System for lubricating a sealed bearing and related method

Abstract

A method for lubricating a sealed bearing (1) comprising a first race (2) and a second race (3) rotatable in relation to each other concentrically and a seal (10, 11, 12, 13) delimiting a sealed chamber (16) together with the first and second races, said method comprising: a) a first step of removing a first predetermined amount of lubricant from the sealed chamber until the pressure in the sealed chamber reaches a first pressure value, and b) a second step of injecting a second predetermined amount of lubricant into the sealed chamber until the pressure in the sealed chamber reaches a second pressure value, said first pressure value and said second pressure value being determined so that the pressure inside the sealed chamber is maintained within a predetermined interval, the boundaries of which are determined according to the characteristics of the seal, so that the sealed chamber remains waterproof to the lubricant when the lubricant is removed from the sealed chamber or injected into the sealed chamber.

Description

TECHNICAL FIELD

[0001] The present invention relates to a sealed bearing, and more particularly to a system for lubricating a sealed bearing and to a method for implementing such a system. BACKGROUND

[0002] Generally, a sealed bearing comprises a first ring and a second ring that are able to rotate concentrically with respect to each other.

[0003] Figure 1 An example of a sealed bearing 1 comprising a first ring 2 and a second ring 3 is shown.

[0004] The first ring 2 comprises a first opening 4 and the second ring 3 comprises a second opening 5, as will be described later.

[0005] Figure 2 A partial cross-section of the sealed bearing 1 is shown.

[0006] The first ring 2 comprises two grooves 6, 7 and the second ring 3 comprises two grooves 8, 9.

[0007] Seals 10, 11 are inserted in the grooves 6, 7 of the first ring 2 so that the lips of the seals 10, 11 rub on the second ring 3 and seals 12, 13 are inserted in the grooves 8, 9 of the second ring 3 so that the lips of the seals 12, 13 rub on the first ring 2.

[0008] The sealed bearing 1 further comprises a row of rolling elements 14 mounted between the first ring 2 and the second ring 3, the rolling elements 14 being provided here in the form of balls. The sealed bearing further comprises a cage 15 for maintaining the rolling elements 14 at regular circumferential intervals.

[0009] The seals 10, 11, 12 and 13, the first ring 2 and the second ring 3 form a sealed chamber 16.

[0010] The sealed chamber 16 generally contains (contains) a lubricant (typically grease) to facilitate the concentric rotation of one ring with respect to the other.

[0011] The lubricant in the sealed chamber needs to be periodically replaced during a relubrication operation.

[0012] The worn lubricant initially placed or placed during a previous relubrication operation is removed from the sealed chamber before adding some fresh lubricant in the sealed bearing.

[0013] The removal of the worn lubricant is generally performed by suction with a pump that creates a depression in the sealed chamber 16, the pump being connected to the first or second openings 4, 5 of the first and second rings and communicating with the sealed chamber 16.

[0014] If the underpressure generated in the sealed chamber is too high, the lips of the seals 10, 11, 12, 13 in the grooves of the first and second races 2, 3 can move so that the sealed chamber is no longer watertight, the lubricant escapes from the sealed chamber, or the seals 10, 11, 12, 13 can leave their grooves.

[0015] Fresh lubricant is introduced into the sealed chamber, for example with a pump connected to another opening 4, 5 communicating with the sealed chamber 16. If the overpressure generated in the sealed chamber by this pump is too high, the lips of the seals can move during the operation of adding some fresh lubricant, also resulting in a non-watertight sealed bearing.

[0016] Depending on the application of the sealed bearing, for example for agricultural food applications, the escape of lubricant from the sealed bearing is not allowed.

[0017] One solution to reduce the underpressure is to perform the suction at low pressure.

[0018] However, the worn lubricant, in particular grease, is difficult to remove and the removal operation of the grease is very slow.

[0019] The patent US 10,088,100 B2 discloses a lubrication system for a bearing comprising a first pumping device configured to introduce a first quantity of lubricant into the bearing, a second pumping device configured to remove a second quantity of lubricant from the bearing, and a control device configured to activate the first and second pumping devices independently from each other.

[0020] However, the underpressure and overpressure generated in the bearing are not controlled, so that the seals or the lips of the seals can move, resulting in a non-watertight sealed bearing for the lubricant.

[0021] The document CA 2886704 discloses a method for removing old grease from a main bearing of a wind turbine.

[0022] The method comprises injecting a cleaning fluid into the bearing to remove the grease and pumping the cleaning fluid and the removed worn grease out of the bearing, the cleaning fluid being used to dissolve the worn grease.

