Reinforced vacuum system component

Abstract

The invention provides a rotor assembly for a vacuum pump. The rotor assembly comprises a hub and one or more rotor blade arrays each comprising at least one rotor blade, each rotor blade extending from a rotor blade root contiguous with the hub to a rotor blade tip, wherein each rotor blade comprises a continuous fibre reinforced matrix material. The invention further provides methods of designing and manufacturing rotor blades, and vacuum systems comprising a component comprising a continuous fibre reinforced matrix material.

Claims

1. A rotor assembly for a vacuum pump, the rotor assembly comprising a hub and one or more rotor blade arrays each comprising at least one rotor blade extending from a rotor blade root contiguous with the hub to a rotor blade tip, wherein the rotor blade comprises a plurality of printed planar layers wherein at least one of the printed planar layers comprises a planar continuous fibre layer comprising a continuous fibre having a length of at least 0.5 meters that extends from said rotor blade to a portion of the hub immediately adjacent said rotor blade within a plane.

2. The rotor assembly according to claim 1, wherein the plurality of printed planar layers further comprises a printed polymer matrix layer.

3. The rotor assembly according to claim 1, comprising a plurality of rotor blade arrays.

4. The rotor assembly according to claim 1, wherein the rotor blade root and/or the rotor blade tip have a higher tensile strength and/or a higher flexural strength and/or higher creep resistance than the remainder of the blade.

5. The rotor assembly according to claim 1, wherein at least one of the plurality of printed planar layers forms part of the hub.

6. The rotor assembly according to claim 1, wherein the planar continuous fibre layer is formed of fused filaments.

7. The rotor assembly according to claim 1, wherein the planar continuous fibre layer is formed of fused composite filaments and is fused to a planar layer of fused filaments.

8. The rotor assembly according to claim 7, wherein the planar layer of fused filaments is printed.

9. The rotor assembly according to claim 1, wherein the continuous fibre is selected from the group consisting of carbon fibre, glass fibre, aramid fibre, metallic fibre, and/or combinations thereof.

10. The rotor assembly according to claim 1, wherein at least one of the plurality of planar layers comprises a metallic matrix.

11. The rotor assembly according to claim 1, wherein at least one of the plurality of planar layers comprises a polymer matrix and the polymer is selected from the group consisting of a thermoset, a thermoplastic, an elastomer, and combinations thereof.

12. The rotor assembly according to claim 1, wherein each rotor blade comprises a lattice core.

13. The rotor assembly according to claim 12, wherein an outer sheet fully encloses the lattice core.

14. The rotor assembly according to claim 13, wherein the sheet and lattice core are a unitary structure.

15. A method of manufacturing a rotor blade assembly of a vacuum pump, each rotor blade assembly comprising at least one rotor blade extending from a rotor blade root contiguous with a hub to a rotor blade tip, the method comprising the steps of fusing a continuous composite filament to form a planar layer containing a continuous fibre and fusing a matrix filament to form a planar layer of matrix material wherein the planar layer containing the continuous fibre defines a part of a rotor blade and a part of the hub such that the continuous fibre extends from the rotor blade to a portion of the hub immediately adjacent the rotor blade root.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Preferred features of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

(2) FIG. 1 shows a schematic representation of a rotor blade assembly according to the invention.

(3) FIG. 2 shows a schematic representation of a rotor blade assembly according to the invention.

(4) FIG. 3 shows a schematic representation of a rotor blade assembly according to the invention.

DETAILED DESCRIPTION

(5) The present invention provides a vacuum system comprising a component having a unitary structure comprising a continuous fibre reinforced matrix material, wherein the type and/or lay-up of the reinforcing continuous fibre within a first portion of the component is different to that in a second portion of the component such that the magnitude of at least one mechanical property of the first portion is different to that of the second portion.

(6) Typically, in use, the component is a moving part of the vacuum system and the first portion has a higher stiffness and/or elastic modulus that the second portion. Additionally, or alternatively, the first portion may have a higher creep resistance than the second portion. Preferably, the component is a rotor blade. Typically, the first portion includes the blade root and the second portion includes the body of the rotor blade. Preferably, the blade root is stiffest and most creep resistant portion of the rotor blade.

(7) As previously disclosed, the invention further provides a rotor assembly for a vacuum pump, the rotor assembly comprising a hub and one or more rotor blade arrays each comprising one or more rotor blades extending radially from a rotor blade root contiguous with the hub to a rotor blade tip, wherein each rotor blade comprises a continuous fibre reinforced matrix material and a continuous fibre that extends from each rotor blade to a portion of the hub immediately adjacent the rotor blade.

(8) When running at full speed, the blade roots, such as those of a turbomolecular pump, are under very high stress. The centrifugal force on the blade is dependent upon the rotational speed, blade geometry, and blade mass. Typically, the blade geometry and rotational speed are fixed for a known performance.

(9) The present invention enables lower density composite materials to be used in the manufacture of the blade; thereby reducing stress at the blade root, enabling faster rotational speeds, improved rotordynamic performance, and requiring less energy to reach full speed.

(10) By stiffening the root of the turbo blade, the effect of creep is reduced because the region of highest stress is reinforced. The use of strategically placed stiffening fibres within the rotor blade can also assists in resisting torsional forces and keep the blade aligned, reducing blade twisting at high loads, which may change the blade shape and detrimentally affect performance.

(11) FIG. 1 shows an example of a rotor blade assembly (1) according to the invention and suitable for use in turbomolecular pumps manufactured by Edwards™. The assembly (1) comprises an annular hub (2) and an array of rotor blades (3) extending radially from the hub (2). The intersection (4) between each rotor blade (3) and the rotor hub (2) is referred to as a rotor blade root. The rotor blade edge (5) extends around the circumference of the rotor blade (3) and includes the rotor blade tip (6) at the radially outermost extremity of the rotor blade (3). The rotor blade body (7) extends in a substantially planar fashion from the rotor blade root (4) to the rotor blade tip (6). The exact geometry of the rotor blades (3) and the rotor blade assembly (1) will depend upon the specific nature of the pump involved.

(12) The geometry of fibre layup is optimised for the application and/or within specific areas of the component and may be, for instance, cylindrical lay, helical, hatched, meshed, planar, tracked etc. Fibres may be internal or external. The rotor blades may have a continuous outer polymer or metallic surface, e.g. free from the continuous fibre, to provide a superior surface finish and/or to tailor performance and/or reduce outgassing.

(13) In the exemplified rotor blades in FIG. 1, planar (8) and tracked (9) lay-ups of continuous fibre are schematically illustrated. The illustrated lay-ups provide resistance to torsional and radial stiffness respectively. The continuous fibre matrix may be continuous carbon fibre in a nylon matrix.

(14) In FIG. 2 an additional arrangement is illustrated wherein the continuous fibre (10) traverses the blade root (4) of the rotor blade (3). This arrangement advantageously reduces creep in the root portion of the rotor assembly (1).

(15) FIG. 3 illustrates a still further arrangement in which the annular rotor hub (2) is reinforced with a helically laid continuous fibre (11). This stiffens the hub and prevents deformation during use.

(16) The components and rotor assemblies of the invention may be manufactured using a X7 carbon fibre printer manufactured by Markforged™.

(17) It will be appreciated that various modifications may be made to the embodiments shown without departing from the spirit and scope of the invention as defined by the accompanying claims as interpreted under patent law.

(18) Although elements have been shown or described as separate embodiments above, portions of each embodiment may be combined with all or part of other embodiments described above.

(19) Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are described as example forms of implementing the claims.