Fluid pump for aircraft turbine, lubrication circuit and aircraft turbine

Abstract

The invention relates to a fluid pump (1) for an aircraft turbomachine, comprising: a non-movable ring (10) having a wall (13) and having a duct (12) passing through the ring along a central axis (101); a rotor (20) rotatable relative to the ring (10) along a main axis (100) offset relative to the central axis (101); a cavity between the ring and the rotor, the volume of the cavity varying according to the angular position of the rotor relative to the ring; a radial inlet space (16) passing through the wall (13) to allow fluid to enter the cavity, and a radial discharge space (11) discharging fluid from the cavity, the pressure in the discharge space being higher than the pressure in the inlet space; and a groove (15) subjecting the cavity to pressure in the discharge space when the rotor rotates, the groove passing through the wall and leading to the discharge space (11). The invention also relates to a lubrication circuit having such a pump and to an aircraft turbine having such a circuit.

Description

Technical Field

[0001] The invention relates to a fluid pump for an aircraft turbomachine, a lubrication circuit having such a pump and an aircraft turbomachine having such a lubrication circuit. Background Art

[0002] Aircraft turbojets have a large number of mechanical equipment items that need lubrication or cooling, including shafts, bearings and gears. To achieve this, these turbojets are equipped with a lubrication circuit that enables oil to be supplied to each equipment item. A supply pump generates a certain flow of oil, which is then distributed in a number of lines to supply the various equipment items of the engine.

[0003] To save oil, this lubrication circuit operates as a closed loop, with the oil delivered to each equipment item being recovered and then reinjected into the lubrication circuit via a recovery pump.

[0004] The increase in flow and output pressure of the pump used to supply the engine (tank towards the engine enclosure) means that new hydraulic phenomena need to be controlled.

[0005] One of the phenomena that needs to be controlled is the pressure pulsation at the outlet of the lubrication unit. Since the aircraft pump is a positive displacement pump, the aircraft pump provides the flow. The outlet pressure is the result of the pressure drop in the downstream circuit and the required flow.

[0006] As a result, pressure pulsations return to flow pulsations. If the discharged flow is not constant, there will also be pressure variations (or pulsations) at the outlet of the lubrication unit. These pulsations may be due to the compressibility of the fluid.

[0007] Pulsations are detrimental in several respects, in particular to the housing of the lubrication unit and to items of oil circuit equipment downstream of the lubrication unit (such as filters, valves, heat exchangers, pipes, etc.).

[0008] A disadvantage of current lubrication units is that they are susceptible to premature failure of one or more of the equipment items of the unit (pulsation fatigue). To avoid such failures, some current lubrication units have oversized equipment items, which results in an overall increase in engine weight.

[0009] Therefore, there is a need to reduce or even eliminate pressure pulsations. Summary of the invention

[0010] To this end, the present invention proposes a fluid pump for an aircraft turbine, which includes: a ring, a pipeline passing through the ring along a central axis; a rotor, which is driven to rotate relative to the ring along a main axis offset from the central axis; a cavity between the ring and the rotor, the volume of the cavity changes according to the angular position of the rotor relative to the ring; an inlet space and a discharge space, the inlet space allows fluid to enter the cavity, the discharge space discharges the fluid from the cavity, and the pressure in the discharge space is higher than the pressure in the inlet space; a groove, when the rotor rotates, the groove exposes the cavity to the pressure of the discharge space.

[0011] Preferably, the ring is immovable and comprises a wall, the discharge space and the inlet space being radial and passing through the wall, and the groove passing radially through the wall and opening into the discharge space.

[0012] In a variant, the groove has an elongated shape along the circumference of the wall.

[0013] In a variant, the groove 15 has a length and a height, the length being greater than 110% of the height.

[0014] In one embodiment, the pump further comprises a sealing area between the fluid inlet space and the fluid outlet space, and the groove extends over a portion of the sealing area.

[0015] In a variant, the groove opens into the discharge space upstream or downstream of the discharge space in the direction of rotation of the rotor.

[0016] In one embodiment, the wall comprises a sealing area between the fluid inlet space and the fluid outlet space, and the groove extends over a portion of the sealing area.

[0017] According to one variant, the pump comprises a plurality of discharge spaces, each having a groove which passes radially through the wall of the ring and opens into the respective discharge space, the cumulative height of the groove in the axial direction of the ring being between 1% and 15% of the height of the ring in the direction of the central axis.

