Damper

Abstract

A damper 30 comprises an annular body comprising an outer circumferential contact portion 52, and an inner circumferential contact portion 54 joined by a connector 56. The connector is flexible such t

Description

The present invention relates to a damper to damp motion in a compressor assembly, particularly to damp radial and axial motions in a compressor assembly for use in a vehicle. The invention relates to a compressor assembly, particularly an e-compressor, and extends to a method of constructing such a compressor assembly. Compressors are used in many different technologies, but the focus of the present invention is compressors for vehicles. Compressors can be included in vehicles for many purposes, for example they may be used in refrigerant cycles for air conditioning or battery cooling, or as a compressor for delivering high pressure air to a hydrogen fuel cell. Some internal combustion engines can be fitted with a turbocharger, supercharger, and / or other devices to force air into a combustion chamber of the internal combustion engine and thereby boost the performance. Vehicles may include one or more electrically driven compressors, or e-chargers, for these purposes. The invention provides a damper to damp motion in a compressor assembly, the damper comprising an annular body comprising an outer circumferential contact portion and an inner circumferential contact portion joined by a connector, the connector being flexible such that the inner circumferential contact portion can move radially and axially with respect to the outer circumferential contact portion, the annular body further comprising an axial stop extending from the inner circumferential contact portion or outer circumferential contact portion. The damper is provided with a flexible connector that allows the inner circumferential contact portion can move radially and axially with respect to the outer circumferential contact portion. This relative movement in the radial and I or axial directions may cause the flexible connector to deform, and the deformation may be substantially elastic in nature so the connector is able to return to substantially an original, or starting, shape once the inner and outer circumferential contact portions return to their original positions. However, there are energy losses during the deformation of the connector. The annular body can therefore be used to damp relative motion between the inner and outer circumferential contact portions, and therefore to damp the relative motion between components with which the inner and outer circumferential contact portions are in contact. The axial stop provided on the damper can be trapped between components of a compressor assembly during assembly to prevent the circumferential contact portion from which the axial stop extends from moving axially, or at least limit the axial movement of the circumferential contact portion from which the axial stop extends. As the axial stop is trapped between components, relative movement of those components may cause deformation of at least a portion of the axial stop. The deformation may be substantially elastic in nature, so the axial stop is able to return to substantially an original, or starting, shape once the components return to their original positions. However, there are energy losses during the deformation of the axial stop. The deformation of the axial stop can damp relative movement between the components trapping the axial stop. The flexibility of the connector may reduce the chances of a sliding contact between the outer circumferential contact portion and I or an inner circumferential contact portion and the part of the compressor assembly with which it is in contact, and this may reduce wear. The relative motion between the components may be vibrations, or other movements. The energy losses in the deformation of the connector and I or the axial stop that is caused by such motions can dissipate energy of the relative motion and therefore damp the movement. The invention further provides a compressor assembly comprising: a rotatable shaft; a compressor wheel that is supported on the shaft; an electric motor to rotate the shaft and the compressor wheel, the electric motor having a rotor associated with the shaft and a stator around the rotor; a housing plate between the compressor wheel and the electric motor, the housing plate having an opening through which the shaft passes and a recess around the opening; a damped bearing assembly arranged in the recess, the damped bearing assembly supporting the shaft and comprising a bearing and a damper surrounding the bearing; the damper being as described above; and the damper arranged such that the annular body is located between the bearing and a wall of the recess to transmit and damp radial forces between the bearing and the housing plate, and the axial stop being trapped against the housing plate by a trapping member to restrict movement the axial stop relative to the housing plate. During operation of such a compressor assembly