil outlet 58 provided in the base 60 and an air outlet 62 provided in an upper portion thereof. In operation, the droplets of oil separate out from the air as previously described and any oil is returned to the chamber 20 via oil outlet 58 and cleaned air is vented to atmosphere via the air outlet 58.

For convenience, both the first and second separation chambers 42, 56 are situated within the collection chamber 20. It will however be appreciated that they may be otherwise situated if suitable ducting for the passage of the air/oil mixture and separated air/oil is provided.

Claims

1. An air removal system comprising: A collection chamber for the storage of fluid therein; a fluid inlet for the supply of fluid to said chamber, and means for reducing the kinetic energy of fluid entering the chamber thereby reducing the possibility of air bubbles situated within the incoming fluid being broken up.

2. An air removal system as claimed in Claim 1 in which the means for reducing the kinetic energy of fluid entering the chamber comprises a deflector member adapted to deflect the incoming fluid in a predetermined manner.

3. An air removal system as claimed in Claim 2 in which the deflector is formed by an arcuate extension of the inlet pipe which curves through an arc of a predetermined magnitude.

4. An air removal system as claimed in Claim 3 in which the magnitude of the arc is greater than 180 degrees.

5. An air removal system as claimed in Claim 3 in which the magnitude of the arc is substantially 250 degrees.

6. An air removal system as claimed in any one of the preceding Claims in which there is provided a means for directing any fluid entering the chamber in a direction substantially parallel to the surface of any fluid situated in said chamber thereby to assist any air bubbles trapped in any fluid entering the chamber to rise to the surface of the fluid in the chamber and to reduce the possibility of any air bubbles being drawn out of the chamber and recirculated through any fluid flow system connected thereto.

7. An air removal system as claimed in Claim 6 in which the means for directing any fluid entering the chamber in a direction substantially parallel to the surface of any fluid in the chamber may also be the means for reducing the kinetic energy of any fluid entering the chamber.

8. An air removal system as claimed in any one of Claims 3 to 7 in which the extension is connected at a first portion to a first side of the inlet and at a second portion to a second side of said inlet at a level above the connection point of said first portion thereby to define a gap between the first and second portion of said extension for the passage of fluid therebetween.

9. An air removal system as claimed in Claim 8 in which the width of the arcuate extension is substantially greater than the width of the inlet and the arcuate extension is formed substantially without sidewalls, thereby to allow any incoming fluid to interact with any fluid situated in the chamber to help reduce the kinetic energy of the incoming fluid as it passes around the arcuate portion.

10. An air removal system as claimed in any one of the preceding Claims in which there is provided a baffle which extends across the surface of any fluid situated in the chamber.

11. An air removal system as claimed in Claim 10 in which one of more gaps are provide between the baffle and the chamber or one or more holes are provided in the baffle for the passage of air therethrough.

12. An air removal system as claimed in any one of the preceding Claims in which there is provided a filtering device comprising a first separation chamber having a plurality of holes provided around the upper periphery thereof for the passage of a fluid/air mixture into the first separation chamber and a drain hole provided in the base of the - first separation chamber through which any separated fluid is returned to the collection chamber.

13. An air removal system as claimed in Claim 12 in which the first separation chamber is connected to a second separation chamber through which the fluid/air mixture is passed before being vented to atmosphere.

14. An air removal system constructed and arranged substantially as described herein with reference to and as shown in Figures 1 to 3 of the accompanying drawings.