WO2018178385A1

WO2018178385A1 - Compressor of an exhaust gas turbocharger

Info

Publication number: WO2018178385A1
Application number: PCT/EP2018/058395
Authority: WO
Inventors: Marius Banica; Heinz-Jürgen FELD
Original assignee: Abb Turbo Systems Ag
Priority date: 2017-03-31
Filing date: 2018-04-03
Publication date: 2018-10-04
Also published as: DE102017107014A1

Abstract

The invention relates to a compressor (100) of an exhaust gas turbocharger, comprising a compressor wheel (110) that can rotate about an axis (111), a main flow channel (120) for supplying a medium to be compressed to the compressor wheel (110), an outer compressor housing (125), and an element (130) arranged radially between the compressor wheel (110) and the compressor housing (125). In the installed state, the element (130) is configured for forming an annular stabiliser channel (135) surrounding the main flow channel, wherein a number (V) of V≥ mco + jB identical struts (140) are provided in the stabiliser channel (135), which are arranged periodically around the perimeter, wherein mco is the first circulating mode, wherein j is the order of the harmonics, and wherein B is the number of rotor blades of the compressor wheel.

Description

COMPRESSOR OF A DEVICE BOLDER

TECHNICAL AREA

The invention relates to the field of exhaust gas turbochargers for supercharged internal combustion engines. In particular, the invention relates to a compressor of such an exhaust gas turbocharger with a circulating chamber delimited from the main flow.

TECHNICAL BACKGROUND

Nowadays exhaust gas turbochargers are used by default for the performance of an internal combustion engine, with a turbine in the exhaust system of the internal combustion engine and with one of the internal combustion engine upstream compressor. The exhaust gases of the internal combustion engine are thereby relaxed in the turbine. The work thus obtained is transmitted by means of a shaft to the compressor, which compresses the internal combustion engine supplied air. By using the energy of the exhaust gases to compress the air supplied to the combustion process in the internal combustion engine, the combustion process and the efficiency of the internal combustion engine can be optimized.

Typically, an exhaust gas turbocharger on a compressor, which is rotatably mounted in a housing. Furthermore, the housing usually has an inlet channel in which an inner wall is inserted, which on the one hand forms the main channel contour and on the other hand limits an annular circulation chamber surrounding the main channel. The interior of the annular chamber, for example, through an opening with the Compressor inlet and be connected in the region of the compressor wheel through a ring slot in the contour wall of the annular chamber with the inlet channel. In this case, the contour wall can be held concentrically via support ribs to the housing. The envisaged in compressors of this kind annular chamber is a so-called map-stabilizing measure. In this case, prior to reaching the compressor pumping limit, a recirculation of the flow from the compressor wheel back into the inlet channel in front of the compressor wheel, take place, whereby the compressor wheel sees an apparently higher throughput. In the operating area near the compressor plug boundary, the annular slot is used by the flow as an additional inlet. So there is no recirculation instead, which has the desired shift the Stopfgrenze to higher throughputs result.

The desired map expansion of the compressor is purchased in addition to loss of efficiency and often by inadmissible noise and vibration development. Responsible for such vibration excitations in the blades may include the support ribs, with which the inner wall of the annular chamber may be attached, for example, to the housing. Accordingly, the known from the prior art compressor, in particular compressors with circulation chambers, certain disadvantages in terms of their noise and vibration development. Therefore, the object of the present invention is to provide a compressor which is improved in this respect, ie has the lowest possible noise and vibration development. SUMMARY OF THE INVENTION

To solve the above problem, a compressor of an exhaust gas turbocharger according to the independent claim 1 is provided. Further aspects, advantages and features of the present invention can be found in the dependent claims, the description and the enclosed figures.

