Compressor inlet with variable geometry

Abstract

Compressor inlet (1) with variable geometry, having a rotationally symmetric inlet pipe (2) with an inlet pipe inner shell surface (2a), a rotationally symmetrical flow body (3) with a flow body outer surface (3a), a trim control (5) which is displaceable coaxially within the inlet tube (2) along an axis of symmetry (2b) of the inlet tube (2) between a first switching position and a second switching position, and which has a radially outer limit (5a) and a radially inner limit (5b), an adjusting device (6) connected to the movable trim control (5), by means of which the movable trim control (5) is moved relative to the inlet pipe (2) and relative to the flow body (3) between the first switching position and the second switching position, wherein in the first switching position a flow cross-section in the area immediately in front of a compressor impeller (4) is determined by the inlet pipe inner shell surface (2a) and in the second switching position, by the radially inner boundary (5b).

Description

Technical area

[0001] The present invention relates to a variable geometry compressor inlet for compressors according to the features of claim 1. State of the art

[0002] To influence the performance map of compressors, adjustable devices are used at the compressor inlet to generate different flow patterns on the compressor wheel, shifting the surge limit toward lower flow rates or the plugging limit toward higher flow rates. The different flow patterns are intended to stabilize compressor operation at the limits and thus expand the operating range. The adjustable devices can be used for axial, radial, and diagonal compressors.

[0003] In particular, devices for changing the trim ratio are used to shift the surge line toward lower flow rates. This creates a narrower compressor inlet and achieves a predominantly axial flow onto the compressor wheel. Since this reduction in the trim ratio is detrimental with increasing flow rates, the devices are designed as adjustable devices, particularly adjustable trim devices.

[0004] In particular, devices for generating swirl flow are used to shift the stuffing line toward higher flow rates in order to optimize the angle of attack on the compressor wheel. Since this swirl flow is detrimental at low flow rates, the devices are designed as adjustable devices, particularly adjustable swirl generation devices.

[0005] These adjustable trim devices and adjustable spin generating devices are preferably combined in a common switchable device in order to keep the technical construction effort low.

[0006] Patent DE 10 2010 026 176 B4 discloses a variably adjustable cone for stabilizing the characteristic map of a compressor. In one illustrated embodiment, the cone is formed from several vanes arranged along the inner circumference of the inflow area, which are held in place by an elastic ring and a movable ring. A variable, tapered funnel shape is formed by the axial displacement of the ring. This changes the trim to stabilize the inflow.

[0007] From patent specification DE 10 2011 121 996 B4, a device for operating a compressor is known which has a variably constrictable element at the compressor inlet with a first flow cross-section and a second, variable flow cross-section spaced apart in the flow direction, and which can impart a swirling movement to the flow. For this purpose, additional flow guide elements are provided on the inner circumference of the element, which, on the one hand, are rotationally fixedly coupled to the compressor inlet in the region of the first flow cross-section and, as the second flow cross-section becomes increasingly smaller, twist or rotate relative to the first flow cross-section. In one embodiment, the flow guide elements are formed by fins and are in operative contact with drivers, which cause the twisting or rotating when the second flow cross-section initially decreases only slightly.

[0008] From patent specification DE 10 2013 018 368 B4, an adjustable swirl generation device for compressors is known, by means of which the flow through a compressor inlet onto a compressor wheel of the compressor is to be stabilized. For this purpose, several flow guide elements are positioned on the inner circumference of the compressor inlet, wherein the flow guide elements are rotatably and pivotably mounted in a housing by means of a first axis of rotation. For this purpose, the first axis of rotation is rotatably and pivotably mounted in a first bearing point and rotatably and displaceably mounted perpendicular to the longitudinal direction of the compressor inlet in a second bearing point spaced apart from the first bearing point in the flow direction. The swirl generation device provides a change in the trim ratio while simultaneously changing the swirl generation, wherein a decrease in the trim ratio results in an increase in swirl generation.

