HK1221496B - Isothermal compression based combustion engine - Google Patents

Description

Isothermal compression based combustion engine

Cross Reference to Related Applications

This application claims priority from us codex 35 section 119(e) to us provisional patent application No.61/906,467 entitled "isothermal combustion engine based compression" filed by Dortch on 2013, month 11, day 20, and us provisional patent application No.61/935,025 entitled "isothermal combustion engine based compression" filed by Dortch on 2014, month 2, day 3, the disclosures of which are incorporated herein by reference in their entirety.

Statement regarding federally sponsored research or development

Not applicable.

Reference to the microfilm appendix

Not applicable.

Background

Conventional combustion engines include an intake stroke followed by a compression stroke. Typically, a mixture of air and fuel is introduced into a combustion chamber of an engine during an intake stroke and is subsequently compressed by a piston during a compression stroke. Compression of the air/fuel mixture significantly increases the temperature and pressure of the mixture. Auto-ignition may occur when the compressed air/fuel mixture reaches a temperature that causes it to spontaneously ignite before the spark plug ignites to ignite the air/fuel mixture, and may result in damage to the engine. Accordingly, design features of conventional combustion engines, such as static compression ratio, forced induction capacitance, power density, fuel economy, and fueling options, are limited by the limits of auto-ignition.

Disclosure of Invention

In some embodiments of the present invention, an isothermal compression based combustion (IsoC) engine is disclosed, comprising: a compressor configured to isothermally compress a volume of air; at least one capacitive sink coupled to the compressor and configured to store a volume of isothermally compressed air; and a combustion engine configured to receive at least a portion of the isothermally compressed volume of air into a cylinder of the combustion engine; at least one of (1) selectively injecting a volume of fuel into the cylinder and igniting the volume of fuel in the presence of the volume of air in the cylinder, and (2) selectively omitting the injection of the volume of fuel and expanding the volume of air in the cylinder without combustion.

In other embodiments of the present invention, a method of operating an isothermal compression based combustion (IsoC) engine is disclosed, comprising: a first volume of isothermally compressed air; transferring the isothermally compressed volume of air to at least one capacitive tank; storing a volume of isothermally compressed air in at least one capacitive tank; injecting a second volume of isothermally compressed air into a cylinder of the combustion engine when the associated piston is approximately at a Top Dead Center (TDC) position; selectively injecting a volume of fuel into a cylinder of a combustion engine; and combusting a mixture of a second volume of isothermally compressed air and the volume of fuel in a cylinder of the combustion engine.

In other embodiments of the present invention, a method of controlling an isothermal compression based combustion (IsoC) engine is disclosed, comprising: selectively injecting a volume of isothermally compressed air into a cylinder of a combustion engine when an associated piston is located at approximately a Top Dead Center (TDC) position; selectively injecting a volume of fuel into the cylinder; selectively receiving input through a user interface; and selectively adjusting at least one of the volume of fuel and the volume of air compressed injected into the cylinder of the combustion engine during a subsequent rotation of a crankshaft of the combustion engine.

Drawings

For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts:

FIG. 1 is a schematic diagram of an isothermal compression based combustion (IsoC) engine according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of an electronic control system for an isothermal compression based combustion engine (IsoC) according to an embodiment of the present invention;

FIG. 3 is a flow chart of a method of operating an isothermal compression based combustion engine (IsoC) according to an embodiment of the present invention; and is

FIG. 4 is a flow chart of a method of controlling an isothermal compression based combustion (IsoC) engine according to an embodiment of the present invention.

Detailed Description

It should be understood at the outset that although illustrative implementations of one or more embodiments are provided below, the disclosed systems and/or methods may be implemented using any number of techniques, whether currently known or in existence. The invention should in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, including the exemplary designs and implementations illustrated and described herein, but may be modified within the scope of the appended claims along with their full scope of equivalents.

Disclosed herein are embodiments of isothermal compression based combustion (IsoC) engines. An IsoC engine may inject ambient temperature compressed air into a combustion engine immediately prior to a combustion event to increase the efficiency of the engine. The IsoC engine may also include a turbocharger coupled to the isothermal compressor and exhaust flow from the combustion engine to increase airflow into the compressor. The IsoC engine may also include capacitive air slots that may be used to drive combustion engine pistons and allow combustion to be selectively terminated to increase fuel efficiency and reduce emissions. The IsoC engine may also be capable of being compatible with regenerative braking. IsoC engines may also use lean combustion (e.g., combustion of a mixture with an excess air-fuel ratio in the combustion chamber) to increase fuel efficiency and reduce emissions. The IsoC engine may also include a carbon sequestration filter to further reduce net carbon emissions. Additionally, the components that support the efficiency of the IsoC engine may provide the hardware necessary to operate the engine as a dual drive hybrid platform. The high pressure pneumatic components of the IsoC engine that promote thermal efficiency may also allow the engine to operate as a zero emissions air motor that does not use combustion at all.

Referring now to FIG. 1, an isothermal compression based combustion (IsoC) engine 100 is shown, according to an embodiment of the present invention. The IsoC engine 100 is a combustion engine that continuously replaces the adiabatic compression utilized in conventional combustion engine cycles with an isothermally cooled compression charge (the charge is at or very near ambient temperature). The lack of heat of compression in the cylinder 156 of the iso c engine 100 prior to spark ignition substantially eliminates auto-ignition, which is a design boundary for combustion engines with isothermal compression. Most typically, the IsoC engine 100 includes an intercooled multi-stage compressor 102 configured to collect and compress ambient air while rejecting heat of compression, at least one capacitive tank 104 configured to store cooled compressed air, and a combustion engine 106, the combustion engine 106 configured to power a drive train or other equipment as a result of injecting isothermally compressed air from the at least one capacitive tank 104 and/or fuel provided by the fuel system 140 into a plurality of cylinders 156 of the combustion engine 106. Additionally, in some embodiments, the IsoC engine 100 may also include a turbocharger 108 configured to increase airflow to the compressor 102.

