Engine braking and air boosting systems for hydrogen internal combustion engines

Abstract

An air intake system for an internal combustion engine and methods of operating the air intake system. The system includes a turbocharger, a supercharger in series with the turbocharger, a first intercooler between the turbocharger and the supercharger, and a second intercooler downstream of the supercharger. The method includes operating the air intake system to support the internal combustion engine in a drive mode by bypassing the supercharger by opening a first throttle valve in a first bypass line and operating the air intake system to support the internal combustion engine in a brake mode by closing the first throttle valve in the first bypass line.

Description

ENGINE BRAKING AND AIR BOOSTING SYSTEMS FOR HYDROGEN INTERNAL COMBUSTION ENGINESRELATED APPLICATIONS

[0001] This application claims priority to United States Provisional Patent Application Serial Numbers 63 / 623,008, filed January 19, 2024; and 63 / 603,993, filed November 29, 2023; United States Patent Application Serial Number 18 / 732,382, filed June 03, 2024; and Indian Provisional Patent Application Serial Number 202411064169, filed August 26, 2024, the entireties of which are incorporated by reference herein.BACKGROUND

[0002] A conventional engine brake system focuses on precise control of the engine's operation to achieve effective braking. This system commonly employs a compression release brake, which releases pressure in the cylinders during the compression stroke, creating resistance and slowing down the engine. Additionally, the system may involve throttle closure to further reduce power. Integration with the transmission, whether manual or automatic, enhances the braking effect through optimized gear selection. The overall design considers a balance between braking performance, fuel efficiency, noise control, and compliance with emission standards to deliver an effective engine braking solution.

[0003] Conventional superchargers are typically driven through by an engine crankshaft via a belt-pulley system and can accordingly be considered to be active devices. In some applications, superchargers are coupled with a clutch to selectively activate the supercharger as continuous operation is sometimes not needed. Such air boosting systems have capacity limitations and are not well suited to certain applications. Improvements are desired.SUMMARY

[0004] Presently, vehicles with internal combustion engines (ICE) often have a compression ratio around 18:1 with braking power to match, which is needed for safe and effective braking of many ICE powered vehicles. Hydrogen ICE (H2 ICE) has a reduced compression ratio to prevent auto-ignition, of about 12: 1 or 11 : 1. H2 ICE is able to match the propulsion power of traditional engines with this reduced compression ratio, but the braking power is significantly reduced, on the order of 25-30%. As disclosed herein, supercharging air within the cylinder during braking operations increases the available braking power.

[0005] Automotive applications having high air boosting requirements, such as hydrogen internal combustion engines, may require multistage air boosting architecture instead of current conventional single stage boosting. Various architectures maybe followed for meeting this high air flow requirement. For example, a turbocharger-supercharger combination, a superchargerturbocharger combination, and / or a two-stage turbocharger. In the case of turbochargersupercharger and supercharger-turbocharger combinations, the supercharger can be used for low-speed high load conditions and transient operations where the turbocharger alone cannot deliver the required performance and likewise to eliminate the turbo lag. It is also noted that any additional boosting device incorporated to achieve a high lambda (2.0-2.5) should also maximize engine efficiency and minimize engine out NOx.

[0006] Examples presented herein relate to an air intake system for an internal combustion engine. The system includes a turbocharger; a supercharger in series with the turbocharger; a first intercooler between the turbocharger and the supercharger; and a second intercooler downstream of the supercharger.

[0007] In some examples, the second intercooler has an outlet temperature of less than or equal to 50 degrees C, and more preferably less than or equal to 40 degrees C, and even more preferably less than or equal to 30 degrees C. In some examples, the first intercooler has an outlet temperature of less than or equal to 50 degrees C, and more preferably less than or equal to 40 degrees C, and even more preferably less than or equal to 30 degrees C.

[0008] In some examples, the system further includes a first bypass line diverting flow around the supercharger during driving operations. In some examples, the first bypass line diverts flow from an inlet of the supercharger to an inlet of the second intercooler. In some examples, the system further includes a first throttle valve in the first bypass line.

[0009] In some examples, the system further includes a second bypass line providing additional flow to an inlet of the supercharger during braking. In some examples, the second bypass line directs flow from an outlet of the second intercooler to the inlet of the supercharger. In some examples, the system further includes a first bypass line diverting flow around the supercharger during driving operations, wherein a diameter of the first bypass line is greater than a diameter of the second bypass line. In some examples, the second bypass line is a rubber hose. In some examples, the system further includes a second throttle valve in the second bypass line.

[0010] In some examples, the supercharger is a clutched supercharger. In some examples, the clutched supercharger includes an integrated clutch. In some examples, the system further includes a speed up device in connection with the clutched supercharger.

[0011] In some examples, the supercharger is pulley-driven, gear-driven, or motor-driven. In some examples, the supercharger is motor-driven and the supercharger is a two-speed supercharger.

[0012] In some examples, the second intercooler discharges into an intake manifold of the hydrogen internal combustion engine.

[0013] Examples presented herein relate to a method of operating an air intake system for an internal combustion engine, the air intake system including, in series, a turbocharger, a first intercooler, a supercharger, and a second intercooler. The method includes operating the air intake system to support the internal combustion engine in a drive mode by bypassing the supercharger by opening a first throttle valve in a first bypass line; and operating the air intake system to support the internal combustion engine in a brake mode by closing the first throttle valve in the first bypass line.

[0014] In some examples, operating the air intake system to support the internal combustion engine in the brake mode further comprises directing air flow from an outlet of the second intercooler to an inlet of the supercharger by opening a second throttle valve in a second bypass line.

[0015] In some examples, the supercharger is a clutched supercharger. In some examples, operating the air intake system to support the internal combustion engine in the drive mode further comprises operating the clutch to place the supercharger is a neutral state. In some examples, operating the air intake system to support the internal combustion engine in the brake mode further comprises operating the clutch to connect the supercharger with a speed up device. In some examples, the supercharger is a motor-driven supercharger with a motor having at least two speeds; wherein operating the air intake system to support the internal combustion engine in the drive mode further comprises running the motor at a first speed; and wherein operating the air intake system to support the internal combustion engine in the brake mode further comprises running the motor at a second speed, wherein the second speed exceeds the first speed.

[0016] In some examples, the internal combustion engine is a hydrogen internal combustion engine.

[0017] Examples presented herein relate to an air intake system for an internal combustion engine includes a turbocharger, a first intercooler, a supercharger, and a second intercooler, in series and arranged in an engine compartment such that: the first intercooler resides at a rear boundary of the engine compartment; the second intercooler resides in front of the firstintercooler; and each of the turbocharger and the supercharger reside in front of the second intercooler.

[0018] In some examples, the system includes a supercharger bypass line arranged between the second intercooler and the supercharger. In some examples, the second intercooler is larger than the first intercooler.

[0019] A variety of additional inventive aspects will be set forth in the description that follows. The inventive aspects can relate to individual features and to combinations of features. It is to be understood that both the forgoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the broad inventive concepts upon which the embodiments disclosed herein are based.BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which are incorporated in and constitute a part of the description, illustrate several aspects of the present disclosure. A brief description of the drawings is as follows:

[0021] FIG. l is a process flow of a typical four-stroke internal combustion engine (ICE) cycle during engine braking.

[0022] FIG. 2 is a graph depicting a typical decompression brake lift profile.

[0023] FIG. 3A is a graph depicting a decompression brake lift profile for a two-stroke braking cycle.

[0024] FIG. 3B is a graph depicting another decompression brake lift profile for a two- stroke braking cycle.

[0025] FIG. 4A is a flowchart of an example method of increasing the braking power of a decompression braking cycle.

[0026] FIG. 4B is a flowchart of another example method of increasing the braking power of a decompression braking cycle.

[0027] FIG. 5 is an example engine and decompression braking system.

[0028] FIG. 6A is an example supercharger arrangement in an engine.

[0029] FIG. 6B is an example of a dry clutch that can be coupled to a drive belt associated with the supercharger shown in FIG. 6A.

[0030] FIG. 6C is an example of the supercharger shown in FIG. 6A provided with an integrated magnetic clutch.

[0031] FIG. 6D is an example of the supercharger shown in FIG. 6A provided with a drive belt coupled with a multi -pl ate clutch.

[0032] FIG. 6E is an example of a three-way clutch that can be coupled to or integrated with the supercharger shown in FIG. 6A.

[0033] FIGS. 7A-7C present examples for increasing a pressure ratio across the supercharger shown in FIGS. 6A-6B.

[0034] FIG. 7D shows a power map demonstrating the effectiveness of increasing the pressure ratio to increase the load exerted by the supercharger.

[0035] FIG. 8 is a block diagram of an example computer system, upon which systems and method embodying aspects of the present disclosure may operate.

[0036] FIG. 9 is a schematic showing a prior art air boosting system.

[0037] FIG. 10 is a schematic showing an hydrogen fuel based internal combustion engine and related intake and exhaust systems having features in accordance with the present disclosure

[0038] FIG. 11 is a schematic showing a turbocharger-supercharger air boosting system usable with the internal combustion engine shown in FIG. 10.

[0039] FIG. 12 is a schematic showing a turbocharger-supercharger air boosting system usable with the internal combustion engine shown in FIG. 10.

[0040] FIG. 13 is a schematic showing a turbocharger-supercharger air boosting system usable with the internal combustion engine shown in FIG. 10.

[0041] FIG. 14 is a schematic showing a turbocharger-supercharger air boosting system usable with the internal combustion engine shown in FIG. 10.

[0042] FIG. 15 is a schematic showing a turbocharger-supercharger air boosting system usable with the internal combustion engine shown in FIG. 10.

[0043] FIG. 16 is a schematic showing a turbocharger-supercharger air boosting system usable with the internal combustion engine shown in FIG. 10.

[0044] FIG. 17 is a schematic showing a supercharger-turbocharger air boosting system usable with the internal combustion engine shown in FIG. 10.

[0045] FIG. 18 is a summary table of architecture details of various embodiments of the present disclosure.

[0046] FIG. 19A is an efficiency map related to the air boosting system shown at FIG. 14.

[0047] FIG. 19B is an efficiency map related to the air boosting system shown at FIG. 13.

[0048] FIG. 20 is a graph showing brake power and a comparison of brake efficiency between clutched and unclutched air boosting system configurations.

[0049] FIG. 21 is a schematic top view of the internal combustion engine shown in FIG.10 using the air boosting system of FIG. 15.

[0050] FIG. 22 is a schematic end view of the internal combustion engine and air boosting system shown in FIG. 21.

[0051] FIG. 23 is a schematic view of a combined combustion and braking system architecture.

[0052] FIG. 24 is a schematic view of an alternative architecture configuration of the combined combustion and braking system of FIG. 23.

[0053] FIG. 25 is a schematic view of a combined combustion and braking system architecture using a two valve architecture.

[0054] FIG. 26 is a schematic view of an alternative architecture configuration of the combined combustion and braking system of FIG. 25.

[0055] FIG. 27 is a schematic view of an alternative architecture configuration of the combined combustion and braking system of FIG. 25.

[0056] FIG. 28 is a pair of graphs showing effects of a speed up device on brake power and boosting power.

[0057] FIG. 29 is an efficiency map related to the speed up device.

[0058] FIG. 30 is a schematic view of a braking speed up device architecture with the supercharger disconnected during braking.

[0059] FIG. 31 A is a graph showing braking performance without the speed up device.

[0060] FIG. 3 IB is a graph showing braking performance with the speed up device.

[0061] FIG. 32 is an efficiency map related to the disconnecting the supercharger during braking.

[0062] FIG. 33 is an exhaust gas recirculation architecture without a speed up device.

[0063] FIG. 34 is an exhaust gas recirculation architecture with a speed up device.

[0064] FIG. 35 is an example exhaust gas recirculation architecture with a supercharger disconnect. FIG. 36 is another example exhaust gas recirculation architecture with a supercharger disconnect.DETAILED DESCRIPTION

[0065] Reference will now be made in detail to exemplary aspects of the present disclosure that are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

[0066] Hydrogen internal combustion engines (H2 ICE) represent a class of internal combustion engines that use hydrogen as a fuel source instead of traditional hydrocarbon-based fuels like gasoline or diesel. These engines operate on the same basic principles as conventionalinternal combustion engines, but with some key differences in fuel properties and combustion characteristics.

