Patent Description:
Fluid machines include a rotor that is supported for rotation therein. The rotor rotates to convert energy of a fluid into mechanical energy or vice versa. For example, vehicle turbochargers include a rotor that rotates within a housing. The rotor may be driven in rotation for boosting the performance of an internal combustion engine. More specifically, these devices can increase the engine's efficiency and power output by forcing extra air into the combustion chamber of an engine.

The rotor preferably may be supported for balanced rotation about a rotation axis. Undesirable vibration or other loads may be reduced if the rotor is sufficiently balanced. However, the balancing method may detrimentally affect the strength or other properties of the rotor. Furthermore, there may be insufficient access to the rotor for performing conventional balancing methods. Also, the balancing method may be difficult, inconvenient, labor-intensive, etc..

Thus, it is desirable to provide a rotor with improved balancing features. It is also desirable to provide a balancing method that accurately and precisely balances the rotor, and that maintains the integrity of the rotor. Furthermore, it is desirable to provide an improved balancing method that is convenient, accurate, and that increases manufacturing efficiency. Other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background discussion. Documents cited during prosecution include <CIT>; <CIT>; and <CIT>.

<CIT> discloses a rotor of a fluid machine comprising a wheel having a hub and a back disc extending radially away from the hub and terminating in a radial direction at an outer rim edge, the back disc having a front face and a back face, blades projecting from the front face of the back disc, an inter-blade area defined circumferentially between a first blade and a second blade, and wherein the wheel includes a first fillet at a transition between the inter-blade area and the first blade and the wheel includes a second fillet at another transition between the inter-blade area and the second blade, and a balancing mark on the wheel and within the inter-blade area, the balancing mark being elongate and having a first end and a second end, the first end and the second end being stepped axially into the inter-blade area, the balancing mark extending arcuately between the first end and the second end, the balancing mark having a depth that varies as the balancing mark extends between the first end and the second end, the balancing mark having a width that varies as the balancing mark extends between the first end and the second end, wherein the first end is deeper than the second end, and wherein the fillets are uninterrupted by the balancing mark.

Aspects and preferred embodiments are defined in the appended claims. A rotor of a fluid machine as defined in claim <NUM> is disclosed herein.

In addition, a method of balancing a rotor of a fluid machine as defined in claim <NUM> is disclosed.

In an addition, a fluid charger device as defined in claim <NUM> is disclosed.

The following detailed description is merely exemplary in nature and is not intended to limit the present invention or the application and uses of the present invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description.

Broadly, the invention disclosed herein relates to a rotor of a fluid machine, such as a turbocharger or other charger device of a vehicle. The rotor includes a wheel, such as a compressor wheel, that is supported for rotation about an axis of rotation. The wheel includes a plurality of blades that are spaced apart about the axis of rotation. Furthermore, the rotor includes at least one balancing mark, such as a recess, groove, notch, channel, or other aperture, that is included in an inter-blade area of the wheel. The balancing mark is elongate and includes a defined and shaped first and second end. At least one end may be cupped (i.e., cupped in shape) to include three-dimensional contour and the elongate balancing mark may extend away from the cupped end(s). In some embodiments, both the first end and the second end may be shaped to have cupped, contoured surfaces, and the elongate balancing mark may extend therebetween. The width and/or depth varies between the first end and the second end. The width, depth, location, and/or other features of the balancing feature may be configured to reduce unbalance of the rotor. In addition, these features may be configured according to predetermined characteristics of the wheel. For example, the width, depth, location, and/or other features may be configured according to a known stress profile of the wheel. In some embodiments, for example, the deepest and/or widest portion of the balancing mark may be disposed proximate a pressure side of one blade whereas the shallower and narrower portions may be disposed proximate a suction side of a neighboring blade. In the embodiments illustrated, there may generally be a higher stress margin at the pressure side; therefore more material may be available for removal without negatively affecting wheel strength, robustness, etc. Furthermore, the balancing mark may be angularly and radially disposed at a predetermined position and may extend along a predetermined area of the wheel. The balancing mark may be located according to the particular characteristics of the wheel. Methods of manufacturing and methods of balancing these rotors are also disclosed according to example embodiments of the present invention.

Accordingly, rotors may be accurately and precisely balanced with a balancing mark, aperture, recess, groove, notch, etc. that is tailored for a particular wheel, wheel configuration, etc. The present teachings provide high quality, balanced rotors and highly efficient methods for manufacturing the same.

<FIG> is a schematic view of an example turbocharger system <NUM> that includes a turbocharger <NUM>. The turbocharger <NUM> generally includes a turbocharger housing <NUM> and a rotor <NUM>. The rotor <NUM> is configured to rotate within the turbocharger housing <NUM> about an axis of rotor rotation <NUM>. The rotor <NUM> may be supported for rotation about the axis <NUM> via one or more bearings (not shown). In some embodiments, the rotor <NUM> may be rotationally supported by thrust bearings and a plurality of journal bearings. Alternatively, other bearings may be included.

