REFERENCES TO RELATED APPLICATIONS

[PARA 1] This application claims priority of US provisional application serial no. 62353371 filed on 06/22/2016 entitled I M PROVED I NLET SYSTEM FOR A RADIAL COM PRESSOR WITH A

WI DE FLOW RANGE REQUIREM ENT, the disclosu re of which is incorporated herei n by reference.

BACKGROUND

FIELD

[PARA 2] This invention relates generally to the field of radial compressors and more particu larly to an inlet for a radia l compressor having a com pressor wheel with blades that define a n inducer and an exducer, a n inlet air passage incorporating two or more concentric regions that are separated from each other from a point adjacent to the inducer to an air filter. RELATED ART

[PARA 3] The flow ra nge of a tu rbocharger compressor, defined as the ratio of choke flow to surge flow at a fixed pressure ratio, is an attribute that always needs improvement.

Turbomachinery is inherently a na rrow range technology due to the fact that flow vectors change with flow, a nd the geometry is designed for specific flow vectors. Therefore, whenever the mass flow is not the design mass flow, the actual flow vectors are different tha n the geometry was designed for. As flow is increased, the limiting factor is choking of the

compressor inducer. As flow decreases, the limiting factor is su rge of the compressor ind ucer or diffuser.

[PARA 4] Turbochargers a re used on wide variety of engines each of which can have different cha racteristics and req uirements. Although there are a complex set of variables that determine the tu rbocharger characteristics, the most dominant characteristic is the speed range of the engine. At one extreme, an example would be high performance gasoline motorcycle engines, some of which have a maxim um speed of 16,000 rpm. At the other end of the spectrum an example would be gen-sets that run at one fixed speed to allow the generator to provide a fixed electrica l AC frequency. Conventional radial compressors work extremely well for the gen-sets, but are inadequate for high speed gasoline engines. Other than constant speed engines such as a gen-set, most other engines require a broad flow range which is the weakest attribute of a radial compressor.

[PARA 5] The second most dominant engine attribute determining the requirements of the compressor is the Brake Mean Effective Pressure (BMEP). The higher the engine BMEP, the higher the compressor boost pressure requirement.

[PARA 6] The maximum flow of a compressor design is determined by the throat area of the inducer. As the inducer flow area is increased relative to the maximum diameter of the compressor wheel, there is a practical limit as the maximum efficiency declines. Therefore, to make significant improvements in flow range to a compressor of fixed diameter, the surge line must be improved, i.e. moved to lower flow.

[PARA 7] The focus of compressor design for turbochargers has been to improve the flow range, especially to move the surge line to the left on the flow versus pressure ratio map. One can look at the historical trends to verify this. Compressors designed in the 1960s using basic principles and slide rule calculations could produce 80% efficiency. Today using computer clusters combined with auto-optimization programs that modify geometric parameters then run computational fluid dynamics programs and finite element stress analysis, also result in about 80% maximum efficiency. However, the flow range of the compressors is significantly improved in today's compressors demonstrating that the engineering focus has been on improving the flow range of compressors.

[PARA 8] An important facet of radial compressor design to note is that there are two surge/stall mechanisms. One is the compressor inducer, the other is the diffuser. This can be seen in many compressor maps as there are two slopes to the surge line. At low pressure ratio, the diffuser stalls, then at higher pressure ratio the inducer stalls.

[PARA 9] A device commonly referred to as a "ported shroud" has been used since the 1980s to improve the flow range of compressors used on high BMEP engines, typically highly boosted diesel engines that operate across a relatively wide speed range (for diesel engines) such as truck engines and industrial/agricultural engines. [PARA 10] A turbocharger compressor with a ported shroud, as shown in FIG. 1, employs a compressor housing 1 and a compressor wheel 2 having an inducer 3 and an exducer 4 feeding a volute 5 through a diffuser 6. Air is received through an inlet 7 and a recirculation channel using a ported shroud cavity 8 receiving air through a slot 9 to increase the mass flow through the inducer which prevents stalling. A noise suppressor or silencer 10 is often incorporated. The recirculation provided by the ported shroud is not thermodynamically free as it increases the work the turbine has to do to pump the extra air in this short loop. But, even worse is that this recirculation heats the air that is recirculated significantly. When this hot air is blended back into the fresh air at the inlet of the compressor, it reduces the efficiency of the

compressor (equation 1) and increases the work required of the turbine (equation 2). If the inlet pressure and temperature are measured far enough upstream not to be impacted by recirculation, the efficiency will be lowered by the recirculated flow. If the inlet temperature and pressure are measured closer to the compressor where the recirculated flow impacts the inlet temperature measurement, then the efficiency will be measured as higher, but the power required by the turbine is still increased by the higher Tl measurement.

