GB2580759A

GB2580759A - Variable inlet diameter unit

Info

Publication number: GB2580759A
Application number: GB1917007.5A
Authority: GB
Inventors: Pawel Kacper Trebicki
Original assignee: BorgWarner Inc
Current assignee: BorgWarner Inc
Priority date: 2018-12-04
Filing date: 2019-11-22
Publication date: 2020-07-29
Also published as: GB201917007D0

Abstract

The present invention relates to a variable inlet diameter unit 10 for a compressor 50. The variable inlet diameter unit 10 comprises a housing 300, a sliding 5 ring 200 arranged at least partially within the housing 300 and axially moveable between a first position and a second position. Furthermore, the variable inlet diameter unit 10 comprises an elastic element 100 of substantially tubular shape arranged within the housing 300, wherein the elastic element 100 defines an inlet diameter 120 and has an axial length 110. The variable inlet diameter unit 10 is adapted such that, upon movement of the sliding ring 200 from the first position towards the second position, a predefined substantially annular leading portion 114 of the elastic element 100 is urged radially inwardly thereby continuously reducing the inlet diameter 120. A second arrangement is also disclosed, in which a chamber (1200, fig 5B) is formed between the elastic element and the housing, the chamber comprising a port (1620, fig 5B) coupled to a pressure supply (1600, fig 5B), which can be used to urge the elastic element radially inward.

Description

Variable inlet diameter unit

Technical Field

This disclosure relates to a variable inlet diameter unit for a compressor. Furthermore, the invention relates to a compressor and a charging apparatus having such a variable inlet diameter unit.

Background

The individual mobility sector is experiencing a disruptive change. Especially, the increasing number of electric vehicles entering the market demands higher efficiencies from traditional internal combustion engine ICE vehicles. Therefore, more and more vehicles are equipped with efficiency increasing measures, such as charging apparatuses or lightweight design. Well known are, for instance, charging apparatuses wherein a compressor, which may be driven by an e-motor and/or an exhaust gas powered turbine, provides compressed air to the ICE. This leads to a performance enhancement of the ICE.

Common compressors thereby comprise a compressor housing and a compressor wheel which is arranged in the housing. In operation, air is sucked through a compressor inlet of the housing and is accelerated by the compressor wheel and then exits the compressor via a volute of the compressor housing. Each compressor has its characterizing compressor map defining its operating range. This operating range is mainly bound by the surge line and the choke line in the compressor map.

Each compressor exhibits its specific compressor map wherein the operation of the compressor is limited to an area in the compressor map between the surge line and the choke line. To further improve the efficiency of the ICE, it is well known to enhance the compressor map, e.g. by preventing surging, i.e. by taking measures to move the surge line to the left.

This can be done, for example, by compressor inlet adjustment mechanisms. Common adjustment mechanisms are configured, for instance, to increase the speed of the air flow, to modify the flow angle or to establish a flow path recirculation. These measures typically require space, may increase the weight and may increase the need for maintenance due to wear.

Accordingly, the objective of the present invention is to increase the efficiency of a compressor.

Summary

The present invention relates to a variable inlet diameter unit for a compressor as set out in claim 1 according to a first embodiment and as set out in claim 9 according to a second embodiment. Furthermore, the invention relates to a corresponding compressor and a corresponding charging device including such a variable inlet diameter unit as set out in claims 14 and 15, respectively. Other aspects of the embodiments are described in the dependent claims.

The variable inlet diameter unit for a compressor according to a first embodiment comprises a housing and a sliding ring. The sliding ring is arranged at least partially within the housing and is axially moveable between a first position and a second position. The variable inlet diameter unit further comprises an elastic element which is of substantially tubular shape. The elastic element is arranged within the housing, defines an inlet diameter and has an axial length. The variable inlet diameter unit is adapted such that, upon movement of the sliding ring from the first position towards the second position, a predefined substantially annular leading portion of the elastic element is urged radially inwardly. By the movement of the elastic element, i.e. the substantially annular leading portion, in a radially inwardly direction the inlet diameter is continuously getting reduced. "Continuously" is not necessarily to be understood as reducing at a constant rate but more like an "enduring" reduction of the inlet diameter for as long as the sliding ring is in motion. By providing the possibility of a reduction of the inlet diameter, the variable inlet diameter unit can improve the compressor map when mounted in a compressor. Furthermore, a compact design is provided as there is, for instance, no need for pivoting vane members or the like as known in the prior art. All in all the variable inlet diameter unit can lead to a more efficient compressor with a wider compressor map leading to a more versatile operation range.

In another aspect, the elastic element may be adapted such that its axial length is continuously reduced upon movement of the sliding ring from the first position towards the second position, such that the elastic element bends in radially inwardly at least at the annular leading portion to reduce the inlet diameter.

In another aspect, which is combinable with the previous aspect, the inlet diameter may be minimal at the second position of the sliding ring and maximal at the first position of the sliding ring. In other words, the inlet diameter may be minimal when the sliding ring is located at the second position and the inlet diameter may be maximal when the sliding ring is located at the first position. That means there is a direct relationship between the sliding ring and the elastic element. Thus, the movement, i.e. the position of the sliding ring controls the movement, i.e. the position or a shape of the elastic element. Between the first position and the second position, the sliding ring can be adjusted to any position in between. Thereby, any inlet diameter in between the maximum and the minimum can be adjusted according to the present sliding ring position. This enables the possibility of a dynamic inlet diameter adjustment with many intermediate positions which leads to a broader operation field and increases the versatility of the device.

In another aspect, which is combinable with any one of the previous aspects, a first axial end portion of the elastic element may be axially and radially coupled to the sliding ring. A second axial end portion of the elastic element may be axially and radially coupled to the housing. In more detail the second axial end portion of the elastic element may be axially and radially coupled to a second axial housing end portion.

In another aspect, which is combinable with the previous aspect, the elastic element may comprise a first transition portion and a second transition portion. The first transition portion may be arranged between the first axial end portion and the annular leading portion. The second transition portion may be arranged between the second axial end portion and the annular leading portion. Upon movement of the sliding ring from the first position towards the second position, the first transition portion and the second transition portion may be formed. In other words, when the sliding ring is in the first position, the first transition portion and the second transition portion may have a substantially cylindrical shape. Upon movement of the sliding ring from the first position towards the second position, a respective shape of the first transition portion and the second transition portion is adapted such that the first transition portion and the second transition portion may increasingly reduce the inlet diameter of the elastic element from the first and second axial end portions, respectively, towards the annular leading portion. Thus, in the direction of the flow, the inlet diameter is first being reduced in the area of the first transition section until reaching a minimum at the substantially annular leading portion. Further downstream of the substantially annular leading portion, the inlet diameter is being increased again in the area of the second transition section. Thus, an inlet diameter can be reduced without producing sharp edges as it is common in many prior art solutions. Thereby, the range of the compressor map can be increased without generating disturbances of air flow which flows through the inlet unit and subsequently into/onto the impeller of a compressor at sharp edges (when the inlet unit is mounted in a compressor).

In another aspect, which is combinable with the previous aspect, the shape of first transition portion and/or the shape of the second transition portion may follow a substantially straight line, a substantially convex curve or a substantially concave curve from the respective end portion towards the annular leading portion. These features are to be understood as seen from a cross-section of the elastic element. Alternatively or additionally, the first transition portion and/or the second transition portion may have a substantially conical shape (this would then correspond to a substantially straight line in the cross-section). It is obvious that these shapes do not refer to a state when the sliding ring is in the first position, wherein the first and the second transition portions in the first position of the sliding ring have a substantially cylindrical shape. In particular, the convex, concave or conical shapes refer to a state when the sliding ring is NOT in the first position. Thus, it refers to a state wherein the first and the second transition portions increasingly reduce the inlet diameter of the elastic element from the first and second axial end portions, respectively, towards the annular leading portion. Generally, any other curve/shape is possible which mainly depends on the material of the elastic element and/or on the mechanical properties which may also be further influenced by other additional elements (see below). Furthermore, the first and the second transition section may have different shapes. To only name one example, the first transition portion may have a convex shape and the second transition portion may have a concave shape.

In another aspect, which is combinable with any one of the previous aspects, the annular leading portion may be arranged in an axial direction closer to the second axial end portion than to the first axial end portion. Alternatively, the annular leading portion may be arranged substantially in the middle between the first axial end portion and the second axial end portion or in an axial direction closer to the first axial end portion than to the second axial end portion. Thus, the position of the annular leading portion relative to the first axial end portion and the second axial end portion can be adjusted variably. Following this, the aerodynamic flow behavior in the inlet unit can be adjusted and/or optimized by adequately positioning the annular leading portion according to the requirements of and the circumstances in the compressor. Thereby, a more versatile inlet unit can be provided, and aerodynamic optimization can be accomplished.

In another aspect, which is combinable with any one of the previous aspects, the elastic element may comprise a polymeric material. For instance, the elastic element may be made from a durable, elastic and/or a rubber material. Thereby a smoother inlet can be provided as the elastic element is capable of adopting a shape without sharp edges.

