Hybrid drives and fuel vaporizers for UAVs and other mobile environments

Abstract

A hybrid drive having a load shaft, a motor / generator coupled to the load shaft, an internal combustion engine, an electromagnetic clutch disposed between the motor / generator and the internal combustion engine configured to releasably couple the internal combustion engine to the load shaft, and an electrical power supply coupled to the motor / generator and the electromagnetic clutch. In one embodiment, the hybrid drive is configured such that the internal combustion engine both drives the load shaft and causes the motor / generator to charge the electrical power supply.

Description

Technical Field

[0001] (Cross - reference to related applications) This application claims the benefit of U.S. Provisional Application No. 63 / 060,367, filed on August 3, 2020, which is hereby incorporated by reference in its entirety.

[0002] (Technical Field) This application relates to the field of hybrid electromechanical drive trains that are insufficient in providing long - term durability with battery - supplied power and thus must be supplemented with energy obtained from fuel during combustion. Examples of such drive trains include manned or unmanned aerial vehicles, where power - to - weight ratio and specific energy are dominant factors. Further, this application also relates to the field of auxiliary devices for enabling efficient startup and operation of multi - fuel engines.

Background Art

[0003] (Background) Electric motors are becoming increasingly popular as many mobile drives such as unmanned aerial vehicles (UAVs) and electric aircraft. However, large and heavy batteries have limitations in specific energy and specific power. A hybrid drive that combines an electric motor and an internal combustion engine is a potential solution. This specification describes a new hybrid drive configuration that enables high specific power and specific energy, battery recharging during takeoff and landing, remote engine restart, and quiet (electric motor only) operation during cruising.

Summary of the Invention

Means for Solving the Problems

[0004] (Summary of Embodiments) In one embodiment, the present invention provides a hybrid drive. The hybrid drive of this embodiment includes a load shaft, a motor / generator coupled to the load shaft, an internal combustion engine, an electromagnetic clutch positioned between the motor / generator and the internal combustion engine, configured to detachably couple the internal combustion engine to the load shaft, and a power supply coupled to the motor / generator and the electromagnetic clutch.

[0005] The present invention also provides a hybrid drive of another embodiment, which includes a load shaft, a second electric motor coupled to the load shaft, an overrunning one-way clutch coupled to the load shaft, a motor / generator detachably coupled to the load shaft via the overrunning one-way clutch, and an internal combustion engine, wherein the load shaft is coupled to the load shaft and the second electric motor so as to be driven by a source selected from the group consisting of a second electric motor, an internal combustion engine in combination with a motor / generator, and an internal combustion engine in combination with a motor / generator and a second electric motor, and a power source coupled to the second electric motor and the motor / generator.

[0006] In the relevant embodiments, the hybrid drive of these embodiments is configured such that the internal combustion engine both drives the load shaft and charges the motor / generator to a power source. Alternatively, or in addition, the hybrid drive is configured such that the internal combustion engine is started by energy from a power source delivered to the motor / generator. The power source may include an electronically controlled unit configured to switch the operating mode of the motor / generator to an operating mode selected from a group consisting of motor operation, generator operation, and combinations thereof. The hybrid drive may include at least one other electric component, such as an additional electric motor. The power source may be configured to supply power to at least one other electric component.

[0007] In some embodiments, the motor / generator may be configured to start the engine. The motor / generator may be configured to start the engine prior to flight. The motor / generator may be configured to restart the engine during flight.

[0008] In another embodiment, an improved fuel vaporizer is provided of a type coupled for use with an internal combustion engine, comprising a body, fuel and air inlets, an air / fuel outlet, and a heater for vaporizing the fuel, wherein the improvement is characterized in that the air inlet is positioned in the direction of the fuel flow deviation such that it causes the formation of an air vortex that rapidly and thoroughly mixes with the fuel from the fuel inlet. Optionally, the heater is operated by an array selected from a group consisting of electric means, exhaust gas, and combinations thereof. In a related embodiment, a hybrid drive according to any of the embodiments described above is provided, and the internal combustion engine comprises the improved fuel vaporizer of the embodiment described in this paragraph.

[0009] In another embodiment, the present invention provides an aircraft having a hybrid drive according to any one of the embodiments described above, the aircraft further comprising a thruster coupled to a load shaft.

