WO2010091973A1

WO2010091973A1 - Method and device for dynamic measurement of the imbalance of the rotor of a turbo charger basic unit

Info

Publication number: WO2010091973A1
Application number: PCT/EP2010/051216
Authority: WO
Inventors: Matthias Breitwieser; Dieter Thelen
Original assignee: Schenck Rotec Gmbh
Priority date: 2009-02-13
Filing date: 2010-02-02
Publication date: 2010-08-19
Also published as: JP5524645B2; DE102009008955B4; JP2010190212A; DE102009008955A1

Abstract

The invention relates to a device for dynamic measurement of the imbalance of the rotor (6) of a turbo charger basic unit (4), wherein the rotor (6) has a turbine wheel (7), a compressor wheel (8) and a shaft that is housed in a central housing (5) of the turbo charger basic unit (4), comprising a compressor housing (2) designed to accommodate the compressor wheel (7) and a turbine housing (1) for accommodating the turbine wheel (7). The compressor housing (2) is mounted on a machine bed (3) and can be moved by means of weak springs in at least two spatial directions and has a tensioning device (23) for tensioning the central housing (5). The turbine housing (1) is removably fastened on the turbine side of the central housing (5) at a distance therefrom on the machine bed (3) allowing movements of the central housing (5) and the turbine wheel (7) in the at least two spatial directions and can be connected to a compressed air source for accelerating the rotor (6) by driving the turbine wheel (7) by compressed air.

Description

Method and apparatus for dynamically measuring the imbalance of the rotor of a turbocharger body group

The invention relates to a method and apparatus for dynamically measuring the imbalance of the rotor of a turbocharger body group, the rotor comprising a turbine wheel, a compressor wheel and a shaft mounted in a center housing of the turbocharger body group.

Exhaust-driven turbochargers have a rotor that rotates in operation at a very high speed of often more than 100,000 revolutions per minute and therefore must be very precisely balanced to avoid noise and excessive bearing loads. As a rule, the rotor consists of a shaft mounted in a bearing housing, which carries a turbine wheel at one end and a compressor wheel at the other end. The measurement of the imbalance of the rotor is made for accuracy reasons usually at a substantially normal operating speed corresponding angular velocity.

EP 0 426 676 B1 discloses a method of the type specified for the dynamic compensation of the imbalance of the high-speed rotor of an exhaust-driven turbocharger, in which the turbocharger center housing, in which the rotor is mounted, has a housing enclosing the turbine wheel and a compressor wheel is firmly connected and the unit thus formed by means of flexible bellows hoses, which engage the two housings, is movably mounted soft in a frame in all three spatial directions. Accelerometers are arranged on the housing parts, the acceleration signals of which are processed in conjunction with an optically measured phase angle for determining the size and position of the imbalance. Here, attached to the turbocharger middle housing housing parts affect the vibration behavior and thus the measurement of imbalance considerably. In another known from DE 10 2005 053 768 A1 method for dynamically measuring the imbalance of a high angular velocity rotating turbocharger rotor, which is mounted in a separate center housing, the center housing is attached to a turbine housing with interposition of resilient members such the middle housing can be moved relative to the turbine housing in three spatial directions, and the turbine wheel of the rotor is arranged in a working position suitable for driving in the turbine housing. The compressor wheel is covered with a cage hood for protection. To accelerate the rotor to a substantially normal operating speed, the turbine wheel of the rotor is driven with air. While the rotor rotates at different speeds and at a substantially normal operating speed, the measurement of the oscillations induced by an imbalance and the determination of the phase angle of the induced oscillations takes place relative to the angular position of the rotor in order to determine therefrom the imbalance of the rotor to be compensated. It has been found that the arrangement of the compressor wheel that does not correspond to the operating conditions affects the measuring accuracy.

The invention has for its object to provide a method of the type mentioned above, which allows an imbalance measurement of high accuracy under close-to-operation conditions and is easy to carry out. It is a further object of the invention to provide a device particularly suitable for carrying out the method.

The above object is achieved with respect to the method by the features specified in claim 1 and in terms of the device by the features specified in claim 3. Advantageous embodiments of the method are given in claim 2 and the device in claims 4 to 11.

According to the invention, the method for dynamically measuring the imbalance of the rotor of a turbocharger body group, wherein the rotor comprises a Turbine, having a compressor wheel and a shaft which is mounted in a center housing of the turbocharger body group, the steps: rigidly connecting the center housing with a compressor housing surrounding the compressor housing, which is mounted by means of soft springs in at least two spatial directions movable on a machine bed .