In another aspect, which is combinable with any one of the previous aspects, the elastic element may comprise a core portion. The core portion may comprise at least one spring element which is configured to deflect radially inwardly, upon movement of the sliding ring from the first position towards the second position. The at least one spring element thereby defines the substantially annular leading portion. Thus, the spring element may define the shape of the substantially annular leading portion and also the position of the substantially annular leading portion relative to the first axial end portion and the second axial end portion.

In another aspect, which is combinable with the previous aspect, the spring element may be a radial compression spring. The spring element may, i.e. the radial compression spring may be configured to urge the elastic element at the annular leading portion radially inwardly, when load on the spring element is reduced. As the radial compression spring tries to constrict itself radially inwardly load on the spring element is reduced upon movement of the sliding ring from the first position towards the second position. On the other hand, the spring element is adapted to be pulled radially outwardly upon movement of the sliding ring from the second position towards the first position. Thereby load is applied on the spring element. The core portion may also comprise more than one spring element being configured as radial compression spring.

Alternatively or additionally, the core portion may comprise a plurality of spring elements distributed circumferentially within the elastic element. Additionally, the spring elements may have a generally oblong shape and/or may be oriented in a substantially axial direction. Alternatively or additionally, the spring elements may be configured to deflect radially inwardly upon axial compressive force. Alternatively or additionally, the core portion may comprise a first ring portion connecting the spring elements at respective first axial ends. Optionally, the core portion may comprise a second ring portion connecting the spring elements at respective second axial ends. Alternatively or additionally, the sliding ring may exert an axial compressive force on the spring elements via their respective first axial ends, upon movement from the first position towards the second position. Upon exertion of an axial compressive force, the spring elements may be configured to bend radially inwardly at a respective middle portion.

In another aspect, which is combinable with any one of the previous aspects and wherein the elastic element comprises a core portion, the core portion defines the shape of the elastic element. Alternatively or additionally, the core portion may be made from a metal material.

In another aspect, which is combinable with any one of the previous aspects, the sliding ring may have a ring portion at a first axial end and a connecting portion extending from the ring portion towards a second axial end. The connecting portion may be configured to couple the sliding ring with an actuation system.

In another aspect, which is combinable with the previous aspect, the ring portion comprises a radially inwardly extending protrusion having a substantially triangular cross-section. The protrusion may define a truncated cone surface between an outer diameter and an inner diameter. Furthermore, the protrusion may rejuvenate in an axial direction towards the connecting portion such that an annular flange surface is formed for interacting with the elastic element and for exerting an axial compression force on the elastic element.

Alternatively or additionally, the connecting portion comprises a plurality of posts. Each of the posts may have a sliding pin at the second axial end to be coupled with an actuation system.

In another aspect, which is combinable with any one of the previous aspects, the variable inlet diameter unit may further comprise an actuation system. The actuation system may be configured to move the sliding ring axially between the first position and the second position. Additionally, the actuation system may comprise a rotating ring with at least one inclined groove. The rotating ring may be arranged inside the housing. The rotating ring, i.e. the groove, may be configured to engage with at least one sliding pin of the sliding ring such that a rotation of the rotating ring causes an axial movement of the sliding ring. Alternatively or additionally, the actuation system may further comprise an actuation lever to rotate the rotating ring. Additionally, the housing may comprise a notch extending in a circumferential direction. The actuation lever may extend through the notch to be coupled to the rotating ring. Alternatively or additionally, the rotating ring may be rotatably supported in the housing by means of multiple bearing rollers circumferentially arranged in respective holes of the housing.

The variable inlet diameter unit for a compressor according to a second embodiment comprises a housing and an elastic element which is of substantially tubular shape and has an axial length. The elastic element is arranged within the housing, defines an inlet diameter of a unit inlet. The variable inlet diameter unit further comprises a chamber which is formed between the elastic element and the housing, and a port which is connected to the chamber. The port is coupleable to a pressure supply unit to vary a pressure in the chamber. The variable inlet diameter unit is adapted such that, when the pressure in the chamber is increased via the port above a pressure in the unit inlet, a predefined substantially annular leading portion of the elastic element is urged radially inwardly. By the movement of the elastic element, i.e. the substantially annular leading portion, in a radially inwardly direction the inlet diameter is continuously getting reduced. "Continuously" is not necessarily to be understood as reducing at a constant rate but more like an "enduring" reduction of the inlet diameter for as long as the pressure in the chamber is increased via the port above a pressure in the unit inlet. By providing the possibility of a reduction of the inlet diameter, the variable inlet diameter unit can improve the compressor map when mounted in a compressor. Furthermore, a compact design is provided as there is, for instance, no need for pivoting vane members or the like as known in the prior art. All in all the variable inlet diameter unit can lead to a more efficient compressor with a wider compressor map leading to a more versatile operation range. The pressure chamber can particularly be a substantially pressure tight chamber. The expression "chamber-is to be understood in the meaning of that it is capable of forming a chamber but does not need to form a chamber in all operating conditions. For instance, when the inlet pressure is much higher than the chamber pressure, the elastic element might get pressed against the housing, thus resulting in a very small or no chamber at that operating condition. The unit inlet is also a compressor inlet, when the variable inlet diameter unit is coupled with a compressor.

In another aspect of the second embodiment, the elastic element may be adapted such that the elastic element bends in radially inwardly at least at the annular leading portion to reduce the inlet diameter when the resulting force from the pressures enacting on the elastic element is directed from the chamber towards the unit inlet.

In another aspect of the second embodiment, which is combinable with the previous aspect, a first axial end portion of the elastic element may be coupled to a first axial housing end portion. A second axial end portion of the elastic element may be coupled to a second axial housing end portion.

In another aspect of the second embodiment, which is combinable with the previous aspect, the elastic element may comprise a first transition portion and a second transition portion. The first transition portion may be arranged between the first axial end portion and the annular leading portion. The second transition portion may be arranged between the second axial end portion and the annular leading portion. Upon movement of the annular leading portion radially inwardly, the first transition portion and the second transition portion of the elastic element may be formed. In other words, when the pressure supplied to the chamber via the port is smaller or equal to the pressure in the unit inlet, the first transition portion and the second transition portion have a substantially cylindrical shape. Upon increasing the pressure supplied to the chamber via the port increasingly exceeding the pressure in the unit inlet, a respective shape of the first transition portion and the second transition portion is adapted or changed such that the first transition portion and the second transition portion increasingly reduce the inlet diameter of the elastic element from the first and second axial end portions, respectively, towards the annular leading portion. Thus, in the direction of the flow, the inlet diameter is first being reduced in the area of the first transition section until reaching a minimum at the substantially annular leading portion. Further downstream of the substantially annular leading portion, the inlet diameter is being reduced again in the area of the second transition section. Thus, an inlet diameter can be reduced without producing sharp edges as it is common in many prior art solutions. Thereby, the range of the compressor map can be increased without generating disturbances of air flow which flows through the inlet unit and subsequently into/onto the impeller of a compressor at sharp edges (when the inlet unit is mounted in a compressor).

In another aspect of the second embodiment, which is combinable with the previous aspect, the shape of first transition portion and/or the shape of the second transition portion may follow a substantially straight line, a substantially convex curve or a substantially concave curve from the respective end portion towards the annular leading portion. These features are to be understood as seen from a cross-section of the elastic element. Alternatively or additionally, the first transition portion and/or the second transition portion may have a substantially conical shape (this would then correspond to a substantially straight line in the cross-section). Analogously to the explanations above concerning the first embodiment, it is obvious that these shapes do not refer to a state when the pressure supplied to the chamber via the port is smaller or equal to the pressure in the unit inlet, wherein the first and the second transition portions have a substantially cylindrical shape. In particular, the convex, concave or conical shapes refer to a state when the pressure supplied to the chamber via the port exceeds the pressure in the unit inlet. Thus, it refers to a state wherein the first and the second transition portions increasingly reduce the inlet diameter of the elastic element from the first and second axial end portions, respectively, towards the annular leading portion. Generally, any other curve/shape is possible which mainly depends on the material of the elastic element and/or on the mechanical properties which may also be further influenced by other additional elements (see below). Furthermore, the first and the second transition section may have different shapes. To only name one example, the first transition portion may have a convex shape and the second transition portion may have a concave shape.

In another aspect of the second embodiment, which is combinable with any one of the previous aspects, the annular leading portion may be arranged in an axial direction closer to the second axial end portion than to the first axial end portion. Alternatively, the annular leading portion may be arranged substantially in the middle between the first axial end portion and the second axial end portion or in an axial direction closer to the first axial end portion than to the second axial end portion. Thus, the position of the annular leading portion relative to the first axial end portion and the second axial end portion can be adjusted variably. Following this, the aerodynamic flow behavior in the inlet unit can be adjusted and/or optimized by adequately positioning the annular leading portion according to the requirements of and the circumstances in the compressor. Thereby, a more versatile inlet unit can be provided, and aerodynamic optimization can be accomplished.

In another aspect of the second embodiment, which is combinable with any one of the previous aspects, the elastic element may comprise a polymeric material. For instance, the elastic element may be made from a durable, elastic and/or a rubber material. Thereby a smoother inlet can be provided as the elastic element is capable of adopting a shape without sharp edges.

