Subject matter disclosed herein relates generally to turbomachinery for internal combustion engines and, in particular, to compressor diffuser plates and assemblies.
Centrifugal compressors typically include a compressor wheel to direct fluid to a diffuser and, subsequently, to a volute. Often a diffuser is defined by surfaces of two components such as a surface of a compressor housing and a surface of a compressor backplate. For turbochargers, a compressor backplate may be a component attached to a center housing or be configured as an integral feature of a center housing. In either instance, during operation, heat energy flows from exhaust directed to a turbine through the center housing and on to the compressor, which, in turn, can increase temperature of fluid passing through the compressor. In general, an increase in temperature causes a decrease in compressor efficiency. Further, where a turbocharged internal combustion engine is operated using exhaust gas recirculation (EGR), in various arrangements, exhaust is directed upstream of the compressor. Such EGR arrangements can be detrimental to compressor and related components.
Various technologies described herein pertain to assemblies that include a diffuser plate to, for example, enhance compressor performance and longevity, particularly where an assembly is exposed to heat and constituents carried by exhaust.
A more complete understanding of the various methods, devices, assemblies, systems, arrangements, etc., described herein, and equivalents thereof, may be had by reference to the following detailed description when taken in conjunction with examples shown in the accompanying drawings where:
Various examples are presented herein that pertain to a deformable diffuser plate, which may be positioned between components of a compressor assembly. Such a plate may include an inner edge disposed at an inner diameter about a central axis; an outer edge disposed at an outer diameter, the outer edge displaced an axial distance from the inner edge; a deformable section disposed between the inner edge and the outer edge; and a spring constant for forced axial displacement of the outer edge with respect to the inner edge where the spring constant is characterized, at least in part, by the deformable section.
With respect to spring characteristics of a diffuser plate, equations that define so-called disc springs may be referenced (e.g., as provided by DIN standards). In various examples described herein, a diffuser plate can optionally include a fulcrum contact surface; noting that, for conventional disc springs, contact typically occurs at an inner edge and outer edge only. Accordingly, equations that describe behavior of conventional disc springs may require some alterations to apply to a diffuser plate deformed about a fulcrum contacting a fulcrum contact surface.
As described herein, in an uncompressed (undeformed) state, a diffuser plate has a shape that may be inadequate for defining a diffuser in that it acquires an adequate shape only upon compression (deformation). In various examples, a deformable diffuser plate includes a deformable section with a substantially S-shaped cross-section disposed between an inner edge and an outer edge of the plate. Such a section may be positioned to accommodate a compressor wheel, particularly an outer edge of a compressor wheel. For example, an S-shaped section of a plate may be a transition that rises axially in a manner that provides for clearance between the plate and a compressor wheel. In such an example, the shape of the plate acts, at least in part, to shape a diffuser (e.g., in conjunction with a contoured surface of a compressor housing).
In various examples, a diffuser plate can provide for one or more gaps (e.g., air gaps) that act to hinder heat transfer. In general, during operation of a turbocharger, heat energy from exhaust is transferred to a compressor, which can decrease compressor efficiency. Accordingly, a diffuser plate that provides for one or more gaps (or pockets) between components can reduce transfer of heat energy to a compressor (e.g., along diffuser flow paths, volute flow paths, etc.).
As described herein, a diffuser plate may be constructed from a material or materials that provide for any of a variety of characteristics. A material of construction may be, for example, stainless steel, or other material, capable of being formed into a shape having sufficient stiffness (e.g., characterized by a modulus of elasticity). In various examples, shape and stiffness of a diffuser plate may allow for spring action to apply a pre-load to a joint (e.g., a bolted joint). A material may be optionally applied to a surface or formed on a surface. As described herein, a treatment process may treat a diffuser plate (e.g., at least a portion of a plate) to provide for characteristics that act to repel oil, reduce corrosion, alter heat transfer, alter boundary layer formation, etc. For example, a sol-gel process may deposit a sol-gel layer (e.g., consider a metal oxide) on a surface of a diffuser plate where the sol-gel layer provides for one or more beneficial characteristics (e.g., hydrophilicity to repel hydrophobic chemicals). As another example, consider electroless nickel deposition or plating. Electroless nickel plating (EN plating) is an auto-catalytic chemical technique used to deposit a layer of a material such as nickel-phosphorus or nickel-boron alloy on a surface. As yet another example, a super finishing technique may be used to provide a diffuser plate with a super finish (e.g., a nano-finish) that helps to prevent corrosion, fouling, deposit formation, etc.
