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(11) | EP 4 242 424 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | VANE FOR ROTARY PUMP |
| (57) A vane (16) for use in a rotary pump "R" is described herein wherein said vane (16)
comprises a first portion P1 having a first thickness T1 and a second portion P2 which
has a second thickness T2 that is greater than the first thickness T1. In some examples,
the vane has an L-shaped cross-section. In other examples, said second portion P2
has a circular cross-section.
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TECHNICAL FIELD
[0001] The methods and systems described herein relate to vanes and in particular vanes that may be used in rotary vane pumps.
BACKGROUND
[0002] Sliding rotary vane pumps may be used in a plurality of different mechanical and industrial applications (e.g. they may be used in both liquid and gas pumping applications) and can be invariable exposed to a wide range of environmental conditions. One type of rotary vane pump is a dry air pumps, which are dry vacuum pumps constructed of carbon vanes and rotors which are self-lubricating. Such dry air pumps may comprise mechanical carbon rots and vanes that operate in a hardened metal cavity. Such pumps may provide a power source in a multitude of applications such as to provide power to pneumatically operated flight instruments, for example.
[0003] Although such dry air pumps do not use a liquid lubricant, they do use other lubricating methods such as self-lubricating coatings, amongst other methods. Although such lubricating methods may work well to some extent, the nature of the vane lubrication technique is still destructive to the parts of the pump. Due to this, parts of the pump, such as the vanes, can wear down over time. This results in the lengths of the vanes eventually being too short to fit into the slot in which it is positioned in use and this can result in failure of the pump. If the pump is used in an aircraft, such failure can result in one or more of the aircraft systems becoming inoperative and, since this would most often occur during use, i.e. in flight, this can be quite problematic. It is therefore important to ensure that any wearing does not continue to such an extent that the vane exits the slot in use.
SUMMARY
[0004] A vane for use in a rotary pump R is described herein wherein said vane comprises a first portion P1 having a first thickness T1 and a second portion P2 which has a second thickness T2 that is greater than the first thickness T1.
[0005] In some examples, the second portion P2 comprises a first ledge 20 provided on one side of the vane.
[0006] In some examples, said ledge protrudes from the first side of the vane and extends along the entire width W of the vane.
[0012] In some examples, said ball-shaped edge does not extend along the entire width W of the vane.
[0013] A rotary pump is also described herein, comprising at least one slot configured to receive said vane in use. In some examples, the rotary pump comprises a plurality of slots, each of which are configured to receive a vane
[0014] In some examples, said at least one slot comprises a first portion S1 that has a first slot width SW1 and a second portion S2 that has a second slot width SW2, wherein the second width SW2 of the second portion S2 of the slot is greater than the first slot width SW.
[0015] In some examples, the junction between the first slot portion S1 and the second slot portion S2 creates an end-stop, configured to contact said vane at the junction between said first vane portion P1 and said second vane portion P2 to thereby prevent the vane from exiting said slot.
[0016] In some examples, said vane has a length L that extends between a first edge of the vane and a second edge and wherein, use, the vane is provided within the slot of the rotor R such that the second edge is closer to a central axis of the rotor R than the first edge of the vane, and wherein said second portion P2 is provided at said second edge.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017]
Figure 1 depicts a perspective view of a cross-section of a known rotary pump, prior to wear of the vanes.
Figure 2 depicts the known pump of figure 1 after the vanes have been worn during use.
Figure 3 depicts a stator comprising a new type of vane, having a cross-sectional thickness that is not uniform along its length, as well as corresponding slots that also have a having a cross-sectional thickness that is not uniform along their length
Figure 4 depicts the new type of vane of figure 3 wherein the vane is prevented from exiting the slot due to ledges acting as an end stop.
Figure 5 is a perspective view of the vane of figures 3 and 4.
Figure 6a depicts a cross-sectional view of a new type of vane having a circular shaped cross-section at one end.
Figure 6b depicts a front view of the vane of figure 6a.
Figure 6c depicts a perspective view of the vane of figures 6a and 6b.
Figure 7a depicts an aerial view of a stator
Figure 7b depicts a cross-sectional view of the stator, with the vane of figures 6a b and 6c inserted therein.
Figure 7c depicts a close up view of the vane of figures 6a to 6c with the vane inserted into the slot of the stator.