The compressor 102 may generally be configured for isothermally compressing air and delivering the compressed air to at least one capacitive tank 104 coupled to the compressor 102. Compressor 102 is typically configured as an intercooled multi-stage piston compressor. In some embodiments, the compressor 102 may be a scroll compressor. In other embodiments, the compressor 102 may be a rotary compressor. However, in still other embodiments, the compressor 102 may be any other type of suitable compressor capable of increasing the pressure of the volume of air contained by the compressor 102. The compressor 102 includes at least one compressor fan 138 and at least one heat exchanger 158 configured to dissipate heat caused by compressing air in the compressor 102. The compressor fan 138 is configured to generate a transport airflow through the heat exchanger 158 to facilitate heat transfer between the transport airflow and the heat exchanger 158. Additionally, the heat exchanger 158 may include fins, radiators, intercoolers, and/or any combination of fins, radiators, intercoolers, and other features configured to facilitate heat transfer between the transport airflow and the heat exchanger 158. In some embodiments, the rejected heat from the heat exchanger 158 of the compressor 102 may be used to provide cabin heating, oil heating, and/or other auxiliary uses in cold climates. The heat exchanger 158 of the compressor 102 may also be configured for liquid cooling. By rejecting heat resulting from compressing the air in the compressor 102, the compressor 102 is able to isothermally compress the air in the compressor 102. In some embodiments, the isothermally compressed air may have a temperature that is approximately equal to the temperature of the ambient air entering the compressor 102. The transport airflow may dissipate heat into the ambient air or may alternatively be diverted through compressor discharge 132. The compressor discharge 132 may be coupled to the hot side 108b of the turbocharger 108. As will be described in further detail later, by transferring heat rejected from the heat exchanger 158 of the compressor 102 through the hot side 108b of the turbocharger 108, the heat energy rejected by the heat exchanger 158 of the compressor 102 can be recovered by the turbocharger 108 to further increase the efficiency of the compressor 102 and/or the IsoC engine 100.

The compressor 102 provides isothermally compressed air to the at least one capacitive tank 104 through a line dryer 112 disposed between the compressor 102 and the at least one capacitive tank 104. The line dryer 112 is configured to remove moisture from the isothermally compressed air from the compressor 102. A check valve 114 may also be disposed between the compressor 102 and the at least one capacitive sink 104. The check valve is configured to prevent the flow of isothermally compressed air from the downstream side closer to the at least one capacitive tank 104 in the upstream direction toward the compressor 102. Additionally, an external fill port 116 may be disposed between the check valve 114 and the at least one capacitive groove 104. The external fill port 116 is configured for coupling to an external compressed air source to allow the at least one capacitive sink 104 to receive compressed air from the external compressed air source through the external fill port 116. Further, the check valve 114 may also prevent compressed air received from an external compressed air source through the external fill port 116 from flowing toward the compressor 102.

Although the IsoC engine 100 is disclosed as having at least one capacitive slot 104, it will be appreciated that the IsoC engine 100 may include a plurality of capacitive slots 104. The capacitive tank 104 is generally configured to store the isothermally compressed air received from the compressor 102. Further, the capacitive sink 104 is configured to supply an amount of isothermally compressed air to the combustion engine 106. The capacitive tanks 104 may generally have a lightweight, high strength construction. In some embodiments, the capacitive slot 104 may comprise a carbon fiber composite construction. In some embodiments, the capacitive slot 104 may be loaded to a pressure of up to about 500 pounds per square inch (psi), up to about 1,000psi, up to about 2,000psi, up to about 3,000psi, up to about 4,000psi, and/or up to about 5,000 psi.

On the downstream side of the capacitive tank 104, the IsoC engine 100 includes a shut-off valve 118. The shutoff valve 118 is selectively operable to substantially limit and/or substantially prevent the transfer of compressed air stored in the capacitive tank 104 into the combustion engine 106. In some embodiments, the shut-off valve 118 may be a manually controlled shut-off valve. However, in other embodiments, the shut-off valve 118 may be an electronically controlled valve that is selectively operable to allow or restrict the flow of compressed air from the capacitive bowl 104 to the combustion engine 106. In yet other embodiments, the shut-off valve 118 may be pneumatically actuated by sudden changes in pressure due to a failsafe emergency interruption. Additionally, as described in further detail herein, the IsoC engine 100 may also include a carbon dioxide sequestration filter 120 between the capacitive tank 104 and the combustion engine 106. The carbon dioxide sequestration filter 120 may generally comprise a sleeve of particulate metal oxide that sequesters free atmospheric carbon dioxide when the associated IsoC engine 100 is operating.

Most typically, the capacitive sink 104 is configured for supplying a load of isothermally compressed air into the cylinder 156 of the combustion engine 106. The capacitance tank 104 is supplied with compressed air through a pressure regulator 122 and to a common air rail 124, where the compressed air is substantially evenly distributed to a plurality of air jets 126. The pressure regulator 122 may generally be configured to selectively control, limit, and/or limit the pressure of compressed air entering the common air rail and/or the cylinders 156 of the combustion engine 106. However, in some embodiments, the pressure regulator 122 may be configured to selectively allow substantially unrestricted flow of compressed air to the common air rail 124, and/or to vary pressure as a type of regulator valve in some modes and states of operation. Typically, each cylinder 156 receives compressed air through a single air injector 126. However, in some embodiments, each cylinder 156 of the combustion engine 106 may receive compressed air via a plurality of air injectors 126. The air injector 126 of the IsoC engine 100 may be mechanically, pneumatically, hydraulically, and/or electromagnetically actuated. It will be appreciated that the delivery of compressed air from the capacitive sink 104 to the air injector 126 and into the cylinder 156 of the combustion engine may be electronically controlled.