As described herein, a treatment may generally be applied prior to installation but may optionally be applied after installation (e.g., clamping) of a diffuser plate (e.g., by flowing treatment fluid, applying electrical charge, etc.). Further, a treatment may be applied to a portion of the diffuser plate based on amount of deformation. For example, if a treatment renders a surface sensitive to cracking, such a treatment may be applied over a portion of a diffuser plate that experiences minimal deformation. Yet further, a material may be applied via a treatment and then finished (e.g., polished, etc.) to provide for desirable flow characteristics or other characteristics. As described herein, a diffuser plate may be color coded, labeled, etc., for example, to facilitate proper assembly (e.g., blue dot to indicate diffuser side and red dot to indicate center housing side).
Below, an example of a turbocharged engine system is described followed by various examples of components, assemblies, methods, etc.
Turbochargers are frequently utilized to increase output of an internal combustion engine. Referring to
Also shown in
Further, to provide for exhaust gas recirculation (EGR), such a system may include a conduit to direct exhaust to an intake path. As shown in
More generally, EGR is an established method of reducing NOx in internal combustion engines, for example, by reducing peak cylinder combustion temperature (e.g., rate of combustion) as well as reducing partial oxygen pressure in a combustion cylinder. As mentioned, EGR can involve diverting a fraction of the exhaust gas into an intake manifold where the re-circulated exhaust gas mixes with incoming air before being inducted into a combustion cylinder. Other techniques to achieve EGR can involve valve control, for example, where an exhaust valve for a combustion cylinder is operated to retain at least some exhaust gas.
Two techniques that rely on recirculation via a pathway or pathways are so-called high pressure EGR and low pressure EGR. High pressure EGR is sometimes referred to as “short route” EGR (SREGR) while low pressure EGR is sometimes referred to as “long route” EGR (LREGR). Referring again to
To address issues associated with LREGR, some systems have included coolers, filters or other equipment. For example, to address heat, a cooler may extract heat from exhaust prior to entry of the exhaust upstream from a compressor. Similarly, to remove at least some contaminants (e.g., particulates), a filter may be positioned along a LGEGR pathway. As described herein, a diffuser plate may be used to reduce at least some detrimental aspects of LGEGR. As described herein, a diffuser plate may optionally be implemented in conjunction with an exhaust cooler, an exhaust filter, etc.
In
The compressor 240 includes a compressor housing 242 that defines a volute 245 and that houses a compressor wheel 244 secured to the shaft 220 by a nut 246. Further, a diffuser plate 290 is shown as being clamped between the housing 242 and the housing 280 to define, at least in part, a surface of a diffuser 247. In
In the example of
During operation, rotation of the wheel 310 acts to compress and direct air (e.g., or air and exhaust) to a diffuser 347 defined in part by a surface 343 of the housing 340 and subsequently to a volute 345 defined in part by the housing 340. In the example of
In a top view of the diffuser plate 390, an outer edge 391, a raised annular section 392, an intermediate section 393, a transition section 394, a lower annular section 395 and an inner edge 396 are shown. A cross-sectional view of the diffuser plate 390 shows the plate in an uncompressed (undeformed) state.
Just below the cross-sectional view of the diffuser plate 390, a cross-sectional view of a portion of the housing 380 shows a recess defined by a raised annular ridge 381, an outer edge 382 that transitions to an annular surface 383, a transition 384 to a lower annular surface 385, an inner edge 386 that rises to a contoured annular surface 387 that terminates at an edge 388 disposed at an inner diameter (e.g., to define a bore configured to cooperate with the collar 370). As shown in the example of
In a cross-sectional view that shows the diffuser plate 390 in an uncompressed state set in the recess of the housing 380, the fulcrum 389 does not contact the plate 390. In such an example, some compression of the plate 390 may occur before contact with the fulcrum 389 (e.g., free deformation). Upon contact with the fulcrum 389, the compression dynamics of the plate 390 are altered. As described herein, a component may include one or more fulcrums for interacting with a diffuser plate, for example, to shape the plate, to provide for biasing characteristics, to provide for an air gap or pocket, etc.
