Patent Description:
Engines, such as internal combustion engines, commonly employ turbochargers. Turbochargers compress air prior to admission to the engine for combustion, generally using residual energy recovered from the exhaust gases issued by the engine during operation. Such turbocharges allow an engine to generate greater output power for a given engine size than otherwise possible, typically with greater efficiency than a non-turbocharged and otherwise equivalent engine.

In some engines the residual energy recovered from the exhaust gases issuing from the engine can exceed the input energy necessary to compress the air for the engine combustion process. To more fully utilize this energy and further improve engine efficiency, compounding can be employed. Compounding is technique of augmenting engine efficiency by returning energy recovered from the engine exhaust that is otherwise unused by a turbocharger, generally through gearing coupling the turbocharger to the engine, when energy in the exhaust stream exceeds that necessary to drive the turbocharger.

Such systems and methods have generally been suitable for their intended purpose. However, there remains a need for improved compounding drives, compounded internal combustion engines and aircraft with compounded internal combustion engines, and methods of compounding output of internal combustion engines. <CIT> relates to a turbo compound engine.

A compounding drive according to claim <NUM> is provided.

An engine arrangement according to claim <NUM> is also provided.

A method of compounding an engine according to claim <NUM> is further provided. The method includes, at a compounding drive as described above, unidirectionally communicating mechanical rotation between the input member and the output member.

Technical effects of the present disclosure include turbo-compounded engines having limited parasitic drag in operating states when the turbo-compressor is not being fed sufficient exhaust to apply power to the engine. In certain embodiments turbo-compressors include an uncoupler module, preventing back-driving of the turbo-compressor to limit (or prevent entirely) damage associated with the limited hydraulic flow that can be present in some operating regimes. In accordance with certain embodiments the uncoupler module can include an overrunning clutch, simplifying the arrangement of the turbo-compressor to provide unidirectional operation when exhaust flow through the turbo-compressor is insufficient to drive the turbo-compressor.

Reference with 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 embodiment of a compounding drive in accordance with the disclosure is shown in <FIG> and is designated generally by reference character <NUM>/<NUM>. Other embodiments of compounding drives, compounded engine arrangements and aircraft having compounded engine arrangements, and methods of compounding internal combustion engines are provided in <FIG>, as will be described. The systems and methods described herein can be used for compounding engines carried by vehicles, such as internal combustion engines on aircraft, though the present disclosure is not limited to engines arrangements carried by aircraft or to internal combustion engines in general.

Referring to <FIG>, an engine arrangement <NUM> is shown. The engine arrangement <NUM> includes an internal combustion engine <NUM>, a turbo-compressor <NUM>, and the compounding drive <NUM>. The engine arrangement <NUM> also includes a propeller <NUM> (e.g., an aircraft propeller), an electric motor/generator <NUM>, a battery <NUM>, and a controller <NUM>. As shown and described herein the engine arrangement <NUM> is carried by a vehicle <NUM>, e.g., an aircraft, and is a hybrid engine, the engine arrangement <NUM> including a generator/motor set <NUM> electrically connected to a battery <NUM> and operably connected/associated with the internal combustion engine <NUM>. As will be appreciated by those of skill in the art in view of the present disclosures other types of engine arrangements can also benefit from the present disclosure, such as engine arrangements in terrestrial, marine, and stationary settings by way of example.

The internal combustion engine <NUM> includes a crankshaft <NUM>, an intake port <NUM>, and an exhaust port <NUM>. The intake port <NUM> is in fluid communication with the exhaust port <NUM> through the internal combustion engine <NUM>. The crankshaft <NUM> is operably connected to the propeller <NUM>, e.g., mechanically connected through a direct mechanical connection or an intervening gearing, for rotating the propeller <NUM>. The intake port <NUM> is in fluid communication with the turbo-compressor <NUM> through an intake conduit <NUM> to receive from the turbo-compressor <NUM> a flow of intake fluid <NUM>, e.g., compressed air. The exhaust port <NUM> is in fluid communication with the turbo-compressor <NUM> through an exhaust conduit <NUM> to provide to the turbo-compressor <NUM> a flow of exhaust fluid <NUM>, e.g., combustion products, from which the turbo-compressor <NUM> extracts work. An output member <NUM>, e.g., shafting or intervening gearing, connects the turbo-compressor <NUM> to the crankshaft <NUM> of the internal combustion engine <NUM>, a portion of the work extracted by the turbo-compressor <NUM> from the exhaust fluid <NUM> being applied to the crankshaft <NUM> to compound output of the internal combustion engine <NUM> and employed to rotate the propeller <NUM>.