[0067] Gaseous hydrogen is typically used as the primary fuel. Hydrogen is considered a clean fuel because its combustion produces only water vapor and heat, making it an environmentally friendly alternative. The engine's design is modified to accommodate the unique properties of hydrogen, such as its wide flammability range and high flame speed.

[0068] The combustion process in a hydrogen internal combustion engine involves the mixing of hydrogen with air in the engine's cylinders. Hydrogen's unique combustion characteristics allow for flexibility in the design of hydrogen-powered engines. Hydrogen engines may often operate at higher compression ratios to take advantage of hydrogen's high octane rating. However, unlike traditional hydrocarbon fuels like diesel, hydrogen does not have the same issues with pre-ignition or knocking. As a result, hydrogen engines can also operate effectively with lower compression ratios compared to diesel engines. Lower compression ratios may be advantageous for certain hydrogen engine designs.

[0069] In some cases, a H2 ICE is configured with a lower compression ratio to prevent auto-ignition of the hydrogen fuel. Lower compression ratios can also be advantageous in terms of reducing mechanical stress on engine components and potentially simplifying the overall engine design. Hydrogen combustion tends to produce lower levels of nitrogen oxides (NOx), which are a major contributor to air pollution. Lower compression ratios in hydrogen engines may also contribute to the reduction of NOx emissions compared to diesel engines. Lower compression ratios may have further implications for the materials used in engine construction. Engine components need to be designed to handle the specific demands of hydrogen combustion, and lower compression ratios may influence the overall stress on these materials. In some implementations of a H2 ICE, a reduced compression ratio may be necessary for effective operation. For example, in a spark ignited H2 ICE, combustion may require a decrease in compression ratio.

[0070] Though lowering the compression ratio comes with advantages like increased tolerance for lower octane fuels, smoother operation, and reduced knocking tendencies, its influence in some areas of the engine’s operation require additional design considerations. In the case of engine braking, a reduced compression ratio lowers the braking power available during engine braking operations. The available cylinder pressure, which determines the available braking power, is driven by compression ratio when no fuel is supplied (as in a braking scenario). The potential power of an engine braking event is therefore reduced as the compression ratio is reduced.

[0071] Disclosed herein are methods and systems for improved engine braking power. In embodiments, an air compressor, such as a supercharger, increases pressure in a cylinder during an intake event such that when the piston is near top dead center (TDC) and the exhaust valve opens for braking, there is more braking power. In embodiments, the increase in pressure is supplied when a piston is near bottom dead center (BDC) of the cylinder. The disclosed system and methods may provide particular advantages for H2 ICE engine braking, and even more particular advantages for H2 ICE’s with a low compression ratio, but the principles of the present disclosure will be applicable to and effective with a variety of engines.

[0072] Though the present disclosure focuses on use of an air compressor to increase braking power, it is noted that the use of such a compressor (e.g., a supercharger) may have additional advantages in operation of the H2 ICE. For example, inclusion of a supercharger may improve the efficiency of an H2 ICE running with high lambda. The term "lambda" in the context of internal combustion engines refers to the air-fuel ratio, specifically the ratio of the actual air-fuel mixture to the stoichiometric air-fuel ratio. The stoichiometric ratio is the chemically ideal ratio at which complete combustion occurs. A lambda value of 1.0 corresponds to a stoichiometric air-fuel ratio. When the engine is running with a lambda greater than 1.0, it means that there is excess air in the mixture compared to the stoichiometric ratio. This condition is often referred to as running “lean.” In a lean mixture, combustion temperatures tend to be higher, which can affect engine performance and emissions. Lean-burn engines are often equipped with technologies such as exhaust gas recirculation (EGR) or catalytic converters to mitigate the impact on emissions.

[0073] Embodiments of the present disclosure include systems configured to have a 2.4 lambda floor. For example, system configurations disclosed herein which use a supercharger to provide sufficient air delivery to a 2.4 lambda floor. Such configurations may be particularly advantageous during transient operations and high load, low speed operations.

[0074] Referring now to FIG. 1, a process flow 100 of a typical four-stroke ICE cycle during engine braking is shown. The process occurs in a cylinder 102 through operation of a piston 104, an intake valve 106, and an exhaust valve 108. At intake stroke 110, air is drawn into cylinder 102 through intake valve 106 as piston 104 is withdrawn. At compression stroke 112, work is performed to compress the air in cylinder 102 as piston 104 is moved toward the top of cylinder 102. During compression release 114, rather than adding fuel to be combusted to the cylinder, as would occur during drive operations of the engine, fuel is not added to cylinder 102 and pressure is release through exhaust valve 108. At power stroke 116, piston 104 is again withdrawn, but there is no expansion and no positive power as would be generatedfollowing a combustion event. At exhaust stroke 118, remaining air in cylinder 102 is expelled through exhaust valve 108.

[0075] Referring now to FIG. 2, a graph 200 depicting a typical decompression brake lift profile is shown. Intake event 202, which may correspond to intake stroke 110 of FIG. 1, follows a first piston stroke 204 as air is drawn into the cylinder. During intake event 202, the piston moves down the cylinder, creating a vacuum that allows the intake valve to open. Air is drawn into the cylinder as the piston reaches bottom dead center (BDC). BDC refers to the position of the piston in an internal combustion engine at the lowest point of its travel in the cylinder during the engine's four-stroke cycle.

[0076] Occurring around the end of intake event 202, but prior a second piston stroke 208, a brake gas recirculation (BGR) event 206 occurs. A BGR event can be accomplished by opening an exhaust or auxiliary valve near BDC of the intake or expansion stroke of the piston and keeping the exhaust or auxiliary valve open during the first portion of the exhaust or compression stroke of the engine. Opening the exhaust or auxiliary valve during this portion of the engine cycle may allow exhaust gas to flow into the engine cylinder from the relatively higher-pressure exhaust manifold. The introduction of exhaust gases from the exhaust manifold into the cylinder may pressurize the cylinder with a charge faster than it would otherwise occur during the compression stroke. The increased gas pressure in the engine cylinder may increase the braking power produced by a subsequent compression-release event.

[0077] A compression release (CR) event 210 may occur just prior to or in conjunction with the second piston stroke 208, which may be associated with a power stroke, such as power stroke 116 of FIG. 1. During the CR event 210, some pressure from the cylinder may be released, such as through an exhaust valve. This opening of the exhaust valve releases the compressed air in the cylinder to the exhaust system, bypassing a true power stroke which would be driven by combustion of fuel in the cylinder. Without combustion happening in the affected cylinder, there's no power stroke to drive the engine. This lack of power stroke creates a braking effect as the engine acts as an air pump, absorbing energy from the vehicle's motion as the piston withdraws from top dead center (TDC). TDC is the position where the piston reaches its highest point in the cylinder during the compression stroke. At TDC, the piston is momentarily stationary before it starts moving downward again during the power stroke. An exhaust event 212 ends the decompression braking profile as remaining air in the cylinder is released through an exhaust valve.

[0078] As disclosed herein, a supercharge event 214 is added to the braking cycle and introduces additional air into the cylinder during the intake event 202. In embodiments,supercharge event 214 may occur at BDC. Air may be supplied for the supercharge event 214 from an air compressor, such as a supercharger, integrated with the ICE. In addition to providing additional braking power by increasing the pressure within the cylinder to be released, the air compressor may exert a parasitic load on the engine which increases the overall braking load. This load varies with the configuration of the compressor and engine and may be significant in embodiments, e.g., up to 20 KW, up to 25 KW, up to 50 KW, up to 60 KW, up to 70 KW, up to 80 KW, or more, in various embodiments. In some examples, the air compressor includes a supercharger in series with a turbocharger, and in some examples, a supercharger that is downstream from a turbocharger.

[0079] In embodiments, inclusion of supercharge event 214 is associated with the removal or elimination of BGR event 206, as the supercharge event provides a more effective pressure increase than the BGR event. As the air supplied from the air compressor is not heated exhaust, such as that supplied by a BGR event, it has greater density and therefore provides more power than exhaust supplied during a BGR event. Further, in some instances, a BGR event may, in effect, reduce braking power by providing an alternative escape path for the supercharged air in the cylinder. Eliminating the BGR event may be preferable, in embodiments, due to further advantages such as simplification of the valvetrain.

[0080] Increasing the pressure in the cylinder during the intake event increases the braking power available during an engine braking cycle. The release of compressed air creates a braking effect as the engine essentially acts as an air pump, absorbing energy from the vehicle's motion, and greater pressure to release results in greater braking power. Further, the addition of air from the air compressor during the supercharge event allows one or both of the intake stroke’ s height and duration to be reduced. In some instances, such as if a simplified valvetrain is preferred, the intake stroke is not altered from its standard stroke.

[0081] Referring now to FIG. 3 A, a graph 300 depicting a decompression brake lift profile for a two-stroke braking cycle is shown. This engine braking profile uses the four strokes of the engine cycle to achieve two two-stroke braking cycles. The four-stroke intake event 202 and exhaust event 214 are also shown for reference.

[0082] First and second intake events 302, 304, are each associated respectively, with first and second BGR events 306, 308, and first and second CR events 310, 312. In this way, an additional CR event, with associated braking power, is applied during each engine cycle. According to the present disclosure, each intake event 302, 304, may also be associated with a SC event 314, 316 to increase the braking power of each braking event. Addition of supercharge events 314, 316, as disclosed herein, may be particularly advantageous in a two-stroke cycle like that shown in FIG. 3A. By incorporating supercharge events, the additional braking event provided in two-stroke braking can be used without the loss in power per braking event which may otherwise be associated.

[0083] Referring now to FIG. 3B, a graph 350 depicting another decompression brake lift profile for a two-stroke braking cycle is shown. In the embodiment depicted in graph 350, the intake stroke is modified to reduce the height and or the duration of the stroke by the addition of air into the cylinder at BDC (180 degrees and 540 degrees in this example). The SC events 318, 320 of this example are shown at BDC and may coincide with the BGR events 306, 308 of traditional two-stroke braking. Accordingly, the BGR event may be eliminated and replaced by the SC events 318, 320 for improved braking performance. In some applications, it advantageous to remove the BGR event to eliminate the possible leakage path through the exhaust, through which the air within the cylinder, provided through the intake, may escape. Due to the increased power provided by the SC events, the intake event overall may need not be as large to achieve the desired braking power.

[0084] Referring now to FIGS. 4 A and 4B, flowcharts of an example method 400 of increasing the braking power of a decompression braking cycle is shown. In embodiments, the method 400 may be performed by a system controller operating or directing operations of one or more components of the engine. In embodiments, the controller includes a propulsion mode and a braking mode. Each mode may be associated with particular operations and parameters. Method 400 may form a part of the operations of the braking mode.

[0085] At operation 402, a piston is withdrawn from the cylinder head and an intake event occurs. At operation 404, a supercharge event is performed during the intake, and compressed air is added to the cylinder from an air compressor. In embodiments, the supercharge event is executed when the piston is at BDC. In embodiments, the supercharge event may occur in conjunction with a BGR event, or there may be no BGR event throughout the decompression braking cycle. At operation 406, the piston is moved toward the top of the cylinder and a compression event occurs, compressing the air in the cylinder as no fuel is present. At operation 408, compressed air is released from the cylinder during a compression release event.

[0086] As the piston is withdrawn following the compression release event, a power stroke 411 may occur without expansion or positive power, as in a standard decompression braking cycle. Any remaining air in the cylinder is then exhausted during the engine’s standard exhaust stroke 413, before another intake stroke is initiated.

[0087] In embodiments where a two-stroke engine braking cycle is used, as the piston is withdrawn following the compression release event 408, an additional, braking only, intakeevent occurs, at operation 410. A supercharge event is applied and air is added to the additional intake event, at operation 412. At operation 414, an additional compression event compresses the air in the cylinder as the piston moves toward the top of the cylinder (what would be the exhaust stroke in a standard braking cycle). At operation 416, an additional compression release event occurs and the piston may be withdrawn to initiate a next cycle.

