FR2764045A1 - LUBRICATION DEVICE FOR TRACTOR GEARBOX, PARTICLE REMOVAL METHODS AND TRACTOR THUS EQUIPPED - Google Patents

Abstract

The lubrication device includes a centrifugal filter to remove particles from the lubricating fluid. The methods include passing transmission lubricant or hydraulic fluid from the tractor hydraulic system through a centrifugal filter.

Description

Lubrication device for tractor gearbox.

  The present invention relates to lubrication devices for tractor gearboxes employing a filter to clean the gearbox oil when it is recycled in the lubrication device. The invention relates in particular to what is commonly called a

  micrometric filtration in the device.

  It is of course known to filter the oil in a tractor gearbox to prevent particles from accumulating in the oil and to cause wear and / or damage to the components of the gearbox. Conventionally, stop filters are used which can be in the form of a perforated metal sheet product for fairly large particles or of an element

  paper / cardboard or fibrous product for particles less than 100 lim.

  Typically, both a micrometric filter and a

large particles.

  A problem with micrometric stop filters is that over time the filter element becomes clogged with particles and loses its effectiveness. Regular replacement is necessary and the time interval between scheduled maintenance for a tractor is often determined by the frequency with which the filter elements have

need to be replaced.

  Other types of filter are known, but in general only stop filters have been used in lubrication devices for tractor gearboxes. Such a type of filter is what is commonly known as a centrifugal filter, in which the fluid is driven in a revolution movement at high speed in a chamber and is efficiently centrifuged, the particulate matter contained in the fluid

  depositing on the inner surface of the outer wall of the chamber.

  Centrifugal filters are known in engine lubrication devices and play their role very well. It is believed that at least partially, the reason that these filters work successfully in engine applications is the nature of the particulate matter filtered from the engine oil (mainly carbon black) and / or the nature of motor oil which contains many additives. It is believed that the additives and / or particulate matter found in used engine oil or a combination of both cause the deposit of filtered material in the filter to stick very effectively to the wall of the filter chamber. centrifugal filter. The result is of course that the filtered material does not return to the filtered oil, which can be a problem with this type of filter, especially when

  the flow of fluid stops and the filter stops rotating.

  Centrifugal filters are believed not to have been used in general in engine gearbox lubrication systems in the past because it was believed that the various particles found in gearbox and / or the different nature of the oil designed specifically for conventional vehicle gearboxes would prevent the formation of a sufficiently viscous deposit on the chamber wall of the filter. This belief has been reinforced by experimentation using centrifugal filters with certain "very pure" oils containing very few additives. The results of these experiments were that an insufficiently viscous film formed in the filter chamber which was returned to the oil circuit when the filter stopped rotating. A tractor gearbox lubricant typically has a higher proportion of friction reducing additives and was thought to be even more likely.

  to prevent the accumulation of viscous deposits in the filter.

  A centrifugal filter with a capacity roughly equivalent to a given stop filter in terms of fluid flow can retain more than ten

  times the mass of particles as the stop filter before becoming ineffective.

  The lubrication device thus requires considerably less maintenance than an equivalent device employing only one or more stop filters. Centrifugal filters are also in general considerably more effective than stop filters in removing very small particles, for example of the order of 30 / m and the use of a centrifugal filter has proven to be much cleaner. the lubricant for tractor gearbox. This may mean that it is possible to increase the interval between transmission oil changes.

  gears without risk of damage to the gearbox.

  A preferred feature of the invention is that the filter chamber which collects the particles, or part of its wall, can be removed and cleaned. In many circumstances this may be preferable to having a disposable chamber (which is also possible), for example especially in parts of the world where

  spare parts are difficult to obtain or expensive.

  It is noted that, in the case where a centrifugal filter is used, no other form of micrometric filtration is necessary. It is therefore preferable that the device uses a centrifugal filter as the only micrometric filtration means. The device would normally also include a perforated sheet metal product filter to separate the largest particles, leaving the lower particles to be removed from the centrifugal filter, say at 500 m, 400 gim, 300 jm,

gm, 100 / m or 50 Mm.

  The invention relates to a lubrication device for a tractor gearbox comprising a centrifugal filter for eliminating

particles of the lubricating fluid.

  The lubrication device according to the invention may also have the following particularity: - the centrifugal filter constitutes the only form of filtration

micrometric in the device.

  The invention also relates to a tractor comprising a system

  gearbox lubrication as defined above.

  The tractor according to the invention can also have the following particular feature - the gearbox lubrication system is part of the

  same circuit as the tractor hydraulics.

  Another subject of the invention is a method for cleaning a lubricant for a tractor gearbox from its particles.

  passing the lubricant through a centrifugal filter.

  The invention finally relates to a method for removing particles from a hydraulic device for a tractor, consisting in making

  pass the hydraulic fluid through a centrifugal filter.

  Either of the two above processes can also have the following particularity: - the lubricant contains one or more of the following additives or a combination of these a dispersant, a viscosity-improving agent, an antioxidant, a detergent, antiwear additive, defoaming additive, acidity adjusting additive, pour point lowering agent,

  a high proportion of friction modifier.

  The invention has been developed specifically for agricultural tractors which are often used in remote parts of the world where the advantages of the centrifugal filter are particularly

apparent.

  On many tractors, the transmission lubricating oil and the hydraulic system oil are the same oil. Preferably, there is provided a device as described above which is also

a hydraulic oil system.