The IsoC engine 100 also includes a fuel system 140 configured to supply fuel to each of a plurality of cylinders 156 of the combustion engine 106. Fuel system 140 includes a fuel reservoir 142 configured to store a volume of fuel, a fuel pump 144 configured to pump fuel from fuel reservoir 142, a fuel filter 146 configured to remove particulates from the fuel, a fuel rail 148, and a plurality of fuel injectors 150. Fuel system 140 is configured to store a volume of fuel in fuel accumulator 142 and pump the fuel from fuel accumulator 142 through fuel filter 146 to fuel rail 148, where the fuel is substantially evenly distributed to a plurality of fuel injectors 150. In some embodiments, the fuel system 140 is configured to transfer fuel to the cylinders 156 of the combustion engine 106 simultaneously with the isothermally compressed air from the capacitive sink 104. However, in some embodiments and modes of operation, only compressed air may be injected into the cylinders 156 of the combustion engine 106. Further, it will be appreciated that the delivery of fuel by the fuel system 140 may be electronically controlled.

Combustion engine 106 is generally configured to operate in response to combusting a mixture of compressed air delivered from capacitive sump 104 and fuel delivered from fuel system 140. In some embodiments, the combustion engine 106 may also be configured for operation in response to injecting only compressed air from the capacitive bowl 104 into the cylinders 156 of the combustion engine 106. In some embodiments, the combustion engine 106 may comprise a four-stroke combustion engine. However, in other embodiments, the combustion engine 106 may comprise a two-stroke combustion engine. Combustion engines typically include a plurality of cylinders 156, each having a piston 160 driven by crankshaft 136. The combustion engine 106 is further configured to exhaust gases through an exhaust manifold 128. Combustion engine 106 is typically coupled to compressor 102 by way of a crankshaft 136 by selectively engaging a compressor clutch 130. Accordingly, compressor 102 is selectively driven by combustion engine 106 by selectively engaging compressor clutch 130. By engaging the compressor clutch 130, the compressor 102 is driven by rotation of the crankshaft 136 caused by operation of the combustion engine 106. In some embodiments, the compressor clutch 130 may include additional design and safety elements, such as gearing, slip clutches, and adjust the speed and torque transmitted from the combustion engine 106 to the compressor 102. Further, in some embodiments, the compressor clutch 130 may be selectively disengaged when the IsoC engine 100 is operating as a compressed air motor.

In some embodiments, the IsoC engine 100 includes a turbocharger 108. The turbocharger 108 is coupled to the exhaust manifold 128 and is configured to recover energy from exhaust gases that may otherwise be lost. The turbocharger 128 may be described as having a cold side 108a and a hot side 108 b. Hot side 108b of turbocharger 108 receives exhaust gas from combustion engine 106 through exhaust manifold 128 and exhausts the exhaust gas to the atmosphere through exhaust duct 152. In some embodiments, the turbocharger 108 may also transmit exhaust gases through the catalytic converter 154, depending on the application of the IsoC engine 100. Exhaust gas passing through the hot side 108b of the turbocharger 108 rotates a shaft in the turbocharger 108 and causes a second impeller compressor of the cold side 108a of the turbocharger 108 to draw ambient air through the air filter 110 and force the air into the compressor 102 through the intake duct 134. When configured for a force-induced (force-induced) compressor 102, the turbocharger 108 acts as an additional pumping stage, thus improving volume transfer while reducing the operating requirements at the compressor 102 and/or the crankshaft 136 of the compressor 102. The output of the turbocharger 108 may also be intercooled before delivering air into the compressor 102. Additionally, in some embodiments, heat rejected from the compressor 102 by the heat exchanger 158 may be transferred to the hot side 108b of the turbocharger 108 and may be recovered by the turbocharger 108 to further increase the efficiency of the compressor 102 and/or the IsoC engine 100. Accordingly, the turbocharger 108 may utilize energy recovered from the exhaust of the combustion engine 106 and/or heat rejected at the compressor 102 to increase volumetric delivery of the compressor 102. However, in alternative embodiments, the IsoC engine 100 may not include the turbocharger 108. In this embodiment without the turbocharger 108, the compressor 102 may be directly coupled to the air filter 110 and configured to draw air directly through the air filter 110 via natural aspiration.

Still referring to FIG. 1, in operation, the IsoC engine 100 is operated by injecting a charge of isothermally compressed air into the cylinders 156 of the combustion engine 106 and injecting fuel provided by the fuel system 140. The charge of compressed air and fuel may then be atomized and/or mixed and combusted to rotate a crankshaft 136 of the combustion engine 106. In some embodiments, the charge of compressed air may be injected simultaneously with the fuel injection. However, in other embodiments, the charge of compressed air may be injected before and/or after fuel injection. Additionally, the IsoC engine 100 is configured for selectively stopping fuel injection and operating as a zero emissions compressed air motor by injecting the charge of compressed air to urge the piston 160 in the associated cylinder 156 downward away from a Top Dead Center (TDC) position. The IsoC engine 100 is also configured to selectively restart fuel injection and operate the combustion engine 106 by restarting combustion of the compressed air and fuel mixture.