[0088] Referring now to FIG. 5, an example engine and decompression braking system is shown. In association with a decompression brake 456, an air compressor 600 (e.g., a supercharger) provides air at the engine intake to raise cylinder pressure during an intake event. A controller 500 provides operation instructions and / or control to the overall engine and / or braking system, or components of the system. In embodiments, controller 500 may execute all of the operations described herein, including braking operations, such as the method 400 discussed above with reference to FIGS. 4A and 4B. Controller 500 may be configured as an electronic vehicle controller, such as the controller 500 of FIG. 8. FIG. 5 also shows an optional driveline retarder 454 and exhaust brake 456 that may also be used in conjunction with the concepts disclosed herein. Driveline retarders 454, decompression brakes 456, and exhaust brakes 457 are well known to those having skill in the art and need not be further described herein.Example Supercharger 600

[0089] Referring now to FIGS. 6A-6E, an example supercharger 600 arrangement, and aspects thereof, are presented. At FIG. 6A, the supercharger 600 is shown as installed in a power plant 700. In the example shown, the power plant 700 is an internal combustion engine 700 configured for operation with hydrogen as a fuel source. As shown, the power plant 700 has an accessory or drive pulley 702 and one or more belts 704 that operably couple the pulley 702 to a corresponding pulley 602 associated with the supercharger 600.

[0090] In one aspect, the supercharger 600 can be a fixed displacement supercharger, such as a Roots-type or twin vortices series (TVS) supercharger, that outputs a fixed volume of air per rotation. In contrast to some devices that change the volume of the working fluid when the fluid is sealed, the volume defined between lobes and the housing of a supercharger is constant as the working fluid traverses the length of the rotors. Accordingly, the supercharger may be referred to as a “volumetric device” as the sealed or partially sealed working fluid volume does not change. In some examples, the supercharger may also be referred to as being a Roots-type supercharger or a twin vortices type supercharger such as a TVS type supercharger manufactured by the Applicant. These types of superchargers are dissimilar to other types ofdevices in which the working fluid is significantly compressed as the working fluid travels through the device.

[0091] The increased air output then becomes pressurized when forced into a plenum. The supercharger is a volumetric device, and therefore is not dependent on rotational speed in order to develop pressure. The volume of air delivered by the supercharger per each rotation of a pair of rotors 626, 628 (illustrated at FIG. 6C) is constant (i.e., does not vary with speed). A supercharger 600 can thus develop pressure at low engine and rotor speeds (where the supercharger is powered by the engine) because the supercharger effectively functions as a pump with compression of the air delivered by the supercharger 600 taking place downstream of the supercharger 600 by increasing the mass of air in the fixed volume engine plenum. Alternatively, the supercharger 600 can be configured as a centrifugal-type supercharger that compresses the air as it passes through the supercharger 600, but with the compression and thus the volume of air delivered to a throttle body 24 and air pressure in the plenum being dependent on compressor speed.

[0092] In one aspect, and as referenced at FIG. 6C, a first rotor 626 rotates on a first shaft and has multiple lobes that mesh via a set of intermeshing timing gears 634, 636 with multiple lobes of a second rotor 628. It should be understood that the rotors 626, 628 mesh in that their lobes interfit with one another when the rotors 626, 628 are rotating. However, the lobes of the rotors 626, 628 do not contact one another. The second rotor 628 rotates on a second shaft which is driven through the set of intermeshing timing gears 634, 636. Specifically, a first gear 634 is mounted on the first shaft to rotate with the first rotor 626. A second gear 636 is mounted on the second shaft to rotate with the second rotor 628. The first gear 634 meshes with the second gear 636. One of the first and second shafts is either directly or indirectly coupled (e.g., via a geartrain) to an input / output shaft 656 which is in turn coupled to pulley 602.

[0093] In embodiments, a clutch 800 is provided for selective engagement and disengagement of the supercharger 600 from the engine. An example of clutch 800 is shown at FIG. 6B, wherein the clutch 800 is configured as a dry clutch that is operatively coupled with the one or more belts via a pulley 802. A clutch with similar features is disclosed in International PCT Publication Number WO 2014 / 150265A2, entitled Dual Ratio Drive for Variable Speed Hybrid Electric Supercharger Assembly, the entirety of which is incorporated by reference herein. This control over the supercharging process allows for a more nuanced approach to use of the supercharger. For example, by disengaging the supercharger during regular driving conditions or low-load scenarios, the clutch helps conserve energy and enhance overall efficiency. This deliberate disconnection also contributes to improved fuel efficiencyand reduced wear on engine components. In embodiments, clutch 800 is a two-position clutch, with a first, engaged position and a second, neutral position. A two-position clutch will generally provide a single ration between the drive, or crankshaft, speed and supercharger speeds. Examples include clutched superchargers used in the automotive gasoline applications, such as a supercharger connected only when needed with an integrated magnetic clutch. An example supercharger and clutch arrangement suitable for use with the principles described herein is shown and described in the WO ‘265 publication.

[0094] Actuation of clutch 800 may be performed, for example, by either a pneumatic or an electrical actuator, such as a linear actuator, commanded by an electrical control unit or operated manually. Clutch 800 may be arranged, in association with the supercharger, according to engine packaging needs. For example, the clutch may be configured on a frontend accessory device, in a supercharger assembly, or geared into the crankshaft, e.g., via the engine flywheel or similar. Clutch 800 may be configured as a two-way clutch, which is either engaged or disengaged (i.e., neutral), or as a three-way clutch, which is either disengaged, engaged in with a first gear ratio, or engaged with a second gear ratio. In either configuration, the clutch 800 may be referred to as a two-speed clutch having first and second gear ratios.

[0095] In accordance with the above, other types of clutch systems are usable for clutch 800. For example, as illustrated FIG. 6C, the supercharger 600 can be provided with an integrated magnetic clutch 800. Other examples include clutched superchargers used to boost heavy duty diesel applications, such as the drive belt coupling at the engine front-end accessory drive using a wet multi-plate clutch, a wet double cone clutch, a dry clutch, etc. FIG. 6D is an example of drive belt coupled with a wet multi-plate clutch. FIG. 6E is an example of a three- way clutch 800. Clutch 800 includes positions for two gear ratios 852, 856 and a neutral position 854. In a first position 852, actuator 858 is moved to the left which likewise moves a dog clutch gear 864 to the left to engage with a gear 860. In a neutral position 854, actuator 858 moves dog clutch gear 864 to be between and disengaged from gears 860, 862. In a second position 856, actuator 858 is moved to the right which likewise moves the dog clutch gear 864 to the right to engage with gear 862. In embodiments, the two ratios are different ratios.

[0096] The controlled boost afforded by the clutch 800 supports performance tuning, offering the flexibility to manually engage or disengage the supercharger based on power or braking requirements. Furthermore, clutch 800 may extend the life of the supercharger and associated parts. By minimizing unnecessary strain during periods when supercharging is not essential, the clutch contributes to the longevity of these components. While not allsupercharger systems incorporate clutches, their presence is a design choice that aligns with specific performance and efficiency goals for a given use.

[0097] In embodiments, additional braking power is obtained from the supercharger by running the supercharger at a higher speed. For example, incorporation of a two-speed ratio device supports a first ratio for boosting and a second ratio for braking. Ratio devices adjust the relationship between input and output parameters. The ratio device may be used to modify the speed, torque, or direction of rotational motion to meet specific operational requirements. In embodiments, the ratio device is incorporated with a clutch associated with the supercharger, such as clutch 800 of FIG. 6A. The ratio device may be incorporated, for example, in the belt pulley drive clutch housing or in the gear takeoff at the flywheel, e.g., for a rear engine mount implementation.

[0098] When clutch 800 is configured as a three-way clutch, such as is described above and / or in the WO ‘265 publication, the clutch 800 can provide a neutral or disengaged state, first gear ratio for nominal operation, and a second, different, gear ratio for braking operation. In this way, clutch 800 integrally serves as the ratio device for supercharger 600. In some cases, the second gear ratio is a faster or higher ratio than the first gear ratio. Neutral, in embodiments, is used to decouple the supercharger 600 when operation of the supercharger 600 is not needed or desired by the a user. Decoupling the supercharger 600 when not desired aides in reducing engine parasitic losses.Approaches for Increasing Pressure Ratio Across Supercharger 600

[0099] In embodiments, the braking load may be further increased by increasing the power consumption of the supercharger to further strengthen the engine braking. For example, the system is configured to increase the pressure ratio (e.g., outlet pressure / inlet pressure) of the supercharger by adding a restriction, such as an operable valve, and / or by further controlling the position and timing of the intake valves. On the outlet side, providing an additional restriction produces an increase in the outlet pressure and, on the inlet side, provides a decrease in the inlet pressure of the supercharger, in effect increasing both the pressure ratio across the supercharger and the work. If mass flow decreases, due to lower inlet density, while keeping the supercharger speed constant, power will still increase.

[0100] With reference to FIGS. 7A-7D, approaches for increasing the pressure ratio across the supercharger 600, by increasing backpressure or causing an inlet pressure depression, are presented. By increasing the pressure ratio across the supercharger 600, pumping losses through the supercharger 600 are increased, which in turn creates additional braking powerduring an engine braking process via parasitic losses. One way to increase the pressure ratio across the supercharger 600 is to provide a controllable valve or orifice located at an inlet or outlet of the supercharger, as is illustrated in the examples shown in FIGS. 7A-7C.

[0101] With reference to FIG. 7A, a system 10 is shown as including a power plant 700 configured as an internal combustion engine 700 configured for use with a hydrogen fuel source. The internal combustion engine 700 is shown as including the above-described accessory or supercharger pulley 702 and drive belt 704 and is also shown as including an intake manifold 706. In one aspect, the system 10 is also shown as including an airflow pathway 12 extending from an air intake or filter arrangement 20 to an intake side of the supercharger 600. A mass airflow sensor 22 and a throttle 24 are shown as being disposed within the airflow pathway 12. The system 10 is further shown as including an outlet airflow pathway 14 extending from an outlet of the supercharger 600 to the intake manifold 706. An air-water intercooler 26 is shown as being disposed within the outlet airflow pathway 14. A bypass airflow pathway 16 is also shown as extending from the outlet side of the supercharger 600, downstream of the air-water intercooler 26, to the intake side of the supercharger 600, at a location between the throttle 24 and the supercharger 600. A bypass valve 28 is shown as being disposed within the bypass pathway 16, as is also illustrated at FIG. 6A. In some arrangements, the bypass valve 28 can be configured as a three-way valve connecting the airflow pathways 14, 16 and operable to divert some or all of the flow from the supercharger 600 to the bypass pathway 16 or to the manifold 706. The airflow pathways 12, 14, 16 may be formed by ductwork, hoses, conduits, internal passageways of the components within the system, and combinations thereof. For example, the bypass airflow pathway 16 can be integrated into the supercharger housing or provided externally with conduits or hoses. With the configuration shown in FIG. 7 A, the engine braking processes described above in relation to FIGS. 2 to 4B is performed with the bypass valve 28 in the closed position such that all air delivered to the intake manifold 706 must be delivered by the supercharger 600. Where the clutch 800 is provided as a two-speed clutch, the clutch 800 can be placed in the high-speed gear ratio during the braking process, as already described above. In some examples, additional resistance can be achieved by operating the position of the throttle 24, independently or in concert with the bypass valve 28, to increase the pressure ratio or pressure differential across the supercharger 600. In some examples, additional resistance can be achieved by operating the position and timing of the engine intake valves to create backpressure for the supercharger 600. These strategies can also be implemented in conjunction with the examples presented in FIGS. 7Band 7C. This configuration also allows for the supercharger to operate in a vacuum while cruising which reduces input power requirements.