[0010] In another embodiment, the present invention provides a method for achieving a silent mode of operation during the operation of a UAV using a hybrid drive according to any of the embodiments described above. In this embodiment, the method is as follows: When silent operation mode is requested, the internal combustion engine is turned off, and the load shaft is driven only by the motor / generator, When silent operation mode is no longer required, the motor / generator is used to restart the internal combustion engine. Includes.

[0011] In a related similar embodiment utilizing a UAV having a previously described hybrid drive including a second electric motor, the present invention provides a method for achieving a silent operating mode, the method being as follows: When silent operation mode is requested, the internal combustion engine is turned off and the load shaft is driven only by the second motor, When silent operation mode is no longer required, the motor / generator is used to restart the internal combustion engine. Includes.

[0012] In another embodiment, a method is provided for achieving dash speed operation of a UAV using the first hybrid drive embodiment described above, the method comprising driving the load shaft using both a motor / generator and an internal combustion engine.

[0013] In another embodiment, a method is provided for achieving dash speed operation of a UAV using a second hybrid drive embodiment described above, the method comprising driving a load shaft using a combination of a motor / generator, a second electric motor, and an internal combustion engine. [Brief explanation of the drawing]

[0014] The features of the aforementioned embodiments will be more readily understood by referring to the accompanying drawings and the following detailed description.

[0015] [Figure 1] Figure 1 shows a photograph of an engine motor / generator hybrid as seen from the wing of a UAV in flight, according to an embodiment of the present invention.

[0016] [Figure 2] Figure 2 shows a block diagram of a hybrid drive according to an embodiment of the present invention, which utilizes an electromagnetic (EM) clutch to disconnect the motor / generator and load shaft from the engine.

[0017] [Figure 3]Figure 3 shows a block diagram of a hybrid drive in which a mechanical one-way clutch is used to disconnect an engine and a firmly attached first motor / generator from a load shaft and a firmly attached second electric motor, according to an embodiment of the present invention.

[0018] [Figure 4] Figures 4A and 4B show carburetors as described in the prior art (available at https: / / www.researchgate.net / publication / 44094150_Effect_of_initial_and_operating_conditions_on_soot_emissions_from_an_HCCI_engine as of July 31, 2020; see Hosseini, Vahid & Neill, William & Thomson, K. & Chippior, Wallace “Effect of initial and operating conditions on soot emissions from an HCCI engine” Proceedings of the Combustion Institute - Canadian Section Spring Technical Meeting (2009)).

[0019] [Figure 5] Figure 5 shows a fuel processor (fuel vaporizer) with very rapid vaporization characteristics resulting from the deviation-direction delivery of air relative to fuel flow, which brings about the formation of an air-fuel mixture, according to an embodiment of the present invention. Such a fuel processor is very compact and avoids the need for compressed air. The filled arrows indicate fuel, the unfilled solid-line contour arrows indicate air, and the unfilled dashed-line contour arrows indicate the air / fuel mixture.

[0020] [Figure 6]FIG. 6 shows a variant of a fuel processor (fuel vaporizer) in which the heating of the fuel is accomplished by exhaust gas instead of or in addition to electrical resistance heating, according to an embodiment of the present invention. The solid arrows filled with paint indicate fuel, the solid arrows not filled with paint indicate air, and the dashed arrows not filled with paint indicate an air / fuel mixture.

Mode for Carrying Out the Invention

[0021] (Detailed Description of Specific Embodiments) Definitions. As used in this specification and the appended claims, the following terms shall have the indicated meanings unless the context otherwise requires.

[0022] "Electric motor / generator" or "motor / generator" is an electromechanical device that can operate as an electric motor (i.e., drive a shaft) when powered by a power supply source and can operate as an electric generator when powered by an engine (the generated power can be used to recharge the power supply source).

[0023] "Power supply source" means a rechargeable power source capable of receiving, storing, and discharging electrical energy, such as a battery, a supercapacitor, or other device.

[0024] "UAV" means an unmanned aerial vehicle.

[0025] "VTOL" means vertical takeoff and landing.

[0026] "Dash speed" means a speed that is usually not economical and cannot be maintained during normal operation but is required for mission requirements, such as performing high-speed cruising.

[0027] "Set" includes at least one member.