Most typically, the charge of isothermal compressed air from the capacitive bowl 104 may be injected into the cylinder when the associated piston 160 is positioned at or near TDC. TDC represents the time when the piston 160 in the cylinder 156 is positioned farthest away from the crankshaft 136. TDC also represents the time when the force acting on the crankshaft 136 is substantially aligned with the longitudinal axis extending through the center of the cylinder 156. Still further, for the purposes of this disclosure, the piston 160 is positioned at TDC when the associated crankshaft 136 angle is at 0. Thus, any negative angle, such as-5 °, represents the angle of rotation of crankshaft 136 before piston 160 reaches its TDC in the associated cylinder 156, and any positive angle, such as +5 °, represents the angle of rotation of crankshaft 136 after piston 160 has passed its TDC in the associated cylinder 156. Additionally, it will be appreciated that the IsoC engine 100 may be configured as a two-stroke combustion engine or alternatively as a four-stroke combustion engine, wherein fuel from the fuel system 140 is also injected into the cylinders 156 of the combustion engine 106.

Two cycle IsoC engine operation

Operation of the IsoC engine 100 when the combustion engine 106 comprises a two-stroke combustion engine includes a power stroke and an exhaust stroke, and may further be characterized by the omission of a conventional adiabatic compression stroke and the omission of a conventional intake stroke in the cylinder 156 of the combustion engine 106. Alternatively, a charge of isothermally compressed air from the capacitive bowl 104 is injected into the cylinder 156 of the combustion engine 106 when the piston 160 of the associated cylinder 156 is at or near TDC. Additionally, a charge of isothermal compressed air from capacitive sump 104 may also be described as being injected just prior to ignition when fuel from fuel system 140 is also added into cylinder 156.

In some embodiments, injection of compressed air into the cylinder 156 may occur when the piston 160 of the cylinder 156 is at TDC (0). However, in other embodiments, the injection of compressed air into the cylinder 156 may occur when the angle of rotation of the crankshaft 136 is between about-30 and about +30, between about-20 and about +20, between about-15 and about +15, between about-10 and about +10, between about-5 and about +5, between about-2 and about +2, and/or between about-1 and about + 1. In still other embodiments, injection of compressed air into the cylinder 156 may begin when the associated piston 160 is positioned at TDC and continue until the angle of rotation of the crankshaft 136 is at about +1, about +2, about +3, about +5, about +10, about +15, and/or about + 30. Still further, in an alternative embodiment, injection of compressed air into the cylinders 156 may begin when the angle of rotation of the crankshaft 136 is between about-30 °, about-15 °, about-10 °, about-5 °, about-3 °, about-2 °, and/or about 0 °, and continue until the angle of rotation of the crankshaft 136 is at about TDC, at about +1 °, about +2 °, about +3 °, about +5 °, about +10 °, about +15 °, and/or about +30 °. In some embodiments, it will be appreciated that the timing and duration of the injection of compressed air may also depend on the rotational speed of crankshaft 136 and/or other operating or design parameters of combustion engine 106.

The two-stroke combustion engine configuration of the IsoC engine 100 eliminates the adiabatic compression utilized in conventional combustion engine cycles. By injecting a charge of isothermal compressed air at or near TDC, adiabatic heat of compression is not introduced into the cycle and the compressed air-fuel mixture remains cooled to the threshold for spark ignition. Thus, the two-stroke IsoC engine 100 has substantially no auto-ignition or explosion limiting conditions, allowing designs and embodiments that may include higher static compression ratios up to about 100:1, greater flexibility in fuel supply selection, improved thermal efficiency, reduced emissions, and the ability to operate efficiently with very dilute air-fuel mixtures. Accordingly, the IsoC engine 100 may combust a lean mixture (e.g., combustion of a mixture of compressed air and fuel with a higher ratio of air to fuel in the cylinder 156), which may increase fuel efficiency and reduce emissions without causing overheating or a greater loss of power. In some embodiments, the ratio of air to fuel may be about 15:1, about 20:1, about 25:1, about 30:1, about 40:1, about 50:1, about 60:1, and/or about 70: 1. In some embodiments, the IsoC engine 100 may obtain an equivalent and/or greater amount of power from combusting a low concentration air-to-fuel ratio mixture than a conventional adiabatic compression engine may obtain by combusting a stoichiometric air-to-fuel mixture. Accordingly, the IsoC engine 100 may allow for a greater power output with lower fuel requirements, thereby giving the IsoC engine 100 a higher fuel efficiency compared to that of conventional adiabatic compression engines.

By enabling combustion engine 106 to operate at air to fuel ratios that may otherwise damage conventional adiabatic compression engines, long-term combustion engine design constraints may be effectively reduced and/or eliminated altogether. Additionally, the higher compression pressures required for higher compression ratio operation are generated and provided by the pneumatic components of the IsoC engine 100, eliminating the need for pressures to be processed in the combustion engine 106. Accordingly, the IsoC engine 100 may include a lighter load configuration of the combustion engine 106 than a conventional combustion engine having a substantially similar static compression ratio.