[0018] In a variant, the groove or grooves are obtained by milling, electro-erosion or wire cutting methods.

[0019] In one embodiment, the pump comprises blades which are movable on the rotor in a radial direction of the rotor and extend to the ring, the blades defining a cavity between them.

[0020] The invention also relates to a lubrication circuit for lubricating an aircraft turbomachine, comprising at least one pump as described above, the groove exposing the cavity to the pressure of the exhaust space and to the pressure of the circuit downstream of the pump.

[0021] The invention also relates to an aircraft turbomachine comprising a lubrication circuit as described above.

[0022] The use of the verb "comprise" and its conjugations and variations herein shall not in any way exclude the presence of elements other than the mentioned elements. The use of the indefinite article "a", "an" or the definite article "the" herein to introduce an element does not exclude the presence of a plurality of these elements.

[0023] The terms “first”, “second”, “third” etc. in this document are only used to distinguish different elements but do not imply any order between these elements.

[0024] All preferred embodiments and all advantages of the ring apply mutatis mutandis to the pump, the lubrication circuit and the turbine and vice versa. The various embodiments may be considered individually or in combination. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Other features and advantages of the present invention will become apparent from the following detailed description, for the understanding of which reference is made to the accompanying drawings, in which:

[0026] - Figure 1 is a schematic diagram of the lubrication circuit;

[0027] - Figure 2 is a perspective view of an example of an embodiment of a fluid pump;

[0028] - Figure 3 yes Figure 2 A perspective view of an example of an embodiment of a pump ring in FIG.

[0029] - Figure 4 yes Figure 2 Another perspective view of an example of an embodiment of a ring of a pump.

[0030] The figures in the accompanying drawings are not drawn to scale. In the accompanying drawings, similar elements are generally represented by similar reference numerals. Within the scope of this document, the same or similar elements may have the same reference numerals. In addition, the presence of reference numbers or letters in the accompanying drawings may not be considered restrictive, even if these numbers or letters are indicated in the claims. DETAILED DESCRIPTION

[0031] The invention relates to a fluid pump for an aircraft turbine, the fluid pump comprising: a ring through which a pipe passes along a central axis; a rotor driven to rotate relative to the ring along a main axis offset relative to the central axis; a cavity between the ring and the rotor, the volume of the cavity varying according to the angular position of the rotor relative to the ring; an inlet space for allowing fluid to enter the cavity; and a discharge space for discharging the fluid from the cavity, the pressure in the discharge space being higher than the pressure in the inlet space. The pump also comprises a groove which exposes the cavity to the pressure of the discharge space when the rotor rotates. Such a groove enables the pump cavity to be pressurized to the outlet pressure, thereby enabling the pressure pulsation at the pump outlet to be reduced or even eliminated. Over time, the service life of the parts of the pump is extended.

[0032] Figure 1 A lubrication circuit 2 for an aircraft turbine is shown. The circuit 2 is used for cooling and / or lubricating various equipment items of the turbine. Within the circuit 2, oil is conveyed from a tank 3 towards equipment items 4 on the turbine, such as bearings or enclosures. The circuit 2 comprises a lubrication unit 5 comprising a circulating pump 1, the technology of which can vary. In the present description, the circulating pump is, for example, a mechanical timing control pallet pump (pompes à palettes desmodromiques) 1 or a gerotor (gérotor) pump 1. The pump 1 supplies the oil to the equipment items 4 via a supply line 6. Downstream of the equipment items 4, a recovery line 7 makes it possible to recover the oil and recirculate it in the circuit 2. Upstream and downstream of the equipment items 4, there can be one pump 1 for each equipment item 4, or there can be one pump 1 for a plurality of equipment items 4, upstream and downstream of the equipment items 4. Depending on Figure 1 In the embodiment of FIG. 4 , by way of example, one pump 1 is provided for each upstream equipment item 4 , and a single pump 1 is provided downstream for all equipment items 4 .