[0023] However, this method is complex, time-consuming and requires the injection of an additional cleaning fluid.

[0024] There is a need to avoid at least some of the previously mentioned drawbacks, in particular by removing the worn lubricant from the sealed bearing and introducing fresh lubricant into the sealed bearing in a simple manner so that the sealed bearing remains watertight for the lubricant and during a reduced duration. SUMMARY

[0025] According to an aspect, there is proposed a method for lubricating a sealed bearing, said sealed bearing comprising a first ring and a second ring able to rotate concentrically relative to each other and a seal delimiting with said first ring and said second ring a sealed chamber.

[0026] The method comprises:

[0027] - a) a first step of removing a first predetermined amount of lubricant from said sealed chamber until a pressure in said sealed chamber reaches a first pressure value, and

[0028] - b) a second step of injecting a second predetermined amount of lubricant into said sealed chamber until a pressure in said sealed chamber reaches a second pressure value,

[0029] The first pressure value and the second pressure value are determined so that the pressure inside said sealed chamber is maintained within a predetermined interval, the boundaries of which are determined according to the characteristics of said seal, so that said sealed chamber remains waterproof to lubricant when lubricant is removed from said sealed chamber or injected into said sealed chamber.

[0030] Controlling the pressure inside the sealed chamber avoids the possibility of the seals leaving their grooves or the lips of the seals moving, so that the sealed chamber remains waterproof to lubricant, without lubricant escaping from the sealed bearing.

[0031] The first predetermined amount of lubricant and the second predetermined amount of lubricant can be equal or different.

[0032] The lubricant is for example grease or oil.

[0033] Advantageously, injecting a predetermined amount of lubricant comprises pressurizing a fluid and spraying the lubricant in said sealed chamber with the pressurized fluid.

[0034] Preferably, injecting a predetermined amount of lubricant comprises activating a supply pumping device configured to introduce a predetermined amount of lubricant into said sealed chamber.

[0035] Advantageously, the first step a) and the second step b) are repeated.

[0036] Preferably, the first predetermined amount of lubricant and the second predetermined amount of lubricant are equal.

[0037] According to another aspect, a system for lubricating a sealed bearing is proposed, said sealed bearing comprising a first ring and a second ring rotatable in a concentric manner with respect to each other and a seal delimiting, with said first ring and said second ring, a sealed chamber.

[0038] The system comprises:

[0039] - a removal device configured to remove from said sealed chamber a first predetermined amount of lubricant until a pressure in said sealed chamber reaches a first pressure value, and

[0040] - an injection device configured to inject into said sealed chamber a second predetermined amount of lubricant until a pressure in said sealed chamber reaches a second pressure value,

[0041] said first pressure value and said second pressure value being determined so that the pressure inside said sealed chamber is maintained within a predetermined interval, the boundaries of said predetermined interval being determined according to the characteristics of said seal, so that said sealed chamber remains waterproof to said lubricant when said lubricant is removed from said sealed chamber and injected into said sealed chamber.

[0042] Preferably, said removal device comprises a depression pump configured to suction lubricant from said sealed chamber.

[0043] Advantageously, said removal device further comprises a pressure sensor configured to measure the pressure in said sealed chamber and a controller configured to activate said depression pump until the measured pressure reaches said first pressure value.

[0044] Preferably, said injection device comprises a supply pump configured to introduce a predetermined amount of lubricant into said sealed chamber.

[0045] Advantageously, said injection device further comprises a pressure sensor configured to measure the pressure in said sealed chamber and a controller configured to activate said supply pump until the measured pressure reaches said second pressure value. BRIEF DESCRIPTION OF DRAWINGS

[0046] Other advantages and features of the present invention will appear on examination of the detailed description of an embodiment, in no way limitative, and of the annexed drawings, in which:

[0047] Figure 1 and Figure 2 a sealed bearing according to the prior art is schematically illustrated;

[0048] Figure 3 An embodiment of a system for lubricating a sealed bearing according to the present application is schematically shown; and

[0049] Figure 4 A second embodiment of the removal device is shown. DETAILED DESCRIPTION

[0050] With reference to Figure 3 , Figure 3 An example of an embodiment of a sealed bearing 1 and of a system 17 for lubricating the sealed bearing 1 connected to a first opening 4 and to a second opening 5 is represented.

[0051] The system 17 comprises a removal device 18 which removes from the sealed chamber 16 a first predetermined quantity of lubricant until the pressure in the sealed chamber reaches a first pressure value PI, and an injection device 19 configured to inject into the sealed chamber 16 a second predetermined quantity of lubricant until the pressure in the sealed chamber reaches a second pressure value P2.

[0052] The lubricant is, for example, grease.