The turbo-compressor <NUM> includes a compressor <NUM>, an interconnect shaft <NUM>, and a turbine <NUM>. The compressor <NUM> has a compressor inlet <NUM> and a compressor outlet <NUM> and is configured to compress air ingested from the external environment <NUM> to generate a flow of the intake fluid <NUM>. In this respect the compressor inlet <NUM> is in fluid communication with the intake port <NUM> of the internal combustion engine <NUM> through the intake conduit <NUM>. Work required by the compressor <NUM> to generate the flow of intake fluid <NUM> is provided to the compressor <NUM> by the turbine <NUM> through the interconnect shaft <NUM>, the interconnect shaft <NUM> operatively associating the turbine <NUM> with the compressor <NUM> by communicating work thereto through mechanical rotation R<NUM>.

The turbine <NUM> has a turbine inlet <NUM> and a turbine outlet <NUM> and is configured to extract work from fluid introduced into the turbine <NUM> through the turbine inlet <NUM> prior to issuing the fluid to the external environment <NUM> through the turbine outlet <NUM>. In this respect the turbine inlet <NUM> is in fluid communication with the exhaust <NUM> of the internal combustion engine <NUM> through the exhaust conduit <NUM> to receive therethrough a flow of the exhaust fluid <NUM>. The turbine is connected to the interconnect shaft <NUM> and the output member <NUM> to provide both the mechanical rotation R<NUM> to the compressor <NUM> compounding mechanical rotation R<NUM> to the crankshaft <NUM> of the internal combustion engine <NUM> using work extracted from the flow of the exhaust fluid <NUM>. The compounding mechanical rotation R<NUM> is provided to the crankshaft <NUM> through the output member <NUM> of the compounding drive <NUM>, which can be coupled to the turbine <NUM> through a direct mechanical connection, intervening gearing, and/or the interconnect shaft <NUM>.

The compounding drive <NUM> includes an input member <NUM>, a hydraulic pump/motor set <NUM>, and an epicyclical gear arrangement <NUM>. The compounding drive <NUM> also includes a first intermediate member <NUM>, a second intermediate member <NUM>, and a third intermediate member <NUM>. The input member <NUM> is connected to the turbine <NUM>. The epicyclical gear arrangement <NUM> interconnects the input member <NUM> to the output member <NUM> and the first intermediate member <NUM>. The second intermediate member <NUM>, the hydraulic pump/motor set <NUM>, and the third intermediate member <NUM> couple the first intermediate member <NUM> to the output member <NUM> to communicate the compounding mechanical rotation R<NUM> to the crankshaft <NUM> of the internal combustion engine <NUM> using work extracted from the flow of exhaust fluid <NUM> and in excess of that required to power the compressor <NUM>. In certain embodiments the compounding drive <NUM> can be as shown and described in <CIT>, the contents of which are incorporated herein by reference in its entirety.

As will be appreciated by those of skill in the art in view of the present disclosure, engines equipped with turbo-compressors typically operate in modes wherein the power extracted by turbine exceeds that required to operate the compressor. This allows the excess power extracted by the turbine to be transferred to the engine through a compounding drive, e.g., by operating the hydraulic pump/motor set <NUM> in a positive torque/speed regime. In some engines it can be necessary to operate the engine in a mode where the residual energy in the engine exhaust is insufficient to power the compressor, such as when an engine is throttled back during a flight-idle operating mode. Such operating modes can reverse the flow of power through the compounding drive, causing the hydraulic pump/motor to set <NUM> to operate in a negative torque/speed regime.

As will also be appreciated by those of skill in the art in view of the present disclosure, operation of some hydraulic pump/motor sets in a negative torque/speed regime can limit the reliability and/or the expected service life of the hydraulic pump/motor set. Further, operation in negative torque/speed regimes can create parasitic draft on the engine coupled to the turbo-compressor, limiting efficiency of the engine. To allow the internal combustion engine <NUM> to operate in modes where the exhaust fluid <NUM> contains insufficient energy to power the compressor <NUM>, limiting (or eliminate entirely) efficiency loses and reliability/service life reductions associated with operation in such modes, the compounding drive <NUM> includes an over-running clutch <NUM>. The over-running clutch <NUM> couples the first intermediate member <NUM> to the third intermediate member <NUM> through the hydraulic pump/motor set <NUM>, allowing the turbo-compressor <NUM> to drive the internal combustion engine <NUM> through the output member <NUM> and preventing the internal combustion engine <NUM> from driving the turbo-compressor <NUM> through the output member <NUM>, as will be described.