Arranging a turbine housing surrounding the turbine wheel on the turbine side of the middle housing in a movement of the center housing and the turbine wheel in the at least two spatial directions permitting spacing thereof and securing the turbine housing to the machine bed,

Connecting the turbine housing to a source of pressurized air and accelerating the rotor by driving the turbine wheel with compressed air to a substantially normal operating speed, measuring the imbalance induced vibrations on the compressor housing or on the center housing while the rotor is rotating at a substantially normal operating speed;

Determining the phase position of the vibrations induced by imbalance to the angular position of the rotor at the measuring speeds at which the vibrations induced by imbalance are measured, using the measured imbalance-induced vibrations and the phase position to determine the imbalance of the rotor to be compensated.

The method according to the invention makes it possible to measure the imbalance of a turbocharger rotor under operating conditions, ie under load. Nevertheless, the oscillatory mass is advantageously small, so that large vibration amplitudes can be achieved. Vibrations and resonances, which affect the measurement accuracy, are largely avoided. In contrast to the turbine housing, the compressor housing does not need any connections because the air can be sucked out of the atmosphere and flowed freely back into it. The device for carrying out the method is inexpensive because only one clamping device for clamping the center - A -

housing is needed. Equally simple is the handling when inserting or removing the turbocharger fuselage group.

According to the invention, an advantageous apparatus for dynamically measuring the imbalance of the rotor of a turbocharger body group, wherein the rotor comprises a turbine wheel, a compressor wheel and a shaft mounted in a center housing of the turbocharger body group, comprises a compressor wheel adapted to receive the compressor wheel Compressor housing, which is mounted by means of soft springs in at least two spatial directions movable on a machine bed and having a clamping device for clamping the center housing, and formed for receiving the turbine wheel turbine housing on the turbine side of the center housing in a movement of the center housing and the Turbine wheel in the at least two spatial directions permitting distance of these on the machine bed can be fastened and which is connected to accelerate the rotor by driving the turbine wheel with compressed air to a compressed air source. The inventive device is simple and inexpensive to produce and allows a measurement of the rotor imbalance with high accuracy.

The invention will be explained in more detail by means of embodiments which are illustrated in the drawing. Show it

Figure 1 shows schematically the design of an unbalance measuring device with arranged therein turbocharger body group, Figure 2 shows a modified embodiment of the turbine housing for a

Unbalance measuring device and Figure 3 shows an enlarged section X of the device according to Figure 2.

The unbalance measuring device shown in Figure 1 comprises a Turbinenge- housing 1, a compressor housing 2 and a machine bed 3, of which only the relevant attachment points are shown. The turbine housing 1 has a turbine chamber 10, a surrounding spiral channel 11 and a central outlet channel 12. On the compressor housing 2 facing side of the turbine housing 1, a limiting device 13 is arranged, which surrounds the opening for the insertion of a turbine wheel in the turbine chamber 10 and preferably consists of a shock-absorbing material.

The compressor housing 2 has, on the side facing the turbine housing 1, a compressor chamber 20 with a central inlet channel 21 and a spiral channel 22 which adjoins the radially outer edge of the compressor chamber 20. The compressor housing 2 is further provided with a clamping device 23 with radially movable clamping elements 24. The compressor housing 2 is supported and held both in the radial and in the axial direction by means of soft springs 25 on the machine bed 3. In order to detect vibrations, vibrating receivers 26, 27 are mounted on the compressor housing 2, which can absorb vibrations in the axial and radial directions.

The turbine housing 1 is connected to the machine bed 3 by rigid attachment means. The fastening means may be detachable and designed to be movable in the axial direction after release, in order to be able to change the distance between the turbine housing 1 and the compressor housing 2 to the degree required for the imbalance measurement or for inserting and removing. Alternatively, the storage of the compressor housing 2 may be formed with a mobility required for changing the distance.

The unbalance measuring device described for receiving a turbocharger body group 4 set up, which comprises a center housing 5 with a rotor 6 mounted therein, which has at its one end a turbine wheel 7 and at its other end a compressor wheel 8. The middle housing 5 has on the compressor wheel 8 side facing a plate-shaped flange 9, on which the turbocharger body group 4 can be stretched. For unbalance measurement, the turbocharger body group 4, as shown in the drawing, with the compressor 8 inserted into the compressor housing 2 and clamped by means of the clamping device 23 to the flange 9. As a result, the middle housing 5 is rigidly connected to the compressor housing 2 and the outer edge of the flange 9 bears tightly against the compressor housing 2.