[0053] The first predetermined quantity of lubricant and the second predetermined quantity of lubricant can be equal or different.

[0054] For example, for a sealed bearing of 2.8 m diameter, the quantity of lubricant contained in the sealed chamber 16 is equal to 3.7 kg of grease, the first predetermined quantity of lubricant and the second predetermined quantity of lubricant can be equal to 3.7 kg if the grease is completely renewed.

[0055] For example, the removal device 18 is connected to the second opening 5 and the injection device 19 is connected to the first opening 4.

[0056] Alternatively, the removal device 18 can be connected to the first opening 4 and the injection device 19 is connected to the second opening 5.

[0057] If the sealed bearing 1 comprises an inspection hole for collecting small quantities of lubricant for analysis, the removal device 18 can be connected to the inspection hole.

[0058] The first pressure value PI and the second pressure value P2 are determined so that the pressure inside the sealed chamber 16 is kept within a predetermined interval, the boundaries of which are determined according to the characteristics of the seals 10, 11, 12, 13, so that the sealed chamber 16 remains waterproof to the lubricant when the lubricant is removed from the sealed chamber 16 and injected into the sealed chamber 16.

[0059] The characteristics of the seals 10, 11, 12, 13 taken into account for determining the boundaries of the interval include, for example, the geometry and / or the material of which the seals are made and / or the anchorage of the seals to the race 2, 3, the anchorage of the seals to the race 2, 3 being characterized, for example, by the form and / or the size of the heels of the seals.

[0060] For example, the interval ranges from 0.5 bar to 1.8 bar.

[0061] The removal device 18 comprises, for example, a depressurization pump 20 connected to the first opening 4, a first pressure sensor 21 measuring the pressure in the sealed chamber 16 and a first controller 22.

[0062] The depressurization pump 20 removes a first predetermined quantity of worn lubricant from the sealed chamber 16.

[0063] The injection device 19 comprises, for example, a supply pump 23 configured to introduce a second predetermined quantity of fresh lubricant into the sealed chamber 16, a second pressure sensor 24 measuring the pressure in the sealed chamber 16 and a second controller 25.

[0064] An example of an embodiment of a method for lubricating a sealed bearing 1 is disclosed.

[0065] In a first step, a first predetermined quantity of worn lubricant is removed from the sealed chamber 16 until the pressure in the sealed chamber reaches a first pressure value P1.

[0066] The first controller 22 drives the depressurization pump 20 until the first pressure sensor 21 measures a pressure value equal to the first pressure value P1.

[0067] The depressurization pump 20 is then stopped.

[0068] In a second step, a second predetermined quantity of lubricant is injected into the sealed chamber 16 until the pressure in the sealed chamber 16 reaches a second pressure value P2.

[0069] The second controller 25 drives the supply pump 23 until the second pressure sensor 24 measures a pressure value equal to the second pressure value P2.

[0070] The supply pump 23 is then stopped.

[0071] In another embodiment (not shown), the fluid is pressurized and the fresh lubricant is sprayed in the sealed chamber with the pressurized fluid.

[0072] Alternatively, the second step is performed before the first step.

[0073] In another embodiment, the first step and the second step are repeated until the first predetermined amount of lubricant is removed from the sealed chamber 16 and a second predetermined amount of lubricant is injected into the sealed chamber 16.

[0074] The system 17 can be permanently connected to the sealed bearing 1 or can be removed after the re-lubrication operation.

[0075] In this case, when the system 17 is not connected to the sealed bearing 1, a plug closes the first opening 4 and the second opening 5.

[0076] The first pressure sensor 21 can be embedded in the pressure reduction pump 20 and the second pressure sensor 24 can be embedded in the supply pump 23.

[0077] Figure 4 A second embodiment of the removal device 18 is represented.

[0078] The removal device 18 comprises a pressure reduction pump 26 driven by the first controller 22 and a first pressure sensor 21.

[0079] The removal device 18 further comprises a container 27 connected to the pressure reduction pump 26 and to the first opening 4 by a lubricant holding member 28.

[0080] The holding member 28 can be for example a valve or a filter to avoid that the pressure reduction pump 26 sucks lubricant, the pressure reduction pump 26 not being configured to suck lubricant.

[0081] When the pressure reduction pump 26 is driven by the first controller 22, the removed lubricant flows into the container 27 as represented by the arrow.

[0082] In the example shown, the sealed bearing unit is provided with a row of rolling elements 14. Alternatively, the rolling bearing can comprise at least two rows of rolling elements. In the example shown, the rolling elements are balls. Alternatively, the rolling bearing can comprise other types of rolling elements, such as rollers. In another variant, the rolling bearing can also be provided with a plain bearing without rolling elements.