With reference to <FIG> and <FIG>, the compounding drive <NUM> is shown. The compounding drive <NUM> includes the input member <NUM>, the epicyclical gear arrangement <NUM>, the output member <NUM>, and the over-running clutch <NUM>. The compounding drive <NUM> also includes the first intermediate member <NUM>, the second intermediate member <NUM>, the hydraulic pump/motor set <NUM>, and the third intermediate member <NUM>.

The hydraulic pump/motor set <NUM> couples the epicyclical gear arrangement <NUM> to the output member <NUM> and includes a fixed displacement hydraulic module <NUM>, a variable displacement hydraulic module <NUM>, and a hydraulic circuit <NUM>. The hydraulic circuit <NUM> fluidly connects the fixed displacement hydraulic module <NUM> to the variable displacement hydraulic module <NUM>. The fixed displacement hydraulic module <NUM> is connected to the over-running clutch <NUM> by the second intermediate member <NUM>. The variable displacement hydraulic module <NUM> is connected to the output member <NUM> by the third intermediate member <NUM>.

The epicyclical gear arrangement <NUM> includes a pinion gear <NUM>, a plurality of planetary gears <NUM>, a planetary gear carrier <NUM>, and a ring gear <NUM>. The pinion gear <NUM> is fixed relative to the input member <NUM>. The planetary gear carrier <NUM> is fixed relative to the output member <NUM>. The planetary gears <NUM> are each supported for rotation relative to the planetary gear carrier <NUM> and are intermeshed between the pinion gear <NUM> and the ring gear <NUM>. The ring gear <NUM> is fixed relative to the first intermediate member <NUM>.

The over-running clutch <NUM> can include, for example a ratcheting free-wheel mechanism or a sprag clutch, and in the illustrated embodiment the over-running clutch <NUM> couples the epicyclical gear arrangement <NUM> to the hydraulic pump/motor set <NUM>. In this respect the over-running clutch <NUM> includes a drive member <NUM>, a driven member <NUM>, and a latch feature <NUM>. The drive member <NUM> is fixed in rotation relative to the first intermediate member <NUM> and is connected by the first intermediate member <NUM> to the ring gear <NUM>. The driven member <NUM> is fixed in rotation relative to the second intermediate member <NUM> and is connected by the second intermediate member <NUM> to the fixed displacement hydraulic module <NUM>. The latch feature <NUM> movable between drive member <NUM> and the driven member <NUM>, the latch feature <NUM> fixing via latching (i.e. latched A) the driven member <NUM> in rotation relative to the drive member <NUM> when the drive member <NUM> overruns the driven member <NUM>.

As shown in <FIG>, when the drive member <NUM> overruns the driven member <NUM>, e.g., the rate of the mechanical rotation R<NUM> is greater than the rate of the mechanical rotation R<NUM>, the latch feature fixes the driven member <NUM> in rotation relative to the drive member <NUM>. This causes the compounding drive <NUM> to communicate torque carried by the input member <NUM>, e.g., associated with the mechanical rotation R<NUM>, to the output member <NUM>, e.g., as the mechanical rotation R<NUM>. Specifically, the ring gear <NUM> rotates the drive member <NUM> through the first intermediate member <NUM>, the drive member <NUM> rotates the driven member <NUM> through the latch feature <NUM>, and the driven member <NUM> generates a flow of pressurized hydraulic fluid F within the fixed displacement hydraulic module <NUM> by operably association of the driven member <NUM> with the fixed displacement hydraulic module <NUM> via the second intermediate member <NUM>. The pressurized hydraulic fluid F is carried by the hydraulic circuit <NUM> to the variable displacement hydraulic module <NUM>, which applies mechanical rotation R<NUM> to the third intermediate member <NUM> and returns low pressure fluid f to the fixed displacement hydraulic module <NUM> via hydraulic circuit <NUM>. The third intermediate member <NUM> in turn applies the torque associated with the mechanical rotation R<NUM> to the output member <NUM>.

As shown in <FIG>, when torque on the drive member <NUM> exceeds torque on the driven member <NUM>, e.g., torque associated with mechanical rotation R<NUM> exceeds torque associated with mechanical rotation R<NUM>, the latch feature <NUM> fixes the driven member <NUM> in rotation relative to the drive member <NUM>. Once unlatched, i.e., unlatched B, the driven member <NUM> is rotatable relative to the drive member <NUM> and substantially no mechanical rotation is communicated from the second intermediate member <NUM> to the first intermediate member <NUM>. As will be appreciated by those of skill in the art in view of the present disclosure, this prevents crankshaft <NUM> (shown in <FIG>) or the internal combustion engine <NUM> (shown in <FIG>) from driving the compressor <NUM> (shown in <FIG>).

