Patent Description:
Aircraft engines vary in efficiency and function over a plurality of parameters, such as thrust requirements, air temperature, air speed, altitude, and the like. Aircraft require the most thrust at take-off, wherein the demand for engine power is the heaviest. However, during the remainder of the mission, the aircraft engines often do not require as much thrust as during take-off. The size and weight of the engines allows them to produce the power needed for take-off, however after take-off the engines are in effect over-sized for the relatively low power required to produce thrust for cruising in level flight.

The conventional techniques have been considered satisfactory for their intended purpose. However, there is an ever present need for improved aircraft engines. This disclosure provides a solution for this need.

<CIT> discloses a hybrid power system for piston engine aircrafts.

<CIT> discloses an unmanned aircraft and operation method for the same.

<CIT> discloses a hybrid contingency power drive system.

<CIT> discloses a helicopter hybrid engine system.

<CIT> discloses a supply of air to an air-conditioning circuit of an aircraft cabin.

<CIT> discloses a hybrid engine installation and a method of controlling such an engine installation.

<CIT> discloses a hybrid electric vehicle and method of controlling driving the same.

<CIT> discloses a hybrid drive for a power-driven aircraft.

<CIT> discloses flow multiplier systems for aircraft.

A hybrid propulsion system including a heat engine configured to drive a heat engine shaft is provided as claimed in claim <NUM>.

So that those skilled in the art to which the subject disclosure appertains will readily understand how to make and use the devices and methods of the subject disclosure without undue experimentation, a preferred embodiment, as well as examples not presently being claimed, will be described in detail herein below with reference to certain figures, wherein:.

Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, a partial view of an exemplary hybrid propulsion system not according to the presently claimed invention, but useful for understanding aspects thereof, is shown in <FIG> and is designated generally by reference character <NUM>. Other hybrid propulsion systems, are provided in <FIG>, as will be described. The systems and methods described herein can be used to provide hybrid propulsion, e.g., for improving fuel efficiency in aircraft.

The hybrid propulsion system <NUM> includes a heat engine (or motor) <NUM> configured to drive a heat engine shaft <NUM>. An electric motor <NUM> is configured to drive an electric motor shaft <NUM>. A transmission system <NUM> includes at least one gearbox. The transmission system <NUM> is configured to receive rotational input power from each of the heat engine shaft <NUM> and the motor shaft <NUM> and to convert the rotation input power to output power, as indicated by the circular arrow in <FIG>.

The at least one gearbox includes a combining gearbox <NUM> connecting to the heat engine shaft <NUM> and to the motor shaft <NUM> to combine rotational input power from the heat engine <NUM> and electric motor <NUM> for providing rotational output power to an output shaft <NUM>, which can drive a reduction gearbox <NUM> for turning an aircraft propeller, fan, or any other suitable type of air mover for example. A turbine gearbox <NUM> is included, which is connected between the heat engine shaft <NUM> and a shaft <NUM> for driving a turbine <NUM> and a compressor <NUM> to drive the turbine <NUM> and compressor <NUM> at a different rotational speed from the heat engine <NUM>. For example, through the turbine gearbox <NUM>, the heat engine <NUM> can run at <NUM> revolutions per minute (RPM), the heat engines exhaust can be recovered by the turbine <NUM> to drive the compressor <NUM> at <NUM>,<NUM> RPM. The turbine gearbox <NUM> can be a two speed transmission or constant velocity transmission (CVT) which can eliminate the need for a variable inlet guide vane (VIGV) controlling the compressor <NUM>. It is also contemplated that the turbine <NUM> and compressor <NUM> can separately connect to the turbine gear box <NUM>, e.g., using a concentric shaft for the compressor such as the shaft <NUM> shown in <FIG>, so that the turbine <NUM> and compressor <NUM> can rotate at different rotational speeds. These types of turbine gearbox can apply to each of the turbine gearboxes described below, even if not specifically repeated.

Those skilled in the art will readily appreciate that while described herein in the context of driving the turbine <NUM> and compressor <NUM>, that the turbine <NUM> can actually add power to the shaft <NUM> and therefore cooperates with the heat engine <NUM> to drive the combining gearbox <NUM>, however, in configurations herein where the turbine <NUM> and compressor <NUM> spin at a common speed the compressor <NUM> and turbine <NUM> are collectively referred to herein as driven.