DETAILED DESCRIPTION
[0018] A known rotary vane pump prior to wear is shown in figure 1. The pump comprises a rotor R that provides a bearing surface for rotary movement of rotor R about its central axis 12. As can be seen in the examples shown in figures 1 and 2, the rotor R is provided with six circumferentially spaced vane slots 15 that are angled slightly from a radial direction and which extend over the entire longitudinal length of rotor R. A graphite vane 16 is inserted into each of the slots 15 in use, as shown in figure 1.
[0019] Each vane 16 is made from a material that during use, wears and produces a form of dry lubrication for the pump when in use. For example, vanes 16 can be made from carbon material, graphite, and various organic binders. In some examples, a self-lubricating coating may be applied to the pump parts to inhibit wear between the slidable vanes 16 and pump rotor R.
[0020] A stator S is provided that surrounds the rotor R. The stator S has two symmetrically opposite lobes 18 and 19, the surfaces of which act as cams that regulate the two extension and retraction cycles for the vanes 16 during each rotation of the rotor R. As is known in the art, the longitudinal spaces defined by the adjacent vanes 16 and the external surface of the rotor R, as well as the surface of a stator lobe, and end plates of the pump serve as pumping pockets which are moved from an intake zone to an exhaust zone to accomplish the pumping action of the pump R.
[0021] During the lifetime of the pump, the vanes wear out and their length becomes shortened. Figure 2 depicts the pump of figure 1 after the vanes 16 have been subjected to significant wear. As a result, vanes may fall out from the slots 15 and lead to pump failure.
[0022] The new examples described herein and depicted in figures 3 to 7c overcome this problem by changing the shape of the vane 16 as well as the shape of the slot 15 into which it is inserted in use, such that the vane 16 is not able to fall out from the slot 15 when the length becomes too short due to wear. This means that the pump will have a longer lifetime and will decrease the probability of sudden failure of the pump.
[0023] In a first example, as shown in figure 3, the vane 16 may be provided so as to extend within a slot 15 of the rotor R.
[0024] As can be seen in figure 5, the vane 16 has a length L that extends between a first edge 16c of the vane 16 and a second edge 16d of the vane end the vane has a width W that extends between a third edge 16a and a fourth edge 16b of the vane 16. In use, the vane 16 is inserted into the slot 15 of the rotor R such that the second edge 16d is closer to the central axis 12 of the rotor R than the first edge 16c of the vane 16. The length L of the vane 16 is therefore dictated by the length of the slot 15 into which it is inserted and the width W of the vane 16 is dictated by the width of the rotor R of the pump.
[0025] In known rotary pumps, such as shown in figure 1, the vane has a uniform thickness and uniformly shaped cross-section that matches the uniform shape of the cross-section of the slot into which it is inserted, as seen in figure 1.
[0026] In the example shown in figures 3 to 5, however, the new type of vane 16 has a non-uniform cross-sectional thickness. In some examples, the non-uniform thickness comprises a non-uniform cross-section, in that it comprises a first portion P1 having a first thickness T1 (which in this case is substantially uniform) and a second portion P2 which has a second thickness T2 that is greater than the first thickness T1. In the examples shown in figures 3 to 5, the second portion P2 having the second thickness T2 comprises a first ledge 20 provided on one side of the vane, such that it protrudes from that side of the vane 16. In these examples, on the opposite side of the vane 16, no ledge is provided. This gives the vane an L-shaped cross-section. In some examples, the ledge 20 protrudes from the first side of the vane 16 and along the entire width W of the vane 16 as shown in figure 15. In other examples, the protrusion may not extend along the entire width W of the vane 16.
[0027] In combination with this, the slot 15 of the examples shown in figures 3 to 5 is also modified in comparison to the slot of known rotors, such as those shown in figures 1 and 2. As can be seen in figures 3 and 4, the slot 15 comprises a first portion S1 that has a first slot width SW1 and a second portion S2 that has a second slot width SW2, wherein the first slot width SW1 of the first portion S1 of the slot is less than the second slot width SW1. This creates an internal, second ledge 21 which protrudes inwardly of the slot and towards the side of the vane 15 that comprises the first ledge 20.
[0028] The second ledge 21 provided within the slot 15 should correspond in shape and size to the first ledge 20 of the vane, such that, when the vane 16 shortens in length, the first and second ledges 20, 21, form an end-stop in that they contact each other and prevent further movement of the vane out from the slot 15. This is depicted in figure 4, wherein the ledges act as an end-stop. That is, the junction between the first slot portion S1 and the second slot portion S2 creates an end-stop, configured to contact the vane at the junction between the first vane portion P1 and the second vane portion P2 to thereby prevent the vane from exiting the slot.