According to one aspect of the invention, a compressor of an exhaust gas turbocharger is provided. The compressor includes a compressor wheel rotatable about an axis, a main flow passage for supplying a medium to be compressed to the compressor wheel, an outer compressor housing, and an element, particularly a housing insert, disposed radially between the compressor wheel and the compressor housing. The element, in particular the housing insert, is configured to form an annular, surrounding the main flow channel stabilizer channel when installed. In the stabilizer channel there are provided a number V of struts identical to V> m _co + B arranged circumferentially, where m _{co is} the absolute minimum order of all non-propagating acoustic modes at the first sheet pass frequency, and B is the number of rotor blades the compressor wheel is.

Thus, a compressor is provided by the compressor according to the invention, which has a lower noise and vibration development compared to known compressors. In particular, the compressor according to the invention allows the restoration of a simple acoustic field, so that wall-mounted silencer (WSD) can advantageously be installed. Thus, with the embodiments of the compressor of the present invention described herein, a compressor is provided that can be made quieter, cheaper, lighter, more efficient, and more compact than known in the art Compressor.

According to a further aspect of the invention, an exhaust gas turbocharger with a compressor according to one of the embodiments described herein is provided, so that advantageously an improved exhaust gas turbocharger can be provided. In particular, an exhaust gas turbocharger can be provided which can be made quieter, cheaper, lighter, more efficient and more compact than exhaust gas turbochargers known from the prior art.

BRIEF DESCRIPTION OF THE FIGURES

In addition, the invention will be explained with reference to embodiments shown in FIGS form, which results in further advantages and modifications. Hereby shows:

Figure 1 is a schematic isometric sectional view of a section of a compressor according to embodiments described herein;

Figure 2a is a schematic representation of a first position of the im

Main flow channel disposed rotatable compressor wheel relative to arranged in the stabilizer channel struts;

Figure 2b is a schematic representation of a second position of the im

Figure 3 is a schematic representation of an axial frontal

A sectional view of a section of a stabilizer channel of a compressor according to an embodiment described herein,

Figure 4 is a schematic representation of a radial plan view of a Section of a stabilizer channel of a compressor according to another embodiment described herein,

Figure 5 is a schematic representation of the arranged in a stabilizer channel struts according to another embodiment of the compressor described herein; and

Figures 6a-6d are schematic representations of possible

Cross-sections, arranged in a stabilizer channel struts according to further embodiments of the compressor described herein.

DETAILED DESCRIPTION OF THE FIGURES

1 shows a schematic isometric sectional view of a section of a compressor 100 of an exhaust gas turbocharger according to embodiments described herein. The compressor may for example be a radial compressor, as shown by way of example in FIG. However, the compressor embodiments described herein are not limited to a radial compressor. In particular, the embodiments of the compressor described herein can also be used in an axial compressor.

As shown by way of example in FIG. 1, the compressor 100 comprises a compressor wheel 110 rotatable about an axis 111, a main flow passage 120 for supplying a medium to be compressed to the compressor wheel 110, an outer compressor housing 125, and an element 130, in particular one Housing insert, which is arranged radially between the compressor 110 and the compressor housing 125. As shown by way of example in FIG. 1, the element 130, in particular the housing insert, is typically configured in such a way as to be annular when installed and surrounding the main flow passage Stabilizer channel 135 to form. In this connection, it should be noted that an annular stabilizer channel means a channel which forms an annular structure arranged around the main flow channel. The annular structure may have any inner contour wall geometry. For example, the stabilizer channel may be annular, with one or both inner contour walls (ie the radially inner contour wall of the stabilizer channel and / or the radially outer contour wall of the stabilizer channel) may be wavy, or may have a differently structured inner contour wall geometry.

According to embodiments of the compressor 100 described herein, in the stabilizer channel 135 there are provided a number V of struts 140 identical to V> m _co + B which are circumferentially arranged periodically. In this case, m _co corresponds to the smallest circumferential order of all non-propagatable acoustic modes, and B corresponds to the number of rotor blades of the compressor wheel.