As mentioned, any of a variety of mechanisms may be employed to attach components to clamp a diffuser plate. As described herein, a diffuser plate can provide a pre-load force to bias a clamping force. Such an arrangement may allow for a reduction in, for example, number of bolts to attach a compressor housing to another housing as a diffuser plate can distribute force more evenly about a circumference. Further, a diffuser plate may provide for sealing about a circumference, which would otherwise be achieved solely by tightening bolts or another mechanism to ensure contact between housings. As an example, consider an arrangement with two housings configured to receive three bolts spaced at about 120 degree intervals where tightening of the bolts clamps a diffuser plate that forms a seal between the two housings. Yet further, since a diffuser plate can act as a spring, it can help to retain the clamping load on a compressor housing. As described herein, stiffness and shape of a diffuser plate can be optimized to ensure that a bolt retained load is enhanced (e.g., where spring action assists a bolt retention load).
As shown in
An approximate equation for spring characteristics of a diffuser plate may be F=−kΔz, where z is an axial dimension and k is a spring constant. Where a fulcrum is used to shape a diffuser plate, the plate may optionally be characterized by more than one spring constant, according to the approximate equation. For example, a diffuser plate may have a spring constant for free deformation and another spring constant for deformation with respect to a fulcrum contact surface.
While the example of
In
In the example of
As described herein, a section of a diffuser plate (e.g., a raised annular section) may contact a housing component proximate to a volute to provide for sealing of the volute. For example, as shown in
As described herein, a diffuser plate can include a transition section, defined along an axis, from a lower axial portion to a higher axial portion. As shown in various examples, the transition section may have substantially an S-shape or be a sloped annular step. As described herein, deformation characteristics of a diffuser plate may be optimized to obtain a desired diffuser width under a given clamping load. For example, where a torque is specified for bolts that join a compressor housing to a center housing (or other component), a diffuser plate may be configured based at least in part on the torque such that a diffuser is formed with specified characteristics (e.g., width, height, shape, etc.). Further, as described herein, such a torque for a bolt or other joining element may optionally be determined at least in part on stiffness of a diffuser plate. Accordingly, an optimization process may be implemented to determine a bolting load to achieve a clamping load for a diffuser plate that properly shapes the diffuser plate and that properly provides for one or more seals.
As to seals, as described herein, a diffuser plate can be configured to provide for radial contact at an inner and an outer location via appropriately shaped sections. For example, as shown in
As described herein, a diffuser plate may be constructed to avoid excitation by high frequency vibrations. For example, modeling and simulation may be performed for a diffuser plate clamped between two components. Such modeling and simulation may account for any of a variety of sources of vibration. For example, vibrations emanating from a bearing system, a turbine wheel, a compressor wheel, flow over one or more surfaces, etc., may be considered to determine whether characteristics of a diffuser plate are suitable to avoid detrimental excitation. Further, should some excitation exist, as described herein, characteristics of an installed diffuser plate may be sufficient to ensure mechanical integrity during operation.
As described herein, a diffuser plate may optionally provide for beneficial heat transfer characteristics. As mentioned, heat energy may be transferred to fluid passing through a compressor and thereby diminish compressor efficiency (e.g., by heating the fluid).
In the examples of
Further, where thermal expansion coefficients differ between two or more components of a compressor assembly, some frictional force may act abrasively at points of contact (e.g., also consider a fulcrum as a point of contact). Accordingly, a diffuser plate may be treated, or alternatively or additionally, one or more other contacting components may be treated (e.g., consider treatment of a portion of a center housing and treatment of a portion of a compressor housing where they contact a diffuser plate).
As mentioned, where exhaust gas recirculation or even where environmental conditions introduce damaging constituents into a compressor, it can be desirable to take measures to avoid damage to a center housing of a turbocharger. For example, a diffuser plate may be relatively inexpensive and readily replaceable when compared to expense of a center housing and replacement of a center housing. Thus, where environmental or operational conditions raise risk of damage to a center housing, a diffuser plate that acts to seal at least a portion (e.g., a diffuser portion) of a center housing can be quite beneficial.
As described herein, a diffuser plate may include one or more treated surfaces that provide anti-fouling properties. For example, where contaminants are hydrophobic, a treatment may provide for a more hydrophilic surface that repels such contaminants. In general, contaminants deposited on a diffuser surface can be detrimental to operational efficiency of a compressor (e.g., due to interference with fluid flow, heat transfer, etc.). Accordingly, at least an outwardly facing surface of a diffuser plate may be treated for anti-fouling. For example, upper surfaces of Zone B and Zone C (e.g., diffuser surface zones) may be treated to impart anti-fouling properties.