[0009] An adjustable air supply device for a compressor arranged in the intake tract of an internal combustion engine is known from published patent application DE 10 2014 006 463 A1. The air supply device has an air duct and an adjustable flow component designed as a cone for variably adjusting the flow cross-section in the air duct. Adjusting the flow component changes the flow cross-section of a flow path located on the outside of the flow component. Furthermore, the flow component is designed as a hollow body, forming an additional internal flow path that is independent of the flow path located on the outside of the flow component. However, swirl generation to stabilize the flow onto the compressor impeller in the area of ​​the surge line is not provided.

[0010] From the published patent application DE 10 2014 007 229 A1, an adjustable swirl generation device for compressors is known. The device comprises a plurality of pivotable flow guide elements arranged at a distance from the inner circumference of a compressor inlet, arranged in a circular manner relative to one another and primarily aligned in the longitudinal direction of the compressor. This forms a main channel and a secondary channel arranged coaxially with the main channel in the compressor inlet, wherein the secondary channel spatially surrounds the main channel and is separated from the main channel by the plurality of flow guide elements. Furthermore, a plurality of swirl generators are arranged in the secondary channel on the flow guide element or on the inner circumference of the compressor inlet. The swirl generation device provides a change in the trim ratio while simultaneously changing the swirl generation, wherein increasing the trim ratio results in an increase in swirl generation.

[0011] From published patent application DE 10 2018 110 557 A1, a compressor inlet with adjustable inlet geometry is known. It comprises a bypass flow section and a swirl section following the bypass flow section in the direction of the compressor flow, within which an axially displaceable sleeve is arranged. In the swirl section, flow guide element pockets are provided in the inner surface of the casing, within which flow guide elements are arranged that can pivot against a spring load. The flow guide elements are actuated by a continuous axial displacement of the sleeve from the bypass flow section to the swirl section, in that they are forced by the sleeve from the pivoted-out state back into the flow guide element pockets.

[0012] A compressor inlet with a switchable swirl generator is known from the subsequently published patent application DE 10 2019 121 754 A1. The compressor inlet is formed from an inlet pipe and a flow body arranged centrally in the inlet pipe. The swirl generator arranged in the compressor inlet has a plurality of guide elements displaceably arranged in the annular gap between the inlet pipe and the flow body, with at least one of the guide elements being designed as a co-swirl guide element and at least one of the guide elements being designed as a counter-swirl guide element. In the compressor inlet, a co-swirl guide element pocket is assigned to the co-swirl guide element and a counter-swirl guide element pocket is assigned to the counter-swirl guide element, so that in a first switching position only the co-swirl guide element and in a second switching position only the counter-swirl guide element is in operative contact with the compressor flow.In one embodiment, the co-swirl guide element pocket is arranged in the flow body and the counter-swirl guide element pocket is arranged in the inlet pipe.

[0013] An inlet adjustment mechanism for a compressor is known from patent US 9,777,640 B2. The inlet adjustment mechanism, comprising an axially elongated ring, is movable between an open position and a closed position in the air inlet of the compressor. In the open position, the radially outer surface of the ring is spaced from a tapered inner surface of the air inlet, allowing air to flow in an annular passage between the tapered surface and the ring. In the closed position, the ring abuts the tapered surface to close the annular passage.

[0014] Published patent application DE 10 2018 211 540 A1 discloses a compressor with a trim adjuster in the compressor's inlet channel. The trim adjuster allows a peripheral section of the compressor impeller's inlet cross-section to be covered to a variable extent. For this purpose, the trim adjuster comprises an axially displaceable flow guide device, which is part of an electromagnetic actuator. Object of the invention

[0015] The object of the invention is to provide an improved compressor inlet. Solution to the task

[0016] The object is achieved by a compressor inlet with variable geometry according to the features of patent claim 1. Advantageous further developments emerge from the subclaims and the exemplary embodiment. Description of the invention

[0017] The invention provides a variable-geometry compressor inlet advantageous according to the invention, which further stabilizes the flow onto a compressor impeller in the surge line region, thus expanding the operating range without significantly affecting the stuffing line. The variable geometry of the compressor inlet is achieved by a switchable change in the flow cross-section of the flow onto the compressor impeller immediately upstream of the compressor impeller, which changes the trim ratio and thus allows the surge line to be shifted toward lower flow rates.