Thus, by the embodiments described herein, and in particular by the provision of a minimum number of identical circumferentially arranged struts in the stabilizer channel, an improved compressor is provided which, as compared to compressors known in the art, has less noise and vibration development , For example, the minimum number Vmin of the identical struts V _{m can be} in> 23. In this way, the embodiments of the compressor according to the invention described herein advantageously make it possible to restore a simple acoustic field, so that optionally wall-mounted silencers (WSD) can advantageously be installed in the main flow channel. Accordingly, with the embodiments of the compressor according to the invention described herein, a compressor is provided which can be made quieter, cheaper, lighter, more efficient and more compact than currently known compressors. As shown by way of example in Figure 1, the stabilizer channel 135 is formed in the interior of the compressor housing 125 as an annular circulation space which radially encloses the main flow channel and which extends from the intake 113 to an at least partially circulating circulation opening 114 in the region of the blades of the compressor wheel 110 extends. Typically, the circulation space is opened via two openings to the main flow channel. Upstream of the compressor wheel can be arranged a radial inlet opening (not shown) and downstream of the leading edge of the compressor wheel and in the overlap area to the inlet, the circulation opening 114 may be arranged. Thus, the stabilizer passage 135 is aerodynamically connected to the main flow passage 120.

Between the peripheral openings of the circulation space is delimited by an annular contour wall 115 against the main flow channel, as shown by way of example in Figure 1. The contour wall 115 can be, for example, a wall of the element 130, in particular of the housing insert, which is designed to form the annular, the main flow channel surrounding stabilizer channel 135 in the installed state. As shown in Figure 1, the struts 140 are typically with a surface opposite the contour wall 115, i. an inner wall of the stabilizer channel connected.

In particular, the stabilizer channel 135 may be designed to be axisymmetric, for example symmetrically about the axis 111 of the rotatable compressor wheel 110. In other words, the stabilizer channel 135 may be designed to provide an axisymmetric flow. Form recirculation channel, wherein the flow recirculation channel is interrupted by regularly arranged, equally spaced in the circumferential direction, identical struts.

For example, arranged in the stabilizer channel 135 struts 140 may be integral with the element 130, in particular the housing insert executed. In other words, the strut-comprising element 130, in particular the housing insert, may be made in one piece, e.g. be executed as a casting.

According to an embodiment that can be combined with other embodiments described herein, all circumferential spacing between adjacent struts of the number V of struts 140 are identical. Furthermore, the struts 140 may be arranged symmetrically about the axis 111 of the rotatable compressor wheel 110, as shown by way of example in FIG. 1. Such an embodiment may be particularly advantageous in terms of a lower noise and vibration development.

For a better understanding of the embodiments described herein, the theory underlying the invention will be discussed briefly below. For explanatory purposes, two different positions of the arranged in the main flow channel rotatable compressor wheel 110 are shown relative to arranged in the stabilizer channel struts 140 in Figures 2a and 2b schematically. In particular, FIG. 2a shows the rotor blades 112 of the compressor wheel 110 in a first position (t, Θ) and FIG. 2b shows the rotor blades 112 of the compressor wheel 110 in a second position (t + At, Θ + ΔΘ). For simplicity, only three rotor blades of the compressor wheel 110 and seven struts 140 arranged in the stabilizer channel are shown in FIGS. 2a and 2b. The point O corresponds to an observation point and Ω corresponds to the rotational speed of the compressor wheel in revolutions per second.

As can be seen from Figures 2a and 2b, the compressor moves in a rotation about the axis of rotation of a first position PI at a first time t and a first angle Θ to a second position P2 at a second time t + At and a second angle Θ + ΔΘ. Due to the circumferential periodic arrangement of the struts 140, the observation point O experiences the same pressure in the first position PI and in the second position P2.