[0102] With reference to FIG. 7B, an alternative configuration is shown in which additional backpressure valves 30a, 30b are provided in the outlet airflow pathway 14 and in which the clutch 800 is configured with two different gear ratios. Although two backpressure valves 30a, 30b are shown, more or fewer could be provided. In one aspect, the backpressure valve 30a is shown as being located between the supercharger 600 and the bypass pathway 16 while the backpressure valve 30b is shown as being located between the manifold 706 and the bypass pathway 16. Although some locations may provide various advantages, the backpressure valves 30a, 30b can be located at any point in the outlet airflow pathway 14, and can also be added to the inlet airflow pathway 12. In one aspect, the backpressure valves 30a, 30b are configured to purposefully increase parasitic pumping losses of the supercharger 600 to effectively provide additional braking of the engine 700. Accordingly, with the configuration shown in FIG. 7B, the engine braking processes described above in relation to FIGS. 2 to 4B is performed with the bypass valve 28 in the closed position such that all air delivered to the intake manifold 706 must be delivered by the supercharger 600 and through valves 30a, 30b with the clutch 800 in the high-speed gear ratio. In some examples, the valves 30a, 30b are positioned by the controller 500 to either a preset position or are throttled to meet a specified operational setpoint, for example, a pressure ratio setpoint or pressure differential setpoint across the supercharger 600. As with the configuration shown at FIG. 7A, this configuration also allows for the supercharger to operate in a vacuum while cruising, which reduces input power requirements.

[0103] With reference to FIG. 7C, an alternative configuration is shown in which the mass airflow sensor 22 and throttle 24 are located within the outlet airflow pathway 14, between the bypass airflow pathway 16 and the intake manifold 706. In some arrangements, the clutch 800 is configured with two different gear ratios. With such a configuration, the throttle 24 and bypass valve 28 work in conjunction during braking with the throttle 24 being controlled based on a desired mass flow and the bypass valve 28 being controlled to maintain a desired pressure ratio. Under normal operation, the bypass valve 28 would be typically open when the throttle 24 is closed. However, under braking in accordance with the processes is described above in relation to FIGS. 2 to 4B, the bypass valve 28 can be actively controlled to maintain a pressure ratio or pressure differential across the supercharger 600. Where a two-speed clutch is utilized, the clutch 800 can be engaged in the high-speed gear ratio during implementation of the brakingprocess. This configuration maintains only a small volume at sub-atmospheric pressure between the throttle and the intake which provides for quick response time.

[0104] With reference to FIG. 7D, power map 900 is shown to demonstrate the effectiveness of increasing the pressure ratio to increase the load exerted by the supercharger. As discussed above, the pressure ratio across the supercharger can be increased by implementing the above-described restriction strategies using one or more valves 24, 28, 30a, 30b in the inlet, outlet, and / or bypass airflow streams 12, 14. FIG. 7D shows an example in which such a strategy is implemented, whereby the pressure ratio is increased from a normal operating condition 910, having a pressure ratio between 1.2 and 1.4 to a second condition 920, having a pressure ratio between 2.0 and 2.2, without changing the speed of the supercharger 600 via clutch 800. This pressure ratio change, which represents about a 50 to 60 percent increase, can result in an associated parasitic power loss of the supercharger 600 of over 150 percent in comparison to the baseline condition 910.

[0105] To illustrate, calculations show that for an example supercharger system associated with the power map 900, a 1900cc supercharger 600 operating at 10,000 rpm has been shown to have a 37 KW power loss at condition 920 in comparison to a power loss of 14 KW at the baseline condition 910. This effect can be further increased when changing the speed of the supercharger, as is shown at conditions 930, 940, and 950. At condition 930, the speed of the supercharger 600 is increased, for example from 10,000 rpm or below at condition 910 to 16,000 rpm at condition 930, which results in a pressure ratio increase to about 1.6, but at a significantly higher mass flow rate in comparison to condition 910. Accordingly, the abovedescribed supercharger example can be expected to have a power loss of about 39 KW in condition 930 which represents a 172 percent increase in power loss over the baseline condition 910.

[0106] Based on the operation and configuration of the restriction valves via any of the above-described approaches, the pressure ratio can be further increased from condition 940 to between 2.2 and 2.5 at conditions 950a, 950b, respectively, albeit at a reduced mass flow rate in comparison to condition 930. Even at the lower pressure ratio condition 950a, the resulting power loss for the supercharger example described above increases to about 66 KW which represents a 359 percent increase in power loss over the baseline condition 910.

[0107] Traditional hydrocarbon-based fuels like gasoline or diesel. These engines operate on the same basic principles as conventional internal combustion engines, but with some key differences in fuel properties and combustion characteristics.

[0108] Gaseous hydrogen is typically used as the primary fuel. Hydrogen is considered a clean fuel because its combustion produces only water vapor and heat, making it an environmentally friendly alternative. The engine's design is modified to accommodate the unique properties of hydrogen, such as its wide flammability range and high flame speed.

[0109] The combustion process in a hydrogen internal combustion engine involves the mixing of hydrogen with air in the engine's cylinders. Hydrogen's unique combustion characteristics allow for flexibility in the design of hydrogen-powered engines. Hydrogen engines may often operate at higher compression ratios to take advantage of hydrogen's high octane rating. However, unlike traditional hydrocarbon fuels like diesel, hydrogen does not have the same issues with pre-ignition or knocking. As a result, hydrogen engines can also operate effectively with lower compression ratios compared to diesel engines. Lower compression ratios may be advantageous for certain hydrogen engine designs.

[0110] In some cases, a H2 ICE is configured with a lower compression ratio to prevent auto-ignition of the hydrogen fuel. Lower compression ratios can also be advantageous in terms of reducing mechanical stress on engine components and potentially simplifying the overall engine design. Hydrogen combustion tends to produce lower levels of nitrogen oxides (NOx), which are a major contributor to air pollution. Lower compression ratios in hydrogen engines may also contribute to the reduction of NOx emissions compared to diesel engines. Lower compression ratios may have further implications for the materials used in engine construction. Engine components need to be designed to handle the specific demands of hydrogen combustion, and lower compression ratios may influence the overall stress on these materials. [OHl] The use of air boosting systems can improve the efficiency of an H2 ICE running with high lambda. The term "lambda" in the context of internal combustion engines refers to the air-fuel ratio, specifically the ratio of the actual air-fuel mixture to the stoichiometric airfuel ratio. The stoichiometric ratio is the chemically ideal ratio at which complete combustion occurs. A lambda value of 1.0 corresponds to a stoichiometric air-fuel ratio. When the engine is running with a lambda greater than 1.0, it means that there is excess air in the mixture compared to the stoichiometric ratio. This condition is often referred to as running “lean.” In a lean mixture, combustion temperatures tend to be higher, which can affect engine performance and emissions. Lean-burn engines are often equipped with technologies such as exhaust gas recirculation (EGR) or catalytic converters to mitigate the impact on emissions. Though lowering the compression ratio comes with a number of advantages, it’s influence in some areas of the engine’s operation require additional design considerations. For example, as thestoichiometric ratio for hydrogen fuel is 34: 1, compared to 14.4: 1 for diesel fuel, over two times the intake airflow is required for H2 ICE engines.

[0112] Referring to FIG. 9, a prior art intake and exhaust system for an internal combustion engine is presented in which the intake side includes an air filter, turbocharger (Tc- Comp), intercooler (IC), and an intake manifold (IM) and in which the exhaust side includes an exhaust manifold (EM), a turbine that is powered by exhaust gases and drives the turbocharger (Tc-Turbine), and an exhaust aftertreatment system (EATS). Referring to FIG. 10, an improved intake system is provided that can provide for additional air boosting to the internal combustion engine. As shown, the intake system of FIG. 10 additionally includes a supercharger (Sc) downstream of the turbocharger (Tc-Comp.) and a valved bypass arrangement for bypassing the supercharger Sc and connecting the outlet of the turbocharger Tc-Comp with the inlet of the intercooler IC. In one aspect, the supercharger and turbocharger can be characterized as being in series with each other.

[0113] FIGS. 11-17 show additional intake system variations that may also be used with the intake air system serving the H2 ICE. FIG. 11 shows an intake system including, in order, an air filter, a turbocharger (Tc-C), a supercharger (Sc), and an intercooler (Intercooler 1). FIG. 12 shows an intake system including, in order, an air filter, a turbocharger (Tc-C), a supercharger (Sc) and valved bypass arrangement, and an intercooler that is configured generally similar to the intake system shown at FIG. 11. FIG. 13 shows an air intake system including, in order, an air filter, a turbocharger (Tc-C), a clutched supercharger (Sc) and valved bypass arrangement, and an intercooler.

[0114] FIG. 14 shows an air intake system including, in order, an air filter, a turbocharger (Tc-C), an intercooler (Intercooler 2), a clutched supercharger (Sc) and valved bypass arrangement, and a further intercooler (Intercooler 1). A particular advantage that can be obtained by providing an intercooler upstream of the supercharger is that the size of the supercharger can be greatly reduced. By cooling the air leaving the turbocharger with the intercooler, the density of the air increases to result in a lower volume for the same mass flow rate of air. As the supercharger is a volumetric device, this decrease in volume allows for a smaller supercharger to be used in comparison to the size that would be required without the intercooler. This advantage also extends to the size of the clutch as the clutch size is dependent on the size of the supercharger.

[0115] FIG. 15 shows an intake system including, in order, an air filter, a turbocharger (Tc-C), an intercooler (Intercooler 2), a supercharger (Sc) and valved bypass arrangement, and a further intercooler (Intercooler 1). FIG. 16 shows an intake system including, in order, an airfilter, a turbocharger (Tc-C), an intercooler (Intercooler 2), a recirculation valve 1602 that returns air to an upstream location of the turbocharger, a supercharger (Sc) and valved bypass arrangement, a further recirculation valve 1604 that returns air from downstream of the supercharger to a location upstream of the turbocharger, and a further intercooler (Intercooler 1).

[0116] FIG. 17 shows an intake system including, in order, an air filter, a clutched supercharger (Sc) and valved bypass arrangement, a turbocharger (Tc-C), and an intercooler. In this arrangement, the supercharger is sized to be bigger than in the configurations discussed above where the supercharger is downstream of the turbocharger. As the corrected mass flow rates increase for the supercharger for a same gear or pulley ratio at any load point. Alternatively, a pulley or gear size can be increased for the same size supercharger used in configurations where the supercharger is downstream of the turbocharger. The compressor size may also be bigger compared to configurations where the supercharger is downstream due to a higher pressure drop in additional piping leading to compressor inlet. The supercharger bypass valve size may also increase, e.g., by about 30% to about 50%, compared to configurations where the supercharger is downstream of the turbocharger. A higher inlet pressure drop in the turbocharger may lead to lower boosting for a same pressure ratio capability, compared to configurations where the supercharger is downstream of the turbocharger.

[0117] FIG. 18 is a summary table of architecture details of various embodiments of the present disclosure.

[0118] FIGS. 19A and 19B respectively show efficiency maps for the systems shown at FIGS. 14 and 17. High efficiency islands 1902, 1904 are identified in each efficiency map. A high efficiency island near low pressure ratio and low corrected mass flow rates are preferred, as seen in 1902 with the architecture as shown in FIG. 14. In FIG. 19B, the supercharger operation will have high supercharger speeds, pressure ratios and higher corrected mass flows having a more dispersed high efficiency island 1904 across higher pressure ratio and higher correct mass flow rate. The engine brake thermal efficiencies (BTEs) in the example of FIG. 19B will be less due to the high power of the supercharger.

[0119] FIG. 20 shows graphs for brake power and brake efficiency for selected clutched supercharger air intake systems. FIGS. 21 and 22 show views of a proposed architecture for an air intake system, such as the example system architectures shown in FIGS. 14 and 15. Architectures including a turbocharger and supercharger in series and including twointercoolers, wherein the supercharger is provided with a valved bypass arrangement, may be packaged as shown in FIGS. 21 and 22, according to embodiments of the present disclosure.

[0120] In FIG. 21, a condenser 2102 is most proximal to a hood boundary 2104. Hood boundary 2104 may define a forward-most boundary of engine compartment 2100. A larger intercooler 2106 lies behind the condenser 2102, or more distal from the hood boundary 2104. In embodiments, larger intercooler 2106 correlates with a first intercooler in the example architectures of FIGS. 14 and 15, or an intercooler arranged between a turbocharger and a downstream supercharger.