[0028] Battery-powered electric motors are becoming increasingly popular due to their small size, durability, and quiet operation. Unfortunately, battery capacity is often insufficient, and using larger batteries is not feasible as it would reduce the system's specific energy. Figure 1 shows a hybrid drive used to fly a UAV. The hybrid drive in Figure 1, including the engine and motor / generator, is enhanced by a fuel vaporizer according to an embodiment of the present invention. Such a drive not only increases the system's durability but also allows the motor / generator to be used as a generator to charge the battery, which is depleted during takeoff, as well as to start the engine before flight and / or restart the engine during flight. Such a configuration is particularly effective for vehicles operating using VTOL (Vertical Take-Off and Landing).

[0029] The block diagram of the hybrid drive in Figure 1 is shown in Figure 2. During takeoff or when a high load is required on the load shaft (e.g., high-speed dash), power to the load shaft is generated by the engine and motor / generator energized by the power source. When the clutch is engaged, the engine is coupled to the motor / generator and maximum power is provided to drive the load shaft. Maximum power can only be provided for a relatively short period of time and depends on the capacity of the power source. For fixed-wing aircraft under typical cruising conditions, only about 20-30% of the maximum power is required, and the motor / generator may be switched to operate as a generator to recharge the depleted power source. Switching between motor operation and generator operation (and vice versa) is controlled by an electronic control unit (ECU) which is part of the power source. When the motor / generator is in generator mode, it is driven by the engine to generate power to recharge the power source. During flight, there may be a need for "silent" operation. During such a silent operation mode, the engine is stopped, the clutch is disengaged from the motor / generator, flight continues, and the motor / generator operates as a motor, fully powered by the power source. After the silent operation mode is complete, the engine may be restarted, often using the motor / generator, at high altitudes and very low temperatures. The solid line shows power consumption from the power source by the motor / generator and EM clutch. The dashed line shows power generation by the motor / generator. In some embodiments, the thruster may be coupled to the load shaft.

[0030] To improve the power-to-weight ratio of the drivetrain, an alternative hybrid drive embodiment of the present invention, shown in Figure 3, may be used. Compared to the configuration shown in Figure 2, the electromagnetic clutch (typically bulky, heavy, and power-intensive to operate) is replaced by a combination of a second electric motor and an overrunning one-way clutch. Solid lines indicate power consumption from the motor / generator and / or motor power source, and dashed lines indicate power generation by the motor / generator. Here, the engine shaft is rigidly coupled to the motor / generator, and the engine shaft is coupled to the load shaft via an overrunning one-way clutch. The load shaft is rigidly coupled to a second electric motor (referred to as the “motor” in Figure 3). Depending on the power requirements of the load shaft during takeoff, cruising, or landing, power to the load shaft may be delivered in one of three ways detailed below.

[0031] In the first embodiment, power to the load shaft may also be delivered by the engine, along with the motor / generator and a second electric motor, which enables the generation of the full power required for takeoff and / or dash speed operation. Takeoff may be horizontal or vertical.

[0032] In the second embodiment, power to the load shaft may be delivered by the engine along with the motor / generator, i.e., without the second electric motor (the windings of the second electric motor are not activated).

[0033] In a third embodiment, power to the load shaft may be supplied solely by a second electric motor. Here, the engine is stopped, and the motor / generator windings are deactivated. Supplying power to the load shaft in this manner may be useful when a quiet operating mode of the vehicle is required.

[0034] In various embodiments, including but not limited to the first and second embodiments detailed above, the system may deliver power to a power source by putting a motor / generator into generator mode, thereby recharging the power source. When in generator mode, the motor / generator is driven by an engine to generate power to recharge the power source. The operation of the motor / generator may be switched from motor operation to generator operation (or vice versa) by an ECU which is part of the power source. The power source may be used to deliver power to other electric components, such as additional electric motors that may be required to meet the needs of VTOL operation or payload.

[0035] In various embodiments, the hybrid drivetrains disclosed herein may be used not only in aircraft vehicles but also in terrain vehicles and boats. In some embodiments, the thrusters may be coupled to the load shaft.

[0036] In various embodiments, including but not limited to the first, second, and third embodiments detailed above, a motor / generator coupled to a power source is configured to start the engine in preparation for flight (prior to flight) and / or restart the engine during flight.

[0037] To enable the internal combustion engine to start or restart when it is at a low temperature (e.g., below 0°C), the engine may be equipped with a fuel treatment device that converts liquid fuel to gaseous fuel, according to embodiments of the present invention, particularly for drive systems operating with heavy fuel in spark ignition mode.