[0018] The compressor inlet is formed by a primarily rotationally symmetrical inlet pipe with an inlet pipe inner surface and a primarily rotationally symmetrical flow body with an outer surface arranged centrally within the inlet pipe. An annular gap is formed between the inlet pipe inner surface and the flow body outer surface, creating an annular flow cross-section. For this purpose, the inlet pipe and the flow body are coaxially aligned with respect to their axis of symmetry. The inlet pipe and the flow body are tapered in the direction of the flow onto the compressor impeller. The taper of the inlet pipe and the taper of the flow body are arranged to at least partially overlap each other in the direction of the flow onto the compressor impeller.The flow onto the compressor impeller changes from a circular cross-section to an annular cross-section near the flow body. The flow cross-section decreases with decreasing distance from the compressor impeller, concentrating the flow onto the compressor impeller.

[0019] For the switchable variation of the flow cross-section of the inflow onto the compressor impeller, a mainly rotationally symmetrical trim adjuster with a radially outer boundary and a radially inner boundary is provided. The boundary here is understood to be an edge or a straight or curved surface, in particular a jacket surface. The trim adjuster, the inlet pipe and the flow body are coaxially aligned with one another with regard to their axis of symmetry. The trim adjuster is accommodated within the inlet pipe so that it can be moved between a first switching position and a second switching position along the axis of symmetry of the inlet pipe. The trim adjuster is designed as a simple annular orifice with an annular orifice outer edge and an annular orifice inner edge, or as a sleeve with a sleeve outer jacket surface and a sleeve inner jacket surface. In particular, the sleeve is designed as a straight sleeve or as a conical sleeve.Particularly advantageously, the sleeve can have a contour with a straight or curved profile of the radially outer boundary or the radially inner boundary. Preferably, the movable trim adjuster has the contour of a flow guide vane.

[0020] The movable trim adjuster is connected to an adjusting device by means of which the movable trim adjuster is displaced within the compressor inlet relative to the inlet pipe and relative to the flow body between a first switching position and a second switching position. The adjusting device has an adjusting drive and an adjusting gear. The adjusting gear is preferably designed as a lever, crank, coupling gear, or cam gear. The adjusting device can also be spring-loaded on one side for displacement, so that an automatic return to the first switching position or the second switching position occurs. The adjusting drive is integrated in the flow body. Alternatively, the adjusting drive is arranged outside the compressor inlet, in which case the adjusting gear extends at least via an access through the inlet pipe.The adjustment drive can be designed as an electrical, electromagnetic or pressure medium-operated actuator.

[0021] In the first switching position, the adjustable trim adjuster is positioned such that the flow cross-section in the area immediately upstream of the compressor impeller is determined by the inner surface of the inlet pipe. The adjustable trim adjuster is positioned far enough away from the compressor impeller that a fluidically relevant area is created between the adjustable trim adjuster and the compressor impeller. In this first switching position, the flow around the adjustable trim adjuster at its radially outer boundary.

[0022] In the first switching position, the movable trim adjuster surrounds the flow body. Preferably, the trim adjuster rests against the flow body. In particular, the radially inner boundary of the movable trim adjuster rests against the flow body's outer surface. Preferably, the flow body has a trim adjuster pocket within which the movable trim adjuster is accommodated in the first switching position. Preferably, the trim adjuster pocket is designed as a groove circumferential to the flow body, into which the trim adjuster is at least partially accommodated.

[0023] Because the movable trim adjuster is placed against the flow body in the first switching position or accommodated in the trim adjuster pocket, the flow around the movable trim adjuster and the flow body is directed radially outward, so that the movable trim adjuster presents little or no flow resistance. The outer contour of the movable trim adjuster is preferably designed in the form of a flow guide vane.