The acoustic field in a channel of circular cross-section is described by the wave equation in cylindrical coordinates whose solutions are infinite sums of Bessel functions. If you set up the pressure field for position 1 and equate it to the pressure field in position 2, you get the following equation:

Where B corresponds to the number of rotor blades of the compressor wheel, k _x corresponds to the axial wave number, x corresponds to the axial coordinate, A _mn corresponds to the wave amplitude, j corresponds to the order of the harmonics, i denotes the complex notation, m corresponds to the circumferential order of acoustic mode, where m is an arbitrary natural number may be (including 0), J _m represents the Bessel function of the first kind of order m, and o _mn with n> 0, the (n + l) th root of the first derivative of J _m .

From this equation it follows that only acoustic modes of Circumference m = k- V + jB can be excited, where k is any natural number (including 0) and V represents the number of struts. This is also known as the Tyler-Sofrin Rule. Without a stabilizer channel, also called recirculation channel, the dominating mode is typically of order (jB, 0). The dominating tonal frequencies are referred to as the fundamental (j ^' = 1) blade passing frequency (BPF = ΒΩ) and their harmonics) BQ of the order (j-) with j> 1.

In practice, the highest frequency of interest is determined by fmax = j -i--Q _m a _X , where Q _{max is} typically the maximum speed. If the maximum frequency f _max thus determined exceeds the audible range, an alternative possibility would be to choose a maximum frequency of fmax = 20 kHz. For a given Einströmungskanalradius Ro, a static temperature T, a ratio of the specific heat of the working gas γ, volume flow V, the main flow channel cross-sectional area A = 7r Ro ^2, gas constant R, sound velocity c, and the Mach number Ma, a certain mode propagates (m, n) not satisfied if the root of the first derivative of J _{m is} greater than the limit:

2nRof _{ma / e}

The variables of the equations listed above may be selected according to the design of the compressor. In order to adjust the acoustic field structure in the main flow channel, the acoustic mode of the absolute smallest order of magnitude (m _co , 0) can be identified, for which the corresponding value of G _mC o, o is greater than Gco.

According to the embodiments described herein, the Number V of struts provided in the stabilizer channel are selected according to the formula V> m _co + jB. In this case, m _co corresponds to the smallest circumferential order of all non-propagatable acoustic modes, j corresponds to the order of the harmonics, and B corresponds to the number of rotor blades of the compressor wheel.

Thus, advantageously all except the k = O mode (ie the modes of order (j -B, n)) in the range above the threshold value G _co and thus not capable of propagation. As a result, only the typically dominating mode (j -B, 0) and possibly some modes of order types (j -B, n> 0) remain. Thus, with the embodiments described herein, an acoustic situation can be established that substantially corresponds to the acoustic situation of a compressor without a recirculation channel. This has the advantage that a simple acoustic field can be produced for the embodiments described herein, so that additional acoustic liners or acoustic resonators (generally WSD) can be effectively used. For example, in the embodiments described herein, acoustic liners or acoustic resonators may be disposed in an area facing the main flow channel. According to an embodiment that may be combined with other embodiments described herein, the struts 140 may be circumferentially tilted at an angle α, as exemplified in FIG. Alternatively or additionally, the struts 140 may be curved in the circumferential direction, as shown by way of example in FIG. This can have an advantageous effect on a lower noise and vibration development.

According to another embodiment, which may be combined with other embodiments described herein, the struts may be relative to the direction of the axis 111 of the rotatable compressor wheel 110 be inclined by an angle ß, as shown by way of example in Figure 4. This can lead to an alternative or additional advantageous reduction of the noise and vibration development.

According to a further embodiment, which can be combined with other embodiments described herein, the struts 140 may be arranged such that in the axial direction of view between adjacent struts a fluid free space 150 is provided for the medium, as shown for example in FIG. 5 is shown. In other words, the struts 140 may be arranged circumferentially so as not to overlap in the axial direction. Alternatively or additionally, the struts may be arranged such that they are tilted in the direction of the axis (111) of the rotatable compressor wheel (110).