In another aspect of the second embodiment, which is combinable with any one of the previous aspects, the elastic element may comprise a core portion. The core portion may comprise at least one spring element which is configured to deflect radially inwardly, upon increasing the pressure in the chamber via the port above the pressure in the unit inlet. The at least one spring element thereby defines the substantially annular leading portion. Thus, the spring element may define the shape of the substantially annular leading portion and also the position of the substantially annular leading portion relative to the first axial end portion and the second axial end portion.

In another aspect of the second embodiment, which is combinable with the previous aspect, the core portion may comprise a plurality of spring elements distributed circumferentially within the elastic element. Additionally, the spring elements may have a generally oblong shape and/or may be oriented in a substantially axial direction. Alternatively or additionally, the spring elements may be configured to deflect radially inwardly upon increasing the pressure in the chamber via the port above the pressure in the unit inlet.

In another aspect of the second embodiment, which is combinable with any one of the previous aspects and wherein the elastic element comprises a core portion, the core portion may comprise a first ring portion connecting the spring elements at respective first axial ends of the spring elements. Optionally, the core portion may comprise a second ring portion connecting the spring elements at respective second axial ends of the spring elements. Alternatively or additionally, the spring elements may be configured to bend radially inwardly at a respective middle portion.

In another aspect of the second embodiment, which is combinable with any one of the previous aspects and wherein the elastic element comprises a core portion. The core portion may define the shape of the elastic element. Alternatively or additionally, the core portion may be made from a metal material.

In another aspect of the second embodiment, which is combinable with any one of the previous aspects, the variable inlet diameter unit may comprise a pressure supply unit coupled to the port for controlling and supplying pressure to the chamber. Additionally the variable inlet diameter unit may comprise a valve. The valve may be coupled between the port and the pressure supply unit.

In another aspect of the second embodiment, which is combinable with any one of the previous aspects, the chamber may comprise an annular portion. The annular portion may be recessed radially outwardly into the housing. Additionally, the annular portion may be fluidically coupled with the port. Additionally, the port may be arranged in the annular portion. Additionally, the port may extend from the annular portion radially outwardly through the housing.

The following explanations refer to both the first embodiment and the second embodiment.

The invention further refers to a compressor. The compressor comprises a compressor housing defining an inlet opening and an outlet with a volute. Furthermore, the compressor comprises an impeller which is rotatably arranged in the compressor housing between the inlet opening and the outlet. Additionally, the compressor has a variable inlet diameter unit according to any one of the previous aspects. Additionally, the variable inlet diameter unit may serve as inlet port of the compressor. The variable inlet diameter unit may be arranged immediately upstream of the inlet opening. Alternatively, the variable inlet diameter unit may be fluidically coupleable with a duct which is arranged upstream of the inlet opening.

The present invention further relates to a charging apparatus. The charging apparatus comprises a drive unit, a shaft and a compressor. The compressor is one according to any one of the previous aspects. Furthermore, the compressor may be rotationally coupled with the drive unit via the shaft. Additionally, the drive unit may comprise a turbine and/or an electric motor.

Description of the Drawings

FIG. 1 shows an isometric view of the variable inlet diameter unit according to the -11 -first embodiment; FIGS. 2A-2B show sectional views of the variable inlet diameter unit of FIG. 1 with the sliding ring in the first position and in the second position, respectively; FIGS. 3A-3D show exemplary configurations of the elastic element in sectional views applying to both the first and the second embodiment; FIGS. 4A-4B show exemplary configurations of the core portion in isometric views applying to both the first and the second embodiment; FIG. 4C shows a sectional view of the core portion with a spring element configured as radial compression spring applying to the first embodiment; FIGS. 5A-5B show sectional views of the variable inlet diameter unit according to the second embodiment in a neutral state and in a state with a reduced inlet diameter, respectively; FIG. 6 show an isometric view of the compressor with a variable inlet diameter unit according to the first embodiment of FIG. 1; FIG. 7 show a sectional view of the charging apparatus with a compressor but without the variable inlet diameter unit.

Detailed Description

In the context of this invention, the expressions axially, axial or axial direction is a direction parallel of or along an axis of the compressor, i.e. the rotation axis of the impeller which is mounted in the compressor housing. Analogously axially, axial or axial direction a direction parallel of or along an axis of the housing of the variable inlet diameter unit or of the elastic element of the variable inlet diameter unit. Thus, with reference to the figures, see, especially FIG. 1, an axial dimension is described with reference sign 22, a radial dimension extending "radially" away from the axial dimension 22 is described with reference sign 24. Furthermore, a circumferential dimension around the axial dimension 22 is described with reference sign 26.

FIG. 1 illustrates the first embodiment of the variable inlet diameter unit 10 for a compressor 50 in an isometric view. The variable inlet diameter unit 10 according to the first embodiment comprises a housing 300, a sliding ring 200 and an elastic element 100. The sliding ring 200 -12 -is arranged within the housing 300. The sliding ring 200 is axially moveable between a first position (see FIG. 2A) and a second position (see FIG. 2B). The elastic element 100 has a substantially tubular shape and is arranged within the housing 300. The elastic element 100 defines an inlet diameter 120 and has an axial length 110. The axial length 110 varies depending upon the position of the sliding ring 200. The variable inlet diameter unit 10 is adapted such that, upon movement of the sliding ring 200 from the first position towards the second position, a predefined substantially annular leading portion 114 of the elastic element 100 is urged radially inwardly. By the movement of the elastic element 10, i.e. the substantially annular leading portion 114, in a radially inwardly direction 24 the inlet diameter 120 is continuously getting reduced. "Continuously" is not necessarily to be understood as reducing at a constant rate but more like an "enduring" reduction of the inlet diameter 120 for as long as the sliding ring 200 is in motion. By providing the possibility of a reduction of the inlet diameter 120, the variable inlet diameter unit 10 can improve the compressor map when mounted in a compressor 50. Furthermore, a compact design is provided as there is, for instance, no need for pivoting vane members or the like as known in the prior art. All in all the variable inlet diameter unit 10 can lead to a more efficient compressor 50 with a wider compressor map leading to a more versatile operation range. As can be seen from FIG. 1 the sliding ring 200 is arranged completely within the housing 300. The housing 300 has a first axial housing end portion 312. The housing 300 further has a second axial housing end portion 316. The second axial housing end portion 316 is opposite of the first axial housing end portion 312 in an axial direction 22. The variable inlet diameter unit 10 further comprises a circlip 320 which is arranged at the first axial housing end portion 312 between the housing 300 and the sliding ring 200. The circlip 320 serves to secure the sliding ring 200 within the housing 300. This may be done alternatively or may not be necessary at all, when the sliding ring 200 is prevented from sliding out of the housing 300, for instance by holding the sliding ring 200 in a groove of an actuation system by means of sliding pins (explained further below). Alternatively, the sliding ring 200 may be arranged at least partially within the housing 300. For instance, in particular when the sliding ring 200 is in the first position, the sliding ring 200 could also extend axially outside the housing 300 in an alternative embodiment.

With reference to FIG. 2A, the variable inlet diameter unit 10 is shown in a neutral state (not reducing the inlet diameter 120). Here, the sliding ring 200 is in the first position. In contrast hereto, with reference to FIG. 2B, the variable inlet diameter unit 10 is shown in a reducing -13 -state (thus, reducing the inlet diameter 120), when the sliding ring 200 has moved from the first position towards the second position. In fact, FIG. 2B shows the sliding ring 200 in the second position in which the inlet diameter 120 is minimal. In the first position of the sliding ring 200 the inlet diameter 120 is maximal. In other words, the inlet diameter 120 is minimal when the sliding ring 200 is located at the second position and the inlet diameter 120 is maximal when the sliding ring 200 is located at the first position. That means there is a direct relationship between the sliding ring 200 and the elastic element 100. The elastic element 100 is adapted such that its axial length 110 is continuously reduced upon movement of the sliding ring 200 from the first position towards the second position (cf. FIGS. 2A and 2B). Thereby, the elastic element 100 bends in radially inwardly at least at the annular leading portion 114 to reduce the inlet diameter 120. Thus, the movement, i.e. the position of the sliding ring 200 controls the movement, i.e. the position or a shape of the elastic element 100. Between the first position and the second position, the sliding ring 200 can be adjusted infinitely to any intermediate position. Thereby, any inlet diameter 120 in between the maximum and the minimum can be adjusted according to the present position of the sliding ring 200. This enables the possibility of a dynamic inlet diameter adjustment with many intermediate positions which leads to a broader operation field and increases the versatility of the variable inlet diameter unit 10 and the compressor 50 when comprising such a variable inlet diameter unit 10.

Again, with reference to FIG.S 2A and 2B, the elastic element 100 comprises a first axial end portion 112 and a second axial end portion 116. Thereby the elastic element 100 is axially and radially coupled to the sliding ring 200 via the first axial end portion 112. Via the second axial end portion 116 the elastic element 100 is axially and radially coupled to the housing 300. In more detail the second axial end portion 116 of the elastic element 100 is axially and radially coupled to the second axial housing end portion 316. The coupling may be accomplished by various methods. For instance, the elastic element 100 may be coupled to the sliding ring 200 and/or to the housing 300 by vulcanization, by clamping (e.g., with an additional clamping element) or by an adhesive connection.