[0024] In the second switching position, the movable trim adjuster is positioned such that the flow cross-section in the area immediately in front of the compressor impeller is determined by the radially inner limit of the trim adjuster. The movable trim adjuster is positioned so close to the compressor impeller that there is no longer any fluidically relevant area between the movable trim adjuster and the compressor impeller. By moving the movable trim adjuster from the first switching position to the second switching position, the flow cross-section immediately in front of the compressor impeller is reduced, whereby the incoming flow is further centered. In the second switching position, the incoming flow flows through the movable trim adjuster at its radially inner limit. The inner contour of the movable trim adjuster is preferably designed in the form of a flow guide vane.This results in a reduction in the trim ratio.

[0025] When the adjustable trim adjuster is in a switching position between the first switching position and the second switching position, the adjustable trim adjuster is located centrally in the flow cross-section of the incoming flow, with the adjustable trim adjuster being flowed around both the radially outer boundary and the radially inner boundary. The contour of the adjustable trim adjuster, acting as a flow guide vane, is oriented toward the compressor impeller, thus supporting the alignment of the incoming flow toward the compressor impeller. Accordingly, a contour centerline is directed toward the compressor impeller, oriented toward the symmetry axis of the inlet pipe.

[0026] If the trim adjuster is designed as a sleeve, or in a particularly advantageous manner according to the invention as a conical sleeve, the movable sleeve is positioned in the first switching position such that the flow cross-section in the area immediately upstream of the compressor impeller is determined by the inlet pipe's inner surface. A fluid-mechanically relevant area is created between the movable sleeve and the compressor impeller. In this first switching position, the flow flows around the movable sleeve at its outer surface.

[0027] In the first switching position, the movable sleeve surrounds the flow body and preferably rests against the flow body. In particular, the inner surface of the sleeve rests against the outer surface of the flow body. Preferably, the movable sleeve is received in a sleeve pocket of the flow body in the first switching position.

[0028] Because the movable sleeve is placed against the flow body in the first switching position or is accommodated in the sleeve pocket, the flow around the movable sleeve and the flow body is directed at its outer surface, so that the movable sleeve presents little or no flow resistance. The outer contour of the movable sleeve is preferably designed in the form of a flow guide vane.

[0029] In the second switching position, the movable sleeve is positioned such that the flow cross-section in the area immediately upstream of the compressor impeller is determined by the inner surface of the sleeve, and there is no longer any fluidically relevant area between the movable sleeve and the compressor impeller. In the second switching position, the flow passes through the movable sleeve at its inner surface. The inner contour of the movable sleeve is preferably designed in the form of a flow guide vane.

[0030] In a switching position of the movable sleeve between the first switching position and the second switching position, the movable sleeve is located centrally in the flow cross-section of the incoming flow, with the movable sleeve being flowed around both via the outer sleeve surface and via the inner sleeve surface.

[0031] Preferably, the flow body is designed such that the end of the flow body facing the compressor impeller extends close to the compressor impeller, so that there is no longer any fluid-mechanically relevant area between the flow body and the compressor impeller.

[0032] A fluid-mechanically relevant area is understood here as a space within the compressor inlet whose dimensions are sufficiently large that a flow can develop within this space, which in turn has a significant influence on the flow onto the compressor impeller as a whole.

[0033] In a particularly advantageous manner according to the invention, a plurality of flow guide elements are additionally provided, distributed over the circumference of the compressor inlet, by means of which a swirling flow is imposed on the incoming flow. Accordingly, the flow guide elements are designed as swirl elements. These flow guide elements are rigidly positioned. Alternatively, the flow guide elements are accommodated within the inlet pipe so that they can be moved along the axis of symmetry and / or perpendicular to the axis of symmetry of the inlet pipe. For this purpose, the flow guide elements are connected to a separate adjustment device. In a particularly advantageous manner, the adjustment device of the movable trim adjuster and the adjustment device of the movable flow guide elements are combined into a common adjustment device.

[0034] In an extremely advantageous manner, at least one exhaust gas inlet is provided in the inlet pipe and / or in the flow body at the compressor inlet. The exhaust gas inlet is closed or opened by moving the adjustable trim adjuster. Example 1

[0035] By way of example, a first advantageous embodiment of a compressor inlet 1 according to the invention with variable geometry is shown here. The accompanying figures show: Fig. 1a a schematic representation of the compressor inlet 1 in a first switching position, Fig. 1b is a schematic representation of the compressor inlet 1 in an intermediate switching position, and Fig. 1c a schematic representation of the compressor inlet 1 in a second switching position.