[0121] A radiator 2108 lies behind larger intercooler 2106, so that larger intercooler 2106 lies between condenser 2102 and radiator 2108 and is more proximal to hood boundary 2104 than radiator 2108. A fan 2110 lies behind radiator 2108, so that radiator 2108 lies between larger intercooler 2106 and fan 2110 and is more proximal to hood boundary 2104 than fan 2110. Engine 2112 is arranged behind fan 2110 and extends from fan 2110 to a rear boundary 2114, so that fan 2110 lies between radiator 2108 and engine 2112 and is more proximal to hood boundary 2104 than a forwardmost part of engine 2112. Rear boundary 2114 is a boundary of engine compartment 2100 that is most distal from hood boundary 2104.

[0122] An air filter 2116 is arranged toward rear boundary 2114 and may coincide with or overlap with a rearward portion of engine 2112. Air filter 2116 may be arranged above engine 2112. Air filter 2116 is arranged off centerline, such that it resides closer to an exhaust side boundary 2118 than an intake side boundary 2120.

[0123] In FIG. 22, engine 2212 is arranged proximal to a hood boundary 2204. Hood boundary 2204 may define a forward-most boundary of engine compartment 2200. A turbocharger (TC) 2222 is arranged at an end of the engine 2212 that is proximal to hood boundary 2204. Turbocharger 2222 is arranged off centerline, such that it resides closer to an exhaust side boundary 2218 than an intake side boundary 2220.

[0124] A conduit 2224 runs from the outlet of the turbocharger 2222 to the inlet of a larger intercooler 2206. Conduit 2224 is generally arranged along an exhaust side 2218 perimeter of engine 2212. In embodiments, larger intercooler 2206 correlates with a first intercooler in the example architectures of FIGS. 14 and 15, or an intercooler arranged between a turbocharger and a downstream supercharger. Larger intercooler 2206 lies behind engine 2212, being more distal from hood boundary 2204. A smaller intercooler 2226 lies behind larger intercooler 2206, and may be the rearmost component in engine compartment 2200, arranged adjacent to a rear boundary 2214. In embodiments, larger intercooler 2206 correlates with a second intercooler in the example architectures of FIGS. 14 and 15, or an intercooler arranged downstream of asupercharger. Larger intercooler 2206 and smaller intercooler 2226 may be arranged generally along the centerline of engine compartment 2200.

[0125] A conduit 2228 runs from the outlet of the larger intercooler 2206 to the inlet of a supercharger 2230. Conduit 2228 is generally arranged behind and toward the intake side 2220 of engine 2212. Supercharger 2230 is arranged at an end of the engine 2212 that is distal from hood boundary 2204. Supercharger 2230 is arranged off centerline, such that it resides closer to intake side boundary 2220 than exhaust side boundary 2218.

[0126] A conduit 2232 runs from the outlet of supercharger 2230 to the inlet of smaller intercooler 2226. Conduit 2232 is generally arranged in a first leg running from supercharger 2230 toward hood boundary 2204, in a second leg generally parallel to hood boundary 2204, and a third leg generally along the exhaust side 2218 perimeter of engine 2212 and larger intercooler 2206.

[0127] A conduit 2234 runs from the outlet of the smaller intercooler 2226 to an intake manifold. A bypass conduit 2236, for bypassing supercharger 2230, runs from conduit 2228 to the third leg of conduit 2232, connecting the outlet of the larger intercooler 2206 with the inlet of the smaller intercooler 2226.

[0128] The arrangement of FIG. 22 in particular demonstrates how the two intercooler design disclosed herein may be configured to occupy a similar footprint within an engine compartment as current designs. The two intercoolers can be configured to provide a comparable heat capacity to current designs, so that the outlet temperature of the second intercooler, downstream of the supercharger, is no more than 50 degrees C, less than 50 degrees C, no more than 40 degrees C, less than 40 degrees C, no more than 30 degrees C, less than 30 degrees C, etc. In embodiments, the outlet temperature of the first intercooler, arranged between the turbocharger and the supercharger, is no more than 50 degrees C, less than 50 degrees C, no more than 40 degrees C, less than 40 degrees C, no more than 30 degrees C, less than 30 degrees C, etc. For example, when the supercharger bypass line is fully closed and the supercharger is in operation. Ensuring the inlet temperature to the supercharger is, for example, no more than 50 degrees, enables the use of common automotive materials for the supercharger, saving on cost and weight when compared with the use of high temperature materials. By example, common automotive materials include steel alloys, aluminum, various plastics, and rubber, while high temp materials often consist of refractory metals like tungsten, molybdenum, tantalum, and specialized ceramics.

[0129] In some implementations, it is advantageous to locate the supercharger downstream of the turbocharger in terms of supercharger size and power consumption as the density of the inlet air received from the turbocharger is greater than that of atmospheric air.

[0130] In examples, a valved bypass arrangement around the supercharger allows the power to drop from 80 KW to 15 KW (13 L; LPDI; Lambda - 2.2 and BMEP 23 bar)

[0131] In examples, providing a clutch for the supercharger allows for the supercharger to consume zero power when not in use, thus resulting in a savings up to 15 KW (13 L; LPDI; Lambda - 2.2 and BMEP 23 bar).

[0132] In examples, and as noted previously, providing an intercooler between the turbocharger and the supercharger allows for the supercharger to be downsized. In some examples, the intercooler is integrated into the supercharger. In some examples, the system includes both a supercharger having an integrated intercooler as well as one or more separate intercoolers. In some examples, the intercooler is separate from the supercharger. As mentioned previously, the arrangements are made possible because of increase in density of inlet air to the supercharger which is a volumetric device that increases mass flow. It is noted that a smaller supercharger has less inertia which make a clutch more viable.

[0133] In examples, the supercharger is located upstream of the turbocharger. With such an arrangement, the supercharger can be clutched or unclutched. Incorporating an intercooler between the turbocharger and the supercharger can allow for downsizing the turbocharger. The intercooler can be integrated into or separate from the supercharger or turbocharger.

[0134] In some configurations, there are at least a couple of possible operational strategies for steady state at low altitude, preferably below 4000 ft, as follows. In one strategy, the supercharger is operated at lower speeds (<1200 RPM) along with turbo-compressor. This can be a preferred strategy considering the system BTE (brake thermal efficiency) as turbo can handle high speeds and loads demands (relatively bigger turbocharger). In examples, the supercharger is operated below 900 RPM of the H2 ICE. In examples, this strategy is implemented when H2 ICE load is above 50% of the maximum load.

[0135] In an alternative strategy, the supercharger is used at high speeds (< 2100 RPM) and high loads ( 50% ~ 100%) in tandem with relatively smaller turbo (lower mass flow rate handling capacity). This strategy may not be as preferred in some applications due to high power consumption of supercharger leading to low BTEs, clutch for supercharger may be needed for low-speed operations (<1200 RPM), and the need for an additional intercooler which may be same as that of truck intercooler

[0136] During transient operations and high altitudes the supercharger and turbocharger can be operated in tandem, for example at conditions above 25% load, above 700 RPM H2 ICE engine speed, and above 4000 feet elevation.

[0137] The supercharger can be configured in various ways. For example, the supercharger can be a standard grade supercharger than can handle outlet temperatures of less than 180 deg C (not that an intercooler may be needed); Inlet temperature can be maximum 140 deg C if the outlet temperatures are within 180 deg C limit. The supercharger can also be configured as a high temperature supercharger that can handle high inlet temperatures (~ 240 deg C. The supercharger can also be belt or motor driven and can be provided with or without a bypass. In examples, the bypass is an electronic bypass or a mechanical bypass, can include an on / off valve or a modulating valve. In examples, a clutch can be provided for the supercharger, for example when the supercharger is a pulley-driven supercharger. In examples where a clutch is not provided, the supercharger can operate at higher engine speeds with very low-pressure ratio and compressor taking up complete boosting requirement. A dual valving arrangement can also be used in a special case of without clutch where set of valves help the supercharger to spin for one pressure ratio and the compressor meeting the boosting requirements via bypass channel to the engine manifold. Clutched configurations can help downsize the supercharger, improve BTE, transient performance and durability provided the increased gear and / or pulley ratios can be handled.

[0138] The supercharger can be used for hydrogen extraction from the crankcase in some applications. In such cases, the supercharger will blow in the oil pan to stay below 3% - 6% H2 levels. This operation can blow or pull the air through oil pan at discrete interval s(preferred) or continuously. This operation can be prevented during transient conditions.

[0139] The supercharger can also be used as a secondary braking device through boosting higher intake manifold pressure.

[0140] FIG. 23 is a schematic view of a combined combustion and braking system architecture 2300 using a three way valve 2302. The architecture of FIG. 23 includes, in order, an air filter, a turbocharger (TC), a first intercooler, (IC 1), a supercharger (SC), a second intercooler (CAC), and reaches an intake manifold. In embodiments, the second intercooler (CAC) may be a charge air cooler. A three-way valve 2302 is provided in place of a supercharger bypass, such as the bypass seen in the example system of FIG. 14. Using the three way valve 2302 in this way provides a recirculation path 2304 in addition to the supercharger bypass path 2306.

[0141] Referring back to FIG. 7D, the power map 900 demonstrates the increased braking power provided by a high speed supercharger as compared with a one speed supercharger. Speed device 2314 of example architecture 2300 is connected to the supercharger (SC) by a clutch 2316 and provides for high speed operation of the supercharger for increased braking power. In examples, speed device 2314 provide a speed factor of 1.1, 1.2, 1.3, 1.4, 1.5, etc., exceeding a baseline speed factor of 1 associated with the supercharger is the absence of the speed device 2314. In embodiments, speed device 2314 may be excluded from the architecture.

[0142] Supercharger bypass path 2306 directs flow from the supercharger inlet 2310 to the supercharger outlet 2308, bypassing the supercharger. In embodiments, supercharger bypass path 2306 may pass 100% of the flow reaching supercharger inlet 2310. Recirculation path 2304 directs flow from the outlet 2312 of a downstream intercooler back to the supercharger inlet 2310. In operation, supercharger bypass path 2306 is used during driving operations.

[0143] During braking, three way valve 2302 is reconfigured to instead use recirculation path 2304, to provide additional load to the supercharger to increase the braking power. The elevated inlet pressure consumes more supercharger power compared to standard inlet pressure condition. The braking power is further increased by the increased density of the fluid as it exits the downstream intercooler.

[0144] FIG. 24 is a schematic view of an alternative architecture 2350 configuration of the combined combustion and braking system of FIG. 23. Example architecture 2350 includes supercharger bypass path 2306 and alternative cooling path 2352. Alternative cooling path 2352 directs flow from the supercharger outlet 2308 to an upstream intercooler inlet 2354. In embodiments, the speed device may be excluded from the architecture.

[0145] FIG. 25 is a schematic view of a combined combustion and braking system architecture using a two valve architecture. The architecture of FIG. 25 includes, in order, an air filter, a turbocharger (TC), a first intercooler, (IC 1), a supercharger (SC), a second intercooler (CAC), and reaches an intake manifold.

[0146] A supercharger bypass line 2502 directs flow from the inlet of the supercharger (SC) to the inlet of the second intercooler (CAC), bypassing the supercharger. Flow through supercharger bypass line 2506 is controlled by a valve in the supercharger bypass line. The valve may be a throttle valve. The valve may generally be open during drive operations, to bypass the supercharger and closed during braking operations to enable the supercharger to assist in braking. The supercharger bypass line 2506 may be configured to pass up to 100% of flow around the supercharger when the valve is fully opened. The supercharger (SC) may alsobe clutched out by clutch 2516 during bypass of the supercharger. In embodiments, the valve in the supercharger bypass line may be throttled during transient or low load driver operations.