[0033] Figure 2A perspective view of an example of an embodiment of a pump 1 is shown, which is a mechanical timing control pallet pump. The pump 1 is a positive displacement pump, which applies a flow rate. The pump 1 comprises a ring 10 (or a cam for such a pump) having a generally rotating cylindrical outer shape. The ring 10 comprises an axial cylindrical duct 12, which passes through the ring 10 along a central axis 101. The ring 10 is immovable. The ring 10 is radially bounded by a wall 13. The ring 10 also comprises a fluid inlet space 16 (or inlet opening) and a fluid discharge space 11 (or discharge opening), which are particularly used for lubricating fluids, and the spaces 11 and 16 are radial and pass through the wall 13. The pressure in the discharge space 11 is higher than the pressure in the inlet space 16; in other words, the discharge space 11 is at high pressure to discharge the fluid to the pump outlet, and the inlet space 16 is at low pressure to allow the fluid to enter from the pump inlet. The ring 10 may comprise one or more inlet spaces 16 and discharge spaces 11 distributed along the main axis 100. In the figures, two inlet spaces 16 and two outlet spaces 11 are shown by way of example; according to another example, the ring 10 may include two inlet spaces 16 (from different pipelines) and one outlet space 11 (returning the fluid to a single pipeline). The spaces 11 and 16 extend along certain angular sections to allow different cavities of the pipe 12 to communicate with the outside.

[0034] The pump 1 also includes a rotor 20 (or shaft) which is rotationally movable about a main axis 100 which is parallel to but eccentric with respect to the central axis 101. The rotor 20 extends along the main axis 100 and passes longitudinally through the duct 12 of the ring 10. The rotor 20 includes a drum 21 which supports a support plate 30. The rotor 20 is supported by trunnions 22 located on both sides of the drum 21 along the axis 100. The trunnions 22 are each rotatably mounted on a bearing 40. The support plate 30 is radial and extends along a radius of the rotor 20 in a plane containing the main axis 100. The support plate 30 is inserted into slots 17 in the drum 21 which extend radially in the drum 21 in a plane containing the main axis 100. As an example, Figure 2 There are four pallets 30 in the embodiment; there may be more pallets 30, such as six or eight.

[0035] The support plate 30 defines a cavity of the pipe 12 that communicates with the outside through the spaces 11 and 16. The cavity is defined between two consecutive support plates along an angular section of the pipe 12 centered on the main axis 100. When the cavity faces the inlet space 16, the cavity allows fluid to enter; when the cavity faces the discharge opening 11, the cavity allows fluid to be discharged.

[0036] The inner surface of the duct 12 of the ring 10 forms a cam surface 18 which, when the rotor 12 rotates, acts on the pallet 30 due to the offset between the main axis of rotation 100 of the rotor 20 and the central axis 101 of the duct 12. For a given pallet 30, as the distance between the rotor 12 and the cam surface 18 decreases, the cam surface 18 pushes the pallet 30 towards the inside of the drum 21, thereby maintaining the seal at the end of the pallet 30 between two consecutive cavities. Then, for a certain pallet 30, as the distance between the rotor 12 and the cam surface 18 increases, the pallet 30 is pushed towards the outside of the drum 21, against the ring surface 18, also maintaining the seal at the end of the pallet 30. The pallet 30 is pressed against the cam surface 18 by various possible means, such as by a spring not shown. Thus, the volume of the cavity varies according to the angular position of the rotor 20 relative to the ring 10.

[0037] As rotor 20 rotates about main axis 100, fluid, such as oil, enters through inlet space 16 into the cavity defined by two consecutive plates 30 inside duct 12. Rotation of rotor 20 drives the cavity toward discharge space 11, increasing the pressure of the fluid by reducing the volume of the cavity.

[0038] Figure 3 and Figure 4 A perspective view of an example of an embodiment of a ring 10 of a pump 1 is shown. Between two inlet spaces 16 and discharge spaces 11 located on the same circumference of the ring 10, the ring comprises a sealing area 19 defined by a wall 13. Thus, when a fluid enters a cavity through the inlet space 16, the fluid does not leak from the cavity when the cavity is driven to rotate by the rotor and faces the sealing area 19; the fluid is only discharged when the cavity faces the discharge space 11. Due to the offset between the axes 100 and 101, the ring 10 comprises a portion 23 of thicker wall 13 and a portion 22 of thinner wall 13; each of the portions 23 and 22 comprises a sealing area 19. Similarly, between two inlet spaces 16 and between two discharge spaces 11 along the main axis 100, the ring 10 comprises a sealing area 19 defined by a wall 13. In this way, the fluid entering the cavity opposite the inlet space 16 does not leak to the adjacent cavity along the main axis 100.