[0036] The first advantageous embodiment of the compressor inlet 1 according to the invention with variable geometry, shown in Fig. 1a, Fig. 1b and Fig. 1c, is formed from a rotationally symmetrical inlet pipe 2 with an inlet pipe inner surface 2a and a rotationally symmetrical flow body 3 with an outer surface 3a. The inlet pipe 2, which tapers in the direction of flow toward a compressor impeller 4, and the flow body 3 are aligned coaxially with each other.

[0037] Furthermore, a coaxial within the inlet pipe 2 along a symmetry axis 2b of the inlet pipe 2 between a first switching position, shown in Fig. 1a, via an intermediate switching position, shown in Fig. 1b, and a second switching position, shown in Fig. 1c, a movable trim adjuster 5 with a radially outer limit 5a and a radially inner limit 5b is accommodated. The movable trim adjuster 5 is designed as a sleeve with a sleeve outer surface as the radially outer limit 5a and a sleeve inner surface as the radially inner limit 5b, has a contour of a flow guide vane and is oriented in the direction of the compressor impeller 4. The movable trim adjuster 5 is connected to an adjusting device 6 with an adjusting drive (not shown) and an adjusting gear 6a, by means of which the movable trim adjuster 5 is displaced within the compressor inlet 1 relative to the inlet pipe 2 and relative to the flow body 3 between a first switching position and a second switching position via the intermediate switching position.The adjustment drive is arranged outside the compressor inlet 1, wherein the adjustment gear 6a extends at least partially via an access 2c through the inlet pipe 2.

[0038] In the first switching position, shown in Fig. 1a, the movable trim adjuster 5 is accommodated within a trim adjuster pocket 3b in the flow body 3, with the incoming flow flowing around the movable trim adjuster 5 at the radially outer boundary 5a. The radially inner boundary 5b rests against the flow body outer surface 3a. The movable trim adjuster 5 is positioned far enough away from the compressor impeller 4 that a fluidically relevant area is created between the movable trim adjuster 5 and the compressor impeller 4. The flow cross-section in the area immediately upstream of the compressor impeller 4 is then determined by the inlet pipe inner surface 2a.

[0039] In the second switching position, shown in Fig. 1c, the movable trim adjuster 5 is positioned directly in front of the compressor impeller 4, so that the flow cross-section in the area directly in front of the compressor impeller 4 is determined by the radially inner boundary 5b, and there is no longer any fluidically relevant area between the movable trim adjuster 5 and the compressor impeller 4. The flow passes through the movable trim adjuster 5 at its radially inner boundary 5b.

[0040] In a switching position of the sliding trim control 5 between the first switching position and the second switching position, shown in Fig. 1b, the movable trim adjuster 5 is located centrally in the flow cross-section of the incoming flow, whereby the movable trim adjuster 5 is flowed around both via the radially outer boundary 5a and via the radially inner boundary 5b. Example 2

[0041] By way of example, a second advantageous embodiment of a compressor inlet 1 according to the invention with variable geometry is shown here. The accompanying figures show: Fig. 2a a schematic representation of the compressor inlet 1 in a first switching position, Fig. 2b a schematic representation of the compressor inlet 1 in an intermediate switching position, and Fig. 2c a schematic representation of the compressor inlet 1 in a second switching position.

[0042] The second advantageous embodiment of the compressor inlet 1 according to the invention with variable geometry, shown in Fig. 2a, Fig. 2b and Fig. 2c, has a flow body 3 in which the trim adjuster pocket 3b is designed as a groove running around the flow body 3. A trim adjuster pocket opening 3c is directed toward the compressor impeller 4, so that upon displacement of the displaceable trim adjuster 5 toward the first switching position, the displaceable trim adjuster 5 is at least partially inserted into the trim adjuster pocket 3b and is thus at least partially received in the trim adjuster pocket 3b. Example 3

[0043] By way of example, a third advantageous embodiment of a compressor inlet 1 according to the invention with variable geometry is shown here. The accompanying figures show: Fig. 3a a schematic representation of the compressor inlet 1 in a first switching position, Fig. 3b a schematic representation of the compressor inlet 1 in an intermediate switching position, and Fig. 3c a schematic representation of the compressor inlet 1 in a second switching position.