[0147] A braking recirculation path 2504 is used during braking operations to provide additional flow and pressure to the inlet of the supercharger (SC). The example of FIG. 25 demonstrates the braking recirculation path 2504 directing flow from the outlet of a downstream intercooler (CAC) to the inlet of the supercharger (SC). In embodiments, a valve in the braking recirculation path 2504 is a throttle valve to provide for control of loading of the supercharger (SC) by controlling the flowrate through the braking recirculation path 2504. A throttle valve in the supercharger bypass line provides for variable control of bypassing the supercharger. For example, the supercharger may be bypassed during a subset of drive condition, with the throttle valve fully open, and throttled or closed when supercharger operation is desired, such as during transient or low speed, high load conditions. Throttling of the supercharger bypass may be in conjunction with operation of a clutch of a clutched supercharger. For example, the supercharger may be placed in a neutral condition when the throttle valve is fully opened, and placed online when the throttle valve is throttled or closed.

[0148] In embodiments, the supercharger bypass is sized to enable 100% of system flow to bypass the supercharger when the bypass is open, e.g., when a valve in the bypass is fully open. In examples, the size of the supercharger bypass may be determined by the outlet of the turbocharger, e.g., the diameter of the bypass is selected to be equal to the outlet path of the turbocharger. In some examples, the diameter of the supercharger bypass line may be 4 inches, 4.5 inches, 5 inches, etc. The recirculation path may be smaller than the supercharger bypass, having a 1 inch, 2 inch, or 3 inch diameter, for example. In examples, the recirculation path may be constructed using a flexible hose, e.g., a rubber hose.

[0149] FIG. 26 is a schematic view of an alternative architecture configuration of the combined combustion and braking system architecture of FIG. 25. The example of FIG. 26 demonstrates a braking recirculation path 2604 directing flow from the outlet of the supercharger (SC) to the inlet of an upstream intercooler (IC 1). In embodiments, the valve in the braking recirculation path 2604 is a throttle valve to provide control of the flowrate through the braking recirculation path 2604.

[0150] FIG. 27 is a schematic view of another alternative architecture configuration of the combined combustion and braking system architecture of FIG. 25. The example of FIG. 27 demonstrates a braking recirculation path 2704 directing flow from the outlet of a downstream intercooler (CAC) to the inlet of an upstream intercooler (IC 1). In embodiments, the valve in the braking recirculation path 2704 is a throttle valve.

[0151] In each of these cases, referring to the examples of combined combustion and braking system architecture of FIGS. 23-27, the braking recirculation path provides for the reduction in temperature of recirculating air going into the supercharger when braking. This enhances air density when passing through an intercooler, such as upstream intercooler (IC 1) or downstream intercooler (CAC), and thus is able to provide more braking power. In some embodiments, one or more intercooler, and in some cases preferably the downstream intercooler, may be a charge air cooler. Increasing the size of the intercooler can further increase braking power in both upstream and downstream cases. The cooled air out of the intercooler has greater density and can therefore contribute greater braking power when directed to the supercharger as the dense air requires more power from the supercharger to move, increase the parasitic load exerted on the system by the supercharger.

[0152] FIG. 28 is a pair of graphs showing effects of a speed up device on brake power and boosting power of the supercharger. In this example, effects are demonstrated based on a speed up device providing a speed factor of 1.4. Mechanical losses associated with the supercharger are almost doubled which improves brake performance by 10% to 45% when supercharger outlet temperature is below 150 deg C. In an example with the supercharger operating beyond 20000 rpm, a larger speed factor (e.g., > 1.4) can be used, and thus more braking power can be achieved.

[0153] Braking power can be increased further by allowing supercharger outlet temperature to increase up to 180 degrees C for short periods of time, such as approximately 2 minutes of continuous duration, for example. A 2 minute duration is generally much longer than a normal engine braking event, that is typical under 30 seconds in duration.

[0154] FIG. 29 is an efficiency map related to the speed up device. 2902 shows efficiency for an example single speed supercharger with a drive ratio of 7 and a speed factor of 1. 2904 shows the change in efficiency when a speed up device is added to the system with the supercharger. The speed up device increases the drive ratio to 9.8 with a speed factor of 1.4, in this example. Introducing the speed up device enables the supercharger to operate at a high pressure ratio with high air flow, increasing supercharger power and providing a higher braking power. More braking power can be harnessed from the supercharger when the supporting boosting device can handle high a high pressure ratio and corresponding higher flow rates. Turbine inlet temperatures are reduced at low speeds due to the high air flow. This helps injector cooling and avoids hotspots in the combustion chamber, contributing to prevention of pre-ignition and misfiring when switched to drive mode.

[0155] FIG. 30 is a schematic view of a combined combustion and braking system architecture 3000 with the supercharger disconnected during braking. The architecture 3000 includes, in order, an air filter, a turbocharger (TC), a first intercooler (IC 1), a first disconnect 3008, a supercharger (SC), a second disconnect 3006, a second intercooler (CAC), and discharges to an intake manifold. In embodiments, one or both of first and second disconnects 3008, 3006 is a three way valve.

[0156] The embodiment of FIG. 30 allows the supercharger (SC) to be disconnected, by opening first and second disconnects 3008, 3006. The supercharger (SC) can then be operated to its full potential to maximize braking performance. A throttle valve 3002 in a supercharger bypass line 3010 allows the supercharger (SC) to be bypassed. Throttle valve 3002 is operated in an open position during braking operations when the supercharger is disconnected.

[0157] Another throttle valve 3004 is downstream of second disconnect 3006, which is arranged at the outlet of the supercharger (SC). Throttle valve 3004 and second disconnect 3006 operate to switch the supercharger (SC) into a standalone supercharger mode. The standalone supercharger mode allows the supercharger to operate at its maximum possible power ratio to churn more power from the driveshaft. In this standalone supercharger mode, fluid may be provided directly from the air filter to the inlet of the supercharger (SC) via the alternate path 3012 provided by first disconnect 3008. The increased supercharger power consumption enables a significant increase in braking power.

[0158] FIG. 31A is a graph showing braking performance without the speed up device. The supercharger’ s power contributes 100% to provide increased braking performance over an unboosted H2 engine at high engine speed. FIG. 3 IB is a graph showing braking performance with the speed up device and the supercharger (SC) disconnected. At 2000 RPM Engine speed, in this example, a disconnected supercharger (SC) gives benefits of extra 28 kW of brake power with speed up device over the supercharger in a loop without speed up device. While the absolute number (in kW) of power increase may vary among difference applications, a % increment in power of 8-10% is consistently achieved by the disclosed designs.

[0159] The braking benefit is present at least at 1600 rpm engine speeds, while the supercharger disconnection without speed up device, gives relatively less benefit (~ 6 kW) over a supercharger in loop without speed up device. FIG. 32 is an efficiency map related to the disconnecting the supercharger during braking. A supercharger disconnected with a speed factor of 1, moves the operation to maximum power ratio and maximum power at the same operating speed as a supercharger in a loop. A supercharger disconnected with a speed factorof 1.4 (e.g., with a speed up device), moves the operation further at maximum speed and maximum power possible from the supercharger.

[0160] FIG. 33 is an example exhaust gas recirculation architecture. FIG. 34 is another exhaust gas recirculation architecture. The architecture of FIG. 34 includes an optional speed up device. The architecture of FIG. 34 also differs from FIG. 33 in providing a braking recirculation line 3404. Each of FIGS. 33 and 34 include, in order, an air filter, a turbocharger (TC), a first intercooler (IC 1), a clutched supercharger (SC) with a bypass line including a throttle valve, a second intercooler (CAC), and discharges to an intake manifold. Exhaust gases from an exhaust manifold are diverted from a turbine through an exhaust gas recirculation (EGR) valve and into an EGR cooler. The cooled gases are then directed to the inlet of the supercharger (SC). Supercharger (SC) of these examples is a pulley driven supercharger, driven via linkage by the engine crank.

[0161] Recirculation of some portion of exhaust gases to a supercharger (SC) inlet allows dense high pressure exhaust flow to further boost the supercharger (SC), pushing more air mass into cylinder and increase braking power. Exhaust gas recirculation (EGR) enables turbine inlet pressure to be lower, reducing the turbocharger (TC) pressure ratio and thus the turbocharger (TC) speed, providing a higher boost capability margin. Including an EGR cooler also lowers the temperature of gases to increase their density. In some embodiments, the EGR cooler may be excluded. An active device such as EGR pump (not shown) can be used to regulate EGR flow instead of an EGR valve, shown upstream of the EGR cooler in the examples of FIGS. 33 and 34. The EGR valve provides control of the recirculation flow rate to achieve max. possible braking.

[0162] FIG. 35 is an example exhaust gas recirculation architecture with a supercharger disconnect. FIG. 36 is another example exhaust gas recirculation architecture with a supercharger disconnect. The architecture of FIG. 36 includes an optional speed up device.. Each of FIGS. 35 and 36 include, in order, an air filter, a turbocharger (TC), a first intercooler (IC 1), a first disconnect 3502, a clutched supercharger (SC) with a bypass line including a throttle valve (throttle valve A), a second disconnect 3504, a second intercooler (CAC), and discharges to an intake manifold. Exhaust gases from an exhaust manifold are diverted from a turbine through an exhaust gas recirculation (EGR) valve and into an EGR cooler. The cooled gases are then directed to the inlet of the supercharger (SC) via first disconnect 3502, which may be a three way valve to receive the alternate inlet EGR path. Second disconnect 3504 may also be a three way valve, with an alternate outlet path which exhaust to atmosphere via a throttle valve (throttle valve B) to allow the supercharger (SC) to be disconnected and run atmaximum power. Supercharger (SC) of these examples is a pulley driven supercharger, driven via linkage by the engine crank.

[0163] Recirculation of some portion of exhaust gases to the supercharger (SC) inlet allows dense high pressure exhaust flow to boost further, resulting in higher supercharger mechanical parasitic load and increase in braking power. A throttle valve (throttle valve B) to ambient air in the downstream supercharger disconnect line, via second disconnect 3504, helps control the supercharger pressure ratio. Controlling the supercharger pressure ratio to a maximum limit provides maximum supercharger power.Controller 500

[0164] Embodiments of the systems and methods disclosed herein can be implemented on a computing device, such as an electronic controller. Referring now to FIG. 8, a block diagram of an example of a controller 500 is shown, upon which aspects of the present disclosure may be implemented. In embodiments, controller 500 is deployed as a component of a cloud computing node.

[0165] Controller 500 can work with other general purpose or special purpose computing system environments or configurations. Examples of well-known computing systems, environments, or configurations that may be suitable for use with controller 500 include, but are not limited to, personal computer systems, server computer systems, thin clients, thick clients, hand-held or laptop devices, multiprocessor systems, microprocessor-based systems, set top boxes, programmable consumer electronics, network PCs, minicomputer systems, mainframe computer systems, and distributed cloud computing environments that include any of the above systems or devices.

[0166] Controller 500 may be described in the general context of computer systemprocessing instructions, such as program modules, being processed by a computer system. Generally, program modules may include routines, programs, objects, components, logic, data structures, and so on that perform particular tasks or implement particular abstract data types. Controller 500 may be practiced in distributed cloud computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed cloud computing environment, program modules may be located in both local and / or remote computer system storage media including memory storage devices.

[0167] As depicted in FIG. 8, controller 500 is shown in the form of a general-purpose computing device. The components of controller 500 may include, but are not limited to, oneor more processors 502, memory 504, and bus 506 that couples various system components, including memory 504, to processor 502.

[0168] Processor 502 processes instructions for software that may be loaded into memory 504. Processor 502 may be a number of processors, a multi-processor core, or some other type of processor, depending on the particular implementation. Further, processor 502 may be implemented using one or more different processor systems in which a main processor is present with secondary processors, and may be on a single chip. In another example, processor 502 may be a symmetric multi-processor system containing multiple processors of the same type.

[0169] Bus 506 represents one or more of any of several types of bus structures, including a memory bus or memory controller, a peripheral bus, an accelerated graphics port, and a processor or local bus using any of a variety of bus architectures. By way of example and not limitation, such architectures include Industry Standard Architecture (ISA) bus, Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA) bus, and Peripheral Component Interconnects (PCI) bus.

[0170] Controller 500 may include a variety of computer system readable media. Such media may be any available media that is accessible by controller 500 and includes both volatile and non-volatile media and removable and non-removable media.