As shown in the illustrated embodiment, the turbocharger housing <NUM> may include a turbine housing <NUM>, a compressor housing <NUM>, and a bearing housing <NUM>. The bearing housing <NUM> may be disposed between the turbine and compressor housings <NUM>, <NUM>. Also, in some embodiments, the bearing housing <NUM> may contain the bearings of the rotor <NUM>.

Additionally, the rotor <NUM> includes a turbine wheel <NUM>, a compressor wheel <NUM>, and a shaft <NUM>. The turbine wheel <NUM> is located substantially within the turbine housing <NUM>. The compressor wheel <NUM> is located substantially within the compressor housing <NUM>. The shaft <NUM> extends along the axis of rotation <NUM>, through the bearing housing <NUM>, to connect the turbine wheel <NUM> to the compressor wheel <NUM>. Accordingly, the turbine wheel <NUM> and the compressor wheel <NUM> rotate together about the axis <NUM>.

The turbine housing <NUM> and the turbine wheel <NUM> cooperate to form a turbine (i.e., turbine section, turbine stage) configured to circumferentially receive a high-pressure and high-temperature exhaust gas stream <NUM> from an engine (e.g., from an exhaust manifold <NUM> of an internal combustion engine <NUM>). The turbine wheel <NUM> and, thus, the rotor <NUM> are driven in rotation around the axis <NUM> by the high-pressure and high-temperature exhaust gas stream <NUM>, which becomes a lower-pressure and lower-temperature exhaust gas stream <NUM> that is released into a downstream exhaust pipe <NUM>. In other embodiments, the engine <NUM> may be of another type, such as a diesel fueled engine.

The compressor housing <NUM> and compressor wheel <NUM> form a compressor (i.e., compressor section, compressor stage). The compressor wheel <NUM>, being driven in rotation by the exhaust-gas driven turbine wheel <NUM>, is configured to compress received input air <NUM> (e.g., ambient air, or already-pressurized air from a previous-stage in a multi-stage compressor) into a pressurized air stream <NUM> that is ejected circumferentially from the compressor housing <NUM>. The compressor housing <NUM> may have a shape (e.g., a volute shape or otherwise) configured to direct and pressurize the air blown from the compressor wheel <NUM>. Due to the compression process, the pressurized air stream <NUM> is characterized by an increased temperature, over that of the input air <NUM>.

The pressurized air stream <NUM> may be channeled through an air cooler <NUM> (i.e., intercooler), such as a convectively cooled charge air cooler. The air cooler <NUM> may be configured to dissipate heat from the pressurized air stream <NUM>, increasing its density. The resulting cooled and pressurized output air stream <NUM> is channeled into an intake manifold <NUM> of the internal combustion engine <NUM>, or alternatively, into a subsequent-stage, in-series compressor. The operation of the system <NUM> may be controlled by an ECU <NUM> (engine control unit) that connects to the remainder of the system via communication connections <NUM>.

Referring now to <FIG>, additional details of the rotor <NUM> will be discussed according to example embodiments. Specifically, the compressor wheel <NUM> of the rotor <NUM> is illustrated according to example embodiments. As will be discussed, the compressor wheel <NUM> includes one or more balancing features <NUM> that balance the rotor <NUM> in rotation about the axis <NUM>. It will be appreciated that one or more balancing features <NUM> may be included on the rotor <NUM> in a location other than the compressor wheel <NUM> without departing from the scope of the present invention. Furthermore, it will be appreciated that balancing features <NUM> may be included on another rotor (e.g., a rotor of a supercharger or e-charger) without departing from the scope of the present invention.

In some embodiments, the compressor wheel <NUM> may be a unitary, one-piece member that is made out of metal or other material. In some embodiments, the compressor wheel <NUM> may be formed at least partly by a casting process.

As shown, the compressor wheel <NUM> includes a hub <NUM>. The hub <NUM> may be cylindrical and may receive the shaft <NUM> of the rotor <NUM>. The hub <NUM> may be fixed to the shaft <NUM> (e.g., with a nut or other fastener) for rotation therewith.