[0029] Although in the examples shown in figures 3 to 5 comprise a ledge, and a vane with an L-shaped cross-section, other examples may be provided wherein the cross-sectional width of the vane is modified such that it does not have a uniform width along its length.
[0030] In the examples shown in figures 6a to 7d, instead of having a ledge on one side of the vane, the vane 16 is instead provided so as to have a circular cross-sectional at its second edge 16d. As discussed above, in use, this second edge 16d is the edge that is closest to the central axis of rotation of the stator.
[0031] In this the new type of vane 16 therefore also has a first portion P1 having a first thickness T1 (which in this case is substantially uniform) and a second portion P2 which has a second thickness T2 that is greater than the first thickness T1 (i.e. the portion having the circular cross-section). In the examples shown in figures 6a to 7d, the second portion P2 having the second thickness T2 comprises a ball shaped edge provided at the second edge 16d of the vane 16 (i.e. the edge that is closest to the central axis of rotation 12 of the rotor R.
[0032] In combination with this, the slot 15 of the examples shown in figures 6a to 7d is also modified in comparison to the slot of known rotors, such as those shown in figures 1 and 2. As can be seen in these figures, the slot 15 comprises a first portion S1 that has a first slot width SW1 and a second portion S2 that has a second slot width SW2, wherein the first slot width SW1 of the first portion S1 of the slot is less than the second slot width SW1. This creates an internal end-stop for the ball-shaped edge of the vane 16, such that when the vane 16 has worn down to the point where the ball-shaped edge meets the first portion S1 of the slot, the vane 16 is prevented from exiting the vane 16.
[0033] As can be seen in figure 6c, the circular cross-section of the ball-shaped edge of the vane 16 can extend along the entire width of the vane 16. In other examples, the circular cross-section can be provided at a discrete point or points along the width of the vane 16.
[0034] In the same way as described above with reference to figures 3 to 5, the junction between the first slot portion S1 and the second slot portion S2 creates an end-stop, configured to contact the vane at the junction between the first vane portion P1 and the second, ball-shaped vane portion P2 to thereby prevent the vane from exiting the slot.
1. A vane (16) for use in a rotary pump "R" wherein
said vane (16) comprises a first portion P1 having a first thickness T1 and a second portion P2 which has a second thickness T2 that is greater than the first thickness T1.
said vane (16) comprises a first portion P1 having a first thickness T1 and a second portion P2 which has a second thickness T2 that is greater than the first thickness T1.
2. The vane (16) of claim 1 wherein said second portion P2 comprises a first ledge 20
provided on one side of the vane.
3. The vane of claim 2 wherein said ledge (20) protrudes from only one side of the vane
16.
4. The vane of claim 2 or 3 wherein said ledge (20) extends along the entire width W
of the vane 16.
5. The vane of claim 2 or 3 wherein said ledge does not extend along the entire width
W of the vane (16).
6. The vane (16) of any preceding claim wherein said vane has an L-shaped cross-section.
7. The vane of claim 1 wherein said second portion P2 comprises a ball-shaped edge.
8. The vane of claim 1 or 6 wherein said second portion P2 of said vane has a circular
cross-section.
9. The vane of claim 7 or 8 wherein said ball-shaped edge extends along the entire width
W of the vane (16).
10. The vane of claim 7 or 8 wherein said ball-shaped edge does not extend along the entire
width W of the vane (16).
11. A rotary pump, comprising at least one slot (15) configured to receive said vane (16)
of any preceding claim.
12. The rotary pump of claim 11 wherein said at least one slot (15) comprises a first
portion S1 that has a first slot width SW1 and a second portion S2 that has a second
slot width SW2, wherein the second width SW2 of the second portion S2 of the slot
is greater than the first slot width SW.
13. The rotary pump of claim 11 or 12 wherein the junction between the first slot portion
S1 and the second slot portion S2 creates an end-stop, configured to contact said
vane (16) at the junction between said first vane portion P1 and said second vane
portion P2 to thereby prevent the vane from exiting said slot (16).
14. The rotary pump of any of claims 11 to 13 wherein said vane (16) has a length L that
extends between a first edge (16c) of the vane (16) and a second edge (16d) and wherein,
use, the vane 16 is provided within the slot (15) of the rotor R such that the second
edge (16d) is closer to a central axis 12 of the rotor R than the first edge 16c of
the vane 16, and wherein said second portion P2 is provided at said second edge (16d).