[0171] Memory 504 can include computer system readable media in the form of volatile memory, such as random access memory (RAM) 508 and / or cache 510. Controller 500 may further include other removable / non-removable, volatile / non-volatile computer system storage media. By way of example only, storage system 512 can be provided for reading from and writing to a non-removable, non-volatile magnetic media, such as a hard drive. Although not shown, a magnetic disk drive for reading from and writing to a removable, non-volatile magnetic disk, and an optical disk drive for reading from or writing to a removable, non-volatile optical disk, or other optical media can be provided. In such instances, each can be connected to bus 506 by one or more data media interfaces. Memory 504 may include at least one program product having a set of program modules that are configured to carry out the functions of embodiments of the invention. As used herein, a set, when referring to items, means one or more items. For example, a set of program modules is one or more program modules.

[0172] Program 514, having a set of program modules 516, may be stored in memory 504, by way of example, as well as an operating system, one or more application programs, other program modules, and program data. Each of the operating systems, one or more application programs, other program modules, and program data or some combination thereof, may includean implementation of a networking environment. Program modules 516 generally carry out the functions and / or methodologies of embodiments of the invention as described herein. Program modules 516 include fusion module 514, weight / confidence module 418, and fault detection module 520.

[0173] Controller 500 may also communicate with one or more external devices 518, such as a keyboard, a mouse, a display, or one or more other devices to enable a user to interact with controller 500. External devices 518 may further include any devices (e.g., network card, modem, etc.) that enable controller 500 to communicate with one or more other computing devices. These communication can occur via VO interface 520. I / O interface 520 may correspond to external interface 518. Controller 500 can communicate with one or more networks, such as a local area network (LAN), a general wide area network (WAN), or a public network, such as the Internet via network adapter 522.

[0174] Network adapter 522 communicates with other components of controller 500 via bus 506. Other hardware and / or software components, which may not be depicted in FIG. 5, are able to be used with controller 500. Examples include, but are not limited to, microcode, device drivers, redundant processor units, external disk drive arrays, RAID systems, tape drives, and data archival storage systems, etc.

[0175] Illustrative examples of the systems and methods described herein are provided below. An embodiment of the system or method described herein may include any one or more, and any combination of, the aspects described below.

[0176] Aspect 1. An air intake system for an internal combustion engine. The system including a turbocharger, a supercharger in series with the turbocharger, a first intercooler between the turbocharger and the supercharger, and a second intercooler downstream of the supercharger.

[0177] Aspect 2. The system of aspect 1, wherein the second intercooler has an outlet temperature of less than or equal to 50 degrees C, and more preferably less than or equal to 40 degrees C, and even more preferably less than or equal to 30 degrees C.

[0178] Aspect s. The system of aspect 2, wherein the first intercooler has an outlet temperature of less than or equal to 50 degrees C, and more preferably less than or equal to 40 degrees C, and even more preferably less than or equal to 30 degrees C.

[0179] Aspect 4. The system of any of aspects 1-3, further including a first bypass line diverting flow around the supercharger during driving operations.

[0180] Aspect 5. The system of claim 4, wherein the first bypass line diverts flow from an inlet of the supercharger to an inlet of the second intercooler.

[0181] Aspect 6. The system of aspect 4 or 5, further including a first throttle valve in the first bypass line.

[0182] Aspect 7. The system of any of aspects 1-6, further including a second bypass line providing additional flow to an inlet of the supercharger during braking.

[0183] Aspect 8. The system of aspect 7, wherein the second bypass line directs flow from an outlet of the second intercooler to the inlet of the supercharger.

[0184] Aspect 9. The system of aspect 7 or 8, further including a first bypass line diverting flow around the supercharger during driving operations, wherein a diameter of the first bypass line is greater than a diameter of the second bypass line.

[0185] Aspect 10. The system of aspect 9, wherein the second bypass line is a rubber hose.

[0186] Aspect 11. The system of any of aspects 7-10, further including a second throttle valve in the second bypass line.

[0187] Aspect 12. The system of any of aspects 1-11, wherein the supercharger is a clutched supercharger.

[0188] Aspect 13. The system of aspect 12, wherein the clutched supercharger includes an integrated clutch.

[0189] Aspect 14. The system of aspect 12 or 13, further comprising a speed up device in connection with the clutched supercharger.

[0190] Aspect 15. The system of any of aspects 1-14, wherein the supercharger is pulley- driven, gear-driven, or motor-driven.

[0191] Aspect 16. The system of aspect 15, wherein the supercharger is motor-driven and the supercharger is a two-speed supercharger.

[0192] Aspect 17. The system of any of aspects 1-16, wherein the second intercooler discharges into an intake manifold of the hydrogen internal combustion engine.

[0193] Aspect 18. A method of operating an air intake system for an internal combustion engine, the air intake system including, in series, a turbocharger, a first intercooler, a supercharger, and a second intercooler. The method includes operating the air intake system to support the internal combustion engine in a drive mode by bypassing the supercharger by opening a first throttle valve in a first bypass line, and operating the air intake system to support the internal combustion engine in a brake mode by closing the first throttle valve in the first bypass line.

[0194] Aspect 19. The system of aspect 18, wherein operating the air intake system to support the internal combustion engine in the brake mode further includes directing air flowfrom an outlet of the second intercooler to an inlet of the supercharger by opening a second throttle valve in a second bypass line.

[0195] Aspect 20. The method of aspect 18 or 19, wherein the supercharger is a clutched supercharger.

[0196] Aspect 21. The method of aspect 20, wherein operating the air intake system to support the internal combustion engine in the drive mode further comprises operating the clutch to place the supercharger is a neutral state when the throttle valve in the first bypass line is opened.

[0197] Aspect 22. The method of aspect 20 or 21, wherein operating the air intake system to support the internal combustion engine in the brake mode further comprises operating the clutch to connect the supercharger with a speed up device.

[0198] Aspect 23. The method of any of aspects 18-22, wherein the supercharger is a motor-driven supercharger with a motor having at least two speeds, wherein operating the air intake system to support the internal combustion engine in the drive mode further comprises running the motor at a first speed, and wherein operating the air intake system to support the internal combustion engine in the brake mode further comprises running the motor at a second speed, wherein the second speed exceeds the first speed.

[0199] Aspect 24. The method of any of aspects 18-23, wherein the internal combustion engine is a hydrogen internal combustion engine.

[0200] Aspect 25. An air intake system for an internal combustion engine including a turbocharger, a first intercooler, a supercharger, and a second intercooler, in series and arranged in an engine compartment such that the first intercooler resides at a rear boundary of the engine compartment, the second intercooler resides in front of the first intercooler, and each of the turbocharger and the supercharger reside in front of the second intercooler.

[0201] Aspect 26. The air intake system of aspect 25, further including a supercharger bypass line arranged between the second intercooler and the supercharger.

[0202] Aspect 27. The air intake system of aspect 25 or 26, wherein the second intercooler is larger than the first intercooler.

[0203] Aspect 28. A method of enhancing decompression engine braking to offset reduced power braking potential in a low compression internal combustion engine. The method includes initiating an engine braking operation in the internal combustion engine, wherein the internal combustion engine consumes a hydrogen fuel and has a compression ratio in a normal operating mode of no more than 14: 1, boosting intake manifold pressure with an air compressor to create a boosted airflow stream, introducing the boosted airflow stream air into a cylinder of theinternal combustion engine, compressing the air in the cylinder with a piston, and releasing the compressed air from the cylinder in a controlled compression release event.

[0204] Aspect 29. The method of aspect 28, wherein increasing pressure in the cylinder with the air compressor occurs when the piston is at bottom dead center of the cylinder.

[0205] Aspect 30. The method of aspect 28 or 29, wherein the air compressor is one of a supercharger, a booster, an e-booster, a turbo, and an e-turbo.

[0206] Aspect 31. The method of aspect 30, wherein the air compressor is the supercharger and the supercharger comprises a clutch.

[0207] Aspect 32. The method of aspect 31, wherein the clutch is a three-way clutch.

[0208] Aspect 33. The method of aspect 32, wherein the three-way clutch includes: a neutral position; a first gearing position for driving; and a second gearing position for braking.

[0209] Aspect 34. The method of aspect 33, wherein the second gearing position operates the supercharger at a higher speed than the first gearing position.

[0210] Aspect 35. The method of aspect 34, wherein the second gearing position connects the supercharger with a speed up device.

[0211] Aspect 36. The method of aspect 35, further comprising operating a valve in a cooling bypass line during the engine braking operation.

[0212] Aspect 37. The method of aspect 36, wherein the cooling bypass line connects one of an outlet of a downstream intercooler and an inlet of the supercharger, an outlet of the supercharger and an inlet of an upstream intercooler, and the outlet of the downstream intercooler and the inlet of the upstream intercooler.

[0213] Aspect 38. The method of aspect 36 or 37, wherein the valve is a three way valve.

[0214] Aspect 39. The method of any of aspects 30-38, wherein the air compressor includes a ratio device with at least two speeds.

[0215] Aspect 40. The method of aspect 39, wherein the at least two speeds include a first speed for driving operations and a second, faster, speed for braking operations.

[0216] Aspect 41. The method of any of aspects 28-40, wherein the air compressor exerts a parasitic load on the internal combustion engine.

[0217] Aspect 42. The method of any of aspects 28-41, wherein the air compressor includes a throttle valve in an inlet stream.

[0218] Aspect 43. The method of any of aspects 28-42, wherein the internal combustion engine has a compression ratio within a range of 10: 1 to 13 : 1.

[0219] Aspect 44. The method of any of aspect 28-43, further including drawing air into the cylinder during a second intake stroke by the piston, wherein the internal combustion enginehas a four-revolution cycle of a crankshaft of internal combustion engine and the second intake stroke is a third revolution of the four-revolution cycle; adding, during the second intake stroke, additional air into the cylinder with the air compressor; compressing the air in the cylinder during an exhaust stroke by the piston; and releasing the compressed air from the cylinder.

[0220] Aspect 45. A system for decompression braking including a hydrogen internal combustion engine (H2 ICE) having at least one cylinder, the at least one cylinder including a piston and an intake valve; an air compressor in communication with the intake valve; and a controller having a propulsion mode and a braking mode, wherein the air compressor is operated by the controller during the braking mode to supply air to the cylinder during an intake stroke by the piston.

[0221] Aspect 46. The system of aspect 45, wherein the intake valve has a lift height and a lift duration and at least one of the lift height and the lift duration is reduced during the braking mode in comparison to the lift height and lift duration during the propulsion mode to increase the pressure ratio across the air compressor.

[0222] Aspect 47. The system of aspect 45 or 46, wherein the system includes a restriction valve arrangement operable in the braking mode to increase a pressure ratio across the air compressor during operation in the braking mode.

[0223] Aspect 48. The system of aspect 47, wherein the controller operates the air compressor at an increased rotational speed in the braking mode in comparison to a rotational speed of the air compressor in the propulsion mode.

[0224] Aspect 49. A method of operating a system including a hydrogen internal combustion engine and a supercharger between a normal operating mode and an engine braking mode. The method includes operating the system in the normal operating mode wherein the supercharger operates at a first rotational speed to deliver air to an intake manifold of the engine; and operating the system in the engine braking mode. The engine braking mode includes operating the supercharger to deliver an airflow stream to the intake manifold; increasing a pressure ratio across the supercharger to increase parasitic losses by one or both of operating the supercharger at a second rotational speed higher than the first rotational speed and operating a restriction valve arrangement; introducing the airflow stream air into a cylinder of the internal combustion engine; compressing the air in the cylinder with a piston; and releasing the compressed air from the cylinder in a controlled compression release event.

[0225] Aspect 50. The method of aspect 49, wherein the step of increasing a pressure ratio across the supercharger includes operating the restriction valve arrangement.

[0226] Aspect 51. The method of aspect 50, wherein the step of increasing a pressure ratio across the supercharger includes operating the supercharger at the second rotational speed.

[0227] Aspect 52. The method of aspect 51, wherein the step of increasing a pressure ratio across the supercharger includes both operating the supercharger at the second rotational speed and operating the restriction valve arrangement.

[0228] Aspect 53. The method of any of aspects 50-52, wherein the restriction valve arrangement is located in either an inlet airflow pathway upstream of the supercharger or an outlet airflow pathway downstream of the supercharger.