Four cycle IsoC Engine operation

The operation of the IsoC engine 100 when the combustion engine 106 comprises a four-stroke combustion engine includes an air motor power stroke, a compression stroke, a combustion power stroke, and an exhaust stroke, and may also be characterized as an air motor power stroke instead of the conventional intake stroke in a four-stroke cycle. Alternatively, operation of the IsoC engine 100 in the four-stroke configuration may be further described as a four-stroke cycle consisting of two interleaved and alternating two-stroke cycles: (1) a two-stroke air motor sub-cycle and (2) a two-stroke combustion engine sub-cycle, wherein two types of power strokes are performed upon alternate rotation of crankshaft 136, and the "exhaust" from the air power stroke becomes the "intake" for the internal combustion process. With the exhaust valve of the cylinder 156 closed, the charge of isothermally compressed air from the capacitive sump 104 is injected into the cylinder 156 of the combustion engine 106 when the piston 160 of the associated cylinder 156 is at or near TDC at the beginning of the air motor power stroke. In some embodiments, injection of compressed air into the cylinder 156 may begin when the associated piston 160 is positioned at TDC, and continue until the angle of rotation of the crankshaft 136 is at about +1 °, about +2 °, about +3 °, about +5 °, about +10 °, about +15 °, and/or about +30 °. Still further, in an alternative embodiment, injection of compressed air into the cylinders 156 may begin when the angle of rotation of the crankshaft 136 is between about-30 °, about-15 °, about-10 °, about-5 °, about-3 °, about-2 °, and/or about 0 °, and continue until the angle of rotation of the crankshaft 136 is at about TDC, at about +1 °, about +2 °, about +3 °, about +5 °, about +10 °, about +15 °, and/or about +30 °. In some embodiments, it will be appreciated that the timing and duration of the injection of compressed air may also depend on the rotational speed of crankshaft 136 and/or other operating or design parameters of combustion engine 106.

A charge of compressed air may fill cylinder 156 and absorb the residual waste heat from the previous combustion event. The charge of compressed air may gain additional expansion due to absorption of waste heat. Accordingly, air in the cylinder 156 may push the piston 160 downward. In some embodiments, by replacing the conventional intake event with a compressed air power stroke, the piston may be significantly reduced from being pushed away from the TDC position and/or conventional pumping losses may be eliminated. Accordingly, the injection of the charge of isothermally compressed air may increase the power output of the IsoC engine 100 via the removal of waste heat without injecting additional fuel into the cylinders.

In some embodiments, the load of compressed air injected into the cylinder 156 may depend on the static compression ratio of the combustion engine 106. For example, a charge of compressed air having a pressure of about 147 pounds per square inch (psi; about 10 bar) may be injected into the cylinder 156 for a combustion engine 106 having a compression ratio of about 10:1 at about TDC. When the piston 160 is at the Bottom Dead Center (BDC) position, this may result in a pressure of about 14.7psi in the cylinder 156 after expansion. Accordingly, the pressure of the charge of compressed air injected into the cylinder 156 may be adjusted such that the pressure inside the cylinder 156 of the combustion engine 106 at BDC is approximately 14.7psi and/or any other pressure that promotes proper combustion in the cylinder 156. In some embodiments, because the isothermal compression loading introduced at TDC has already expanded at a 10:1 ratio when the piston 160 reaches BDC, assuming it is at a lower temperature than the ambient air temperature at the beginning of the upstroke, the compression stroke may begin in a cooler environment as compared to conventional adiabatic compression engines. Additionally, during the compressed air power stroke, the heated plane of the cylinder 156 may drive more expansion of the compressed gas, reject this waste heat and transfer the waste heat in the form of additional work to the crankshaft 136. Due to the cooler environment, the crankshaft 136 may experience a reduced load in the upstroke that promotes a cooler compression load and increased efficiency from the combustion event that occurs as the piston 160 returns to the TDC position as fuel is injected into the cylinder 156. After ignition and combustion, the power and exhaust strokes of the four-stroke IsoC engine 100 may be substantially similar to those of a conventional four-stroke adiabatic compression engine.

Still referring to FIG. 1, the IsoC engine 100 may be mounted in a vehicle and configured for propelling the vehicle. The present disclosure contemplates that the IsoC engine 100 may be used in a number of applications, including, but not limited to, vehicles, heavy machinery, power plants, generator sets, combustion engine powered tools and equipment, surface and submersible vessels, and any other suitable combustion engine powered equipment, where it may benefit from increased fuel efficiency, reduced emissions, reduced operating temperatures, and/or less restrictive design constraints.

Embodiments of the two-stroke combustion engine configuration and the four-stroke combustion engine configuration of the IsoC engine 100 may also provide additional benefits. The IsoC engine 100 is configured for regenerative braking by coupling the compressor 102 to the combustion engine 106 through the crankshaft 136 by selectively engaging the compressor clutch 130, which may further increase the efficiency of the IsoC engine 100. During deceleration of the IsoC engine 100, energy may be transferred to the compressor 102 by engaging the compressor clutch 130 via the crankshaft 136. Thus, the compressor 102 can recover the energy that is typically lost during deceleration and use that energy to isothermally compress additional air and replenish the amount of compressed air stored in the capacitive tanks 104. As a result, "brake loading" may be used to propel a vehicle or other piece of equipment from an idle position, further reducing fuel consumption and emissions.

The IsoC engine 100 may also not have similar idling requirements as current hybrid gas-electric applications. When the vehicle or other device that includes the IsoC engine 100 is not demanding power requirements and/or the vehicle or device remains idle, the IsoC engine 100 may be stopped completely by interrupting the injection of compressed air from the capacitive sump 104 or by selectively operating the shutoff valve 118. Additionally, the IsoC engine 100 may also stop fuel delivery from the fuel system 140. The IsoC engine 100 may then be restarted as a compressed air motor using only compressed air injection. The IsoC engine 100 may resume injection of compressed air into the combustion engine 106 once acceleration is requested, and may also resume fuel combustion and fuel injection of the compressed air and fuel mixture when fuel combustion may be performed at maximum efficiency. The dual drive function of the IsoC engine 100 operating as a combustion engine and a compressed air motor can be selectively managed to optimize performance, efficiency, and emissions.