[0039] When the fluid is discharged from the pipeline through the discharge space 11, pressure pulsations are generated. Since the pump 1 is a positive displacement pump, the pump provides flow. The outlet pressure is the result of the pressure drop in the downstream circuit and the required flow. As a result, the pressure pulsation returns to the flow pulsation. If the discharged flow is not constant, there will also be pressure changes (pulsations) at the outlet of the lubrication unit 5. These pulsations may be caused by the compressibility of the fluid. In order to reduce or even eliminate pressure pulsations, the ring 10 includes a groove 15 visible in the accompanying drawings, which exposes the cavity to the pressure of the discharge space 11 when the rotor 20 rotates. This groove 15 ensures that the cavity of the pipeline 12 is gradually pressurized before the fluid is discharged. This makes it possible to avoid premature damage to one or more equipment items in the oil circuit, and also avoids oversizing of equipment items to prevent breakage.

[0040] Since the cavity is already at high pressure when discharging, the reduction in cavity volume as the rotor 20 rotates means that the fluid can be discharged directly. In the absence of the groove 15, the initial moment of the cavity volume reduction is only used to pressurize the fluid (by compressing / reducing the volume of the cavity). Therefore, there is a delay during which the cavity is not discharged, resulting in a change in flow at the outlet of the pump 1 (and thus pressure pulsation). Therefore, the presence of the groove 15 helps to start the discharge and reduce or even offset the pressure pulsation.

[0041] More specifically, the groove 15 passes radially through the wall 13 along the circumference of the ring 10 and opens into the discharge space 11. The groove 15 extends over a portion of the sealing area 19 defined in the wall 13 between the fluid inlet space 16 and the fluid discharge space 11. The presence of the groove 15 in the sealing area destroys the seal between the inlet and outlet of the fluid cavity, but enables the cavity to be pressurized before it is discharged into the discharge space 11. In other words, according to the direction of rotation of the rotor 20 in the duct 12, the fluid enters the cavity between the two pallets 30 through the inlet space 16, and the cavity is then directed toward the discharge space 11; the groove 15 is in the sealing area between the inlet space 16 and the discharge space 11 upstream of the discharge space 11, and the groove enables the cavity of the pump to reach the outlet pressure while limiting leakage and discharge of the fluid.

[0042] according to Figure 3 and Figure 4, the groove 15 is located upstream of the discharge space 11 at one end 14 of the discharge space 11. This is the cavity of the duct or the end that is first reached during the rotational movement of the rotor 20. Alternatively or in combination, the groove 15 can also be located downstream of the discharge space 11 at one end of the discharge space 11. The presence of the groove shape leading to the discharge space enables a gradual change in the pressure in the discharge space. The presence of one or more grooves upstream and / or downstream enables a gradual change in the cavity pressure and reduces the mechanical load on the elements of the lubrication circuit caused by sudden pressure changes.

[0043] The size of the groove 15 is small enough to limit leakage (or return flow) while ensuring that the cavity is gradually pressurized before the cavity is discharged. A groove that is too large will result in unacceptable leakage, while a groove that is too small will have no effect on the cavity pressurization. To achieve this, the cumulative height of the groove 15 is between 1% and 15% of the height of the ring 10. The groove 15 has an elongated shape. The groove 15 is an elongated orifice. The groove 15 is elongated around the circumference of the ring 10 (and the wall 13). The groove 15 is a longitudinal notch in the wall 13. The groove 15 is a longitudinal notch in the wall 13 along the circumference of the ring 10. The size of the groove 15 in one direction (circumferential direction of the ring 10 and the wall 13) is greater than the size in another direction (along the central axis 101 of the ring 10). The groove 15 has a length and a height, and the length is greater than 110% of the height. The length of the groove 15 is the circumferential dimension of the ring 10 (and the wall 13). In other words, the length of the groove 15 is along the directrix of the cylindrical ring 10. The height of the groove 15 is the dimension along the central axis 101 of the ring 10. In other words, the height of the groove 15 is along the generatrix of the cylindrical ring 10. The groove 15 passes radially through the wall 13 and opens into the discharge space 11 along the circumference of the ring 10 at one end where the dimension of the groove is the largest. A groove is an orifice that is long in one direction and narrow in another direction. The shape and arrangement of the groove passing through the wall and associated with the discharge space 11 ensure that the cavity is gradually pressurized before it is discharged. Alternatively or in combination, the shape and arrangement of the groove passing through the wall and associated with the discharge space 11 ensure that the cavity pressure changes gradually after the cavity is discharged.