[0038] For example, to enable multi-fuel capability, the engine may, when liquid fuel is used, be supplied with an air / fuel mixture obtained by evaporating the fuel in a fuel treatment device, such as a fuel vaporizer. Exemplary fuel vaporizer configurations are shown in Figures 5 and 6. The fuel vaporizer can improve engine starting performance using spark ignition (SI) operating with heavy fuels such as kerosene, Jet A, JP8, or diesel fuel. Heavy fuels generally do not vaporize in engines at low temperatures (e.g., below 0°C) at the low compression ratios of a typical SI engine. Because heavy fuel remains in liquid form and the permissible air-fuel mixture ratio is not available at the spark plug / ignition source, high compression ratios are not possible in SI configurations once the engine starts, due to detonation and knocking (although 0°C is provided as a reference temperature indicating a “cold” engine, the actual temperature at which an SI-based engine is considered “cold” and constitutes a candidate for the use of a fuel vaporizer depends on a wide range of factors including, but not limited to, engine size, engine thermal mass, ambient temperature, and engine geometry, RPM, and compression ratio). The use of controlled rapid fuel evaporation in combination with airflow improves the quality of the air / fuel mixture at the spark plug, enabling faster starting, more reliable starting, and lower emissions in cold conditions. Furthermore, vaporizers can be used not only during engine starting but throughout the entire time the engine is running.

[0039] In conventional carburetors, such as those shown in Figures 4A and 4B, the engine requires several minutes, not seconds, to start, which is an unacceptable duration for many applications. In some embodiments of the present invention, fuel carburetors operating on a 12V / 24V DC power supply have been tested and shown to start an engine (26cc / chamber spark-ignition jet fuel LPI engine, chilled at -25°C for 24 hours) within seconds.

[0040] Referring to Figures 5A and 5B, in an embodiment of the present invention, fuel (indicated by a filled arrow) is supplied from a metering device (not shown) into the fuel inlet 502 of the fuel vaporizer and heated in the annular section between the heating element and the casing by a suitable heat source such as a glow plug (506 in Figures 5A and 5B) or an electric helix (606 in Figure 6) until vaporized. An air inlet 510 supplies fresh air (indicated by an unfilled, solid-line outlined arrow) in a direction deviating from the direction of fuel flow to create an air vortex. Such a configuration achieves rapid vaporization of the fuel and excellent air / fuel vapor mixing as the vortex carries the fuel through the air / vaporized fuel outlet 508 into the engine's working chamber. Furthermore, we have determined that the suction generated by the engine's rotor or piston is sufficient to produce sufficient evaporation of the fuel and mixing of air with the fuel only when the vortex is formed downstream of the fuel inlet, thus eliminating the need to pressurize the air. Airflow is generated, partially or entirely, by the induction of air into the engine's working chamber. The fuel vaporizers described herein may complement conventional fuel systems and may be used to assist in cold starting of the engine. In some embodiments, the fuel vaporizer may operate only during a period before, during, or after engine starting. In some embodiments, an electronic control system may switch the fuel source from the fuel vaporizer to the main fuel system when the engine is fully started and running. A set of thermocouples or other temperature sensing devices located on or inside the evaporator body 504 are used for feedback to the controller. A valve may optionally be provided at the fuel inlet, and another valve may optionally be provided at the air inlet. In other embodiments, the fuel vaporizer may be used as the sole source of the fuel / air mixture to the engine, rather than as an intermittent source.

[0041] Heating of the fuel vaporizer can be achieved by various methods. In some embodiments, the glow plug shown in Figure 5 may be replaced with a heater wire installed inside a spirally wound heat conductor 504 that is in contact with the fuel. Heating may also be achieved electrically, similar to the glow plug configuration shown in Figure 5. In other embodiments, electric heating may be supplemented by flowing hot exhaust gas through the fuel vaporizer to reduce electrical energy consumption. In some embodiments, starting of the fuel vaporizer may be achieved by electrical means. In some embodiments, for example, heating of the fuel vaporizer may be achieved entirely by using exhaust gas when the temperature of the exhaust gas is sufficient to evaporate the fuel.

[0042] In some embodiments, the tubes in the fuel vaporizer that come into contact with the fuel may be coated with a catalytic material to reduce the energy requirements of the vaporizer.

