WO2010144046A1

WO2010144046A1 - Lubricating system for circulation lubrication of larger units of machine parts

Info

Publication number: WO2010144046A1
Application number: PCT/SE2010/050652
Authority: WO
Inventors: Patrik Broman; Martin Ottosson; Erik Larsen
Original assignee: Pmc Hytech Ab
Priority date: 2009-06-11
Filing date: 2010-06-11
Publication date: 2010-12-16
Also published as: SE533840C2; SE0950445A1

Abstract

The present invention relates to a lubricating system for circulation lubrication of larger units of machine parts at heavy loads, comprising an oil tank (1), at least one distribution pipe (3) for supplying at least one lubricating point (4) with lubricating oil and at least one return pipe (5) for returning oil to the oil tank (1). Lubricating oil, with a viscosity corresponding to at least 1000 cSt at 4O°C, is pumped from the oil tank (1) to the lubricating point (4), whereby the oil is distributed with a substantially maintained viscosity via at least one nozzle (9) directly at said lubricating point (4).

Description

LUBRICATING SYSTEM FOR CIRCULATION LUBRICATION OF LARGER UNITS OF MACHINE PARTS

Field of the invention

The present invention relates to a lubricating system for circulation lubrication of larger units of machine parts at heavy loads, comprising an oil tank, at least one distribution pipe for supplying at least one lubricating point with lubricating oil and at least one return pipe for returning oil to the oil tank.

Background of the invention

When lubricating heavily loaded units such as rolling mills or open gear wheels for mills, which are used within the mining industry, lubricating grease has previously been used exclusively. The lubricating grease meets the extremely high demands on lubricants, which are necessary in harsh environments with high temperatures, shock impacts, impurities such as filth, dust, and water. The lubricating grease is distributed to different lubricating points using different systems for central lubrication, whereby the lubricating grease is fed to the lubricating point at a certain time interval. Used lubricating grease is collected and lead away from the unit for destruction or depositing. Even if the use of lubricating grease provides a satisfactory lubrication, the consumption and the managing of consumed lubricating grease leads to considerable costs for the user. When lubricating for example rotary mills or corresponding industrial machinery with gear drive, one can also use a lubricating oil for lubricating bearings or gear drives using circulation lubrication. The lubricating oil can be pumped from a vessel to the lubricating point, after which it is collected and returned to the lubricating point after filtration. It is well known that the lubricating oil requires a higher viscosity during higher loads. At heavily loaded units, one must use lubricating oils having a high viscosity; this viscosity often exceeds what is normally used for circulation lubrication.

The viscosity for lubricating oils is given in the unit "Centistoke (cSt)", and since this unit depends on temperature the viscosity at 40⁰C is usually given for comparison. General lubricating oils usually have a viscosity between 20 and 80 cSt at 4O⁰C₁ but at higher loads it is possible to use up to 500 cSt at 4O⁰C. The ability to pump the lubricating oil decreases with an increase of viscosity, and for lubricating oils with a viscosity exceeding 1000 cSt at 4O⁰C, the ability to pump is considered so low that oil bath lubrication is used, which means that the machine parts are immersed in an oil bath. For larger units, oil bath lubrication is not practically applicable.

Summary of the invention

It is an object of the present invention to accomplish circulation lubrication for larger units of machine parts at heavy loads, such as for example within the mining industry, in order to replace the use of lubricating grease.

According to the present invention, this object is achieved by a lubricating system for circulation lubrication of larger units of machine parts at heavy loads, comprising an oil tank, at least one distribution pipe for supplying at least one lubricating point with lubricating oil and at least one return pipe for returning oil to the oil tank, characterised by the oil tank comprising means for heating the oil and by lubricating oil, with a viscosity corresponding to at least 1000 cSt at 4O⁰C, being pumped from the oil tank to the lubricating point, whereby oil bearing parts are kept at a temperature where the desired viscosity is maintained in order to distribute the oil with a substantially maintained viscosity via at least one nozzle directly at said lubricating point.

Preferably, the lubricating oil has a viscosity corresponding to at least 220O cSt at 4O⁰C

In one preferred embodiment, the lubricating oil has a viscosity corresponding to at least 11000 cSt at 4O⁰C.