As described herein, a diffuser plate may be manufactured from stainless steel and have a “super” finish that can optionally alleviate a need for any additional coating. A super finishing process may provide for beneficial nanoscale surface characteristics (e.g., a so-called nano finishing or polishing process). Such finishing may provide a highly mirrored surface with anti-fouling properties.
Further, as described herein, a deformable diffuser plate may be provided and installed with requiring any additional components other than, for example, conventional components for attaching a compressor housing to a center housing. In such an example, attaching the compressor housing to the center housing locks the diffuser plate therebetween. In such an arrangement, biasing force exerted by the plate may act to maintain the position of the plate during operation and non-operation.
As described herein, a diffuser plate for a centrifugal compressor can include an inner edge disposed at an inner diameter about a central axis; an outer edge disposed at an outer diameter, the outer edge displaced an axial distance from the inner edge; a deformable section with a substantially S-shaped cross-section, the deformable section disposed between the inner edge and the outer edge; and a spring constant for forced axial displacement of the outer edge with respect to the inner edge, the spring constant characterized, at least in part, by the deformable section. Such a plate may further include an axially stepped annular section disposed adjacent to the outer edge.
As described herein, a diffuser plate can include a fulcrum contact surface disposed between an inner edge and an outer edge, for example, where the fulcrum contact surface includes a fulcrum contact surface diameter. Such a plate can be configured for free deformation responsive to application of force to displace the outer edge with respect to the inner edge and configured for deformation about the fulcrum contact surface responsive to application of force to displace the outer edge with respect to the inner edge.
As described herein, a deformable section can be configured to form an annular countered surface of a diffuser of a centrifugal compressor assembly upon application of force to displace the outer edge with respect to the inner edge.
As described herein, a diffuser plate can include an anti-fouling surface treatment, for example, where the anti-fouling surface treatment resists fouling of the diffuser plate by one or more constituents in exhaust of an internal combustion engine or one or more reaction constituents of exhaust of an internal combustion engine. As explained, an anti-fouling surface treatment or other treatment may exist over only a portion of a diffuser plate.
As described herein, a compressor assembly can include a diffuser plate that includes an inner edge disposed at an inner diameter about a central axis and an outer edge disposed at an outer diameter, the outer edge displaced an axial distance from the inner edge; a first housing component that includes a fulcrum disposed at a fulcrum diameter about a central axis, the fulcrum diameter greater than the inner diameter of the inner edge and less than the outer diameter of the outer edge of the diffuser plate; and a second housing component that includes a clamping surface where the clamping surface has an inner dimension less than the outer diameter of the outer edge of the diffuser plate, where, for a clamped configuration of the diffuser plate, the diffuser plate applies a biasing force between the fulcrum of the first housing component and the clamping surface of the second housing component. In such an example, the diffuser plate can have one or more spring constants. Further, such a plate can include a fulcrum contact surface.
As to clamping, a clamping surface can extend radially outwardly from a surface of a housing that defines, at least in part, a volute. As described herein, a deformable diffuser plate, for the clamped configuration, can include a deformed surface that defines, in part, shape of a diffuser.
As described herein, a diffuser plate can optionally include at least one surface treated with a treatment selected from, for example, an anti-fouling treatment, a heat transfer treatment, a flow modification treatment, and a corrosion resistant treatment.
As described herein, a method can include positioning a deformable diffuser plate for a centrifugal compressor between a first housing component and a second housing component; forcing the first housing component to the second housing component against a biasing force applied by the deformable diffuser plate; and, responsive to the forcing, deforming the deformable diffuser plate to shape a surface of a diffuser of the centrifugal compressor. In such a method, the first housing component and the second housing component may be a compressor housing and a center housing and where the diffuser plate provides for an air gap between the compressor housing and the center housing. As described herein, a method can include deforming a diffuser plate, for example, such as one or more of freely deforming and deforming against a fulcrum.
As described herein, various acts may be performed by a controller (see, e.g., the controller 190 of
Although some examples of methods, devices, systems, arrangements, etc., have been illustrated in the accompanying Drawings and described in the foregoing Detailed Description, it will be understood that the example embodiments disclosed are not limiting, but are capable of numerous rearrangements, modifications and substitutions without departing from the spirit set forth and defined by the following claims.