[0044] The groove 15 is located at the end of the sealing area 19 upstream of the discharge space 11 in the direction of rotation of the rotor 20. Depending on the design of the ring 10, this sealing area 19 may correspond to a thinner portion 22 of the wall 13 (e.g. Figure 3 and Figure 4 ), but can also be located in the thicker part 23 of the wall 13. The groove 15 can also be located at the beginning of the sealing area 19 downstream of the discharge space 11 in the direction of rotation of the rotor 20.

[0045] The groove 15 can be obtained, for example, by milling, electro-erosion or wire cutting methods, so that the size of the groove can be controlled and the appropriate size can be obtained. A groove that is too large will cause unacceptable leakage, while a groove that is too small will have no effect on the cavity pressurization.

[0046] Elements of the pump 1, such as the rotor 20, the journal 22, the roller 21, the support plate 30 and the ring 10, may be made of steel; the bearing 40 may be made of bronze.

[0047] The invention also relates to a lubrication circuit 2 and an aircraft turbine comprising a pump 1. The grooves 15 make it possible to reduce or even eliminate pressure pulsations in the lubrication circuit. This has no effect on the interface with the pump. This also makes it possible to improve the fluid circulation and prevent premature damage to one or more equipment items in the oil circuit. This means a longer equipment service life. It is also avoided that the equipment items are oversized, thereby avoiding an increase in the overall weight of the turbine.

[0048] The present invention has been described above in conjunction with specific embodiments, which are illustrative and should not be considered as limiting. In general, it is obvious to those skilled in the art that the present invention is not limited to the examples shown and / or described above.

Claims

1. A fluid pump for an aircraft turbine, the fluid pump comprising: a ring (10) through which the pipe (12) passes along a central axis (101), said ring (10) being immovable and comprising a wall (13), - a rotor (20) driven in rotation relative to the ring (10) along a main axis (100) offset from the central axis (101), - a cavity between the ring (10) and the rotor (20), the volume of which varies according to the angular position of the rotor (20) relative to the ring (10), - an inlet space (16) allowing the fluid to enter the cavity and a discharge space (11) discharging the fluid from the cavity, the pressure in the discharge space (11) being higher than the pressure in the inlet space (16), the discharge space (11) and the inlet space (16) being radial and passing through the wall (13), A groove (15) which exposes the cavity to the pressure of the discharge space (11) when the rotor (20) rotates, the groove passing radially through the wall (13) and opening into the discharge space (11).

2. The pump (1) according to claim 1, wherein: The groove has an elongated shape along the circumference of the wall (13).

3. The pump (1) according to claim 1 or 2, wherein: The groove 15 has a length and a height, and the length is greater than 110% of the height.

4. A pump (1) according to any one of the preceding claims, further comprising a sealing area (19) between the fluid inlet space (16) and the fluid discharge space (11), the groove (15) extending over a portion of the sealing area (19).

5. Pump (1) according to any one of the preceding claims, wherein The groove (15) opens into the discharge space (11) upstream or downstream of the discharge space (11) in the rotation direction of the rotor (20).

6. Pump (1) according to any one of the preceding claims, wherein The wall (13) comprises a sealing area (19) between the fluid inlet space (16) and the fluid outlet space (11), and the groove (15) extends over a portion of the sealing area.

7. A pump (1) according to any one of the preceding claims, comprising a plurality of discharge spaces (11), each of which has a groove (15) which radially passes through the wall (13) of the ring and opens into the corresponding discharge space (11), the cumulative height of the groove (15) in the axial direction of the ring (10) being between 1% and 15% of the height of the ring in the direction of the central axis (101).

8. Pump (1) according to any one of the preceding claims, wherein The groove or grooves (15) are obtained by milling, electro-erosion or wire cutting.

9. Pump (1) according to any of the preceding claims, comprising support plates (30) which are movable on the rotor in a radial direction of the rotor and extend to the ring, the support plates defining the cavity between them.

10. A lubrication circuit (2) for lubricating an aircraft turbomachine, comprising at least one pump (1) according to any one of the preceding claims, the groove exposing the cavity to the pressure of the discharge space (11) and to the pressure of the circuit downstream of the pump.

11. An aircraft turbomachine comprising a lubrication circuit (2) according to the preceding claim.

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