The compressor <NUM> compresses air and supplies the compressed air to the heat engine <NUM> through the air line <NUM>, which includes heat exchanger <NUM> for cooling the compressed air. After combustion in the heat engine <NUM>, the combustion products are supplied through a combustion products line <NUM> to the turbine <NUM>, which extracts power from the compressed combustion products before exhausting them. The configurations shown in <FIG> also include similar air lines <NUM>, heat exchangers <NUM>, and combustion products lines <NUM>, and the details for such are not repeated below for each Figure. Also, unless specified otherwise, the configurations in each of <FIG> include an output shaft <NUM> connecting between a combining gearbox (e.g. combining gearbox <NUM>) and reduction gearbox <NUM>, the details of which will not be repeated below for each Figure. The electric motor <NUM> can be powered to boost horse power, e.g., for take-off, in parallel with the heat motor <NUM>, and can be powered down, e.g., for cruising in level flight, where only the heat motor <NUM> is needed for power. It is also contemplated that the electric motor <NUM> can be used as a generator to recharge the battery, e.g. source <NUM> of <FIG>, when power is available from the heat engine <NUM> or form wind milling the propeller to drive the reduction gear box <NUM>. The compressor <NUM> and turbine <NUM> improve the thermal efficiency of the heat engine <NUM>. Similar benefits are derived with the configurations described below with respect to <FIG>. The dashed line in <FIG> schematically indicates that the turbine <NUM> can optionally be moved to connect directly to the combining gearbox <NUM>, much as described below with respect to <FIG>, which switch in turbine position can also be applied to other arrangements described below wherein the compressor and turbine are shown and described as being on a common shaft.

With reference now to <FIG>, a system <NUM> not according to the presently claimed invention, but useful for understanding aspects thereof, includes a combining gearbox <NUM> connecting to the heat engine shaft <NUM>, the motor shaft <NUM>, and a shaft <NUM> for driving the turbine <NUM> and compressor <NUM>. The combining gearbox <NUM> combines rotational input power from the heat engine (or motor) <NUM> and electric motor <NUM> for providing rotational output power to an output shaft <NUM> and to drive the turbine <NUM> and compressor <NUM>. While connected on a common shaft <NUM>, the turbine <NUM> and compressor <NUM> can be connected on opposite sides of the combining gearbox <NUM> as shown in <FIG>. It is also contemplated that the turbine <NUM> and compressor <NUM> can both be connected on one side of the combining gearbox <NUM>, as shown in <FIG> not according to the presently claimed invention, but in an example useful for understanding aspects thereof.

The portion of the combining gearbox <NUM> that drives the shaft <NUM> can be a two speed transmission or constant velocity transmission (CVT) which can eliminate the need for a variable inlet guide vane (VIGV) controlling the compressor <NUM>. This applies to arrangements described below wherein the turbine and compressor connect directly to a combined gearbox, even if not specifically repeated.

With reference now to <FIG>, a system <NUM> not according to the presently claimed invention, but useful for understanding aspects thereof, is shown wherein the heat engine shaft <NUM> and the electric motor shaft <NUM> are connected for common rotation. A reduction gearbox <NUM>, e.g. for ultimately outputting power to a propeller, is connected to a common output shaft <NUM> of the electric motor <NUM> and the heat engine <NUM>. A turbine gearbox <NUM> is connected between the heat engine shaft <NUM> and a shaft <NUM> for rotation of the turbine <NUM> and compressor <NUM> at a different rotational speed from the heat engine <NUM> and electric motor <NUM>. The broken line in <FIG> indicates that the position of the heat engine <NUM> and electric motor <NUM> can be reversed on the common shaft <NUM>. If there is a requirement to guarantee power from one of the heat engine <NUM> or electric motor <NUM> in the event of stoppage of the other, each of the heat engine <NUM> and electric motor can be connected to the reduction gearbox <NUM> through a concentric shaft, e.g. as indicated by the broken lines between the electric motor <NUM> and the reduction gear box <NUM>. The same applies to other configurations herein where the heat engine and electric motor are shown and described as having a common output shaft.

With reference now to <FIG>, in the system <NUM> not according to the presently claimed invention, but useful for understanding aspects thereof, the heat engine shaft <NUM> and electric motor shaft <NUM> are concentric with a shaft <NUM> for rotation of the turbine <NUM> and compressor <NUM>. The heat engine shaft <NUM> and electric motor shaft <NUM> can be a common shaft <NUM> as shown in <FIG>, or can themselves be concentric with one another as indicated by the broken lines in <FIG>. A reduction gearbox <NUM> is connected to each of the heat engine shaft <NUM> and the electric motor shaft <NUM>, e.g., for driving a propeller with rotational input from the heat engine <NUM> and electric motor <NUM>. The reduction gearbox <NUM> connects to a shaft <NUM> for rotation of the turbine <NUM> and compressor <NUM>.