In the figures 6a - 6d, various possible cross sections of the struts are shown. For example, the struts 140 may have a circular cross section or an elliptical cross section, as shown by way of example in FIGS. 6a and 6b. Alternatively, the struts 140 may have a triangular cross-section or a diamond-shaped cross-section, as shown by way of example in FIGS. 6c and 6d. The strut cross sections illustrated in FIGS. 6a-6d can extend over the entire length of the strut. Alternatively, the strut cross sections shown in FIGS. 6a-6d may be limited to a certain length range of the struts, for example, the struts may be configured such that a circular cross section merges into an elliptical cross section.

Although Figure 1 shows a radial compressor, the present invention, as mentioned above, is not limited to a radial compressor, but can also be applied to axial compressor. For example, an axial compressor may also be as described herein Element, in particular a housing insert having a stabilizer channel with a number V of V> m _co + jB identical struts, which are circumferentially arranged periodically.

Accordingly, in the embodiments described herein, in the design of the compressor, in particular in the design of the struts in the stabilizer channel, advantageously structures in the main flow channel are taken into account, so that an optimization of the compressor with respect to a reduction of noise and vibration development is made possible. In other words, in the selection of the strut number V arranged in the stabilizer channel according to the formula V> m _co + jB, the structures in the secondary flow field (ie in the stabilizer channel) are advantageously linked to the structures in the main flow channel. In contrast, in the prior art, the number of struts is determined solely for structural mechanics considerations. This leads to a scattering of the acoustic modes and a destruction of the otherwise simple acoustic field, which can be substantially prevented in the embodiments described herein.

Accordingly, by the use of a radial or axial compressor described herein advantageously, an exhaust gas turbocharger may be provided which is quieter, cheaper, lighter, more efficient and more compact than currently known exhaust gas turbochargers.

LIST OF REFERENCE NUMBERS

100 compressors

110 compressor wheel

111 rotation axis of the compressor wheel

112 rotor blades

113 intake area

114 Circulation opening

115 annular contour wall

120 main flow channel

125 compressor housing

130 element / housing insert

135 stabilizer channel

140 struts

150 flow clearance

Claims

A compressor (100) of an exhaust gas turbocharger, comprising:

a compressor wheel (110) rotatable about an axis (111), a main flow passage (120) for supplying a medium to be compressed to the compressor wheel (110),

an outer compressor housing (125), and

a member (130) disposed radially between the compressor wheel (110) and the compressor housing (125), wherein the member (130) is configured to form an annular stabilizer passage (135) surrounding the main flow passage when installed; the stabilizer channel (135) is provided with a number (V) of struts (140) identical to V> m _co + B arranged circumferentially, where m _{co is} the absolute minimum order of all non-propagating acoustic modes at the first sheet pass frequency, and B is the number of rotor blades of the compressor wheel.

A compactor (100) according to claim 1, wherein all circumferential distances between adjacent struts are equal to the number (V) of struts (140).

3. The compressor (100) according to claim 1 or 2, wherein the struts (140) are arranged symmetrically about the axis (111) of the rotatable compressor wheel (110).

4. compressor (100) according to one of claims 1 to 3, wherein the struts are tilted in the circumferential direction by an angle (a). A compressor (100) according to any one of claims 1 to 4, wherein the struts are inclined relative to the direction of the axis (111) of the rotatable compressor wheel (110) by an angle (β), and / or wherein the struts are arranged so that Struts in the direction of the axis (111) of the rotatable compressor wheel (110) are tilted.

The compressor (100) according to any one of claims 1 to 5, wherein the struts (140) are curved in the circumferential direction.

A compressor (100) according to any one of claims 1 to 6, wherein the struts (140) have a circular cross section or an elliptical cross section or a triangular cross section or a diamond shaped cross section.

Compressor (100) according to any one of claims 1 to 7, wherein the struts (140) are arranged such that in the axial direction of view between adjacent struts a medium for the flow unhindered clearance (150) is present.

A compressor (100) according to any one of claims 1 to 8, wherein the compressor is a radial compressor or an axial compressor.

Exhaust gas turbocharger, comprising a compressor according to any one of the preceding claims 1-9.