a rotating assembly comprising the shaft, compressor wheel and rotor rotates, and oscillations may be induced in the rotating assembly. The oscillations may be induced at one or more natural frequencies of the rotating assembly, for example a first bending frequency. Providing a damper between the housing and the rotating assembly can damp such oscillations and this may improve the longevity of the compressor assembly. The shaft, rotor and compressor may be any suitable shape and configuration, and many suitable examples are known in the art. The electric motor includes the rotor and stator and may be any suitable motor capable of rotating the rotor, and thereby the shaft and compressor wheel. A housing plate is provided between the compressor wheel and the electric motor. The housing plate may form part of a housing which contains the electric motor. The housing plate has an opening through which the shaft can pass. The shaft may be supported in the opening by a spacer. The spacer may provide a seal between the compressor wheel and an interior of the housing. The housing plate includes a recess around the opening. The recess may open on one side of the housing plate, for example the side of the housing plate closest to the rotor. The recess may be substantially circular in shape, may be stepped such that an outer portion of the recess is wider than an inner portion. The recess may be defined by one or more substantially cylindrical walls. The damper may be to damp axial and radial motion in a compressor assembly. The connector may be any suitable shape and may connect to any part inner and outer circumferential contact portion. The connector may be curved and have a concave or convex shape. The outer circumferential contact portion may comprise, or be, a substantially cylindrical wall. The inner circumferential contact portion may comprise, or be, a substantially cylindrical wall. The connector may be connected to an end of each of the inner and outer circumferential contact portions. The end of each of the inner and outer circumferential contact portions to which the connector is connected may the same end. For example, when installed in a compressor assembly, the connector may be connected to an end of each of the inner and outer circumferential contact portions which is closest to the rotor, or closest to the compressor wheel. The annular body may have a substantially ‘II’, ‘C’, or ‘V’ shaped cross section. The axial stop may comprise a radial projection which extends radially inwardly from the inner circumferential contact portion, or radially outwardly from the outer circumferential contact portion. The axial stop may extend from an end of the inner or outer circumferential portion that is opposite the end to which the connector is connected. The axial stop may comprise a plurality of radial projections. The plurality of radial projections may be substantially evenly distributed around the annular body. A thickness of each of the radial projections may be substantially the same. The radial projection may form an annular wall. A thickness of the annular wall in the axial direction may be non-uniform around the annular body. The annular wall may include one or more irregularities, for example cutout portions, thinned portions, or thickened, portions. The irregularities may be substantially regularly distributed around the annular body. By varying the nature of the axial stop, the mechanical properties of the axial stop can be adjusted so that the damping properties of the axial stop is appropriate for the compressor assembly. The mechanical properties of the axial stop can be varied by changing the shape of the axial stop and I or changing the material form which the axial stop is constructed. For example, a layer of different material, for example an elastomeric material, could be added on a surface of the axial stop. The damper may be formed from any suitable process. The damper may be a moulded component as this provides a reliable and cost-effective way of forming the damper. The damper may be formed from a plastic material. The plastic material may be a PEEK material, and may include glass fibre reinforcement. It has been found that the mechanical properties of PEEK do not alter significantly over the temperature range within which the compressor is intended to function, particularly at the lower end of the temperature range. Some of the shapes suggested for the annular body noted above, a substantially ‘II’, ‘C’, or ‘V’ shaped cross section, may facilitate moulding of the damper. The damped bearing assembly comprises a bearing and the damper. The damper is arranged around the bearing and is as described above. The bearing may be any sort of bearing, for example a roller bearing. The bearing may comprise an inner ring, an outer ring and rolling elements. The inner ring may be arranged within the outer ring and the rolling elements may be arranged between the inner and outer rings. The inner and outer rings may define a track within which the rolling elements are arranged