With reference now to <FIG>, a system <NUM> not according to the presently claimed invention, but useful for understanding aspects thereof, has a heat engine shaft <NUM> and the electric motor shaft <NUM> connected for common rotation. A combining gearbox <NUM> connects to the common output shaft <NUM> of the electric motor <NUM> and the heat engine <NUM> and a shaft <NUM> for driving a turbine <NUM> and compressor <NUM>, to combine rotational input power from the heat engine <NUM> and electric motor <NUM> for providing rotational output power to an output shaft <NUM> and to drive the turbine <NUM> and compressor <NUM>. The turbine <NUM> and compressor <NUM> are connected on opposite sides of the combining gearbox <NUM>. As shown in the example of <FIG> not according to the presently claimed invention, but useful for understanding aspects thereof, it is also contemplated that the turbine <NUM> and compressor <NUM> can both be on one side of the combining gearbox <NUM>. The broken lines in <FIG> schematically indicate that the positions of the heat motor <NUM> and electric motor <NUM> can be switched.

Referring now to <FIG>, a system <NUM> not according to the presently claimed invention, but useful for understanding aspects thereof, includes a combining gearbox <NUM> connecting to the heat engine shaft <NUM> and to the electric motor shaft <NUM> to combine rotational input power from the heat engine <NUM> and electric motor <NUM> for providing rotational output power to an output shaft <NUM>. A turbine driver motor/generator <NUM> is connected to a shaft <NUM> for driving a turbine <NUM> and a compressor <NUM> to drive the turbine <NUM> and compressor <NUM> at a different rotational speed ratio from the heat engine <NUM> and electric motor <NUM>. The compressor <NUM> can therefore be a variable speed compressor. An electrical system <NUM> includes a storage <NUM>, e.g., a battery, battery bank, capacitor, capacitor bank, super capacitor or super capacitor bank, flywheel or flywheel bank, or the like, is connected to a first inverter/rectifier component <NUM> for supplying power from the storage <NUM> to drive the electric motor <NUM> or in an energy recovery mode, to store into the storage <NUM> energy generated by driving the electric motor <NUM> in a generator mode. The electrical system <NUM> includes a second invert/rectifier component <NUM> for supplying power to drive the turbine driver motor <NUM>, or to recover energy into the storage <NUM> from the turbine drive motor <NUM> if run in a generator mode. The broken line in <FIG> schematically indicates that the position of the motor <NUM> and compressor can be switched on the shaft <NUM>. <FIG>, <FIG>, <FIG>, and <FIG> each show similar electrical systems <NUM> and the description thereof is not repeated below.

With reference now to <FIG>, a system <NUM> not according to the presently claimed invention, but useful for understanding aspects thereof, has the heat engine shaft <NUM> and the electric motor shaft <NUM> are connected for common rotation. A reduction gearbox <NUM> connected to a common output shaft <NUM> of the electric motor <NUM> and the heat engine <NUM>. A turbine driver motor <NUM> is connected to a shaft <NUM> for driving a turbine <NUM> and a compressor <NUM> at a different rotational speed from the heat engine <NUM> and electric motor <NUM>. The broken arrows in <FIG> schematically indicate that the position of the heat engine <NUM> and the electric motor <NUM> can be switched on the common shaft <NUM>, and that the positions of the motor <NUM> and compressor <NUM> can be switched on the shaft <NUM>.

Referring now to <FIG>, in the system <NUM> not according to the presently claimed invention, but useful for understanding aspects thereof, the heat engine shaft <NUM> and the electric motor shaft <NUM> are connected for common rotation. A reduction gearbox <NUM> is connected to a common output shaft <NUM> of the electric motor <NUM> and the heat engine <NUM>. A turbine gearbox <NUM> is connected through a clutch <NUM> between the heat engine shaft <NUM> and a shaft <NUM> for driving a turbine <NUM> and a compressor <NUM> at a different rotational speed ratio from the heat engine <NUM> and electric motor <NUM> when the clutch <NUM> is engaged. The shaft <NUM> for driving the turbine <NUM> and compressor <NUM> is connected to a turbine driver motor <NUM> to drive the turbine <NUM> and compressor <NUM> independently from the heat engine <NUM> and electric motor <NUM> when the clutch <NUM> is disengaged. The broken lines in <FIG> schematically indicate that the positions of the clutch <NUM> and the turbine gearbox <NUM> can be switched. The clutch <NUM> can prevent electrical losses at steady state because the clutch engages when system <NUM> steady state operation, e.g., cruising in level flight, so the shaft <NUM> is connected to the heat engine <NUM> to avoid electrical conversion losses. In transients, the clutch <NUM> can open or disconnect to allow the motor <NUM> to drive the shaft <NUM> at a different speed ratio from the heat engine <NUM> as described above.