With reference to <FIG> and <FIG>, the compounding drive <NUM> is shown. The compounding drive <NUM> is similar to the compounding drive <NUM> (shown in <FIG>) and additionally includes an over-running clutch <NUM> coupling the second intermediate member <NUM> to the third intermediate member <NUM>. More particularly, the compounding drive <NUM> includes the input member <NUM>, an epicyclical gear arrangement <NUM>, the output member <NUM>, and the over-running clutch <NUM>. The compounding drive <NUM> also includes a first intermediate member <NUM>, a second intermediate member <NUM>, a hydraulic pump/motor set <NUM>, and a third intermediate member <NUM>.

The hydraulic pump/motor set <NUM> couples the epicyclical gear arrangement <NUM> to the output member <NUM> and includes a fixed displacement hydraulic module <NUM>, a variable displacement hydraulic module <NUM>, and a hydraulic circuit <NUM>. The hydraulic circuit <NUM> fluidly connects the fixed displacement hydraulic module <NUM> to the variable displacement hydraulic module <NUM>. The fixed displacement hydraulic module <NUM> is in turn connected to first intermediate member <NUM> and the variable displacement hydraulic module <NUM> is connected to the second intermediate member <NUM>. The over-running clutch <NUM> connects the second intermediate member <NUM> to the third intermediate member <NUM>, the third intermediate member <NUM> in turn coupling the second intermediate member <NUM> to the output member <NUM> through the over-running clutch <NUM>.

As in the compounding drive <NUM> (shown in <FIG>), the over-running clutch <NUM> can include, for example a ratcheting free-wheel mechanism or a sprag clutch, and in the illustrated embodiment the over-running clutch <NUM> couples the epicyclical gear arrangement <NUM> through the hydraulic pump/motor set <NUM> to the output member <NUM> through the third intermediate member <NUM>. In this respect the over-running clutch <NUM> includes a drive member <NUM>, a driven member <NUM>, and a latch feature <NUM>. The drive member <NUM> is fixed in rotation relative to the second intermediate member <NUM> and is connected by the hydraulic pump/motor set <NUM> and the first intermediate member <NUM> to the ring gear <NUM>. The driven member <NUM> is fixed in rotation relative to the third intermediate member <NUM> and is connected by therethrough to the output member <NUM>. The latch feature <NUM> is movable between drive member <NUM> and the driven member <NUM>, the latch feature <NUM> fixing the driven member <NUM> in rotation relative to the drive member <NUM> when torque on the drive member <NUM> exceeds torque on the driven member <NUM>.

As shown in <FIG>, when torque on the drive member <NUM> exceeds torque on the driven member <NUM>, e.g., torque associated with mechanical rotation R<NUM> exceeds torque associated with mechanical rotation R<NUM>, the latch feature <NUM> fixes the driven member <NUM> in rotation relative to the drive member <NUM>. Rotational fixation of the driven member <NUM> with the drive member <NUM> causes the compounding drive <NUM> to communicate torque carried by the input member <NUM>, e.g., associated with the mechanical rotation R<NUM>, to the output member <NUM>, e.g., as the mechanical rotation R<NUM>. In this respect the ring gear <NUM> rotates the first intermediate member <NUM>. The first intermediate member <NUM> in turn pressurizes hydraulic fluid in the hydraulic fluid circuit <NUM> through operable association with the fixed displacement hydraulic module <NUM> to generate a flow of pressurized hydraulic fluid F, which the hydraulic circuit communicates to the variable displacement hydraulic module <NUM>.

The variable displacement hydraulic module <NUM> in converts the flow of pressurized hydraulic fluid F to mechanical rotation R<NUM> of the second intermediate member <NUM>, which the (latched) over-running clutch <NUM> communicates to the third intermediate member <NUM>. The third intermediate member <NUM> in turn communicates the mechanical rotation R<NUM> to the output member <NUM>, which compounds the output of the internal combustion engine <NUM> (shown in <FIG>).