The compressor wheel <NUM> also includes a back disc <NUM>. The back disc <NUM> extends radially away from the hub <NUM> and terminates in the radial direction at an outer rim edge <NUM>. The outer rim edge <NUM> may be substantially circular, may extend continuously about the axis <NUM>, and may be substantially centered on the axis <NUM>. The back disc <NUM> also includes a front face <NUM> and a back face <NUM>. Both the front face <NUM> and the back face <NUM> may extend radially between the axis <NUM> and the outer rim edge <NUM>. The back face <NUM> may generally face toward the turbine wheel <NUM> of the rotor <NUM> (<FIG>), and the front face <NUM> may face generally in the opposite direction (away from the turbine wheel <NUM>). The front face <NUM> may be contoured and may extend substantially in the axial direction (i.e., along the axis <NUM>) proximate the hub <NUM>, may extend substantially in the radial direction proximate the outer rim edge <NUM>, and may have a gradual concave contour between the hub <NUM> and the outer rim edge <NUM>.

The compressor wheel <NUM> further includes a plurality of blades <NUM>. The blades <NUM> may be relatively thin and are attached to the front face <NUM> of the back disc <NUM>. The blades <NUM> project from the front face <NUM>. The blades <NUM> may also be arranged about the axis of rotation <NUM> and may radiate outward therefrom. The outer radial ends of the blades <NUM> may terminate at the outer rim edge <NUM>. The blades <NUM> may be spaced apart substantially evenly in the circumferential direction about the axis <NUM>. The blades <NUM> may have a predetermined shape, profile, size, etc. for moving the input air <NUM> through the compressor housing <NUM>, compressing the input air <NUM>, and creating the pressurized air stream <NUM> as the rotor <NUM> rotates about the axis <NUM>.

It will be appreciated that the blades <NUM> may have a number of different configurations without departing from the scope of the present invention. In the illustrated embodiments, for example, the compressor wheel <NUM> may have a splitter blade wheel configuration where every other blade <NUM> is shorter than the full blade next to it. Moreover, the blades <NUM> may have a backward-curved impellor configuration such that at least some of the blades <NUM> (e.g., the so-called "full blades") curve backward relative to the direction of rotation, which is clockwise as indicated by arrow <NUM>.

The plurality of blades <NUM> include a first blade <NUM> and a neighboring second blade <NUM>. The first blade <NUM> may be axially longer than the second blade <NUM> (i.e., may project outward further axially from the back disc <NUM>) in some embodiments. Also, the first blade <NUM> includes a pressure side <NUM> and a suction side <NUM>. The wheel <NUM> also includes a pressure side fillet <NUM>, which may be concave to define a smooth transition between the front face <NUM> and the pressure side <NUM> of the first blade <NUM>. Likewise, the wheel <NUM> includes a suction side fillet <NUM>, which may be concave to define a smooth transition between the front face <NUM> and the suction side <NUM> of the first blade <NUM>. Similarly, the second blade <NUM> includes a pressure side <NUM> and a suction side <NUM>. There is a pressure side fillet <NUM>, which may be concave to define a smooth transition between the front face <NUM> and the pressure side <NUM> of the second blade <NUM>. Likewise, there is a suction side fillet <NUM>, which may be concave to define a smooth transition between the front face <NUM> and the suction side <NUM> of the second blade <NUM>.

Moreover, the compressor wheel <NUM> includes a plurality of inter-blade areas defined between neighboring ones of the blades <NUM> on the front face <NUM> of the compressor wheel <NUM>. This includes an inter-blade area <NUM> defined between the first blade <NUM> and the second blade <NUM>. The inter-blade area <NUM> may extend radially between the hub <NUM> and the outer rim edge <NUM> (i.e., may radiate relative to the axis of rotation <NUM>). Also, the inter-blade area <NUM> may be contoured along a radiating direction of the wheel <NUM> (i.e., curved as the area <NUM> extends radially between the hub <NUM> and the outer rim edge <NUM>). This contour in the radiating direction may correspond to that of the plurality of blades <NUM>. Moreover, the width of the inter-blade area <NUM> (measured circumferentially between the first and second blades <NUM>, <NUM>) may be tapered and may increase gradually in the radial direction from the hub <NUM> to the outer rim edge <NUM>.

In addition, the compressor wheel <NUM> includes the balancing feature <NUM>. Generally, the balancing feature <NUM> may distribute the weight of the rotor <NUM> to cause the center of gravity of the rotor <NUM> to be located substantially on the axis <NUM>. The balancing feature <NUM> may ameliorate unbalance due to, for example, stackup of manufacturing and assembly tolerances relating to the rotor <NUM>. Thus, the balancing feature <NUM> may provide substantially balanced rotation of the rotor <NUM> about the axis <NUM>. While the balancing feature <NUM> is included on the compressor wheel <NUM> in the illustrated embodiments, it will be appreciated that the turbine wheel <NUM> may include the balancing feature <NUM> in some embodiments of the present invention.

The balancing feature <NUM> includes one or more marks comprising as a recess, groove, channel, or other aperture. The back disc <NUM> includes a first balancing mark <NUM> (<FIG>) that provides balancing with respect to a first plane (e.g., a plane that is normal to the axis <NUM>). Also, as shown in <FIG>, the hub <NUM> may include a second balancing mark <NUM> that balances the rotor <NUM> with respect to a plane that is parallel to the axis <NUM>. Thus, the balancing marks <NUM>, <NUM> may cooperate to provide two-plane balancing for the rotor <NUM>.