[PARA 11] In the area of the map where the ported shroud is not necessary, it creates an additional loss and reduces the efficiency there as well. The ported shroud generally reduces the peak efficiency of a compressor by 1-3 points.

(γ-Χ)Ιγ

I ^fla ^x c _P a ^{x T} 1 i ^x ^ JLc ^{~ ?} (Equation 2)

[PARA 12] One device that eliminates the hot air from the ported shroud being recirculated to the inlet is shown in US Patent 8,511,083, Ported Shroud with filtered external ventilation. But, the other losses of the ported shroud are still present.

[PARA 13] The ported shroud is only effective at moving the surge line to lower flow at higher pressure ratios. The ported shroud is not used on most gasoline and diesel passenger car engines because their compressor map width req uirement is most severe at lower pressure ratio values where the ported shroud is not effective. [PARA 14] Another negative feature of a ported shroud is that it can ca use noise issues and often req uires a noise baffle be incorporated into the design. This audible vibration can a lso fail the compressor blades if a resonance condition is present.

[PARA 15] There is an unfilled need in tu rbocharger technology for a device that improves the surge performance of a compressor at both high and low pressure ratio, and does not reduce the efficiency of the compressor or induce vibrations that are audible or ca use resonant with the blades.

SUMMARY

[PARA 16] The embodiments herein disclose an apparatus for use with a radial compressor having a compressor wheel with blades that define an ind ucer and a n exducer, an inlet air passage with a first region and a second region separated from the first region from a point adjacent to the inducer to an air filter, each region having a separate air filter.

BRIEF DESCRIPTION OF THE DRAWINGS

[Para 1 ] The features, functions, and advantages that have been discussed can be achieved independently in various embodiments of the present disclosure or may be combined in yet other embodiments, further details of which can be seen with reference to the following description and drawings.

[PARA 17] FIG. 1 is a section view of a typica l prior a rt ported shroud with silencer;

[PARA 18] FIG. 2 is a section view of a first embodiment of a basic Wide Flow Range I nlet ; [PARA 19] FIG. 3 is a section view showing the embodiment of the basic wide flow range inlet and showing inlet connections;

[PARA 20] FIG. 4 is a section view showing an embodiment of the wide flow range inlet with axial and radial inlets;

[PARA 21] FIG. 5 is a phantom view showing swirl vanes in the outer region of the inlet; [PARA 22] FIG. 6 is a section view of an embodiment of an wide flow range inlet with an active design in the non-activated flow condition; FIG . 7 is a section view of the embodiment of FIG. 5 in the activated condition;

[PARA 23] FIG. 8 is a section view showing an embodiment of a wide flow range inlet combined with a Ported Shroud; and, [PARA 24] FIG. 9 is a section view with a schematic representation of a heat exchange cooling system.

DETAILED DESCRIPTION

[PARA 25] The embodiments shown herein for a wide flow range inlet solves these problems. Referring to the drawings, FIG. 2 shows a tu rbocharger compressor 100 having a compressor housing 101 and a compressor wheel 102 having an inducer 103 and a n exducer 104 feeding a volute 105 through a diffuser 106. Air is received through a n inlet 107. A wide flow range inlet 108 splits the inlet flow passage into a first inner region 109 and a second inner region 110 concentrica lly separated by an inlet divider wall 111 which separates the second region from the first region a nd terminates at an inlet plane 112 of the inducer 103. This eliminates the losses associated with the ported shroud as well as eliminates the recircu lation of hot gas into the compressor. While defined as an inlet pla ne, the profiles on the compressor blades in alternative embodiments may employ a sweep in the inducer resulting in a region of flow into the blades which extends along the inlet axis and the termination of the divider wa ll is positioned at a point in the blade profile to segregate flow in the regions for desired

characteristics as will be described su bseq uently.

[PARA 26] The wide flow range inlet separates the incoming air stream into mu ltiple, concentric regions, the simplest version being the inner and outer regions 109, 110 of the first embodiment. I n a lternative embodiments, m ultiple concentric regions each separated by concentric divider walls terminating proximate the ind ucer inlet plane (or at points along the blade profile) may be employed. For the shown embodiment with two concentric regions, feedback of the subsonic flow through the inducer blades back into the inlet flow stream allows two different amou nts of swirl to be generated, which can improve the efficiency of the compressor. A movable array of vanes may be included in one or all of the regions to induce positive or negative swirl to the flow in the associated passages.