Preferably, the oil tank comprises at least two vessels, a first return vessel which separates substantially larger impurities, and a second main vessel where the oil is kept at the desired viscosity.

The oil in the main vessel is pumped through a filter before being lead into said distribution pipe, and preferably the oil is pumped from the main vessel to a delivery pipe which supplies said distribution pipe with pressurised lubricating oil. A pressure intensifier can be provided at said distribution pipe, whereby the lubricating oil is pressurised to at least 40 bar, in order to spread the pressurised lubricating oil through said nozzles. The lubricating oil can be pressurised up to 420 bar.

Preferably, the first return vessel comprises at least one first heater for the oil, and the second main vessel comprises at least one second heater for the oil. Thereby, the oil in the return vessel is kept at a first temperature and the oil in the main vessel is kept at a second, higher temperature, where the desired viscosity is maintained. Preferably, substantially all oil bearing parts, comprising at least one pump and said filter, are located in the main vessel and immersed in oil. Preferably, the temperature in the oil tank is kept over 20⁰C. Finally, the lubricating oil can be supplied intermittently at said lubricating point.

Brief description of the drawings The present invention will now be described in more detail, with reference to the appended drawings showing, by way of example, a currently preferred embodiment of the invention.

Fig. 1 shows a diagrammatical sketch of a lubricating system according to the present invention, Fig. 2 schematically shows a first view of an oil tank according to figure

1, and

Fig. 3 schematically shows a second view of an oil tank according to figure 1.

Detailed description

The present invention thus relates to a circulation lubrication system for accomplishing a constant flow of lubricating oil of suitable viscosity and pressure, in order to assure satisfactory lubrication of a gear drive (not shown) of a mill for mining. The lubrication system comprises an oil tank 1 with an outgoing delivery pipe 2 and at least one distribution pipe 3 for supplying at least one lubricating point 4 with lubricating oil, and at least one return pipe 5 for returning the oil to the oil tank 1 , whereby the oil tank 1 comprises means 6 for heating of the oil. Preferably, the temperature in the oil tank 1 is maintained above 2O⁰C. A pressure switch 7 is provided in the delivery pipe 2 and at least one pump 8 regulates the flow of lubricating oil to the distribution pipe 3. The flow can, for example, be regulated between 0 and 9 l/m at a pressure of approximately 4,5 bar, preferably the flow is regulated to approximately 5 l/m. The distribution pipe 3 preferably comprises a number of holes or nozzles 9 evenly distributed across the width of the gear drive, whereby the lubricating oil is distributed across the gear drive. A pressure intensifier 20 can be provided at said distribution pipe 3, whereby the lubricating oil is pressurized to at least 40 bar and up to 420 bar, for spreading the pressurized lubricating oil through said nozzles 9. By means of this pressure intensification, it is possible to design the nozzles such that the lubricating oil is directed into said lubricating point 4. This provides a more efficient lubrication and it is also possible to supply the lubricating oil intermittently at said lubricating point 4. After lubrication, the excess is collected in a tray 10 and returned by gravitation to the oil tank 1. In the shown embodiment of the present invention, the oil tank 1 is divided into a first return vessel 12, in which substantially larger impurities are separated by sinking to the bottom of the return vessel 12. When the return vessel 12 is filled, the lubricating oil flows over a partition wall 13 into a second main vessel 14. There is at least one heater 15 in the return vessel 12, in order to keep the return oil at a suitable temperature. In the shown embodiment, the heater 15 is of 1500 W and keeps the oil at about 3O⁰C. In the main vessel 14, there is at least one more heater 16. In the shown embodiment, there are four heaters 16, each of 1500 W, which are intended for heating the lubricating oil to approximately 4O⁰C. In the shown embodiment, there are two pumps 8a and 8b in parallel, each or both together pumping the heated oil through at least one filter 17, comprising a filter element 18, with for example filter mesh openings of 25 μm, for filtering of any impurities. Thereafter, the lubricating oil is yet again lead into the delivery pipe 2. Substantially all oil bearing parts, comprising at least the pumps 8 and said filter 17, but also piping between these and valves etc., are located in the main vessel 14 and immersed in oil, whereby the parts are kept at a temperature where the desired viscosity is maintained. In the shown embodiment, the oil tank holds 1800 kg of lubricating oil, which tank is filled at the oil inlet 19. A suitable oil quality for the shown embodiment is Klϋberfluid™ CF3 with a viscosity of 16500 cSt at 4O⁰C or Klϋberfluid™ CF7 with a viscosity of 22000 cSt at 40⁰C, or an equivalent oil quality from other suppliers.