The elastic element 100 further comprises a first transition portion 113 and a second transition portion 115. The first transition portion 113 is located between the first axial end portion 112 and the annular leading portion 114. The second transition portion 115 is located between the second axial end portion 116 and the annular leading portion 114. Upon movement of the -14 -sliding ring 200 from the first position towards the second position, the first transition portion 113 and the second transition portion 115 may be formed. In other words, when the sliding ring 200 is in the first position, the first transition portion 113 and the second transition portion 115 may have a substantially cylindrical shape (see FIG. 2A). Still in this state the first transition portion 113 and the second transition portion 115 are present, as is also the annular leading portion 114. However, similar as the annular leading portion 114, the transition portions 113, 115 do not form a specific shape in this state in the meaning of transitioning between two different diameters. Instead upon movement of the sliding ring 200 from the first position towards the second position, a respective shape of the first transition portion 113 and the second transition portion 115 is adapted such that the first transition portion 113 and the second transition portion 115 increasingly reduce the inlet diameter 120 of the elastic element 100 from the first and second axial end portions 112, 116, respectively, towards the annular leading portion 114 (see FIG. 2B). Thus, in the direction of the flow, the inlet diameter 120 is first being reduced in the area of the first transition section 113 until reaching a minimum at the substantially annular leading portion 114. Further downstream of the substantially annular leading portion 114, the inlet diameter 120 is being increased again in the area of the second transition section 115. Thus, an inlet diameter 120 can be reduced without producing sharp edges as it is common in many prior art solutions. Thereby, the range of the compressor map can be increased without generating (substantial) disturbances of air flow which flows through the inlet unit 10 and subsequently into/onto the impeller of a compressor 50 at sharp edges (when the inlet unit is mounted in a compressor).

With reference to FIGS. 3A-3D different exemplary shapes of the elastic element 100 are shown. The expression "shape" is to be understood in the meaning of a profile of the elastic element 100, i.e. a profile of the sub-elements (e.g. transition portions) of the elastic element 100, as seen in a cross-sectional view analogously to FIGS. 2A and 2B. According to FIGS. 3A and 3C the shape of the first transition portion 113 and the shape of the second transition portion 115 follow a substantially straight line. In other words, the shape of the first transition portion H3 and the shape of the second transition portion 115 follow a straight line, i.e. a straight tubular form, which extends from the respective end portion 112, 116 to the substantially annular leading portion 114. FIG. 3A thereby shows the elastic element 100 when the sliding ring 200 is in the first position. Thereby the first and the second transition portions 113, 115 have a substantially cylindrical shape. FIG. 3C instead, shows the elastic element 100 when the sliding ring 200 is in the second position. Thereby the first and the -b -second transition portions 113, 115 have a substantially conical shape (see also FIG. 2B). Alternatively, the shape of the first transition portion 113 and the shape of the second transition portion 115 may follow a substantially concave curve from the respective end portion 112, 116 towards the annular leading portion 114 (see FIG. 3B). Alternatively, the shape of the first transition portion 113 and the shape of the second transition portion 115 may follow a substantially convex curve. Therefore, see FIG. 3D which exemplary shows only the first transition portion 113 having a shape following a convex curve. Generally, any other curve/shape is possible which mainly depends, for instance, on the material of the elastic element 100 and/or on the mechanical properties which may also be further influenced by other additional elements (such as a core portion 400 as explained further below).

Furthermore, the first and the second transition section 113, 115 may have different shapes. Therefore, FIG. 3D exemplary shows the first transition portion 113 having a convex shape and the second transition portion 115 having a concave shape. It is to be understood that these shapes, except the cylindrical shape, do not refer to a state when the sliding ring 200 is in the first position. In particular, the convex, concave or conical shapes refer to a state when the sliding ring is not in the first position. Thus, it refers to a state wherein the first and the second transition 113, 115 portions increasingly reduce the inlet diameter 120 of the elastic element 100 from the first and second axial end portions 112, 116, respectively, towards the annular leading portion 114. Therefore, not only second position but also positions in between first and second position can exhibit such shapes, however, in intermediate positions of the sliding ring 200, the respective shape may not be profiled as strong as in the second position.

The annular leading portion 114 is generally shown in all figures as being arranged substantially in the middle between the first axial end portion 113 and the second axial end portion 115 (see, e.g., FIGS. 2B or 3B). In alternative configurations the annular leading portion 114 may be arranged in an axial direction 22 closer to the second axial end portion 116 than to the first axial end portion 112 or in an axial direction 22 closer to the first axial end portion 112 than to the second axial end portion 116. Thus, the position of the annular leading portion 114 relative to the first axial end portion 112 and the second axial end portion 116 can be adjusted variably. Following this, the aerodynamic flow behavior in the inlet unit 10 can be adjusted and/or optimized by adequately positioning the annular leading portion 114 according to the requirements of and the circumstances in the compressor 50. Thereby, a more versatile inlet unit 10 can be provided, and aerodynamic optimization can be accompli shed.

-16 -The elastic element 100 generally comprises a polymeric material. For instance, the elastic element 100 may be made from a durable, elastic and/or a rubber material. Thereby a smoother inlet can be provided as the elastic element 100 is capable of adopting a shape without sharp edges.

The elastic element 100 comprises a core portion 400 which is schematically depicted in FIGS. 2A and 2B. FIGS. 4A to 4C show the core portion 400 in more detail in three exemplary configurations. In each configuration the core portion 400 comprises at least one spring element 410 which is configured to deflect radially inwardly, upon movement of the sliding ring 200 from the first position towards the second position. Thereby the at least one spring element 410 defines the substantially annular leading portion 114. Thus, the spring element 410 defines the shape of the substantially annular leading portion 114 and also the position (position in axial and/or radial direction) of the substantially annular leading portion 114 relative to the first axial end portion 112 and the second axial end portion 116.

FIG. 4C shows the core portion 400 having exactly one spring element 410. In this configuration the spring element 410 is configured as a radial compression spring. The spring element 410, i.e. the radial compression spring is configured to urge the elastic element 100 at the annular leading portion 114 radially inwardly, when load on the spring element 410 is reduced. In other words, the spring element 410 defines the substantially annular leading portion 114. As the radial compression spring tries to constrict itself radially inwardly, load on the spring element 410 is reduced upon movement of the sliding ring 200 from the first position towards the second position. On the other hand, the spring element 410 is adapted to be pulled radially outwardly upon movement of the sliding ring 200 from the second position towards the first position. Thereby load is applied on the spring element 410. The core portion 400 may also comprise more than one spring element 410 being configured as radial compression spring.

FIGS. 4A and 4B show the core portion 400 comprising a plurality of spring elements 410.

The spring elements 410 are distributed circumferentially within the elastic element 100 (not depicted in these figures). The spring elements 410 have a generally oblong shape with respective first axial ends 412 and respective second axial ends 416 and are oriented in a substantially axial direction 22 The spring elements 410 are configured to deflect radially -17 -inwardly upon axial compressive force. More precisely, the spring elements 410 are configured to bend radially inwardly at a respective middle portion 414 upon exertion of an axial compressive force. This is accomplished by the sliding ring 200 which exerts an axial compressive force on the spring elements 410 via their respective first axial ends 412, upon movement of the sliding ring 200 from the first position towards the second position. The position at which the spring elements 410 bend radially inwardly may be controlled, for instance by a thinner structure at the desired position, i.e. in this case at the respective middle portion 414. Apart from that, many other ways to adapt the spring force and the bending behavior of the spring elements 410 are possible, for instance a varying thickness or the provision of additional elements for such as pins 415. Not necessary but shown in the configurations of FIGS. 4A and 4B, the core portion 400 comprises a first ring portion 420 connecting the spring elements 410 at their respective first axial ends 412. Furthermore, the core portion 400 comprises a second ring portion 430 connecting the spring elements 410 at their respective second axial ends 416. In general, the core portion 400 is a sub-element or a characteristic of the elastic element 100 stiffening and/or adapting the bending behavior of the elastic element 100. Thus, the core portion 400 is the main driver (apart from, inter alia, actuation force, material of elastic element, etc.) which defines the shape of the elastic element 100. The core portion 400 is thereby embedded in the elastic element 100 (see, e.g., FIGS. 2A and 2B). Thereby the elastic element 100 may, for instance, be extruded onto the core portion 400. In particular, the core portion 400 is made from a metal material.

Alternatively, the core portion 400 may be made from any other suitable material being able to generate a similar bending behavior.

Back with reference to FIGS. 2A and 2B, the sliding ring 200 has a first axial end 222 and a second axial end 226. The sliding ring 200 comprises a ring portion 210 at the first axial end 222. Furthermore, the sliding ring 200 comprises a connecting portion 230 extending from the ring portion 210 towards the second axial end 226. The connecting portion 230 is configured to couple the sliding ring 200 with an actuation system 600. The ring portion 210 comprises a radially inwardly extending protrusion 213. The protrusion 213 has a substantially triangular cross-section. The protrusion 213 defines a truncated cone surface 213a between an outer diameter 212 and an inner diameter 214. Thus, the ring portion 210, i.e. the protrusion 213 rejuvenates in an axial direction 22 from the first axial end 222 towards the connecting portion 230 such that an annular flange surface 213b is formed for interacting with the elastic element 100 and for exerting an axial compression force on the elastic element 100. The -18 -flange surface 213b is arranged opposite the truncated cone surface 213a in an axial direction 22. The connecting portion 230 comprises a plurality of posts 232. In the exemplary embodiment of FIGS. 2A and 2B, the connecting portion 230 comprises four posts 232. In alternative embodiments the connecting portion 230 may also comprise more or less than four posts 232. Each of the posts 232 has a sliding pin 234 at the second axial end 226 (or close thereto) to be coupled with the actuation system 600.