[0044] The third advantageous embodiment of the compressor inlet 1 according to the invention with variable geometry, shown in Fig. 1a, Fig. 1b and Fig. 1c, has a flow body 3, in which an end 3d of the flow body 3 facing the compressor impeller 4 extends close to the compressor impeller 4, so that there is no longer any fluid-mechanically relevant area between the flow body 3 and the compressor impeller 4.

[0045] In addition, the adjustment drive (not shown) is integrated in the flow body 3, wherein the adjustment gear 6a extends out of the flow body 3 at least via an output 3e. Example 4

[0046] By way of example, a fourth advantageous embodiment of a compressor inlet 1 according to the invention with variable geometry is shown here. The accompanying figures show: Fig. 4a a schematic representation of the compressor inlet 1 in a first switching position and Fig. 4b a schematic representation of the compressor inlet 1 in a second switching position.

[0047] The fourth advantageous embodiment of the compressor inlet 1 according to the invention with variable geometry, shown in Fig. 4a and Fig. 4b, has several flow guide elements 7 distributed over the circumference of the compressor inlet 1, by means of which a swirling flow is imposed on the inflow. The flow guide elements 7 are slidably accommodated within the inlet pipe 2 perpendicular to the symmetry axis 2b of the inlet pipe 2. For this purpose, the flow guide elements 7 are connected to a separate adjustment device (not shown). In the first switching position, shown in Fig. 4a, the flow guide elements are positioned in the incoming flow to impart a swirling motion to the incoming flow. In the second switching position, shown in Fig. 4b, the flow guide elements are not positioned in the incoming flow. List of reference symbols used 1 Compressor inlet 2 inlet pipe 2a Inlet pipe inner surface 2b Axis of symmetry of the inlet pipe 2 2c Access through inlet pipe 2 3 flow bodies 3a Flow body outer surface 3b Trim adjuster pocket 3c Trim adjuster pocket opening 3d End of flow body 3 3e Exit from the flow body 3 4 Compressor impeller 5 adjustable trim controls 5a radially outer limit of the trim adjuster 5 5b radially inner limit of the trim adjuster 5 6 Adjustment device 6a Variable speed gear 7 Flow guide element

Claims

[1] Compressor inlet (1) with variable geometry, comprising a rotationally symmetrical inlet pipe (2) with an inlet pipe inner surface (2a), a rotationally symmetrical flow body (3) with a flow body outer surface (3a), a trim adjuster (5) which is displaceable coaxially within the inlet pipe (2) along an axis of symmetry (2b) of the inlet pipe (2) between a first switching position and a second switching position and has a radially outer limit (5a) and a radially inner limit (5b), an adjusting device (6) connected to the displaceable trim adjuster (5), by means of which the displaceable trim adjuster (5) is displaced relative to the inlet pipe (2) and relative to the flow body (3) between the first switching position and the second switching position, wherein in the first switching position a flow cross-section in the area immediately in front of a compressor impeller (4) is determined by the inlet pipe inner surface (2a) and in the second switching position by the radially inner boundary (5b). [2] Compressor inlet (1) with variable geometry according to claim 1, characterized by that in the first switching position the movable trim adjuster (5) rests against the flow body (3). [3] Compressor inlet (1) with variable geometry according to one of the preceding claims, characterized by that the flow body (3) has a trim adjuster pocket (3b) within which the displaceable trim adjuster (5) is accommodated during the first switching position. [4] Compressor inlet (1) with variable geometry according to claim 3, characterized by that the trim control pocket (3b) is designed as a groove running around the flow body (3). [5] Compressor inlet (1) with variable geometry according to one of the preceding claims, characterized by that the movable trim adjuster (5) has a contour of a flow guide vane and is aligned in the direction of the compressor impeller (4).

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