to support rotation of the inner ring relative to the outer ring. The rolling elements may be substantially spherical, for example ball bearings. The bearing may comprise a bearing cage arranged between the inner and outer ring. The bearing cage may determine the position of the rolling elements, for example it may separate the rolling elements from one another. The bearing cage may maintain the rolling elements in an arrangement in which the rolling elements are spaced around the circumference substantially equally. The damped bearing assembly may comprise a seal ring arranged between the bearing and the damper. The seal ring may function as a spacer between the bearing and the damper. The bearing may be a press fit into the seal ring. The seal ring may comprise at least one axial channel through which gas may pass. The trapping member may be the seal ring. The trapping member may be the bearing, for example the outer ring of the bearing. The trapping member may be the stator, or a stator spacer. The invention also provides a method of manufacturing compressor assembly comprising: providing a housing plate, the housing plate having an opening therethrough, and a recess around the opening on one side of the housing plate; arranging a damped bearing assembly in the recess, the damped bearing assembly supporting the shaft and comprising a bearing and a damper surrounding the bearing; passing a shaft through the bearing of the damped bearing assembly and the opening and supporting the shaft for rotation relative to the housing plate; coupling a compressor wheel to the shaft on the side of the housing plate opposite the recess; coupling the rotor of an electric motor to the shaft such that the electric motor can rotate the shaft and compressor wheel, the electric motor being on the same side of the housing plate as the recess; wherein the damper being as described above; and the damper arranged such that the annular body is located between the bearing and a wall of the recess to transmit and damp radial forces between the bearing and the housing plate, and the axial stop being trapped against the housing plate by a trapping member to restrict movement the axial stop relative to the housing plate. The damped bearing assembly may be assembled before it is arranged in the recess of the housing plate, or the damped bearing assembly could be assembled in the recess. The damped bearing assembly may be push-fit into the recess. The compressor assembly made by the process may be a compressor assembly as described above. The invention will now be described by way of example only with reference to the following figures in which: Figure 1 shows a compressor assembly with a housing; Figure 2 shows a compressor assembly without some of the housing; Figure 3 shows a detailed view of the compressor assembly of Figure 2 with a first damper; Figure 4 show a view of the first damper; Figure 5 shows a detailed view of the compressor assembly of Figure 2 with a second damper; and Figure 6 shows a view of the second damper. Figure 1 shows a compressor assembly 1 with a housing 2. The housing 2 comprises a rear housing 4, a compressor wheel housing 6 and a housing plate 8, in this case a base plate. The compressor assembly 1 comprises a rotatable shaft 10. The rotatable shaft 10 supports a compressor wheel 12. An electric motor 14 is included to rotate the shaft 10 and the compressor wheel 12. The electric motor 14 has a rotor associated 16 with the shaft 10 to rotate therewith and a stator 18 around the rotor 10. The housing plate 8 between the compressor wheel 12 and the electric motor 14 includes an opening 20, in this case a cylindrical opening, through which the shaft 10 passes and a recess 22 around the opening 20. A spacer 24 supports the shaft 10 in the opening 20. The spacer 24 may include circumferential grooves and ridges to provide a seal between the shaft 10 and the opening 20. The grooves of the spacer may include ring seals, for example piston seals. A damped bearing assembly 26 is arranged in the recess 22. The damped bearing assembly is a push-fit into the recess 22. The damped bearing assembly 26 supports the shaft 20 and comprises a bearing 28 and a damper 30 surrounding the bearing 28. In this example there is a seal ring 32 arranged between the bearing 28 and the damper 30. The damper 30 and its arrangement in the assembly will be described in more detail with reference to later figures. The compressor assembly 1 further comprises a stator spacer 34 between the stator 18 and the housing plate 8. In this example, the seal ring 32 is held axially between the housing plate 8 and the stator spacer 34. The spacer 24 is held axially between the compressor wheel 12 and a ridge 36 on the shaft 10. The bearing 28 is held axially between a ridge 38 on the shaft and the spacer 24. The compressor assembly 1 is manufactured by providing the housing plate 8, arranging a damped bearing assembly 26 in the recess 22 of the housing plate 8 so that the damped bearing assembly 26 supports the shaft 10. The