With respect to <FIG>, a system <NUM> not according to the presently claimed invention, but useful for understanding aspects thereof, includes a heat engine shaft <NUM> and electric motor shaft <NUM> that are concentric with the shaft <NUM> for rotation of the turbine <NUM> and compressor <NUM> similar to the arrangement in <FIG>. A reduction gearbox <NUM> is connected to each of the heat engine shaft <NUM> and the electric motor shaft <NUM>, e.g., as a common shaft <NUM> or concentric with one another as described above with respect to <FIG>. A clutch <NUM> in the shaft <NUM> connects between the heat engine <NUM> and a turbine driver motor <NUM> for rotating the turbine <NUM> and compressor <NUM> with the reduction gear box <NUM> when the clutch <NUM> is engaged, and to drive the turbine <NUM> and compressor <NUM> independently from the heat engine <NUM> and electric motor <NUM> when the clutch <NUM> is disengaged.

With reference now to <FIG>, a system <NUM> not according to the presently claimed invention, but useful for understanding aspects thereof, includes a heat engine shaft <NUM> and electric motor shaft <NUM> are connected for common rotation. A reduction gearbox <NUM> is connected to a common output shaft <NUM> of the electric motor <NUM> and the heat engine <NUM>. The upper broken lines in <FIG> schematically indicate that the positions of the heat engine <NUM> and the motor <NUM> can be switched on the shaft <NUM>. A clutch <NUM> connects between the reduction gearbox <NUM> and a turbine driver motor <NUM> connected to a shaft <NUM> for driving a turbine <NUM> and a compressor <NUM> with rotational power from the heat engine <NUM> and electric motor <NUM> (through the reduction gearbox <NUM>) when the clutch <NUM> is engaged, and to drive the turbine <NUM> and compressor <NUM> independently from the heat engine <NUM> and electric motor <NUM> when the clutch <NUM> is disengaged. The lower broken line in <FIG> schematically indicates that the positions of the motor <NUM> and the compressor <NUM> can be switched on the shaft <NUM>.

Referring now to <FIG>, a system <NUM> is shown wherein the heat engine shaft <NUM> and the electric motor shaft <NUM> are connected for common rotation. A combining gearbox <NUM> connects to a common output shaft <NUM> of the electric motor <NUM> and the heat engine <NUM>, and to a shaft of a turbine <NUM> to combine rotational input power from the heat engine <NUM>, electric motor <NUM>, and turbine <NUM> for providing rotational output power to an output shaft <NUM>. A reduction gearbox <NUM> is connected to the output shaft <NUM>, wherein a compressor <NUM> is connected to be driven on the output shaft <NUM>. An electrical system <NUM> includes a storage <NUM> connected through an inverter/rectifier component <NUM> to supply power to the motor <NUM>, or to recover power from the motor <NUM> in a generator mode to store in the storage <NUM>. The other arrangements described above that do not specifically show an electrical system can include a system similar to electrical system <NUM>, and <FIG> includes a similar system <NUM> even though the details are not repeated. In examples not presently being claimed, the compressor <NUM> can also be connected to the reduction gearbox <NUM> on its own shaft concentric with the shaft <NUM>, much as described below with respect to <FIG>. The broken lines in <FIG> indicate that optionally the turbine <NUM> can be mechanically decoupled from the CGB to drive a generator <NUM>, which can be connected through an inverter/rectifier component <NUM> to charge the storage <NUM>, which can similarly be applied to other arrangements disclosed herein with the turbine decoupled from the compressor. As indicated by broken lines in <FIG>, in examples not presently being claimed, the compressor and a gear box <NUM> can be connected to the heat engine <NUM> in lieu of connecting the compressor <NUM> on the output shaft <NUM>.

With reference now to <FIG>, a system <NUM> not according to the presently claimed invention, but useful for understanding aspects thereof, is shown wherein the heat engine shaft <NUM> and the electric motor shaft <NUM> are connected for common rotation. A reduction gearbox <NUM> connected to a common output shaft <NUM> of the electric motor <NUM> and the heat engine <NUM>. A turbine gearbox <NUM> is connected between the heat engine shaft <NUM> and a shaft <NUM> of a turbine <NUM> so the turbine can rotate at a different rotational speed from the heat engine <NUM> and electric motor <NUM>. A compressor <NUM> is connected to the reduction gearbox <NUM> through a compressor shaft <NUM> concentric with the common output shaft <NUM> so the compressor can be driven at a different speed from the common output shaft <NUM>.