[0083] In the example shown, the removal device 18 and the injection device 19 are controlled by the first controller 22 and the second controller 25. Alternatively, the removal device 18 and the injection device 19 comprise manual pumps instead of the pumps 20, 23, the injection pressure and the removal pressure of the lubricant in the sealed chamber being controlled by the operator operating the manual pumps.

[0084] The sealed bearing 1 comprises four seals 10, 11, 12 and 13. Alternatively, the sealed bearing 1 can comprise a different number of seals, for example only two seals, so that the two seals, the first ring 2 and the second ring 3 form the sealed chamber 16.

[0085] In another embodiment, all seals are mounted on the same ring 2, 3.

[0086] The method for lubricating the sealed bearing 1 does not require additional cleaning fluid.

[0087] The removal of the worn lubricant from the sealed chamber and the filling of the sealed chamber with fresh lubricant can at least partially be performed simultaneously, so that the duration of the regreasing operation is reduced.

[0088] The pressure inside the sealed chamber is controlled, which avoids damaging components inside the sealed chamber due to too high or too low pressure, and which avoids that the seals can leave their grooves or that the lips of the seals can move, so that the sealed chamber remains watertight for the lubricant, without lubricant escaping from the sealed bearing.

Claims

1. A method for lubricating a sealed bearing (1), the sealed bearing (1) comprising a first race (2) and a second race (3) that can rotate concentrically with respect to each other and a seal (10, 11, 12, 13) that delimits with the first race and the second race a sealed chamber (16), the method comprising: - a) a first step: removing from the sealed chamber (16) a first predetermined amount of lubricant until the pressure in the sealed chamber reaches a first pressure value (PI), and - b) a second step: injecting into the sealed chamber (16) a second predetermined amount of lubricant until the pressure in the sealed chamber reaches a second pressure value (P2), the first pressure value (PI) and the second pressure value (P2) being determined so that the pressure inside the sealed chamber (16) remains within a predetermined interval, the boundaries of which are determined as a function of the characteristics of the seal (10, 11, 12, 13) so as to avoid the movement of the lips of the seal when lubricant is removed from the sealed chamber or injected into the sealed chamber, the sealed chamber (16) remaining watertight to lubricant.

2. The method of claim 1, wherein, Injecting a predetermined amount of lubricant comprises pressurizing a fluid and spraying the lubricant in the sealed chamber (16) with the pressurized fluid.

3. The method of claim 1, wherein, Injecting a predetermined amount of lubricant comprises activating a supply pumping device (23) configured to introduce a predetermined amount of lubricant into the sealed chamber (16).

4. The method according to any one of claims 1 to 3, characterized in that, The first step a) and the second step b) are repeated.

5. The method according to any one of claims 1 to 3, characterized in that, The first predetermined amount of lubricant and the second predetermined amount of lubricant are equal.

6. A system (17) for lubricating a sealed bearing (1), the sealed bearing (1) comprising a first race (2) and a second race (3) that can rotate concentrically with respect to each other and a seal (10, 11, 12, 13) that delimits with the first race and the second race a sealed chamber (16), the system comprising: - a removal device (18) configured to remove from the sealed chamber a first predetermined amount of lubricant until the pressure in the sealed chamber (16) reaches a first pressure value (PI), and - an injection device (19) configured to inject into the sealed chamber (16) a second predetermined amount of lubricant until the pressure in the sealed chamber reaches a second pressure value (P2), the first pressure value and the second pressure value being determined so that the pressure inside the sealed chamber remains within a predetermined interval, the boundaries of which are determined as a function of the characteristics of the seal so as to avoid the movement of the lips of the seal when lubricant is removed from the sealed chamber and injected into the sealed chamber, the sealed chamber remaining watertight to lubricant.

7. The system of claim 6, wherein, The removal device (18) comprises a pressure reduction pump (20) configured to suction lubricant from the sealed chamber.

8. The system of claim 7, wherein, The removal device (18) also comprises a pressure sensor (21) configured to measure the pressure in the sealed chamber (16) and a controller (22) configured to activate the pressure reduction pump (20) until the measured pressure reaches the first pressure value (PI).

9. The system of any one of claims 6 to 8, wherein, The injection device (19) comprises a feed pump configured to introduce a predetermined quantity of lubricant into the sealed chamber (16).

10. The system of claim 9, wherein, The injection device also comprises a pressure sensor (24) configured to measure the pressure in the sealed chamber (16) and a controller (25) configured to activate the feed pump until the measured pressure reaches the second pressure value (P2).

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