shaft 10 can be passed through the through the bearing 28 of the damped bearing assembly 26 and spacer 24 in the opening 20. The compressor wheel 12 can then be coupled to the shaft 10 on the side of the housing plate 8 opposite the recess 22. Coupling the compressor wheel 12 to the shaft can provide a clamping force which secures the spacer 14 and bearing 28 to the shaft 10. The rotor 16 of the electric motor 14 is connected to the shaft 10 such that the electric motor 14 can rotate the shaft 10 and compressor wheel 12. The electric motor 14 is on the same side of the housing plate as the recess. During use, the compressor wheel 12 may generate an axial force on the compressor wheel 12 away from the housing plate 8. The axial force act on the 10 and is resisted by the engagement of the damped bearing assembly 26 with the shaft 10 and housing plate 8. A pre-load ay be applied to the shaft 10. In this example, a spring 64 located in the rear housing 4 acts on an end of the shaft 10 opposite an end to which the compressor wheel 12 is attached and provides a pre-load in the same direction as the axial force generated during use of the compressor assembly. The spring 64 may act on the shaft 10 via a bearing 66. Figure 2 shows a view T of the compressor assembly 1 of Figure 1 without the rear housing 4, stator 18, and the compressor wheel housing 6 for ease of viewing. The bearing 28 of this example comprises an inner ring 40, an outer ring 42 and rolling elements 44. In this example, the inner ring 40 is in contact with the shaft 10, the outer ring 44 is push fit into a recess 46 in the seal ring 32. The inner ring 40 may be arranged within the outer ring 42 and the rolling elements 44 may be arranged between the inner and outer rings 40,42. The inner and outer rings 40,42 may define a track within which the rolling elements 44 are arranged to support rotation of the inner ring 40 relative to the outer ring 42. The rolling elements 44 may be substantially spherical, for example ball bearings. The bearing 32may comprise a bearing cage 48 arranged between the inner and outer rings 40,42. The bearing cage 48 may determine the position of the rolling elements 44, for example it may separate rolling elements 44 from one another. The bearing cage 44 may maintain the rolling elements 44 in an arrangement in which the rolling elements 44 are spaced substantially equally around the circumference. Figure 3 shows a magnified view of a portion of Figure 2 showing the damper 30 in the assembly. Figure 4 shows a view of the damper 30 of Figure 3. The damper 30 is to damp motion in the compressor assembly 1. The damper 30 comprises an annular body 50 comprising an outer circumferential contact portion 52, in this case a substantially cylindrical portion, and an inner circumferential contact portion 54, in this case a substantially cylindrical portion. The inner and outer circumferential contact portions 52,54 are joined by a connector 56 such that the cross section of the annular body 56 is substantially ‘II’ shaped, with the connector 56 extending from the ends of the inner and outer circumferential portions 52,54 which are furthest from the compressor wheel 12. The connector 56 is flexible such that the inner circumferential contact portion 54 can move radially and axially with respect to the outer circumferential contact portion 52. The annular body 56 further comprises an axial stop 58 extending from the inner circumferential contact portion 54 in this example. The damper 30 is arranged such that the annular body 50 is located between the bearing 32 and a wall of the recess 22 to transmit and damp radial forces between the bearing 32 and the housing plate 8. The axial stop 58 is trapped against the housing plate 8 by a trapping member, in this case the seal ring 28. This trapping restricts movement the axial stop 58 relative to the housing plate 8. As shown in Figure 4, the axial stop 58 comprises a plurality of radial projections 60 substantially evenly spaced around the inner circumference of the inner circumferential contact portion 54. The radial projections 60 are separated by gaps. 5 Figure 5 shows a magnified view of a portion of a different embodiment of a compressor assembly 101. Figure 6 shows a view of the damper 30 of Figure 5. The compressor assembly 101 is similar to the compressor assembly 1 of Figure 1 and like components are given the same reference numerals incremented by 100. In this example 10 the damper 130 comprises an annular body 150 which is arranged between the seal ring 128 and the recess 122. In this example the inner and outer contact portions 152,154 are rings and the connector 156 extends from ends of the inner and outer contact portions 152,154 nearest the compressor wheel 112 such that the annular body 150 is substantially ‘V’ or ‘C’ shaped. The axial stop 158 extends axially from the outer contact portion 152 and 15 is trapped between the stator spacer 134 and the housing plate 108. As shown in Figure 6, the axial stop 158 is a substantially continuous wall.