[PARA 27] With the wide flow range inlet, each of the concentric regions is separated at the filter end of the inlet ducting from the other concentric regions and each region receives inlet air through a separate air filter. At the end proximate the inducer inlet, the regions are separated by the divider wall(s) until close proximity of the blade profile of the compressor wheel.. Each concentric region has the possibility of flow going in either direction.

[PARA 28] As seen in FIG. 3, for the embodiment of two concentric regions, the divider wall 111 is connected to the compressor housing 120 with at least one strut 113 (multiple struts may be spaced circumferentially about the divider wall) extending through the outer concentric region 110. The inner concentric region 109 remains segregated by an inner tube 114 connecting the divider wall 111 to a first air cleaner 115 (not shown to scale) to provide a main air passage 116 into the inner concentric region. An outer hose 117 engages the compressor housing 120 at the outer circumference of the outer concentric region 110 connecting to a second air cleaner 118 (which may concentrically surround the first air cleaner but is separated from the first air cleaner 115) to provide a secondary air passage 119 into the outer concentric region. The flow from the first and second air cleaners into the inner and outer concentric regions is substantially axial. As shown by arrows 121 flow in the outer concentric region 110, which provides a bi-directional cavity, and the secondary air passage 119, which provides a bidirectional air passage, may flow in either direction. Flow rejected by the inducer may thereby be expelled outwardly. Vanes 138, which may be movable and arranged in one or more arrays, may be employed to induce swirl as will be described subsequently.

[PARA 29] In a first alternative embodiment seen in FIG. 4, the main air passage 116 is engaged to the first air cleaner 115 providing axial flow, while a secondary air passage 122 connecting to outer concentric region 110 turns to receive inlet flow radially from a second air cleaner 123.

[PARA 30] In the design of a compressor wheel or impeller, the blade shape at the inducer has a varying angle to the incoming flow from hub to shroud. This is because the tip speed of the blade increases from hub to shroud. Being subsonic flow in the passage before the inducer, the flow field in the inducer feeds back into the passage flow field and creates a swirl in the passage, with the highest swirl in the outer part of the passage, and the least swirl in the center of the passage.

[PARA 31] As sub-sonic flow, this swirl tends to be self-aligning. Having the separate concentric regions in the inlet passage, as previously described, tends to allow different regions of the inlet passage to align with the corresponding region in the wheel inducer.

Further, each region may employ vanes 139 or texturing over a portion of or the entire length producing subdivided passages that are constructed with a positive or negative swirl angle as seen in FIG. 5.

[PARA 32] A second alternative embodiment shown in FIGs. 6 and 7 allows the use of just one inlet with one air cleaner. This embodiment includes a valve 124 that can be opened or closed. When the valve is open as shown in FIG. 6, air flows from the air cleaner 125 to through secondary air passage 122 into the outer region 110 and into the compressor inducer 103 as indicated by arrows 126. This flow then augments the primary flow (indicated by arrows 127) through inner region 109 into the inducer.

[PARA 33] When closed as shown in FIG. 7, the valve 124 directs flow rejected from the inducer (indicated by arrows 128) into an exit duct 129

[PARA 34] The valve 124 for an exemplary embodiment is passive, using the vacuum and pressures existing within the housing to move a control piston 130 carried in cylinder 131 to either of two positions with appropriate porting of the cylinder. It can also be designed to be actively controlled, wherein the boost pressure can be applied in the cylinder 131 to one side of the piston if a solenoid (not shown) is energized, or the cylinder vented to ambient or sub- ambient pressure from the inlet stream if the solenoid is not activated.

[PARA 35] As shown in FIG. 8, the wide flow range inlet may also be incorporated with a ported shroud. An additional passage is provided in the form of a ported shroud cavity 8 from the outer region 110 of the air inlet passage to a slot 9 adjacent to a compressor shroud line 132, substantially midway (40 - 60%) down the compressor shroud line between the inducer and exducer.

[PARA 36] Another alternative to adding a second air filter is to cool the hot air in the outer concentric region when rejected by the inducer and then merge it back into the main flow in the inner concentric region as shown in FIG. 9. Engine cooling water is typically too hot to provide cooling so a low temperature cooling source would be necessary. Various engines now have a second cooling loop 134 which is very close to ambient temperature, and thus would be an appropriate cooling source for attachment to a heat exchanger 135 located in the outer concentric region 110 distal from the plane of the inducer. Divider wall 111 terminates past the heat exchanger in a common inlet plenum 135 proximate the air filter 125. Flow rejected by the inducer flows through the heat exchanger 136 and is then returned to the inner concentric region 109 (as represented by arrows 137).