As shown in <FIG>, the first balancing mark <NUM> comprises an elongated recess, slot, notch, or groove. The first balancing mark <NUM> is formed at least partly in the front face <NUM> of the wheel <NUM>, within the inter-blade area <NUM>. The first balancing mark <NUM> is recessed within the front face <NUM>.

As shown in <FIG>, the balancing mark <NUM> extends across the inter-blade area <NUM> along an axis <NUM> and includes a first end <NUM> and a second end <NUM>. The axis <NUM> is arcuate and may be centered substantially on the axis <NUM> so as to be substantially concentric with the outer rim edge <NUM>. The axis <NUM> may be spaced inwardly in the radial direction at a distance from the outer rim edge <NUM>.

As shown in <FIG>, the balancing mark <NUM> has a width <NUM> (i.e., a width dimension), which may be measured transverse to the axis <NUM>. The width <NUM> may be measured in the radial direction relative to the axis <NUM> between an inboard edge <NUM> and an outboard edge <NUM> of the mark <NUM>. As shown in <FIG>, the width <NUM> varies as the balancing mark <NUM> extends arcuately between the first end <NUM> and the second end <NUM>.

The balancing mark <NUM> may have an elongated bean-shape in some embodiments. The inboard edge <NUM> may be more contoured than the outboard edge <NUM>.

Additionally, as shown in <FIG>, the first end <NUM> is recessed into the pressure side fillet <NUM>. The second end <NUM> terminates at or before reaching the suction side fillet <NUM>. In other words, the suction side fillet <NUM> is uninterrupted by the second end <NUM>.

The width <NUM> of the balancing mark <NUM> may be configured to reduce unbalance of the rotor <NUM>. Furthermore, the width <NUM> may vary according to a particular stress profile of the wheel <NUM>. For example, there may be more stress margin on the pressure side <NUM> than on the suction side <NUM> of the neighboring blade <NUM>. As such, the width <NUM> may be larger proximate the first end <NUM> as compared to the second end <NUM>. In other words, there may be more material available for removal at the pressure side <NUM>; therefore, the balancing mark <NUM> may be wider at the first end <NUM> without negatively affecting strength or robustness of the wheel <NUM>.

Additionally, as shown in <FIG>, the balancing mark <NUM> has a depth <NUM> (i.e., a depth dimension), which may be measured substantially in an axial direction along the axis <NUM>. The depth <NUM> may be measured in the axial direction and may be the distance recessed from the front face <NUM>, in areas adjacent the balancing mark <NUM>. As shown in <FIG>, the depth <NUM> varies as the balancing mark <NUM> extends arcuately between the first end <NUM> and the second end <NUM>.

The depth <NUM> of the balancing mark <NUM> may be configured to reduce unbalance of the rotor <NUM>. In addition, the depth <NUM> may vary according to a particular stress profile of the wheel <NUM>. As mentioned, there may be more stress margin on the pressure side <NUM> than on the suction side <NUM>. As such, the depth <NUM> may be larger proximate the first end <NUM> as compared to the second end <NUM>. Also, as shown in <FIG>, the depth <NUM> may vary to define a first segment <NUM> and a second segment <NUM>. The second segment <NUM> may be shallower than the first segment <NUM>.

Also, as shown in <FIG>, the first end <NUM> may be a cupped end (i.e., cupped in shape). In other words, the first end <NUM> may have a hemispherical or ball-segment-shaped concave contour on its outer edge, except where the mark <NUM> extends from the first end <NUM> toward the second end <NUM>. Likewise, the second end <NUM> may be a cupped end (i.e., cupped in shape). As such, the second end <NUM> may have a hemispherical or ball-segment-shaped concave contour on its outer edge, except where the mark <NUM> extends from the second end <NUM> toward the first end <NUM>. Both the first end <NUM> and the second end <NUM> may be cupped in shape. The depth <NUM> of the mark <NUM> may vary between the cupped first end <NUM> and cupped second end <NUM>. As shown in <FIG>, there may be a first step <NUM> at the transition between the front face <NUM> and the cupped, contoured surface of the first end <NUM>. Likewise, there may be a second step <NUM> at the transition between the front face <NUM> and the contoured surface of the second end <NUM>. The balancing mark <NUM> may be stepped in the axial direction along the axis <NUM> at the steps <NUM>, <NUM>, and the inboard edge <NUM> and the outboard edge <NUM> may be continuous with the edge defined at the first step <NUM> and the second step <NUM>.