[0043] Figure 6 shows an alternative embodiment of the fuel vaporizer. The fuel entering the fuel inlet 602 (indicated by the filled arrow) fills a portion of the thermal insulator 604, leaving space for the fuel to evaporate and optionally mix with fresh air entering from the air inlet 610 (indicated by the unfilled, solid-line outlined arrow) prior to exiting from the air / fuel outlet 608. In some embodiments, it is desirable not only to evaporate the fuel but also to superheat it, in which case the fuel may be injected into the engine at a higher pressure. In some embodiments, a fuel vaporizer heating element, such as a spiral heating element 606, is electrically heated. Other embodiments use exhaust gas to heat the fuel (e.g., through heating the entire fuel vaporizer, or using an additional heating pipe configured to circulate exhaust gas through it, or a combination thereof). Care must be taken to monitor the temperature of the heating element 606 and / or the air / fuel mixture to prevent the vaporized fuel from coking in the fuel vaporizer and to prevent the air / fuel mixture formed in the vaporizer from spontaneously igniting. In some embodiments, fuel vaporizers that do not require pressurized air may be used with, for example, spark ignition engines, reaction-controlled compression ignition engines, and homogeneous charge compression ignition engines. In some embodiments, fresh air may be pressurized above the pressure in the engine's operating chamber so that the fuel vaporizer can be used with compression ignition (CI) engines.

[0044] The combination of fuel vaporizer embodiments disclosed above may be used within a single device to achieve fuel vaporization and mixing.

[0045] The embodiments of the present invention described above are intended to be illustrative only, and numerous variations and modifications will be apparent to those skilled in the art. All such variations and modifications are intended to fall within the scope of the present invention as defined in the accompanying claims.

Claims

1. A hybrid drive, A load shaft; a motor / generator coupled to the load shaft; an internal combustion engine; an electromagnetic clutch configured to releasably couple the internal combustion engine to the load shaft, the electromagnetic clutch being disposed between the motor / generator and the internal combustion engine; a power supply coupled to the motor / generator and the electromagnetic clutch; a fuel carburetor coupled to the internal combustion engine, the fuel carburetor configured to provide a combustible air-fuel mixture to the internal combustion engine, the fuel carburetor including a body, a fuel inlet, an air inlet, an outlet for the air-fuel mixture, and a heater for rapidly vaporizing the fuel, the air inlet being disposed downstream of the fuel inlet at a location where the fuel is vaporized by the heater, and air flowing from the air inlet in a tangential direction to the flow of the vaporized fuel to cause the formation of an air vortex that mixes with the vaporized fuel from the fuel inlet, thereby forming the combustible air-fuel mixture; A hybrid drive equipped with

2. The hybrid drive of claim 1 , wherein the internal combustion engine is configured to both drive the load shaft and cause the motor / generator to charge the power supply.

3. The hybrid drive of claim 1 , wherein the internal combustion engine is configured to be started by energy from the power source delivered to the motor / generator.

4. A fuel carburetor of a type adapted for use with an internal combustion engine, the fuel carburetor comprising: a body, a fuel inlet, an air inlet, an outlet for an air-fuel mixture, and a heater for vaporizing the fuel, the air inlet being positioned downstream of the fuel inlet at a location where the fuel is rapidly vaporized by the heater, and air flowing from the air inlet in a tangential direction to the flow of the vaporized fuel so as to cause the formation of an air vortex that mixes with the vaporized fuel from the fuel inlet, thereby forming a mixture of air and fuel.

5. 5. The fuel vaporizer of claim 4, wherein the heater is powered by electrical means and / or exhaust gases.

6. 10. The hybrid drive of claim 1, wherein the heater is operated by electrical means and / or exhaust gases.

7. The aircraft having a hybrid drive according to claim 1 , further comprising a thruster coupled to the load shaft.

8. 10. The hybrid drive of claim 1, wherein the power supply includes an electronic control unit configured to switch an operating mode of the motor / generator to an operating mode selected from the group consisting of motor operation, generator operation, and combinations thereof.

9. The hybrid drive of claim 1 , 2, 3, 6, and 8, wherein the hybrid drive includes at least one other electrically powered component.

10. The hybrid drive of claim 9 , wherein the power supply is configured to deliver power to the at least one other electrically powered component.

11. The hybrid drive of claim 9 , wherein the at least one other electrically powered component is an additional electric motor.

12. 12. The hybrid drive of claim 1, wherein the motor / generator is configured to start the engine.

13. 13. The hybrid drive of claim 1, wherein the motor / generator is configured to start the engine prior to flight.

14. 14. The hybrid drive of claim 1, wherein the motor / generator is configured to restart the engine in flight.

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