The IsoC engine 100 may also be configured for a zero emissions mode. In some embodiments, the IsoC engine 100 may be operated without fuel from the fuel system 140 and with only a charge of compressed air provided by the capacitive bowl 104 by driving the piston 160 of the combustion engine 106. For example, in a short trip and/or an alternating of frequent start stops, the IsoC engine 100 may first utilize its zero emissions air motor mode and employ fuel combustion only when combustion can be performed with maximum efficiency. Further, while traveling at highway speeds and/or during extended cruising, fuel combustion may be selectively engaged to provide continuous power and replenish any depleted capacitance of the capacitor tank 104.

The IsoC engine 100 may also be configured to reduce carbon emissions. The IsoC engine 100 includes a carbon dioxide sequestration filter 120 between the capacitive tank 104 and the combustion engine 106. The carbon dioxide sequestering filter 120 comprises a replaceable sleeve of particulate metal oxide that sequesters carbon dioxide during continuous load operation. Fueling the iso c engine 100 with a truly carbon neutral biofuel, while the pneumatic hardware is configured for sequestration of free atmospheric carbon dioxide, may result in a net carbon negative operating cycle.

The IsoC engine 100 may also be configured for mains-powered operation. The IsoC engine 100 includes an external fill port 116, the external fill port 116 configured for coupling to an external compressed air source to allow the at least one capacitive sink 104 to receive compressed air from the external compressed air source through the external fill port 116. Accordingly, the capacitor tank 104 may be filled using a stationary pump and/or other stationary or movable source of compressed air.

The IsoC engine 100 may be configured to utilize some or all of the efficiency-enhancing benefits described herein. This benefit, such as increased static compression ratio, improved lean-burn capability, greater flexibility in fueling options, regenerative braking, no engine idle requirements, and zero emissions air motor mode, may be selectively employed to maximize the efficiency of a vehicle or other device having the IsoC engine 100. Accordingly, by recovering the otherwise rejected thermal energy and selectively performing fuel combustion, the IsoC engine 100 is able to achieve a greater increase in fuel efficiency relative to conventional adiabatic compression engines. In some embodiments, the IsoC engine 100 may also achieve higher fuel efficiency compared to conventional gas-electric hybrid vehicles. For example, in some embodiments, passenger vehicles having an IsoC engine 100 may achieve a fuel efficiency of at least about 40 miles per gallon (mpg), at least about 50mpg, at least about 60mpg, at least about 70mpg, at least about 80mpg, and/or at least about 90 mpg. Additionally, for higher performance and racing purposes, as well as other applications where fuel efficiency is considered to be a secondary requirement for maximizing power output and performance, the IsoC engine 100 may be selectively configured such that its characteristics are directed toward maximizing power density and power output rather than fuel economy.

Referring now to FIG. 2, a schematic diagram of an electronic control system 200 of an isothermal compression based combustion (IsoC) engine 100 is shown, according to an embodiment of the present invention. The electronic control system 200 is electronically coupled to the IsoC engine 100 of fig. 1. The electronic control system 200 includes an Electronic Control Unit (ECU)202, the ECU202 configured to monitor operating parameters of the iso c engine 100 via a plurality of sensor inputs 206. The ECU202 also includes a plurality of control outputs 208 and is configured to control operation of the IsoC engine 100 through the plurality of control outputs 208 in response to monitored operation of the IsoC engine 100 through the sensor input 206. The electronic control system 200 also includes a user interface 204, which user interface 204 may be configured to selectively input a demand from the IsoC engine 100 for power, efficiency, acceleration, and/or a reduction in acceleration. The user interface 202 may include a pedal, a toggle switch, a regulator valve, a trigger, or any other adjustable mechanism for selectively inputting a demand for power, efficiency, acceleration, and/or a reduction in acceleration of a vehicle or other device that includes the IsoC engine 100.

The ECU202 may generally be configured as an Application Specific Integrated Circuit (ASIC) and/or include a general purpose processor. The ECU202 may also be configured to be programmable and/or store one or more of a fuel map and an air map to allow the ECU202 to control the operation of the IsoC engine 100 via the control output 208 resulting from monitoring the sensor input 206. For example, ECU202 may use more compressed air from capacitive sump 204 at lower crankshaft 136 rotational speeds and fuel system 140 at higher crankshaft 136 rotational speeds in a manner similar to a conventional hybrid gas electric engine. Further, the ECU202 may be configured to manage pressure and temperature throughout the iso c engine 100, govern the balance between air motor and fuel combustion drive modes, and vary the combustion mixture due to one or more fuel maps stored in the ECU 202.

To perform control of the IsoC engine 100, the ECU202 may monitor a plurality of sensor inputs 206 that transmit information to the ECU 202. The information may include the temperature and/or pressure of the compressor 102, combustion engine 106, turbocharger 108, pressure regulator 122, air rail 124, air injector 126, exhaust manifold 128, compressor discharge 132, intake conduit 134, fuel system 140, fuel reservoir 142, fuel pump 144, fuel rail 148, fuel injector 150, discharge conduit 152, catalytic converter 154, cylinder 156, and/or any other component of the IsoC engine 100. Additionally, the sensor input 206 may transmit information to the ECU202 relating to the air capacitance magnitude of the capacitive bowl 104, the state of the check valve 114, the connection status to the external fill port 116, the function of the air injector 126, the fuel level in the fuel reservoir 142, the function of the fuel injector 150, the crankshaft 136 angle, the crankshaft 136 rotational speed, and/or any other operational and/or status parameters necessary for the ECU202 to display control of the iso engine 100.