Accordingly, the mark <NUM> may be shaped along its elongate length to a high degree of precision and accuracy. The width <NUM> and depth <NUM> may vary as a function of the angular position within the inter-blade area <NUM>. Both ends <NUM>, <NUM> may be shaped to a high degree of contour in some embodiments to precisely balance the rotor <NUM> while also retaining high strength and robustness of the wheel <NUM>. The balancing mark <NUM> may be tailored for a particular wheel <NUM>, for a particular wheel configuration, for a particular stress profile of the wheel <NUM>, etc..

Moreover, the location of the mark <NUM> may be advantageous because it is highly accessible (e.g., during a machining process). Also, there is a relatively large amount of area for the balancing mark <NUM> at this location. Therefore, the balancing procedure may be performed with high precision and accuracy.

Referring now to <FIG>, a method <NUM> of balancing the rotor <NUM> and forming the balancing mark <NUM> will be discussed according to example embodiments of the present invention. In some embodiments, a balancing apparatus <NUM> (<FIG>) may be employed for performing the method <NUM>.

Embodiments of the present invention may be described herein in terms of functional and/or logical block components and various processing steps. For example, an embodiment of the present invention may employ various integrated circuit components, e.g., memory elements, digital signal processing elements, logic elements, look-up tables, or the like, which may carry out a variety of functions under the control of one or more microprocessors or other control devices. In addition, those skilled in the art will appreciate that embodiments of the present invention may be practiced in conjunction with any number of systems, and that the air quality control system described herein is merely one exemplary embodiment of the present invention.

It should be noted that many alternative or additional functional relationships or physical connections may be present in an embodiment of the present invention.

As shown in <FIG>, the balancing apparatus <NUM> may support the rotor <NUM> for rotation about the axis <NUM>. The rotor <NUM> may be supported within the bearing housing <NUM> when performing the balancing method <NUM>. More specifically, as shown in <FIG>, the rotor <NUM> may include the compressor wheel <NUM>, the shaft <NUM>, and the turbine wheel <NUM>. The rotor <NUM> may be supported on one or more bearings and may be provided within the bearing housing <NUM>. The front face <NUM> of the compressor wheel <NUM> may remain exposed outside the bearing housing <NUM> during the balancing method <NUM>.

The balancing apparatus <NUM> may also include a cutting tool <NUM>. The cutting tool <NUM> may be one of a variety of tools used to remove material from a workpiece. For example, as shown in <FIG>, the cutting tool <NUM> may include a cutter <NUM>, such as a ball-end or hemispherical milling cutter. The cutter <NUM> may have any suitable radius and may be operatively connected to a milling machine. However, it will be appreciated that the method <NUM> may be employed using a different cutting tool <NUM> without departing from the scope of the present invention.

The balancing apparatus <NUM> may further include a control system <NUM>. The control system <NUM> may be configured as a computing device with at least one processor <NUM> and memory device <NUM>. The control system <NUM> may be in communication with an actuator system <NUM>. The control system <NUM> may include a hard-wired computing circuit (or circuits). The control system <NUM> may also be configured as a hydraulic, electrical or electro-hydraulic controller, or otherwise. As such, the control system <NUM> may be configured to execute various computational and control functionality with respect to the actuator system <NUM>.

The actuator system <NUM> may include one or more electric motors, hydraulic actuators, pneumatic actuators, etc. In some embodiments, the actuator system <NUM> may selectively actuate the rotor <NUM> relative to the cutter <NUM>. For example, the actuator system <NUM> may selectively rotate the rotor <NUM> about the axis <NUM> as indicated by arrow <NUM>. In some embodiments, the actuator system <NUM> may selectively rotate the rotor <NUM> in either the clockwise or counterclockwise direction. Additionally, the actuator system <NUM> may selectively actuate the cutter <NUM> relative to the rotor <NUM>. For example, the actuator system <NUM> may selectively rotate the cutter <NUM> about a cutter axis <NUM>. In some embodiments, the cutter axis <NUM> may be disposed at an acute angle <NUM> relative to the axis <NUM> of the rotor <NUM>. (The cutter axis <NUM> may lie within the plane of <FIG>. ) Additionally, the actuator system <NUM> may actuate the cutter <NUM> linearly (telescopingly) back and forth along the cutter axis <NUM> as indicated by arrow <NUM>. Furthermore, the actuator system <NUM> may selectively move the cutter <NUM> linearly along and substantially parallel to the axis <NUM> of the rotor <NUM> as indicated by arrow <NUM>.

The control system <NUM> may include various modules. As used herein, the term "module" refers to any hardware, software, firmware, electronic control component, processing logic, and/or processor device, individually or in any combination, including without limitation: application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that executes one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality.