Claims

2514Claims1. A damper to damp motion in a compressor assembly, the damper being moulded and comprising an annular body comprising an outer circumferential contact portion and an inner 5 circumferential contact portion joined by a connector, the connector being flexible such that the inner circumferential contact portion can move radially and axially with respect to the outer circumferential contact portion, the annular body further comprising an axial stop extending from the inner circumferential contact portion or outer circumferential contact portion.10 2. A damper as claimed in claim 1, in which the damper is to damp axial and radial motionin a compressor assembly.

3. A damper as claimed in claim 1 or claim 2, in which the annular body has a substantially ‘LT, ‘C’, or ‘V’ shaped cross section.

154. A damper as claimed in any preceding claim, in which the outer circumferential contact portion is a substantially cylindrical wall, and the inner circumferential contact portion is a substantially cylindrical wall.20 5. A damper as claimed in any preceding claim, in which the axial stop comprises a radialprojection which extends radially inwardly from the inner circumferential contact portion.

6. A damper as claimed claim 5, in which the axial stop comprises a plurality of radial projections.

257. A damper as claimed in claim 6, in which the plurality of radial projections are substantially evenly distributed around annular body.

8. A damper as claimed in claim 5, in which the radial projection forms an annular wall.

309. A damper as claimed in claim 8, in which a thickness of the annular wall is not uniform around the circumference of the damper body.35 10. A damper as claimed in any preceding claim, in which the damper is made of a plasticmaterial.30 09 2511. A damper as claimed in claim 10, in which the damper is made of a PEEK material.

12. A compressor assembly comprising:5 a rotatable shaft;a compressor wheel that is supported on the shaft;an electric motor to rotate the shaft and the compressor wheel, the electric motor having a rotor associated with the shaft and a stator around the rotor;a housing plate between the compressor wheel and the electric motor, the housing 10 plate having an opening through which the shaft passes and a recess around the opening;a damped bearing assembly arranged in the recess, the damped bearing assembly supporting the shaft and comprising a bearing and a damper surrounding the bearing;the damper being as claimed in any preceding claim; andthe damper arranged such that the annular body is located between the bearing and a 15 wall of the recess to transmit and damp radial forces between the bearing and the housing plate, and the axial stop being trapped against the housing plate by a trapping member to restrict movement the axial stop relative to the housing plate.

13. A compressor assembly as claimed in claim 12, in which the damped bearing assembly 20 comprises a seal ring arranged between the bearing and the damper.

14. A compressor assembly as claimed in claim 13, in which the trapping member is the seal ring.25 15. A compressor assembly as claimed in any of claims 12 preceding claim, in which aspacer is arranged to support the shaft in the opening through the housing plate.

16. A method of manufacturing compressor assembly comprising:providing a housing plate, the housing plate having an opening therethrough, and a 30 recess around the opening on one side of the housing plate;arranging a damped bearing assembly in the recess, the damped bearing assembly supporting the shaft and comprising a bearing and a damper surrounding the bearing;passing a shaft through the bearing of the damped bearing assembly and the opening and supporting the shaft for rotation relative to the housing plate;35 coupling a compressor wheel to the shaft on the side of the housing plate opposite therecess;coupling the rotor of an electric motor to the shaft such that the electric motor can rotate the shaft and compressor wheel, the electric motor being on the same side of the housing plate as the recess; whereinthe damper being as claimed in any of claims 1 to 12; and5 the damper arranged such that the annular body is located between the bearing and awall of the recess to transmit and damp radial forces between the bearing and the housing plate, and the axial stop being trapped against the housing plate by a trapping member to restrict movement the axial stop relative to the housing plate.10 17. A method as claimed in claim 16, in which the damped bearing assembly is push-fitinto the recess.30 09 25s

Images