As a result of monitoring the sensor inputs 206, the ECU202 may control the IsoC engine 100 via a plurality of control outputs 208. Control output 208 may generally include selectively operating compressor 102, distributing compressed air from capacitor sump 104, selectively operating combustion engine 106, selectively operating shutoff valve 118, selectively adjusting pressure regulator 122, selectively controlling and/or operating air injector 126, selectively engaging and disengaging compressor clutch 130, selectively operating compressor fan 138, selectively controlling and/or operating fuel system 140, and/or selectively controlling and/or operating fuel injector 150. The ECU202 may also control the IsoC engine 100 through a plurality of control outputs 208 due to changes in the requirements for power, efficiency, acceleration, and/or reduction in acceleration received by the ECU202 through the user interface 204. The ECU202 may also control the IsoC engine 100 via control output 208 based on a pre-loaded fuel map and/or air map stored in the ECU 202. Additionally, the ECU202 may be configured to continuously change the timing of compressed air injection, the timing of fuel injection, and the timing of spark ignition.

Referring now to FIG. 3, a flowchart of a method 300 of operating an isothermal compression based combustion (IsoC) engine 100 is shown, according to an embodiment of the present invention. The method 300 may begin at block 302 by using the compressor 102 to isothermally compress air. In some embodiments, the compressor 102 may compress air isothermally by dissipating heat through the at least one heat exchanger 158. The method may continue at block 304 by storing compressed air in the at least one capacitive tank 104. The method may continue at block 306 by selectively injecting a volume of isothermally compressed air into the cylinder 156 of the combustion engine 106 when the associated piston 160 is approximately at Top Dead Center (TDC). The method may continue at block 308 by selectively injecting a volume of fuel into the cylinder 156. In embodiments having a two-stroke combustion engine, a volume of fuel may be injected simultaneously with the compressed air. In embodiments having a four-stroke combustion engine, a volume of fuel may be injected during the air motor power stroke and/or compression stroke of the four-stroke combustion engine 106. However, in some embodiments, a volume of fuel may not be injected into the cylinder 156. The method may end at block 310 by combusting a mixture of a volume of isothermally compressed air and a volume of fuel in a cylinder of the combustion engine 106. In some embodiments, combustion of the mixture of the volume of isothermally compressed air and the volume of fuel may be initiated by selectively igniting spark plugs in the cylinders 156 of the combustion engine 106.

Referring now to FIG. 4, a flowchart of a method 400 of controlling an isothermal compression based combustion (IsoC) engine 100 is shown, according to an embodiment of the present invention. The method 400 may begin at block 402 by selectively injecting a volume of isothermally compressed air into the cylinder 156 of the combustion engine 106 when the associated piston 160 is approximately at Top Dead Center (TDC). The method may continue at block 404 by selectively injecting a volume of fuel into the cylinder 156. In embodiments having a two-stroke combustion engine, a volume of fuel may be injected simultaneously with the compressed air. In embodiments having a four-stroke combustion engine, a volume of fuel may be injected during the air motor power stroke and/or compression stroke of the four-stroke combustion engine. However, in some embodiments, a volume of fuel may not be injected into the cylinder 156. The method may continue at block 406 by selectively receiving input through the user interface 204. The method may end at block 408 by selectively adjusting at least one of a volume of compressed air and a volume of fuel injected into the cylinder 156 of the combustion engine 106. In some embodiments, selectively adjusting at least one of the volume of compressed air and the volume of fuel may be performed by ECU202 in communication with at least one control output 208 and/or controlling at least one control output 208. Further, in some embodiments, the ECU202 may perform selective adjustment of at least one of the volume of compressed air and the volume of fuel in response to communication with the at least one sensor input 206.

At least one embodiment is disclosed, and variations, combinations, and/or modifications of the embodiments and/or features of the embodiments made by those skilled in the art are within the scope of the invention. Alternative embodiments resulting from the incorporation, integration, and/or omission of features of the embodiments are also within the scope of the invention. Where numerical ranges or limitations are expressly stated, such express ranges or limitations should be understood to include iterative ranges or limitations of like magnitude falling within the expressly stated ranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4, etc., as opposed to 0.10, including 0.11, 0.12, 0.13, etc.). For example, whenever there is a lower limit R₁And upper limit Ru, any numerical value falling within the range is specifically disclosed. In particular, the following numbers in the range are specifically disclosed as R ═ R₁+k*(Ru-R₁)，Where k is a variable ranging from 1% to 100% with 1% increments, i.e., k is 1%, 2%, 3%, 4%, 5%, …, 50%, 51%, 52%, …, 95%, 96%, 97%, 98%, 99%, or 100%. Unless otherwise specified, the term "about" shall mean 10% more or less than the subsequent value. In addition, any numerical range defined by two R numbers, as defined above, is also specifically disclosed. Use of the term "optionally" with respect to any element of a claim means that the element is required, or alternatively, the element is not required, both alternatives being within the scope of the claim. The use of broad terms, such as "including," "comprising," and "having," should be understood to provide support for narrow terms, such as "consisting of …," "consisting essentially of, and" consisting essentially of. Accordingly, the scope of protection is not limited by the description set out above, but is only limited by the claims which follow, that scope including all equivalents of the subject matter of the claims. As further disclosed, each and every claim is incorporated into the specification, and the claims are embodiments of the present invention. The discussion of the references herein is not an admission that they are prior art, especially any references that have a publication date after the priority date of this application. The disclosures of all patents, patent applications, and publications cited herein are hereby incorporated by reference, to the extent that they provide exemplary, procedural or other details supplementary to those set forth herein.