In some embodiments, the control system <NUM> may include an actuator module <NUM>. The actuator module <NUM> may be used to generate and output control signals or control commands to the actuator system <NUM> for selectively moving the cutter <NUM> relative to the rotor <NUM> and/or selectively moving the rotor <NUM> relative to the cutter <NUM>. The control system <NUM> may further include an unbalance detection module <NUM>. The unbalance detection module <NUM> may be used for detecting that the rotor <NUM> is unbalanced for rotation about the axis <NUM>. The unbalance detection module <NUM> may also detect an amount or degree to which the rotor <NUM> is unbalanced. In some embodiments, the unbalance detection module <NUM> may be operatively connected to a sensor, such as a vibration sensor, that detects unbalance in the rotation of the rotor <NUM> during rotation. Moreover, the control system <NUM> may include a balance model module <NUM>. The balance model module <NUM> may be used to generate an electronic (computerized) module of the rotor <NUM> with balancing marks <NUM> suitable for balancing the rotor <NUM>. The module <NUM> may determine the width <NUM>, depth <NUM>, location, and/or other characteristics of the balancing mark <NUM>. The module <NUM> may determine these characteristics for sufficiently balancing the rotation of the rotor <NUM>, while also considering the stress profile of the wheel <NUM>. Once the module <NUM> generates the model, it may be saved in the memory device <NUM>.

As shown in <FIG>, the method <NUM> may begin at <NUM> at which an unbalance test of the rotor <NUM> is performed. For example, the actuator module <NUM> may generate a control command for rotating the rotor <NUM> about the axis <NUM>. The rotor <NUM> may be rotated continuously for a predetermined amount of time and at a predetermined angular velocity. Meanwhile, one or more vibration sensors may detect the amount of vibration in the rotor <NUM>. The unbalance detection module <NUM> may receive vibration data from the sensors and process the signal and calculate and determine the unbalance in the rotor <NUM>.

Next, at <NUM> of the method <NUM>, the control system <NUM> may determine whether the rotor <NUM> is sufficiently balanced. For example, the unbalance detected at <NUM> may be compared to a predetermined threshold amount of unbalance. This predetermined threshold may be stored in the memory device <NUM> and may be accessed by the control system <NUM> when making the determination of <NUM>. If the amount of unbalance detected at <NUM> is below the predetermined threshold (i.e., rotor is sufficiently balanced), then the method may terminate as shown in <FIG>. In contrast, if at <NUM> the control system <NUM> determines that the detected unbalance is above the threshold, then the method <NUM> may continue at <NUM>.

At <NUM>, the balance model module <NUM> may be used to generate a computer model of the rotor <NUM> with one or more balancing marks <NUM> suitable for balancing the rotation of the rotor <NUM>. The balance model module <NUM> may rely on computerized logic and modeling software to determine the size, dimension, etc. of the balancing mark(s) <NUM> as well as the placement of such mark(s) <NUM> on the compressor wheel <NUM>. The marks <NUM> generated in the model may be sized, shaped, and placed on the compressor wheel <NUM> as discussed above with respect to <FIG> in some embodiments.

The model may also be generated to indicate how the actuator system <NUM> should be used to form the mark <NUM>. In other words, the model may be used to generate control signals for the actuator system <NUM> for moving the cutter <NUM> and/or the wheel <NUM> for forming the mark <NUM>. Once the balance model module <NUM> generates the model of the balanced rotor <NUM>, the model may be saved in the memory device <NUM>. It will be appreciated that the model may also dictate the process steps for creating the balancing marks <NUM>.

Next, at <NUM> of the method <NUM>, the rotor <NUM> may be machined to create the balancing marks <NUM> according to the model generated at <NUM>. Specifically, the actuator module <NUM> may access the model (generated at <NUM> and saved in the memory device <NUM>) and actuate the rotor <NUM> and/or the cutter <NUM> according to the model.

The actuator module <NUM> may generate control signals for rotating the cutter <NUM> about the cutter axis <NUM> at a predetermined angular speed according to the model. The actuator module <NUM> may also generate and send control commands to the cutter <NUM> for moving the cutter <NUM> along the cutter axis <NUM> (at least partly along the axis <NUM>) and to position the cutter <NUM> at a radial distance <NUM> away from the axis <NUM> according to the model generated at <NUM>. The actuator module <NUM> may also generate control commands for moving the cutter <NUM> parallel to the axis <NUM> toward the wheel and to a predetermined depth <NUM> into the back disc <NUM> of the compressor wheel <NUM> according to the model. This movement may cause the cutter <NUM> to contact and cut material away from the compressor wheel <NUM> as represented in <FIG>.

Moreover, control commands may be generated for moving the cutter <NUM> axially (parallel to the axis <NUM>, along the axis, etc.) and away from the back disc <NUM>, for example, at the first end <NUM> or the second end <NUM>. In so doing, the cutter <NUM> may shape the cupped first end <NUM> and/or the cupped second end <NUM> before being withdrawn from the wheel <NUM>.