As already mentioned, the variable inlet diameter unit 10 further comprises an actuation system 600 (see FIGS. t, 2A and 2B). The actuation system 600 is configured to move the sliding ring 200 axially between the first position and the second position. Therefore, the actuation system 600 comprises a rotating ring 610 with four grooves 612 (corresponding to the four posts 232, i.e. to the four sliding pins 234). In alternative embodiments the rotating ring 610 may comprise more or less than four inclined grooves 612. The rotating ring 610, i.e. the grooves 612, are configured to engage with one respective sliding pin 234 of the sliding ring 200. Thereby a rotation of the rotating ring 610 causes an axial movement of the sliding ring 200. The actuation system 600 further comprises an actuation lever 620 which is coupled with the rotating ring 610 to rotate the rotating ring 610. The housing 300 comprises a notch 310 extending in a circumferential direction 26. The actuation lever 620 extends through the notch 310 to be coupled with the rotating ring 610. The rotating ring 610 is arranged inside the housing 300. More specific, the rotating ring 610 is rotatably supported in the housing 300 by means of multiple bearing rollers 614. For this purpose, there are arranged four bearing rollers 614 circumferentially spaced apart in respective holes 314 of the housing 300. In alternative embodiments more or less than four bearing rollers 614 may be provided in respective holes 314 in the housing 300.

FIGS. 5A and 5B illustrate the second embodiment of the variable inlet diameter unit 1010 for a compressor 50 in a sectional side views (analogously to FIGS. 2A and 2B). The variable inlet diameter unit 1010 according to the second embodiment comprises a housing 1300 and an elastic element 1100 which has a substantially tubular shape and an axial length 1110. The elastic element 1100 is arranged within the housing 1300 and defines an inlet diameter 1120 of a unit inlet 1122. The variable inlet diameter unit 1010 further comprises a chamber 1200 which is formed between the elastic element 1100 and the housing 1300, and a port 1620 which is connected to the chamber 1200. The port 1620 is coupled to a pressure supply unit 1600 to vary a pressure in the chamber 1200. The variable inlet diameter -19 -unit 1010 is adapted such that, when the pressure in the chamber 1200 is increased via the port 1620 above a pressure in the unit inlet 1122, a predefined substantially annular leading portion 1114 of the elastic element 1100 is urged radially inwardly. By the movement of the elastic element 1010, i.e. the substantially annular leading portion 1114, in a radially inwardly direction the inlet diameter 1120 is continuously getting reduced. Analogously as explained further above, "continuously" is not necessarily to be understood as reducing at a constant rate but more like an "enduring" reduction of the inlet diameter 1120 for as long as the pressure in the chamber 1200 is increased via the port 1620 above a pressure in the unit inlet 1122. By providing the possibility of a reduction of the inlet diameter 1120, the variable inlet diameter unit 1010 can improve the compressor map when mounted in a compressor 50. Furthermore, a compact design is provided as there is, for instance, no need for pivoting vane members or the like as known in the prior art. All in all the variable inlet diameter unit 1010 can lead to a more efficient compressor 50 with a wider compressor map leading to a more versatile operation range. The pressure chamber 1200 can particularly be a substantially pressure tight chamber 1200. The expression "chamber" is to be understood in the meaning of that it is capable of forming a chamber but does not necessarily forms a chamber in all operating conditions. For instance, when the pressure in the unit inlet 1122 is much higher than the pressure in the chamber 1200, the elastic element 1100 might get pressed against the housing 1300, thus resulting in a very small or no chamber at that operating condition. The unit inlet 1010 serves also as a compressor inlet section 56 or may inserted into a compressor inlet section 56, when the variable inlet diameter unit 1010 is coupled with a compressor 50. The elastic element 1100 is adapted such that it bends in radially inwardly at least at the annular leading portion 1114 to reduce the inlet diameter 1120 when the resulting force from the pressures enacting on the elastic element 1100 is directed from the chamber 1200 towards the unit inlet 1122.

The housing 1300 has a first axial housing end portion 1312. The housing 1300 further has a second axial housing end portion 1316. The second axial housing end portion 1316 is arranged opposite of the first axial housing end portion 1312 in an axial direction 22. The elastic element 1100 comprises a first axial end portion 1112 and a second axial end portion 1116. Thereby the elastic element 1100 is axially and radially coupled to the first axial housing end portion 1312 via the first axial end portion 1112. Via the second axial end portion 1116 the elastic element 1100 is axially and radially coupled to the housing 1300. In more detail, the second axial end portion 1116 of the elastic element 1100 is axially and -20 -radially coupled to the second axial housing end portion 1316. The coupling may be accomplished by various methods. For instance, the elastic element 1100 may be coupled to the housing 1300 by vulcanization, by clamping (e.g., with an additional clamping element) or by an adhesive connection. Thereby it is important that the connection between the elastic element 1100 and the housing 1300 is substantially pressure tight, i.e. only allows very little leakage in order to establish a respective pressure in the chamber 1200 to urge the elastic element 1100 radially inwardly.

With further reference to FIGS. 5A and 5B (analogously to the first embodiment), the elastic element 1100 further comprises a first transition portion 1113 and a second transition portion 1115. The first transition portion 1113 is located between the first axial end portion 1112 and the annular leading portion 1114. The second transition portion 1115 is located between the second axial end portion 1116 and the annular leading portion 1114. Upon movement of the annular leading portion 1114 radially inwardly, the first transition portion 1113 and the second transition portion 1115 may be formed.

In other words, when the pressure supplied to the chamber 1200 via the port 1620 is smaller or equal to the pressure in the unit inlet 1122, the first transition portion 1113 and the second transition portion 1115 may have a substantially cylindrical shape (see FIG. 5A). Still in this state the first transition portion 1113 and the second transition portion 1115 are present, as is also the annular leading portion 1114. However, similar as the annular leading portion 1114, the transition portions 1113, 1115 do not form a specific shape in this state in the meaning of transitioning between two different diameters. Instead, upon increasing the pressure supplied to the chamber 1200 via the port 1620 increasingly exceeding the pressure in the unit inlet 1122, a respective shape of the first transition portion 1113 and the second transition portion 1115 is adapted such that the first transition portion 1113 and the second transition portion 1115 increasingly reduce the inlet diameter 1120 of the elastic element 1100 from the first and second axial end portions 1112, 1116, respectively, towards the annular leading portion 1114 (see FIG. 5B). Thus, in the direction of the flow, the inlet diameter 1120 is first being reduced in the area of the first transition section 1113 until reaching a minimum at the substantially annular leading portion 1114. Further downstream of the substantially annular leading portion 1114, the inlet diameter 1120 is being increased again in the area of the second transition section 1115. Thus, an inlet diameter 1120 can be reduced without producing sharp edges as it is common in many prior art solutions. Thereby, the range of the -21 -compressor map can be increased without generating disturbances of air flow which flows through the inlet unit 1010 and subsequently into/onto the impeller of a compressor 50 at sharp edges (when the inlet unit is mounted in a compressor 50) Analogously to the first embodiment, the elastic element 1100 of the second embodiment can also be configured in different shapes (see FIGS. 3A-3D). The only difference is, that the elastic element 1100 of the second embodiment is cylindrically shaped (see FIG. 5A) in a neutral state of the variable inlet diameter unit 1010 when the pressure supplied to the chamber 1200 via the port 1620 is smaller or equal to the pressure in the unit inlet 1122 (analogous to first position of the sliding ring 200). On the other hand, a state of the inlet unit 1010 according to the second embodiment, wherein the pressure supplied to the chamber 1200 via the port 1620 is increasingly exceeding the pressure in the unit inlet 1122, is to be seen analogously to a state of the inlet unit 10 according to the first embodiment, wherein the sliding ring 200 is being moved from the first position towards the second position. In such a state the first and the second transition portions 1113, 1115 have a substantially conical shape in the example of FIG. 5B. Therefore, the explanations as set out further above with regard to the first embodiment can be applied analogously to the second embodiment. That is, to name only one example, the convex, concave or conical shapes refer to a state when the pressure supplied to the chamber 1200 via the port 1620 exceeds the pressure in the unit inlet 1122.

The annular leading portion 1114 is generally shown in all figures as being arranged substantially in the middle between the first axial end portion 1113 and the second axial end portion 1115 (see, e.g., FIGS. 3B or 5B). In alternative configurations the annular leading portion 1114 may be arranged in an axial direction 22 closer to the second axial end portion 1116 than to the first axial end portion 1112 or in an axial direction 22 closer to the first axial end portion 1112 than to the second axial end portion 1116. Thus, the position of the annular leading portion 1114 relative to the first axial end portion 1112 and the second axial end portion 1116 can be adjusted variably. Following this, the aerodynamic flow behavior in the inlet unit 10 can be adjusted and/or optimized by adequately positioning the annular leading portion 1114 according to the requirements of and the circumstances in the compressor 50.