Claims (20)

1. An isothermal compression based combustion engine comprising:

a compressor configured for isothermally compressing a volume of air;

at least one capacitive sink coupled to the compressor and configured to store the volume of isothermally compressed air; and

a combustion engine configured for:

directly receiving at least a portion of the isothermally compressed volume of air from the at least one capacitive sink into a cylinder of a combustion engine; and

at least one of (1) selectively injecting a volume of fuel into the cylinder and igniting the volume of fuel in the presence of at least a portion of the volume of isothermally compressed air in the cylinder, and (2) selectively omitting injection of the volume of fuel and expanding at least a portion of the volume of isothermally compressed air in the cylinder without combustion.

2. The isothermal compression based combustion engine of claim 1, wherein:

the volume of air is received into the cylinder when the associated piston is at a top dead center position.

3. The isothermal compression based combustion engine of claim 1, wherein:

the volume of air is received into the cylinder when the associated piston is between a top dead center position and a position that rotates 20 ° beyond the top dead center position.

4. The isothermal compression based combustion engine of claim 1, wherein:

the compressor includes a multi-stage intercooled compressor and is configured to dissipate heat generated as a result of compressing the volume of air.

5. The isothermal compression based combustion engine of claim 1, wherein:

the volume of compressed air received into the cylinder has a temperature that is the ambient temperature of the surrounding environment.

6. The isothermal compression based combustion engine of claim 1, wherein:

the combustion engine is configured to eliminate auto-ignition of a volume of fuel selectively injected into a cylinder.

7. The isothermal compression based combustion engine of claim 1, further comprising:

a turbocharger driven by exhaust flow from the combustion engine and configured to forcibly induce inspiration of the compressor.

8. The isothermal compression based combustion engine of claim 1, wherein:

the compressor is coupled to a crankshaft of the combustion engine by a compressor clutch, and wherein the crankshaft is configured to operate the compressor when the compressor clutch is engaged.

9. The isothermal compression based combustion engine of claim 1, wherein:

the combustion engine includes a two-stroke operating cycle having an exhaust stroke and a working stroke, and wherein receiving at least a portion of the volume of air from the at least one capacitive sink and into isothermal compression in the cylinder and selectively injecting the volume of fuel into the cylinder occur simultaneously.

10. The isothermal compression based combustion engine of claim 1, wherein:

the combustion engine includes a four-stroke operating cycle having an air motor power stroke, a compression stroke, a combustion power stroke, and an exhaust stroke, wherein the at least a portion of the volume of air that undergoes isothermal compression is injected into the cylinder when an associated piston is at a top dead center position at a beginning of the air motor power stroke, and wherein the selective injection of the volume of fuel occurs during at least one of the air motor power stroke and the compression stroke.

11. A method of operating an isothermal compression based combustion engine, comprising:

isothermally compressing a first fixed volume of air;

transferring the isothermally compressed volume of air to at least one capacitive tank;

storing an isothermally compressed volume of air in the at least one capacitive cell;

injecting a second volume of isothermally compressed air directly from the at least one capacitive slot into a cylinder of the combustion engine when the associated piston is at a top dead center position;

selectively injecting a volume of fuel into a cylinder of a combustion engine; and is

Combusting a mixture of a second volume of isothermally compressed air and the volume of fuel in a cylinder of the combustion engine.

12. The method of claim 11, wherein:

the selective injection of a volume of fuel into a cylinder of a combustion engine occurs simultaneously with the injection of a second volume of isothermally compressed air.

13. The method of claim 11, further comprising the steps of:

selectively stopping injection of a volume of fuel into the combustion cylinder; and is

Continuing to inject a second volume of isothermally compressed air into the cylinder of the combustion engine when the associated piston is at the top dead center position to cause operation of the combustion engine.

14. The method of claim 11, wherein:

the injection of the second volume of isothermally compressed air into the cylinder of the combustion engine and the selective injection of the volume of fuel into the cylinder of the combustion engine occur simultaneously.

15. The method of claim 11, wherein:

injection of a second volume of isothermally compressed air into the cylinder of the combustion engine occurs when the associated piston is at a top dead center position prior to the air motor power stroke, and selective injection of the volume of fuel into the cylinder of the combustion engine occurs during at least one of the air motor power stroke and the compression stroke.

16. A method of controlling an isothermal compression based combustion engine, comprising:

selectively injecting a volume of isothermally compressed air directly from a capacitive sink into a cylinder of a combustion engine when an associated piston is at a top dead center position;

selectively injecting a volume of fuel into the cylinder;

selectively receiving input through a user interface; and is

Selectively adjusting at least one of the volume of isothermally compressed air and the volume of fuel injected into the cylinder of the combustion engine during a subsequent rotation of a crankshaft of the combustion engine.

17. The method of claim 16, wherein:

selectively adjusting at least one of the volume of isothermally compressed air and the volume of fuel injected into the cylinder is performed by an electronic control unit in response to monitoring at least one sensor input.

18. The method of claim 17, wherein:

selectively adjusting at least one of the volume of isothermally compressed air and the volume of fuel injected into the cylinder is performed by an ECU in communication with at least one control output.

19. The method of claim 18, wherein:

selectively adjusting at least one of the volume of isothermally compressed air and the volume of fuel injected into the cylinder is performed by the ECU in response to an input received through the user interface.

20. The method of claim 19, wherein:

the ECU is configured to selectively control the IsoC engine based on at least one of a pre-load fuel map stored in the ECU and a pre-load air map stored in the ECU.