For the onset of the turbocharger fuselage group 4 in the device and attaching to the compressor housing 2, the turbine housing 1 is previously released from the machine bed 3 and axially removed from the compressor housing 2 until the necessary space for insertion between the turbine and compressor housing. After tightening the turbocharger body group 4 to the compressor housing 2, the turbine housing 1 is returned to the position shown in the drawing and attached to the machine bed 3. In this position, the turbine housing 1 with respect to the turbine wheel 7 and with respect to the center housing 5 at such a distance that it does not come to a contact between the turbine housing 1 on the one hand and turbine wheel 7 and center housing 5 on the other hand due to the vibrations occurring during a measurement run. In addition, the limiting device 13, against which the middle housing 5 abuts before the turbine wheel 7 can contact the wall of the turbine chamber 10, protects against excessive oscillation amplitudes.

To measure an imbalance of the rotor 6, the turbine wheel 7 is driven by compressed air and the rotor 6 is accelerated to a speed substantially corresponding to its normal operating speed. To avoid blast noise, a flexible seal can be attached to the turbine housing 1, which bears sealingly against the middle housing 5.

By an existing imbalance of the accelerated rotor 6 oscillations are induced in the oscillating mass of turbocharger fuselage group 4 and compressor housing 2, with the help of the vibration sensor 26, 27 at different speeds are measured. At the same time, the respective phase position of the measured vibrations with respect to the rotor 6 is determined by a rotary encoder. From the measured values, the angular position and size of the imbalance to be compensated is then calculated with the aid of an electronic computer.

The unbalance measuring device shown in Figure 2 corresponds in its basic structure of the unbalance measuring device according to Figure 1, but it has a modified turbine housing 101. This modification takes into account the fact that turbochargers often have between the turbine wheel 7 and the center housing 5 as a heat shield disc-shaped heat plate 29, which is centered and fixed axially only when fixedly mounted on the center housing 5 turbine housing. With the turbine housing removed, the heat sheet 29 is loose, thereby preventing the rotor 6 from rotating freely. So that in the unbalance measurement, the heat sheet 29 can not grind on the rotor 6 and in particular on the turbine wheel 7, a fixation of the heat plate 29 is absolutely necessary.

In the unbalance measuring device according to the invention, a rigid connection between the middle housing 5 of the turbocharger body group 4 and the turbine housing 101 is not present, but a sufficiently large gap ensures that the turbine side of the turbocharger body group 4 swing freely within the turbine housing 101 can. In order for this to be possible even when the heat sheet 29 is present, the turbine housing 101 shown in FIG. 2 and partially in FIG. 3 has a holding element 30, by means of which the heat sheet 29 can be fastened to the middle housing 5. The holding element 30 consists of an annular disc 31 which carries on one side an axially extending, annular spring 32. The spring 32 has a funnel-shaped insertion opening, which is followed by a bead-shaped clamping area inside. The holding element 30 is arranged in an annular recess 33 of a lid 34, which is fastened on the compressor housing 2 facing side to the turbine housing 101. The recess 33 is adjacent to a the lid 34 penetrating opening 35, through which the turbine wheel 7 is inserted into the turbine housing 101. In the recess 33, the cover 34 has a flat, radially extending stop surface 36, a conical surface 37 separated therefrom by a recessed step, and an axial abutment surface 38 adjoining it. A radially inwardly projecting collar 39 bounds the recess 33 on the side facing the compressor housing and holds the holding element 30 in the recess 33.

As the turbocharger body group 4 is axially inserted into the turbine housing 101, the heat plate 29 is aligned concentrically with the rotor axis through the funnel-shaped insertion opening of the spring 32. The spring 32 then slips with its clamping area on the centering collar of the center housing 5, wherein it is radially expanded. By expanding a radial spring force is generated by which the spring 32 of the holding member 30 is frictionally held on the centering collar of the center housing 5. The axial insertion of the turbocharger body group 4 is continued until the holding member 30 is axially supported on the stop surface 36 and the heat sheet 29 is pressed by the holding member 30 fixed to the center housing 5. The turbine chamber 10 of the turbine housing 101 is dimensioned so that the turbine wheel 7 does not touch the turbine housing 101 in this position of the turbocharger body group 4.

For the subsequent measurement run, the turbocharger fuselage group 4 is moved out of the turbine housing 101 by returning it again. As a result, the holding element 30 passes in the recess 33 in a central position in which it has on all sides a distance from the recess 33 delimiting surfaces, namely the abutment surfaces 36, 38 of the conical surface 37 and the collar 39. In this way, free swinging of the turbocharger trunk group 4 and of the retaining element 30 fixed thereto is possible without rubbing. The disk 31 of the resonating support member 30 holds the heat sheet 29 pressed against the center housing 5. larger Vibration amplitudes are limited during the measuring run by radial abutment of the disc 31 of the Haleelements 30 to the stop surface 38. Scrubbing of the turbine wheel 7 due to excessive vibration amplitudes is thereby avoided.