Thereby, a more versatile inlet unit 1010 can be provided, and aerodynamic optimization can be accomplished.

-22 -The elastic element 1100 generally comprises a polymeric material. For instance, the elastic element 1100 may be made from a durable, elastic and/or a rubber material. Thereby a smoother inlet can be provided as the elastic element 100 is capable of adopting a shape without sharp edges.

The elastic element 1100 comprises a core portion 1400 which is schematically depicted in FIGS. 5A and 5B. FIGS. 4A to 4B show the core portion 1400 in more detail in two exemplary configurations which are identical to those of the first embodiment. In each configuration the core portion 1400 comprises at least one spring element 1410 which is configured to deflect radially inwardly, upon increasing the pressure in the chamber 1200 via the port 1620 above the pressure in the unit inlet 1122. Thereby the at least one spring element 1410 defines the substantially annular leading portion 1114. Thus, the spring element 1410 defines the shape of the substantially annular leading portion 1114 and also the position (position in axial and/or radial direction) of the substantially annular leading portion 1114 relative to the first axial end portion 1112 and the second axial end portion 1116. The spring elements 1410 are configured to deflect radially inwardly upon increasing the pressure in the chamber 1200 via the port 1620 above the pressure in the unit inlet 1122.

FIGS. 4A and 4B show the core portion 1400 comprising a plurality of spring elements 1410.

The spring elements 1410 are distributed circumferentially within the elastic element 1100 (not depicted in these figures). The spring elements 1410 have a generally oblong shape with respective first axial ends 1412 and respective second axial ends 1416 and are oriented in a substantially axial direction 22 The spring elements 1410 are configured to deflect radially inwardly upon increasing the pressure in the chamber 1200 via the port 1620 above the pressure in the unit inlet 1122. More precisely, the spring elements 1410 are configured to bend radially inwardly at a respective middle portion 1414 upon increasing the pressure in the chamber 1200 via the port 1620 above the pressure in the unit inlet 1122. The position at which the spring elements 1410 bend radially inwardly may be controlled, for instance by a thinner structure at the desired position, i.e. in this case at the respective middle portion 1414.

Apart from that, many other ways to adapt the spring force and the bending behavior of the spring elements 1410 are possible, for instance a varying thickness or the provision of additional elements for such as pins 1415. Not necessary but shown in the configurations of FIGS. 4A and 4B, the core portion 1400 comprises a first ring portion 1420 connecting the spring elements 1410 at their respective first axial ends 1412. Furthermore, the core portion -23 - 1400 comprises a second ring portion 1430 connecting the spring elements 1410 at their respective second axial ends 1416. In general, the core portion 1400 is a sub-element or a characteristic of the elastic element 1100 stiffening and/or adapting the bending behavior of the elastic element 1100. Thus, the core portion 1400 is the main driver (apart from, inter alia, actuation force, material of elastic element, etc.) which defines the shape of the elastic element 1100. The core portion 1400 is thereby embedded in the elastic element 1100 (see, e.g., FIGS. 5A and 5B). Thereby the elastic element 1100 may, for instance, be extruded onto the core portion 1400. In particular, the core portion 1400 is made from a metal material. Alternatively, the core portion 1400 may be made from any other suitable material being able to generate a similar bending behavior.

Again with reference to FIGS. 5A and 5B, the variable inlet diameter unit 1010 comprises a pressure supply unit 1600 coupled to the port 1620 for controlling and supplying pressure to the chamber 1200. For this purpose, the variable inlet diameter unit 1010 further comprises a valve 1610. The valve 1610 is thereby coupled between the port 1620 and the pressure supply unit 1600. The valve 1610 is thereby coupled to the port 1620 from an outer side of the housing 1300. Alternatively, the valve 1610 can be integrated into the housing 1300 and/or into the port 1620.

The chamber 1200 comprises an annular portion 1210. The annular portion 1210 is recessed radially outwardly into the housing 1300. Thereby, the annular portion 1210 is fluidically coupled with the port 1620. The port 1620 is arranged in the annular portion 1210. Furthermore, the port 1620 extends from the annular portion 1210 radially outwardly through the housing 1300.

The following explanations refer to both the first embodiment and the second embodiment. As depicted in FIG. 6, the invention further relates to a compressor 50. The compressor 50 comprises a compressor housing 52 defining an inlet opening 52a and an outlet 52b with a volute 52c. Furthermore, the compressor 50 comprises an impeller (not depicted in FIG. 6).

The impeller is rotatably arranged in the compressor housing 52 between the inlet opening 52a and the outlet 52b. The inlet opening 52a shall be defined as an opening immediately upstream of the impeller. The compressor 50 further has a variable inlet diameter unit 10, 1010 according to any one of the previous aspects. Although in FIG. 6 only the variable inlet diameter unit 10 according to the first embodiment is depicted, it is to be -24 -understood that alternatively also the variable inlet diameter unit 1010 according to the second embodiment may be comprised in the compressor 50. In the example of FIG. 6, the variable inlet diameter unit 10 is inserted into a compressor inlet section 56 of the compressor 50. The compressor inlet section 56 is a cylindrical part of the compressor 50 which may be attached to the compressor 50 via a flange connection or, as depicted in FIG. 6 may be integrally formed with the compressor 50. The compressor housing 52, i.e. the compressor inlet section 56 comprises a notch 54 which corresponds to the notch 310 of the housing 300 such that the actuation lever 620 can extend therethrough to couple with and actuate the rotating ring 610. Thereby, the variable inlet diameter unit 10, 1010 serves as inlet port for the compressor 50. Thus, instead of the compressor inlet section 56, the variable inlet diameter unit 10, 1010 may be flanged directly to the compressor housing 52 without the need for the compressor inlet section 56. In any case the variable inlet diameter unit 10, 1010 may be arranged immediately upstream of the inlet opening 52a (see FIG. 6). Alternatively, the variable inlet diameter unit 10, 1010 may be fluidically coupleable with a duct which is arranged upstream of the inlet opening 52a, such that the variable inlet diameter unit 10, 1010 be arranged not immediately upstream of the inlet opening 52a.

With reference to FIG. 7, the present invention further relates to a charging apparatus 40. The charging apparatus 40 comprises a drive unit 60, a shaft 70 and a compressor 50. The compressor 50 is one according to any one of the previous aspects. Thus, although not depicted in FIG. 7, the charging apparatus 40 comprises the inventive variable inlet diameter unit 10, 1010. The compressor 50 is generally rotationally coupled with the drive unit 60 via the shaft 70. The drive unit 60 comprises a turbine. Alternatively, the drive unit 60 may comprise a turbine and an electric motor or the drive unit 60 may only comprise an electric motor.

-25 -It should be understood that the present invention can also alternatively be defined in accordance with the following embodiments: 1. A variable inlet diameter unit (10) for a compressor (50) comprising: a housing (300); a sliding ring (200) arranged at least partially within the housing (300) and axially moveable between a first position and a second position; and an elastic element (100) of substantially tubular shape arranged within the housing (300), wherein the elastic element (100) defines an inlet diameter (120) and has an axial length (110); wherein the variable inlet diameter unit (10) is adapted such that, upon movement of the sliding ring (200) from the first position towards the second position, a predefined substantially annular leading portion (114) of the elastic element (100) is urged radially inwardly thereby continuously reducing the inlet diameter (120).

2. The variable inlet diameter unit (10) of embodiment 1, wherein the elastic element (100) is adapted such that its axial length (110) is continuously reduced upon movement of the sliding ring (200) from the first position towards the second position, such that the elastic element (100) bends in radially inwardly at least at the annular leading portion (114) to reduce the inlet diameter (120).

3. The variable inlet diameter unit (10) of any one of the previous embodiments, wherein the inlet diameter (120) is minimal at the second position of the sliding ring (200) and maximal at the first position of the sliding ring (200).

4. The variable inlet diameter unit (10) of any one of the previous embodiments, wherein a first axial end portion (112) of the elastic element (100) is axially and radially coupled to the sliding ring (200) and a second axial end portion (116) of the elastic element (100) is axially and radially coupled to the housing (300).

The variable inlet diameter unit (10) of embodiment 4, wherein, upon movement of the sliding ring (200) from the first position towards the second position, a first transition portion (113) of the elastic element (100) is formed between the first axial end portion -26 - (112) and the annular leading portion (114), and a second transition portion (115) of the elastic element (100) is formed between the second axial end portion (116) and the annular leading portion (114).

6. The variable inlet diameter unit (10) of embodiment 5, wherein, when the sliding ring (200) is in the first position, the first transition portion (113) and the second transition portion (115) have a substantially cylindrical shape, and wherein, upon movement of the sliding ring (200) from the first position towards the second position, a respective shape of the first transition portion (113) and the second transition portion (115) is adapted such that the first transition portion (113) and the second transition portion (115) increasingly reduce the inlet diameter (120) of the elastic element (100) from the first and second axial end portions (112, 116) towards the annular leading portion (114), respectively.