  A particular embodiment of the invention, provided solely by way of example, is described below with reference to the appended drawings in which: FIG. 1 is a schematic view showing a part of the gearbox lubricant circuit speeds of the particular embodiment and Figure 2 is a section through a centrifugal filter of the type used in

  the particular mode of implementation.

  If we refer first to FIG. 1, this simply represents a hydraulic bypass line 1 coming from the main gearbox lubrication circuit. A centrifugal filter 3 is disposed on a branch 2 from line 1 and the outlet of this centrifugal filter 3 returns to the cover 4 of the device. The bypass line 1 continues until a valve 5 sensitive to the effect of the pressure which is

  itself connected to the cover 4 of the device.

  The valve 5 is adjusted to block the passage until the pressure reaches approximately 5 or 6 bars, point at which it allows the fluid to pass directly to the tank 4. In this way, the routing of the fluid to the filter 3 is subject to regulation. This pressure fixation produces a flow of approximately 3 to 5 liters / min through the filter. If we now refer to Figure 2, the filter itself

  comprises a housing 6 and a base 7 in which a pin 8 is mounted.

  The axis 8 has a central passage 11, supplied from an inlet passage 14 located in the base 7, and fluid outlets 12 located towards the upper part. A centrifugal assembly 13 is rotatably mounted on bearings 9, 10. The assembly 13 comprises a central element 15 on which are mounted an element forming an interior wall of chamber 16 and an element forming an exterior wall of chamber 17, which is mounted a removable way. The interior and exterior walls 16, 17 define

a centrifugal chamber 25.

  Inlet openings 18, 20 are provided respectively in the central member 15 and the inner wall member 16. An outlet opening 19 is also provided in the inner wall member 16, leading to an outlet chamber 21 defined in the base of the central element 15. The base of the central element is provided with circumferentially directed outlet openings 22 leading to the space delimited between the housing / base and

  the centrifugal assembly 13. Finally, an outlet 23 is provided in the base 7.

  The oil passes in the manner indicated by the arrows 24, from the inlet passage 14 of the base 7, going up in the axis passage 11, then leaving through the openings 12 of the axis and the openings 18, 20 of the central element 15 and of the interior wall 16 to reach the centrifugal chamber 25. The assembly 13 rotates, as explained below, and the fluid is projected onto the interior surface of the exterior wall 17 in the deposition process the particles contained in the fluid. The fluid then leaves the chamber 25 through the openings 19 and enters the outlet chamber 21 from which it exits through the openings 22 to pass into the

base 7.

  Since the openings 22 are directed circumferentially, the fluid leaving the centrifugal assembly under pressure tends to cause it to perform a movement of revolution in

its bearings 9, 10.

  After leaving the centrifugal assembly, the fluid leaves under the effect

  of its weight through the outlet 23 of the base and returns to the cover 4.

  It can be seen that during use, a sticky slurry is formed on the inner surface of the outer wall 17 and that the system oil is very free of particles - more than would be the case with a filter. classic stop. This is the case even when the system is repeatedly switched off and restarted, which means that there is practically no slurry coming out of the filter under the effect of its weight

  when the filter stops rotating.

  The type of oil used in the system was a multigrade oil suitable for lubrication of tractor diesel engine, lubrication of gearbox and use in the hydraulic system. The oil contained the following additives: dispersant, viscosity improving agent, detergent, antiwear additive, defoaming additive, acidity adjusting additives, pour point lowering agent, antioxidant,

  a high proportion of friction modifier.

  In contrast, a simple oil would normally contain only a small proportion of friction modifying agent, viscosity improving agent and antioxidant, antiwear and defoaming additives. A simple hydraulic only oil would normally contain only small amounts of antiwear additive, defoamer and possibly a pour point lowering agent and

an antioxidant.

  Experiments using a "purer" oil comprising fewer additives, namely anti-wear, anti-foaming and antioxidant additives, have resulted in the formation, on the inside of the outer wall 17, of a film which, when the device was stopped and the filter stopped turning, dripped out of the filter under the effect of its weight and would therefore cause, during use, a return of particles to the device.

Claims (8)

  1. Lubrication device for tractor gearbox, characterized in that it comprises a centrifugal filter to eliminate particles of the lubricating fluid.   2. Device according to claim 1, characterized in that the centrifugal filter constitutes the only form of micrometric filtration in the device.   3. Tractor with a gearbox lubrication system   speeds according to one of claims 1 and 2.   4. Tractor according to claim 3, characterized in that the gearbox lubrication system is part of the same circuit   than the tractor hydraulics.   5. Method for cleaning a lubricant for tractor gearbox from its particles, characterized in that it consists in making   pass the lubricant through a centrifugal filter.   6. Method according to claim 5, characterized in that the lubricant contains one or more of the following additives or a combination thereof: a dispersant, a viscosity improving agent, an antioxidant, a detergent, an antiwear additive, an additive anti-foaming agent, an acidity adjusting additive, an agent lowering the flow weight,   a high proportion of friction modifier.   7. Method for removing particles from a hydraulic device for a tractor, characterized in that it consists in passing the   hydraulic fluid in a centrifugal filter.   8. Method according to claim 7, characterized in that the lubricant contains one or more of the following additives or a combination thereof: a dispersant, a viscosity improving agent, an antioxidant, a detergent, an antiwear additive, an additive defoamer, acidity control additive, pour point lowering agent,   a high proportion of friction modifier.