Between the disc 31 and the radially inner edge of the conical surface 37, a flexible sealing ring 40 is arranged, which has no sealing effect in the position shown. At high measuring speeds and correspondingly high pressures in the spiral channel 11, the sealing ring 40 is pressed radially outwards, whereby it rests against the disc 31 and the conical surface 37 and seals the gap between the disc 31 and the conical surface 37. As a result, excessive gap losses and associated noise are prevented.

After the measurement run, the turbocharger body group 4 is pulled out of the turbine housing 101 by moving apart from turbine housing 101 and compressor housing 2, so that it can be removed from the unbalance measuring device after the tensioning device 23 has been released. In this process, the holding element 30 is held by the collar 39 in the recess 33, so that the spring 32 slips off from the centering collar of the center housing 5. The retaining element 30 thus remains in the recess 33 of the turbine housing 101 and is therefore again ready for the fixation of the heat plate of the next turbocharger body group.

Claims

A method of dynamically measuring the rotor imbalance of a turbocharger body group, wherein the rotor comprises a turbine wheel, a compressor wheel, and a shaft disposed in a center housing

Turbocharger body group is mounted, characterized by the steps: rigidly connecting the center housing (5) with a compressor wheel (8) surrounding the compressor housing (2) by means of soft springs (25) in at least two spatial directions movably mounted on a machine bed (3) is

Arranging a turbine housing (1) surrounding the turbine wheel (7) on the turbine side of the middle housing (5) in a movement of the center housing (5) and the turbine wheel (7) in the at least two spatial directions permitting distance from them and securing the turbine housing (7) on the machine bed (3), connecting the turbine housing (1) to a compressed air source and accelerating the rotor (6) by driving the turbine wheel (7) with compressed air to a substantially normal operating speed, measuring the imbalance induced vibrations on the compressor housing (2) or on the center housing (5) while the rotor (6) rotates at a substantially normal operating speed, determining the phase position of the vibrations induced by unbalance to the angular position of the rotor (6) at the measuring speeds at which the vibrations induced by unbalance are measured,

Using the measured vibrations induced by imbalance and the phase position to determine the imbalance of the rotor (6) to be compensated.

2. The method according to claim 1, characterized in that the oscillation amplitudes of the center housing (5) by means of a turbine on the turbine Housing (1) arranged limiting device (13) are limited to a the rubbing of the turbine wheel (7) preventing measure.

3. A device for dynamically measuring the imbalance of the rotor of a turbocharger body group, wherein the rotor is a turbine wheel, a

Compressor and having a shaft which is mounted in a middle housing of the turbocharger body group, with a formed for receiving the compressor wheel compressor housing which is mounted by means of soft springs in at least two spatial directions movable on a machine bed and having a clamping device for clamping the center housing, characterized by a for receiving the turbine wheel (7) formed turbine housing (1) on the turbine side of the center housing (5) in a movement of the center housing (5) and the turbine wheel (7) in the at least two spatial directions permitting distance from the machine bed (3) is attachable and that is for accelerating the rotor (6) by driving the turbine wheel (7) by means of compressed air to a compressed air source connected.

4. Apparatus according to claim 3, characterized in that on the turbine housing (1) a limiting device (13) for limiting the oscillation amplitudes to a the rubbing of the turbine wheel (7) preventing measure is arranged.

5. Device according to one of claims 3 or 4, characterized in that the turbine housing (1) has a flexible seal is attached, which is sealingly connectable to the central housing (5).

6. Device according to one of claims 3 to 5, characterized marked, that on the compressor housing (2) vibration sensor (26,

27) are arranged.

7. Device according to one of the preceding claims, characterized in that the turbine housing (1) and the compressor housing (2) in the axial direction are adjustable relative to each other.

8. Device according to one of the preceding claims, characterized by a holding element (30) through which a between the turbine wheel (7) and the middle housing (5) arranged as heat protection, disc-shaped heat plate (29) on the central housing (5) is firmly held.

9. Apparatus according to claim 8, characterized in that the holding element (30) between stops in a recess (33) of the turbine housing (101) is arranged axially and radially movable.

10. Device according to one of claims 8 or 9, characterized marked, that the holding element (30) has a spring (32) which is adapted to engage around a centering collar of the center housing (5) with radial spring force.

11. Device according to one of claims 8 to 10, characterized marked, that in the recess (33) a sealing element (40) is arranged, which is movable depending on the pressure in the turbine housing in a position in which it sealingly on the Wall of the recess (33) and on the holding element (30) rests.