[0229] Aspect 54. The method of any of aspects 50-53, wherein the restriction valve arrangement includes a plurality of restriction valve arrangements.

[0230] Aspect 55. The method of any of aspects 50-54, wherein the restriction valve arrangement is located between the engine intake manifold and the supercharger.

[0231] Aspect 56. The method of any of aspects 50-55, wherein the system includes a throttle valve arrangement and a supercharger bypass valve arrangement that are separate from the restriction valve arrangement.

[0232] Aspect 57. The method of aspect 56, wherein a mass airflow sensor is located between the supercharger and the engine intake manifold, and wherein one or both the throttle valve arrangement and the bypass valve arrangement is at least partially operated based on an input from the mass airflow sensor in the engine braking mode.

[0233] Aspect 58. The method of any of aspects 49-57, wherein the step of increasing a pressure ratio across the supercharger includes operating the supercharger at the second rotational speed higher than the first rotational speed.

[0234] Aspect 59. The method of aspect 58, wherein operating the supercharger includes operating a clutch.

[0235] Aspect 60. The method of aspect 59, wherein a speed up device is connected to the supercharger via the clutch.

[0236] Aspect 61. The method of aspect 60, wherein the speed up device is used to raise the second rotational speed during engine braking operations.

[0237] Aspect 62. The method of aspect 60 or 61, wherein the system includes a supercharger bypass valve arrangement separate from the restriction valve arrangement, the supercharger bypass valve arrangement including a three way valve.

[0238] Aspect 63. The method of aspect 62, wherein a first path provided by the three way valve directs flow from an outlet of the supercharger to an inlet of the supercharger and asecond path provided by the three way valve directs flow from an outlet of a downstream intercooler to the inlet of the supercharger.

[0239] Aspect 64. The method of aspect 62 or 63, wherein a first path provided by the three way valve directs flow from an outlet of the supercharger to an inlet of the supercharger and a second path provided by the three way valve directs flow from the outlet of the supercharger to an inlet of an upstream intercooler.

[0240] Aspect 65. The method of any of aspects 60-64, wherein the system includes a supercharger bypass valve arrangement separate from the restriction valve arrangement, the supercharger bypass valve arrangement including a throttle valve.

[0241] Aspect 66. The method of aspect 65, wherein the system includes a first three way valve upstream of the supercharger and a second three way valve downstream of the supercharger and together the first and second three way valves disconnect the supercharger.

[0242] Aspect 67. The method of aspect 66, further including disconnecting the supercharger during engine braking operations.

[0243] Aspect 68. An air intake system for delivering ambient air to an intake manifold of a low compression internal combustion engine. The air intake system including a turbocharger; a clutched supercharger in series with the turbocharger; and a valved bypass configured to selectively bypass air around the clutched supercharger.

[0244] Aspect 69. The air intake system of aspect 68, wherein the supercharger is downstream from the turbocharger.

[0245] Aspect 70. The air intake system of aspect 68 or 69, wherein the supercharger is upstream from the turbocharger.

[0246] Aspect 71. The air intake system of any of aspects 68-70, further including a first intercooler located between the supercharger and the turbocharger.

[0247] Aspect 72. The air intake system of aspect 71, further including a second intercooler located downstream of the supercharger.

[0248] Aspect 73. The air intake system of aspect 72, wherein at least one of the first intercooler and the second intercooler is integrated with the supercharger in a shared housing.

[0249] Aspect 74. The air intake system of aspect 72 or 73, wherein at least one of the first intercooler and the second intercooler is separate from the supercharger.

[0250] Aspect 75. The air intake system of any of aspects 68-74, wherein the supercharger is motor driven.

[0251] Aspect 76. The air intake system of any of aspects 68-75, wherein the supercharger is pulley driven.

[0252] Aspect 77. An air intake system for delivering ambient air to an intake manifold of a low compression internal combustion engine. The air intake system including a turbocharger; a clutched supercharger in series with and downstream from the turbocharger; an intercooler located downstream of the turbocharger and upstream of the supercharger; and a valved bypass configured to selectively bypass air around the clutched supercharger.

[0253] Aspect 78. The air intake system of aspect 77, further including another intercooler located downstream of the supercharger.

[0254] Aspect 79. The air intake system of aspect 77 or 78, further including a speed up device associated with the clutched supercharger.

[0255] Aspect 80. The air intake system of aspect 79, further including another valved bypass connecting an outlet of the supercharger and an inlet of the intercooler.

[0256] Aspect 81. The air intake system of any of aspects 77-80, further including an exhaust gas recirculation path.

[0257] Aspect 82. The air intake system of aspect 81 , wherein the exhaust gas recirculation path directs exhaust flow to an in let of the supercharger.

[0258] Aspect 83. The air intake system of aspect 81 or 82, wherein the exhaust gas recirculation path includes at least one of a control valve and a pump.

[0259] Aspect 84. The air intake system of any of aspects 81-83, wherein the exhaust gas recirculation path includes a cooler.

[0260] Aspect 85. A method of operating an air intake system, the method including operating a clutched supercharger during transient operations, wherein the clutched supercharger is in series with a turbocharger; and bypassing, with a valved bypass line, the clutched supercharger during drive operations.

[0261] Aspect 86. The method of aspect 85, further including operating the clutched supercharger during low speed stead state operations.

[0262] Aspect 87. The method of aspect 85 or 86, wherein low speed stead state operations include operations with a steady state RPM of no more than 1400.

[0263] Aspect 88. The method of aspect 87, wherein low speed stead state operations include operations with a steady state RPM of no more than 1200.

[0264] Aspect 89. The method of aspect 88, wherein low speed stead state operations include operations with a steady state RPM of no more than 1000.

[0265] Aspect 90. An air intake system for delivering ambient air to an intake manifold of a low compression internal combustion engine, the air intake system including a front boundary and opposite back boundary disposed along a first axis, an intake side boundary and an oppositeexhaust side boundary disposed along a second axis, wherein the second axis is perpendicular with the first axis, a compartment defined by the combination of the front boundary, the back boundary, the intake side boundary, and the exhaust side boundary. The low compression internal combustion engine arranged within the compartment such that a turbocharger arranged toward the front boundary along the first axis and toward the exhaust side along the second axis; and a supercharger arranged behind the turbocharger along the first axis and toward the intake side along the second axis.

[0266] Aspect 91. The air intake system of aspect 90, further including a bypass line configured to bypass the supercharger, wherein the bypass line is arranged behind the supercharger along the first axis and centrally along the second axis.

[0267] Aspect 92. The air intake system of aspect 91, wherein the bypass line is further configured to bypass an intercooler.

[0268] Aspect 93. The air intake system of aspect 92, wherein the intercooler is downstream of the supercharger.

[0269] Aspect 94. The air intake system of aspect 93, wherein the intercooler is arranged at the back boundary of the compartment along the first axis and centrally along the second axis.

[0270] Aspect 95. The air intake system of any of aspects 92-94, wherein the intercooler is upstream of the supercharger.

[0271] Aspect 96. The air intake system of aspect 95, wherein the intercooler is arranged behind the supercharger along the first axis and centrally along the second axis.

[0272] Aspect 97. The air intake system of any of aspects 91-96, wherein the front boundary coincides with an external hood boundary.

[0273] Aspect 98. The air intake system of any of aspects 91-97, a top boundary and opposite bottom boundary disposed along a third axis, the third axis perpendicular with each of the first axis and the second axis.

[0274] Having described the preferred aspects and implementations of the present disclosure, modifications and equivalents of the disclosed concepts may readily occur to one skilled in the art. However, it is intended that such modifications and equivalents be included within the scope of the claims which are appended hereto.

Claims

What is claimed is:

1. An air intake system for a low compression ratio internal combustion engine, the system comprising: a turbocharger; a supercharger downstream of the turbocharger; a first intercooler between the turbocharger and the supercharger; and a second intercooler downstream of the supercharger.

2. The system of claim 1, wherein the supercharger is a clutched supercharger.

3. The system of claim 2, wherein the clutched supercharger includes an integrated clutch.

4. The system of claim 2 or 3, further comprising a speed up device in connection with the clutched supercharger.

5. The system of any of claims 1-4, wherein the supercharger is constructed with aluminum rotors.

6. The system of any of claims 1-5, further comprising a supercharger bypass line diverting flow around the supercharger during driving operations.

7. The system of claim 6, wherein the supercharger bypass line diverts 100% of the flow from an inlet of the supercharger to an inlet of the second intercooler.

8. The system of claim 6 or 7, further comprising a bypass throttle valve in the supercharger bypass line.

9. The system of any of claims 1-8, further comprising a braking recirculation line extending from a location downstream of the second intercooler to a location between the first intercooler and the supercharger.

10. The system of claim 9, further comprising a supercharger bypass line diverting flow around the supercharger during driving operations, wherein a diameter of the supercharger bypass line is greater than a diameter of the braking recirculation line.

11. The system of claim 10, wherein the braking recirculation line is a rubber hose.

12. The system of any of claims 9-11, further comprising a recirculation throttle valve in the braking recirculation line.

13. The system of any of claims 1-12, wherein the supercharger is pulley-driven, gear- driven, or motor-driven.

14. The system of claim 13, wherein the supercharger is a two-speed supercharger.

15. The system of any of claims 1-14, wherein the second intercooler discharges into an intake manifold of the low compression ratio internal combustion engine.

16. A method of operating an air intake system for an internal combustion engine, the air intake system including, in series, a turbocharger, a first intercooler, a supercharger, and a second intercooler, the method comprising: operating the air intake system to support the internal combustion engine in a brake mode by closing a throttle valve in a supercharger bypass line; and operating the air intake system to support the internal combustion engine in a drive mode by selectively operating the throttle valve in the supercharger bypass line according to a load condition, wherein the throttle valve is fully open when the load condition is a low load condition.

17. The method of claim 16, wherein the load condition is met when engine loading is less than 50%18. The system of claim 16 or 17, wherein operating the air intake system to support the internal combustion engine in the brake mode further comprises directing air flow from anoutlet of the second intercooler to an inlet of the supercharger by opening a second throttle valve in a braking recirculation line.

19. The method of any of claims 16-18, wherein the supercharger is a clutched supercharger.

20. The method of claim 19, wherein operating the air intake system to support the internal combustion engine in the drive mode further comprises operating the clutch to place the supercharger is a neutral state when the throttle valve in the supercharger bypass line is opened.

21. The method of claim 19 or 20, wherein operating the air intake system to support the internal combustion engine in the brake mode further comprises operating the clutch to connect the supercharger with a speed up device.

22. The method of any of claims 16-21, wherein the supercharger is a motor-driven supercharger with a motor having at least two speeds; wherein operating the air intake system to support the internal combustion engine in the drive mode further comprises running the motor at a first speed; and wherein operating the air intake system to support the internal combustion engine in the brake mode further comprises running the motor at a second speed, wherein the second speed exceeds the first speed.

23. The method of any of claims 16-22, wherein the internal combustion engine is a hydrogen internal combustion engine.

24. The method of any of claims 16-23, wherein, during the drive mode, the second intercooler has an outlet temperature of less than or equal to 50 degrees C, and more preferably less than or equal to 40 degrees C, and even more preferably less than or equal to 30 degrees C.

25. The method of claim 24, wherein, during the drive mode, the first intercooler has an outlet temperature of less than or equal to 50 degrees C, and more preferably less than or equal to 40 degrees C, and even more preferably less than or equal to 30 degrees C when the throttle valve in the supercharger bypass line is closed and the supercharger is clutched-in.

26. An air intake system for an internal combustion engine, the system comprising: a turbocharger, a first intercooler, a supercharger, and a second intercooler, in series and arranged in an engine compartment such that: the second intercooler resides at a rear boundary of the engine compartment; the first intercooler resides in front of the first intercooler; and each of the turbocharger and the supercharger reside in front of the second intercooler.

27. The air intake system of claim 26, further comprising a supercharger bypass line arranged between the first intercooler and the supercharger.

28. The air intake system of claim 26 or 27, wherein the first intercooler is larger than the second intercooler.

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