Referring now to <FIG>, a system <NUM> not according to the presently claimed invention, but useful for understanding aspects thereof, includes a heat engine shaft <NUM> and the electric motor shaft <NUM> that are connected for common rotation. A super position gearbox <NUM> connects to a common output shaft <NUM> of the electric motor <NUM> and the heat engine <NUM>, and to a shaft <NUM> for driving a turbine <NUM> and compressor <NUM> to combine rotational input power from the heat engine <NUM> and electric motor <NUM> for providing rotational output power to an output shaft <NUM> and to drive the turbine <NUM> and compressor <NUM>. The super position gearbox <NUM> is configured so the speed ratio between the common output shaft <NUM> and the shaft <NUM> for driving the turbine <NUM> and compressor <NUM> can vary, e.g., to adjust the speed of the compressor <NUM> for altitude or for ground idle.

The turbine <NUM> can optionally be decoupled from the compressor <NUM> to drive a generator as described above with reference to <FIG>. Similarly, the arrangement in <FIG> can be modified so the turbine <NUM> is decoupled from the compressor <NUM> to drive a generator. The heat engine, e.g., heat engine <NUM> in <FIG>, can be split and connected on opposite sides of the respective gear box, e.g., the combined gearbox <NUM> in <FIG>, as indicated in <FIG> with the broken line box <NUM>. This split can be applied to other arrangements above besides the one in <FIG>. Disconnect clutches or mechanism, e.g., clutch <NUM> in <FIG>, can be included, e.g., in each of the shafts <NUM> and <NUM> as indicated in <FIG> by the broken lines crossing the shafts <NUM> and <NUM>, for disconnecting the heat engine <NUM> or electric motor <NUM> as needed. Even if modules are represented schematically herein vertically on top of each other, those skilled in the art having the benefit of this discourse will readily appreciate that they can be located side by side, one above the other or in any geometrical arrangement and in any order in physical implementations. Similarly, those skilled in the art having had the benefit of this disclosure will readily appreciate that modules represented on one side (right or left) of the respective gearbox herein can also potentially be installed on the other side or even trapped between a respecting reduction gearbox and combining gear box. Module disclosed herein can be installed directly on the respective combining gear box or reduction gear box with a proper speed ratio. Although modules are represented herein with an axial orientation, those skilled in the art having the benefit of this disclosure will readily appreciate that the use of bevel gears (or other mechanical or electrical devices) allows the installation of modules in any suitable orientation. Those skilled in the art having the benefit of this disclosure will readily appreciate that accessories not explicitly represented herein can be included and can potentially be connected mechanically to any module or driven electrically similar to the modules and components disclosed herein. Those skilled in the art having had the benefit of this disclosure will readily appreciate that combining gearboxes and reduction gearboxes disclosed above can be combined into a single respective gearbox. Finally, those skilled in the art having had the benefit of this disclosure considering the number of parts, will readily appreciate that each architecture disclosed herein can be recombined with other architectures disclosed herein to results in dozens of additional configurations, several examples of which are described above, and all of which are within the scope of this disclosure insofar as they fall within the scope defined by the appended claim.

Claim 1:
A hybrid propulsion system (<NUM>) comprising:
a heat engine (<NUM>) configured to drive a heat engine shaft (<NUM>) thereof;
an electric motor (<NUM>) configured to drive an electric motor shaft (<NUM>) thereof;
a turbine (<NUM>) having a shaft;
a compressor (<NUM>); and
a transmission system including at least one gearbox, wherein the transmission system is configured to receive rotational input power from each of the heat engine shaft (<NUM>) and the electric motor shaft (<NUM>) and to convert the rotation input power to output power;
and wherein:
the heat engine shaft (<NUM>) and the electric motor shaft (<NUM>) are connected for common rotation; and
the at least one gearbox includes:
a combining gearbox (<NUM>) connecting to a common output shaft (<NUM>) of the electric motor (<NUM>) and the heat engine (<NUM>), and to the shaft of the turbine (<NUM>), for providing rotational output power to an output shaft (<NUM>) of the combining gearbox (<NUM>);
characterised in that the combining gearbox (<NUM>) is configured to combine rotational input power from the heat engine (<NUM>), electric motor (<NUM>), and turbine (<NUM>); and
in that the at least one gearbox further includes a reduction gearbox (<NUM>) connected to the output shaft (<NUM>), wherein the compressor (<NUM>) is connected to be driven on the output shaft (<NUM>).