The variable inlet diameter unit (10) of any one of embodiments 5 or 6, wherein the shape of first transition portion (113) and/or the shape of the second transition portion (115) follow a substantially straight line, a substantially convex curve or a substantially concave curve from the respective end portion (112, 116) towards the annular leading portion (114).

The variable inlet diameter unit (10) of any one of embodiments 5 to 7, wherein the first transition portion (113) and/or the second transition portion (115) have a substantially conical shape.

The variable inlet diameter unit (10) of any one of embodiments 4 to 7, wherein the annular leading portion (114) is arranged closer to the second axial end portion (116) than to the first axial end portion (112).

The variable inlet diameter unit (10) of any one of the previous embodiments, wherein the elastic element (10) comprises a polymeric material.

The variable inlet diameter unit (10) of any one of the previous embodiments, wherein the elastic element (100) comprises a core portion (400) with at least one spring element (410) which is configured to deflect radially inwardly, upon movement of the 7. 9. 10. 11.

-27 -sliding ring (200) from the first position towards the second position, thereby defining the substantially annular leading portion (114).

12. The variable inlet diameter unit (10) of embodiment 11, wherein the spring element (410) is a radial compression spring which is adapted to urge the elastic element (100) at the annular leading portion (114) radially inwardly, when load on the spring element (410) is reduced, upon movement of the sliding ring (200) from the first position towards the second position, and which is adapted to be pulled radially outwardly upon movement of the sliding ring (200) from the second position towards the first position.

The variable inlet diameter unit (10) of embodiment 11, wherein the core portion (400) comprises a plurality of spring elements (410) distributed circumferentially within the elastic element (100).

The variable inlet diameter unit (10) of embodiment 13, wherein the spring elements (410) have a generally oblong shape and are oriented in a substantially axial direction (22).

The variable inlet diameter unit (10) of any one of embodiments 13 or 14, wherein the spring elements (410) are configured to deflect radially inwardly upon axial compressive force.

The variable inlet diameter unit (10) of any one of embodiments 13 to 15, wherein the core portion (400) comprises a first ring portion (420) connecting the spring elements (410) at respective first axial ends (412), and optionally, wherein the core portion (400) comprises a second ring portion (430) connecting the spring elements (410) at respective second axial ends (416).

The variable inlet diameter unit (10) of any one of embodiments 13 to 16, wherein the sliding ring (200), upon movement from the first position towards the second position, exerts an axial compressive force on the spring elements (410) via their respective first axial ends (412), the spring elements (410) being configured to bend radially inwardly at a respective middle portion (414). 13. 14. 15. 16. 17.

-28 - 18. The variable inlet diameter unit (10) of any one of embodiments 11 to 17, wherein the core portion (400) defines the shape of the elastic element (100).

19. The variable inlet diameter unit (10) of any one of embodiments 11 to 18, wherein the core portion (400) is made from a metal material.

20. The variable inlet diameter unit (10) of any one of the previous embodiments, wherein the sliding ring (200) has a ring portion (210) at a first axial end (222) and a connecting portion (230) extending from the ring portion (210) towards a second axial end (226), the connecting portion (230) being configured to couple the sliding ring (200) with an actuation system (600).

The variable inlet diameter unit (10) of embodiment 20, wherein the ring portion (210) comprises a radially inwardly extending protrusion (213) having a substantially triangular cross-section, the protrusion (213) defining a truncated cone surface (213a) between an outer diameter (212) and an inner diameter (214), the protrusion (213) rejuvenating in an axial direction (22) towards the connecting portion (230) such that an annular flange surface (213b) is formed for exerting an axial compression force on the elastic element (100).

The variable inlet diameter unit (10) of any one of embodiments 20 to 21, wherein the connecting portion (230) comprises a plurality of posts (232), each of which having a sliding pin (234) at the second axial end (226) to be coupled with an actuation system (600).

The variable inlet diameter unit (10) of any one of the previous embodiments, further comprising an actuation system (600) configured to move the sliding ring (200) axially between the first position and the second position.

The variable inlet diameter unit (10) of embodiment 23, wherein the actuation system (600) comprises a rotating ring (610) with at least one inclined groove (612) configured to engage with at least one sliding pin (234) of the sliding ring (200) such 21. 22. 23. 24.

-29 -25. 26. 27. 28.

that a rotation of the rotating ring (610) causes an axial movement of the sliding ring (200).

The variable inlet diameter unit (10) of any one of embodiments 23 or 24, wherein the actuation system (600) further comprises an actuation lever (620) to rotate the rotating ring (610).

The variable inlet diameter unit (10) of embodiment 25, wherein the housing comprises a notch (310) extending in a circumferential direction (26), the actuation lever (620) extending therethrough to be coupled to the rotating ring (610).

The variable inlet diameter unit (10) of any one of embodiments 24 to 26, wherein the rotating ring (620) is rotatably supported in the housing (300) by means of multiple bearing rollers (614) circumferentially arranged in respective holes (314) of the housing (300).

A variable inlet diameter unit (1010) for a compressor (50) comprising: a housing (1300); an elastic element (1100) of substantially tubular shape arranged within the housing (1300), wherein the elastic element (1100) defines an inlet diameter (1120) of a unit inlet (1122) and has an axial length (1110); a chamber (1200) formed between the elastic element (1100) and the housing (1300); and a port (1620) connected to the chamber (1200) and coupleable to a pressure supply unit (1600) to vary a pressure in the chamber (1200), wherein the variable inlet diameter unit (1010) is adapted such that, when the pressure in the chamber (1200) is increased via the port (1620) above a pressure in the unit inlet (1122), a predefined substantially annular leading portion (1114) of the elastic element (1100) is urged radially inwardly thereby continuously reducing the inlet diameter (1120).

29. The variable inlet diameter unit (1010) of embodiment 28, wherein the elastic element (1100) is adapted such that the elastic element (1100) bends in radially inwardly at least at the annular leading portion (1114) to reduce the inlet diameter (1120) when the -30 -resulting force from the pressures enacting on the elastic element (1100) is directed from the chamber (1200) towards the unit inlet (1122).

30. The variable inlet diameter unit (1010) of any one of the previous embodiments, wherein a first axial end portion (1112) of the elastic element (1100) is coupled to a first axial housing end portion (1312) and a second axial end portion (1116) of the elastic element (1100) is coupled to a second axial housing end portion (1316).

31. The variable inlet diameter unit (1010) of embodiment 30, wherein, upon movement of the annular leading portion (1114) radially inwardly, a first transition portion (1113) of the elastic element (1100) is formed between the first axial end portion (1112) and the annular leading portion (1114), and a second transition portion (1115) of the elastic element (1100) is formed between the second axial end portion (1116) and the annular leading portion (1114).

32. The variable inlet diameter unit (1010) of embodiment 31, wherein, when the pressure supplied to the chamber (1200) via the port (1620) is smaller or equal to the pressure in the unit inlet (1122), the first transition portion (1113) and the second transition portion (1115) have a substantially cylindrical shape, and wherein, upon increasing the pressure supplied to the chamber (1200) via the port (1620) increasingly exceeding the pressure in the unit inlet (1122), a respective shape of the first transition portion (1113) and the second transition portion (1115) is adapted such that the first transition portion (1113) and the second transition portion (1115) increasingly reduce the inlet diameter (1120) of the elastic element (1100) from the first and second axial end portions (1112, 1116) towards the annular leading portion (1114), respectively.

33. The variable inlet diameter unit (1010) of any one of embodiments 31 or 32, wherein the shape of first transition portion (1113) and/or the shape of the second transition portion (1115) follow a substantially straight line, a substantially convex curve or a substantially concave curve from the respective end portion (1112, 1116) towards the annular leading portion (1114). -31 -

34. The variable inlet diameter unit (1010) of any one of embodiments 31 to 33, wherein the first transition portion (1113) and/or the second transition portion (1115) have a substantially conical shape.

35. The variable inlet diameter unit (1010) of any one of embodiments 30 to 34, wherein the annular leading portion (1114) is arranged closer to the second axial end portion (1116) than to the first axial end portion (1112).

36. The variable inlet diameter unit (1010) of any one of the previous embodiments, wherein the elastic element (1100) comprises a polymeric material.

37. The variable inlet diameter unit (1010) of any one of the previous embodiments, wherein the elastic element (1100) comprises a core portion (1400) with at least one spring element (1410) which is configured to deflect radially inwardly, upon increasing the pressure in the chamber (1200) via the port (1620) above the pressure in the unit inlet (1122), thereby defining the substantially annular leading portion (1114).

38. The variable inlet diameter unit (1010) of embodiment 37, wherein the core portion (1400) comprises a plurality of spring elements (1410) distributed circumferentially within the elastic element (1100).

39. The variable inlet diameter unit (1010) of embodiment 38, wherein the spring elements (1410) have a generally oblong shape and are oriented in a substantially axial direction (22).

40. The variable inlet diameter unit (1010) of any one of embodiments 38 or 39, wherein the spring elements (1410) are configured to deflect radially inwardly upon increasing the pressure in the chamber (1200) via the port (1620) above the pressure in the unit inlet (1122).

