Patent Application
20130319359
Not Applicable
Not Applicable.
Hydrogen and natural gas are cleaner, safer, and more readily available than petroleum-based fuels, making hydrogen and natural gas vehicles an attractive and more economical alternative to conventional petroleum fuel vehicles. A downside to using either hydrogen or natural gas as fuel for a vehicle is the energy that must be expended to compress the gas into a high-pressure tank or cylinder for storage within the vehicle. When the compressed gas is required by the vehicle engine, it is released from the cylinder and must pass through a pressure regulator that expands the gas to almost atmospheric pressure.
The present invention provides a power train for a hybrid electric vehicle. The power train includes a storage cylinder storing a compressed gas, an internal combustion engine, a generator, and a turbine. The turbine is positioned between the storage cylinder and the internal combustion engine and receives the compressed gas from the storage cylinder, reduces the pressure of the compressed gas, and supplies the compressed gas at a reduced pressure to the internal combustion engine. The turbine is also connected to the generator and uses energy extracted from the pressure reduction of the compressed gas to drive the generator. The power train also includes a battery connected to the generator. The battery is charged by at least the generator.
The present invention also provides a method for energy recovery in a hybrid electric vehicle. The method includes passing a compressed gas from a storage tank, through a turbine, to an internal combustion engine, expanding the compressed gas as it passes through the turbine, and recovering energy released from the gas expansion through motion of the turbine. The method also includes converting motion of the turbine to electric energy using a generator connected to the turbine and transferring the electric energy to a battery of the hybrid electric vehicle.
The foregoing and other objects and advantages of the invention will appear from the following detailed description. In the description, reference is made to the accompanying drawings which illustrate a preferred embodiment of the invention.
a and 2b are block diagrams of fuel compression and storage for the power train of
The present invention provides energy recovery solutions for a hybrid electrical vehicle using a compressed, combustible gas, such as hydrogen or natural gas. In such hybrid electrical vehicles, a turbine is positioned between the compressed gas storage cylinder and the internal combustion engine. The turbine reduces the pressure of the compressed gas from its storage pressure to a pressure usable by the internal combustion engine and uses the energy extracted from the pressure reduction to the drive a generator. The additional power generated by the generator can be used to charge a battery powering the vehicle's electric motor. Hybrid vehicles can also include a Stirling engine and second generator positioned to receive and extract energy from the hot exhaust of the internal combustion engine.
The power train 10 of
As described above, the electric motor 12 of the power train 10 drives the final drive 26. The electric motor 12 is connected to and powered by the battery 14, which is further connected to a plug 36 (shown in
A third method for charging the battery 14 is through energy generated by the internal combustion engine 16 (i.e., via the first generator 18). The internal combustion engine 16 operates by combusting a mixture of hydrogen and air, or natural gas and air, and converting the energy released by the combustion to kinetic energy, which is then used to drive the first generator 18 for providing power to the battery 14. The hydrogen or natural gas stored in the fuel storage cylinder 24 must first be conditioned so that it is at an optimal pressure and/or temperature for use by the internal combustion engine 16. For example, compressed hydrogen or compressed natural gas must be stored at very high pressures, but the pressure must be reduced to near atmospheric pressure for use with the internal combustion engine 16. This pressure reduction is conventionally carried out by a pressure regulator. In the present invention, the pressure reduction is carried out by the turbine 20, either alone or in conjunction with a pressure regulator. In another example, liquefied natural gas is stored at very low temperatures and must be heated, or vaporized, for use with the internal combustion engine 16.
A fourth method for charging the battery 14 is through energy generated by the turbine 20 (i.e., via the second generator 22). As described above, the turbine 20 replaces or works in conjunction with a pressure regulator in order to reduce the pressure of the stored compressed gas before it is supplied to the internal combustion engine 16. The energy released by the pressure reduction, which is conventionally expelled as heat, can be recovered by the turbine 20. More specifically, as the compressed gas passes through the turbine 20, expansion (i.e., pressure reduction) of the compressed gas causes rotation of the turbine 20, which then drives the second generator 22 for providing power to the battery 14. As a result, the energy originally input to compress the gas so that it is suitable for storage in the fuel storage cylinder 24 (e.g., through a compressor 38 from a natural gas line 40, as shown in
A fifth method for charging the battery 14 is through energy generated by the Stirling engine 32 (i.e., via the third generator 34). As described above, the internal combustion engine 16 operates by combusting a mixture of fuel and air. For example, using hydrogen as the fuel component, the byproduct of the combusted fuel/air mixture is water. Conventionally, the water, at a substantially high temperature, is merely exhausted by the internal combustion engine 16 into the air outside the vehicle. In the present invention, the hot water exhaust can be used as an external heat source to operate the Stirling engine 32 for additional energy recovery. More specifically, a sealed gas inside the Stirling engine 32 is heated by the hot water exhaust, causing a pressure increase inside the engine and subsequent movement of pistons inside the Stirling engine 32, which then drive the third generator 34 for providing power to the battery 14. The Stirling engine 32 can be heated, and perform as described above, by engine exhaust other than hot water, for example from engines using other fuel sources such as natural gas or conventional petroleum fuels.
The above-described power train 10 and energy recovery methods can be used in any type of hydrogen or natural gas hybrid electric vehicle including, but not limited to, hybrid electric cars, trucks, tractors, buses, trains, boats and/or planes. In addition, a combination of one or more of the components described above with respect to the power train 10 can be used in power generation systems for applications other than vehicles. For example, the energy recovery methods, including using a turbine located upstream from a combustion engine, or combustion chamber, to expand a compressed gas from a fuel source and supply the expanded gas to the combustion chamber, can be used in additional applications. In any such applications, including those which include a single of multiple combustion chambers, the turbine can be located upstream from all combustion chambers (i.e., essentially acting as a pre-combustion turbine). In another example, a boat power train can include solar cells and a hydrogen-fueled internal combustion engine. The solar cells can generate power to operate a compressor for compressing or liquefying hydrogen gas, which can then be stored in a cylinder as fuel for use by the internal combustion engine (and resulting in water being the only byproduct of boat operation). Rather than the energy generated by the solar cells being stored in a battery for use by an electric motor, the generated energy is essentially stored as the compressed or liquefied gas itself, for later use by the internal combustion engine.
While there has been shown and described what are at present considered the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention defined by the appended claims.