Previously, oil with a viscosity of 1000 cSt at 4O⁰C has been considered the maximum viscosity, and if this quality is heated in accordance with the present invention to 30⁰C, equivalent to 2200 cSt, the viscosity will exceed the viscosity which previously was considered the upper limit for circulation systems. In a shown embodiment, the oil in the return vessel 12 is not pumped at the lower temperature, but flows over the partition wall 13 into the second main vessel 14 in the same way as for example an oil quality for oil bath lubrication, which previously has shown a maximum viscosity equivalent to 11000 cSt at 40⁰C. By for example heating the oil in the second main vessel 14 relatively quickly to approximately 4O⁰C, it is possible to pump a highly viscous oil quality, through the filter 17 and through the delivery pipe 2 and via the distribution pipe 3 to the lubricating point 4, without the oil cooling considerably and for such a short time that the quality of oil does not deteriorate to any considerable extent.

The person skilled in the art realizes that many modifications of the above described embodiment are possible within the scope of invention, such as defined by the appended claims.

Claims

1. Lubrication system for circulation lubrication of larger units of machine parts at heavy loads, comprising an oil tank (1), at least one distribution pipe (3) for supplying at least one lubricating point (4) with lubricating oil, and at least one return pipe (5) for returning oil to the oil tank

(1), c h a r a c t e r i s e d by the oil tank (1) comprising means (6) for heating the oil and by lubricating oil, with a viscosity corresponding to at least 1000 cSt at 40⁰C, being pumped from the oil tank (1) to the lubricating point (4), whereby oil bearing parts are kept at a temperature where the desired viscosity is maintained in order to distribute the oil with a substantially maintained viscosity via at least one nozzle (9) directly at said lubricating point (4).

2. Lubricating system according to claim ^characterised by the lubricating oil having a viscosity corresponding to at least 2200 cSt at 40⁰C.

3. Lubricating system according to claim ^characterised by the lubricating oil having a viscosity corresponding to at least 11000 cSt at 4O⁰C.

4. Lubricating system according to any of claims 1 -3, characterised by the oil tank (1) comprising at least two vessels; a first return vessel (12) which separates substantially larger impurities, and a second main vessel (14) where the oil is kept at the desired viscosity.

5. Lubricating system according to claim 4, characterised by the oil in the main vessel (14) being pumped through a filter (17) before being lead into said distribution pipe (3).

6. Lubricating system according to claim 5, characterised by the oil being pumped from the main vessel (14) to a delivery pipe (2) which supplies said distribution pipe (3) with pressurised lubricating oil.

7. Lubricating system according to claim 6, characterised by a pressure intensifier (20) being provided at said distribution pipe (3), whereby the lubricating oil is pressurised to at least 40 bar, in order to spread the pressurised lubricating oil through said nozzles (9).

8. Lubricating system according to claim 7, characterised by the lubricating oil being pressurised up to 420 bar.

9. Lubricating system according to any of claims 4-8, characterised by the first return vessel (12) comprising at least one first heater (15) for the oil.

10. Lubricating system according to any of claims 4-9, characterised by the second main vessel (14) comprising at least one second heater (16) for the oil.

11. Lubricating system according to claim 10, characterised by the oil in the return vessel (12) being kept at a first temperature and the oil in the main vessel (14) being kept at a second, higher temperature, where the desired viscosity is maintained.

12. Lubricating system according to any of claims 5-11, characterised by substantially all oil bearing parts, comprising at least one pump (8) and said filter (17), being located in the main vessel and immersed in oil.

13. Lubricating system according to any of claims 7-12, characterised by the temperature in the oil tank (1 ) being kept over 2O⁰C.

14. Lubricating system according to any of claims 7-13, characterised by the lubricating oil being supplied intermittently at said lubricating point (4).