41. The variable inlet diameter unit (1010) of any one of embodiments 38 to 40, wherein the core portion (1400) comprises a first ring portion (1420) connecting the spring elements (1410) at respective first axial ends (1412), and optionally, wherein the core -32 -portion (1400) comprises a second ring portion (1430) connecting the spring elements (1410) at respective second axial ends (1416).

42. The variable inlet diameter unit (1010) of any one of embodiments 38 to 41, wherein the spring elements (1410) being configured to bend radially inwardly at a respective middle portion (1414).

43. The variable inlet diameter unit (1010) of any one of embodiments 37 to 42, wherein the core portion (1400) defines the shape of the elastic element (1100).

44. The variable inlet diameter unit (1010) of any one of embodiments 37 to 43, wherein the core portion (1400) is made from a metal material.

45. The variable inlet diameter unit (1010) of any one of the previous embodiments, further comprising a pressure supply unit (1600) coupled to the port (1620) for controlling and supplying pressure to the chamber (1200).

46. The variable inlet diameter unit (1010) of embodiment 45, further comprising a valve (1610) coupled between the port (1620) and the pressure supply unit (1600).

47. The variable inlet diameter unit (1010) of any one of the previous embodiments, wherein the chamber (1200) comprises an annular portion (1210) which is recessed radially outwardly in the housing (1300) and, optionally, wherein the annular portion (1210) is fluidically coupled with the port (1620).

48. The variable inlet diameter unit (1010) of embodiment 47, wherein the port (1620) is arranged in the annular portion (1210) and, optionally wherein the port (1620) extends from the annular portion (1210) radially outwardly through the housing (1300).

49. A compressor (50) comprising: a compressor housing (52) defining an inlet opening (52a) and an outlet (52b) with a volute (52c); an impeller rotatably arranged in the housing (52) between the inlet opening (52a) and the outlet (52b); and -33 -a variable inlet diameter unit (10; 1010) of any one of the previous embodiments.

50. The compressor (50) of embodiment 49, wherein the variable inlet diameter unit (10; 1010) serves as inlet port of the compressor (50) and is arranged immediately upstream of the inlet opening (52a).

51. A charging apparatus (40) comprising: a drive unit (60); a shaft (70); and a compressor (50) of any one of embodiments 49 or 50, wherein the compressor (50) is rotationally coupled with the drive unit (60) via the shaft (70).

52. The charging apparatus (40), wherein the drive unit (60) comprises a turbine and/or an electric motor.

-34 -

Claims

CLAIMS1. A variable inlet diameter unit (10) for a compressor (50) comprising: a housing (300); a sliding ring (200) arranged at least partially within the housing (300) and axially moveable between a first position and a second position; and an elastic element (100) of substantially tubular shape arranged within the housing (300), wherein the elastic element (100) defines an inlet diameter (120) and has an axial length (110); wherein the variable inlet diameter unit (10) is adapted such that, upon movement of the sliding ring (200) from the first position towards the second position, a predefined substantially annular leading portion (114) of the elastic element (100) is urged radially inwardly thereby continuously reducing the inlet diameter (120).
The variable inlet diameter unit (10) of claim 1, wherein the inlet diameter (120) is minimal at the second position of the sliding ring (200) and maximal at the first position of the sliding ring (200).
3. The variable inlet diameter unit (10) of any one of the previous claims, wherein a first axial end portion (112) of the elastic element (100) is axially and radially coupled to the sliding ring (200) and a second axial end portion (116) of the elastic element (100) is axially and radially coupled to the housing (300), and optionally, wherein, upon movement of the sliding ring (200) from the first position towards the second position, a first transition portion (113) of the elastic element (100) is formed between the first axial end portion (112) and the annular leading portion (114), and a second transition portion (115) of the elastic element (100) is formed between the second axial end portion (116) and the annular leading portion (114).
The variable inlet diameter unit (10) of claim 3, wherein, when the sliding ring (200) is in the first position, the first transition portion (113) and the second transition portion (115) have a substantially cylindrical shape, and wherein, upon movement of the sliding ring (200) from the first position towards the second position, a respective shape of the first transition portion (113) and the second transition portion (115) is adapted such that the first transition portion (113) and the second transition portion (1 15) increasingly reduce the inlet diameter (120) of the elastic element (100) from the first and second axial end portions (112, 116) towards the annular leading portion (114), respectively.
5. The variable inlet diameter unit (10) of any one of the previous claims, wherein the elastic element (100) comprises a core portion (400) with at least one spring element (410) which is configured to deflect radially inwardly, upon movement of the sliding ring (200) from the first position towards the second position, thereby defining the substantially annular leading portion (114).
The variable inlet diameter unit (10) of any one of the previous claims, wherein the sliding ring (200) has a ring portion (210) at a first axial end (222) and a connecting portion (230) extending from the ring portion (210) towards a second axial end (226), the connecting portion (230) being configured to couple the sliding ring (200) with an actuation system (600), and optionally, wherein the ring portion (210) comprises a radially inwardly extending protrusion (213) having a substantially triangular cross-section, the protrusion (213) defining a truncated cone surface (213a) between an outer diameter (212) and an inner diameter (214), the protrusion (213) rejuvenating in an axial direction (22) towards the connecting portion (230) such that an annular flange surface (213b) is formed for exerting an axial compression force on the elastic element (100).
The variable inlet diameter unit (10) of claim 6, wherein the connecting portion (230) comprises a plurality of posts (232), each of which having a sliding pin (234) at the second axial end (226) to be coupled with an actuation system (600).
The variable inlet diameter unit (10) of any one of the previous claims, further comprising an actuation system (600) configured to move the sliding ring (200) axially between the first position and the second position, and optionally, wherein the actuation system (600) comprises a rotating ring (610) with at least one inclined groove (612) configured to engage with at least one sliding pin (234) of the sliding 6. 7. 8.ring (200) such that a rotation of the rotating ring (610) causes an axial movement of the sliding ring (200).
9. A variable inlet diameter unit (1010) for a compressor (50) comprising: a housing (1300); an elastic element (1100) of substantially tubular shape arranged within the housing (1300), wherein the elastic element (1100) defines an inlet diameter (1120) of a unit inlet (1122) and has an axial length (1110); a chamber (1200) formed between the elastic element (1100) and the housing (1300); and a port (1620) connected to the chamber (1200) and coupleable to a pressure supply unit (1600) to vary a pressure in the chamber (1200); wherein the variable inlet diameter unit (1010) is adapted such that, when the pressure in the chamber (1200) is increased via the port (1620) above a pressure in the unit inlet (1122), a predefined substantially annular leading portion (1114) of the elastic element (1100) is urged radially inwardly thereby continuously reducing the inlet diameter (1120).
10. The variable inlet diameter unit (1010) of claim 9, wherein a first axial end portion (1112) of the elastic element (1100) is coupled to a first axial housing end portion (1312) and a second axial end portion (1116) of the elastic element (1100) is coupled to a second axial housing end portion (1316).
11. The variable inlet diameter unit (1010) of claim 10, wherein, upon movement of the annular leading portion (1114) radially inwardly, a first transition portion (1113) of the elastic element (1100) is formed between the first axial end portion (1112) and the annular leading portion (1114), and a second transition portion (1115) of the elastic element (1100) is formed between the second axial end portion (1116) and the annular leading portion (1114), and optionally, wherein, when the pressure supplied to the chamber (1200) via the port (1620) is smaller or equal to the pressure in the unit inlet (1122), the first transition portion (1113) and the second transition portion (1115) have a substantially cylindrical shape, and wherein, upon increasing the pressure supplied to the chamber (1200) via the port (1620) increasingly exceeding the pressure in the unit inlet (1122), a respective shape of the first transition portion (1113) and the second transition portion (1115) is adapted such that the first transition portion (1113) and the second transition portion (1115) increasingly reduce the inlet diameter (1120) of the elastic element (1100) from the first and second axial end portions (1112, 1116) towards the annular leading portion (1114), respectively.
12. The variable inlet diameter unit (1010) of any one of the previous claims, wherein the elastic element (1100) comprises a core portion (1400) with at least one spring element (1410) which is configured to deflect radially inwardly, upon increasing the pressure in the chamber (1200) via the port (1620) above the pressure in the unit inlet (1122), thereby defining the substantially annular leading portion (1114), and optionally, wherein the core portion (1400) comprises a plurality of spring elements (1410) distributed circumferentially within the elastic element (1100).The variable inlet diameter unit (1010) of any one of the previous claims, further comprising a pressure supply unit (1600) coupled to the port (1620) for controlling and supplying pressure to the chamber (1200), and optionally, further comprising a valve (1610) coupled between the port (1620) and the pressure supply unit (1600).A compressor (50) comprising: a compressor housing (52) defining an inlet opening (52a) and an outlet (52b) with a volute (52c); an impeller rotatably arranged in the housing (52) between the inlet opening (52a) and the outlet (52b); and a variable inlet diameter unit (10; 1010) according to any one of the previous claims.A charging apparatus (40) comprising: a drive unit (60); a shaft (70); and a compressor (50) according to claim 14, wherein the compressor (50) is rotationally coupled with the drive unit (60) via the shaft (70). 13. 14. 15.