Furthermore, as shown in <FIG>, the actuator module <NUM> may generate control commands for rotating the rotor <NUM> about the axis <NUM> for a predetermined amount of angular displacement according to the model. In some embodiments illustrated in <FIG>, the compressor wheel <NUM> may be rotated clockwise about the axis <NUM>. In additional embodiments illustrated in <FIG>, the compressor wheel <NUM> may be rotated counterclockwise about the axis <NUM>. Furthermore, in some embodiments, the cutter <NUM> may remain at a fixed angular location relative to the axis <NUM> during the machining process. Additionally, the cutter <NUM> and/or the wheel <NUM> may be moved axially simultaneously while the compressor wheel <NUM> is rotated according to the model generated at <NUM>. This may provide the varying with <NUM> and depth <NUM> discussed above.

In some embodiments, the entire mark <NUM> may be created in a single pass with the cutter <NUM> and wheel <NUM> moving relative to each other in both the axial direction and the angular (circumferential) direction. Accordingly, the mark <NUM> may be formed in a highly efficient manner. However, in other embodiments, the mark <NUM> may be created through multiple passes of the cutter <NUM>, and the cutter <NUM> may be progressively moved deeper and deeper into the back disc <NUM> for each pass until the mark <NUM> is fully formed.

Once the mark <NUM> is formed at <NUM>, the method <NUM> may loop back to <NUM>, where the unbalance of the wheel <NUM> may be re-checked. Then, at <NUM>, if it is determined that the wheel <NUM> is sufficiently balanced, then the method <NUM> may terminate. However, if the wheel <NUM> shows significant unbalance, then the method <NUM> may continue to <NUM>, where an updated model may be generated, and then the mark <NUM> may be re-shaped and/or a new mark <NUM> may be added to the wheel <NUM>. The method <NUM> may continue until the wheel <NUM> is sufficiently balanced.

Accordingly, rotors of fluid machines may be accurately and precisely balanced according to the present teachings in an efficient and repeatable fashion. Balancing marks may be formed and shaped to be tailor-made for the wheel <NUM> without compromising wheel strength and robustness.

Additional embodiments not falling within the scope of the claims are illustrated in <FIG>. (Features that correspond to those of <FIG> are indicated with corresponding reference numbers increased by <NUM>. ) The mark <NUM> may extend along its arcuate axis <NUM> within the inter-blade area <NUM> between the first end <NUM> and the second end <NUM>. The mark <NUM> may be substantially centered on the axis <NUM>. Also, in some embodiments, the width <NUM> may vary as the mark <NUM> extends along the axis <NUM> between the first end <NUM> and the second end <NUM>. Moreover, like the embodiments of <FIG>, the depth of the mark <NUM> may vary as the mark <NUM> extends along the axis <NUM> between the first end <NUM> and the second end <NUM>. Furthermore, both the first end <NUM> and the second end <NUM> may be cupped in shape in some embodiments, similar to the embodiments discussed above in relation to <FIG>.

The arcuate axis <NUM> may be arcuate such that the mark <NUM> bows and curves along the inter-blade area <NUM>. For reference purposes, the arcuate axis <NUM> may curve and arc with respect to a second axis <NUM>. In some embodiments, the arcuate axis <NUM> of the mark <NUM> may be circular and centered about the second axis <NUM>. Also, the second axis <NUM> may be misaligned with the axis of rotation <NUM>. The axis <NUM> may be parallel to the axis of rotation <NUM>; however, the axis <NUM> may be spaced apart at a radial distance therefrom. However, it will be appreciated that the mark <NUM> may arc along a non-circular path with respect to the axis <NUM> in other embodiments.

Furthermore, the arcuate axis <NUM> may bow, arc, or bend with respect to the outer rim edge <NUM>. For example, the arcuate axis <NUM> may bow inwardly from the adjacent portion of the outer rim edge <NUM> and slightly toward the axis of rotation <NUM>. Also, as shown in the illustrated embodiment, the first end <NUM> may be disposed further outward radially from the axis of rotation <NUM> as compared to the second end <NUM>. The balancing mark <NUM> may be routed along areas of the wheel that are generally subject to less stress, that include more material available for removal, etc..

Further embodiments not falling within the scope of the claims are illustrated in <FIG>. (Features that correspond to those of <FIG> are indicated with corresponding reference numbers increased by <NUM>. ) The mark <NUM> may extend along its arcuate axis <NUM> within the inter-blade area <NUM> between the first end <NUM> and the second end <NUM>. Also, in some embodiments, the width <NUM> may vary as the mark <NUM> extends along the axis <NUM> between the first end <NUM> and the second end <NUM>. Moreover, like the embodiments of <FIG>, the depth of the mark <NUM> may vary as the mark <NUM> extends along the axis <NUM> between the first end <NUM> and the second end <NUM>. Furthermore, both the first end <NUM> and the second end <NUM> may be cupped in shape in some embodiments, similar to the embodiments discussed above in relation to <FIG>.

The arcuate axis <NUM> may be arcuate with respect to a second axis <NUM>. In some embodiments, the axis <NUM> may be centered about the second axis <NUM>. Also, the second axis <NUM> may be misaligned with the axis of rotation <NUM>. The axis <NUM> may be parallel to the axis of rotation <NUM>; however, the axis <NUM> may be spaced apart at a radial distance therefrom.

Furthermore, the arcuate axis <NUM> may bow outwardly toward an adjacent portion of the outer rim edge <NUM> of the wheel with the first end <NUM> disposed further outward radially from the axis of rotation <NUM> as compared to the second end <NUM>. Moreover, the arcuate axis <NUM> be bowed generally in the same direction as the contour of the blades and the inter-blade area <NUM>. The balancing mark <NUM> may be routed along areas of the wheel that are generally subject to less stress, that include more material available for removal, etc..

Additional embodiments not falling within the scope of the claims are illustrated in <FIG>. (Features that correspond to those of <FIG> are indicated with corresponding reference numbers increased by <NUM>. ) The mark <NUM> may extend along its arcuate axis <NUM> within the inter-blade area <NUM> between the first end <NUM> and the second end <NUM>. Also, in some embodiments, the width <NUM> may vary as the mark <NUM> extends along the axis <NUM> between the first end <NUM> and the second end <NUM>. Moreover, like the embodiments of <FIG>, the depth of the mark <NUM> may vary as the mark <NUM> extends along the axis <NUM> between the first end <NUM> and the second end <NUM>. Furthermore, both the first end <NUM> and the second end <NUM> may be cupped in shape in some embodiments, similar to the embodiments discussed above in relation to <FIG>.

The arcuate axis <NUM> may be arcuate with respect to a second axis <NUM>. In some embodiments, the axis <NUM> may be centered about the second axis <NUM>. Also, the second axis <NUM> may misaligned with the axis of rotation <NUM>. The axis <NUM> may be parallel to the axis of rotation <NUM>; however, the axis <NUM> may be spaced apart at a radial distance therefrom.

Furthermore, the arcuate axis <NUM> may bow outwardly toward an adjacent portion of the outer rim edge <NUM> of the wheel. Also, the arcuate axis <NUM> may bow opposite the direction of rotation of the wheel as shown. Additionally, as shown in the illustrated embodiment, the first end <NUM> may be disposed further inward radially from the axis of rotation <NUM> as compared to the second end <NUM>. The balancing mark <NUM> may be routed along areas of the wheel that are generally subject to less stress, that include more material available for removal, etc. Thus, in some embodiments, the first end <NUM> may define the deepest portion of the mark <NUM>, and the mark <NUM> may get progressively shallower until it terminates at the shaped second end <NUM>.

Claim 1:
A rotor of a fluid machine comprising:
a wheel (<NUM>) that is supported for rotation about an axis of rotation (<NUM>), the wheel having a hub (<NUM>) and a back disc (<NUM>) extending radially away from the hub and terminating in a radial direction at an outer rim edge (<NUM>), the back disc having a front face (<NUM>) and a back face (<NUM>);
a plurality of blades (<NUM>) included on the wheel, the plurality of blades projecting from the front face of the back disc (<NUM>);
an inter-blade area (<NUM>) defined circumferentially between a first blade (<NUM>) and a second blade (<NUM>) of the plurality of blades (<NUM>) with respect to the axis of rotation, wherein the first blade includes a pressure side (<NUM>), and the second blade includes a suction side (<NUM>), the pressure side facing toward the suction side across the inter-blade area, and wherein the wheel includes a first fillet (<NUM>) at a transition between the inter-blade area and the first blade and the wheel includes a second fillet (<NUM>) at another transition between the inter-blade area and the second blade; and
a balancing mark (<NUM>) on the wheel and within the inter-blade area, the balancing mark being elongate and having a first end (<NUM>) and a second end (<NUM>), the first end and the second end being stepped axially into the inter-blade area, the balancing mark extending arcuately between the first end and the second end, the balancing mark having a depth (<NUM>) that varies as the balancing mark extends arcuately between the first end and the second end, the balancing mark having a width (<NUM>) that varies as the balancing mark extends arcuately between the first end and the second end, wherein the first end is disposed proximate the pressure side of the first blade, and wherein the second end is disposed proximate the suction side of the second blade, wherein the first end is deeper than the second end; and wherein the first end is recessed into the first fillet and the second fillet is uninterrupted by the second end.