As shown in <FIG>, when the driven member <NUM> overruns the drive member <NUM>, e.g., the rate of the mechanical rotation R<NUM> of the third intermediate member <NUM> exceeds the rate of the mechanical rotation R<NUM>, the latch feature <NUM> unlatches the driven member <NUM> from the drive member <NUM>. Once unlatched, the driven member <NUM> is rotatable relative to the drive member <NUM> - and substantially no mechanical rotation is communicated from the third intermediate member <NUM> to the second intermediate member <NUM>. As will be appreciated by those of skill in the art in view of the present disclosure, this also prevents crankshaft <NUM> (shown in <FIG>) or the internal combustion engine <NUM> (shown in <FIG>) from driving the compressor <NUM> (shown in <FIG>). In certain embodiments the hydraulic pump/motor set <NUM> can be idled, manually, by the above-described operation of the over-running clutch <NUM>.

With reference to <FIG>, a method <NUM> of compounding output of an engine, e.g., the internal combustion engine <NUM> (shown in <FIG>), is shown. As shown with box <NUM>, torque is recited at a least one of an input member and an output member of a compounding drive, e.g., the input member <NUM> (shown in <FIG>) and the output member <NUM> (shown in <FIG>) of the compounding drive <NUM> (shown in <FIG>). In certain embodiments the torque can be received that the input member, e.g., when a turbo-compressor extracts energy in excess of that required to drive a compressor, e.g., the turbo-compressor <NUM> (shown in <FIG>) with the compressor <NUM> (shown in <FIG>), as shown with box <NUM>. In accordance with certain embodiments the torque can be received at the output member, e.g., when energy in a flow of exhaust fluid issuing from the internal combustion engine is insufficient to drive the compressor. It is contemplated that torque flow unidirectionally through the compounding drive, e.g., by unidirectionally communicating mechanical rotation through the compounding drive, as shown with bracket <NUM>.

As shown with box <NUM>, when torque carried by the input member is greater than torque carried by the output member, e.g., torque associated with the mechanical rotation R<NUM> (shown in <FIG>) exceeds torque associated with the mechanical rotation R<NUM> (shown in <FIG>), the torque is communicated through the compounding drive. In certain embodiments the torque is communicated by connecting an epicyclical gear arrangement to a hydraulic pump/motor set with an over-running clutch, e.g., the epicyclical gear arrangement <NUM> (shown in <FIG>) to the hydraulic pump/motor set <NUM> (shown in <FIG>) with the over-running clutch <NUM> (shown in <FIG>), as shown with box <NUM>. In accordance with certain embodiments, the torque can be communicated by connecting a hydraulic pump/motor set to the output shaft with an over-running clutch and intervening intermediate member, e.g., the hydraulic pump/motor set <NUM> (shown in <FIG>) and the third intermediate member <NUM> (shown in <FIG>), as shown with box <NUM>.

As shown with box <NUM>, when torque carried by the input member is less than torque carried by the output member, e.g., the torque associated with the mechanical rotation R<NUM> (shown in <FIG>) is less than torque associated with the mechanical rotation R<NUM> (shown in <FIG>), no torque is communicated through the compounding drive. In certain embodiments an epicyclical gear arrangement can be disconnected from a hydraulic pump/motor set with an over-running clutch, e.g., the epicyclical gear arrangement <NUM> (shown in <FIG>) disconnected from the hydraulic pump/motor set <NUM> (shown in <FIG>) with the over-running clutch <NUM> (shown in <FIG>), as shown with box <NUM>. In accordance with certain embodiments, a hydraulic pump/motor set can be disconnected from the output shaft and an intermediate member with the over-running clutch, e.g., the hydraulic pump/motor set <NUM> (shown in <FIG>) from the output shaft <NUM> (shown in <FIG>) and the intermediate shaft <NUM> (shown in <FIG>) with the over-running clutch <NUM> (shown in <FIG>), as shown with box <NUM>.

When the torque carried by the input member exceeds torque carried by the input member the torque is communicated through the compounding drive and applied to the output of the internal combustion engine, compounding the output of the internal combustion engine, as shown with box <NUM>. When the torque carried by the output member exceeds torque carried by the input member no torque is communicated through the compounding drive, and to the turbo-compressor, as shown with box <NUM>.

Claim 1:
A compounding drive (<NUM>), comprising:
an input member (<NUM>);
an epicyclical gear arrangement (<NUM>) connected to the input member (<NUM>);
an output member (<NUM>) connected to the input member (<NUM>) via the epicyclical gear arrangement (<NUM>); and
a hydraulic pump/motor set(<NUM>) connecting the epicyclical gear arrangement to the output member (<NUM>) through an overrunning clutch (<NUM>) for unidirectional communication of mechanical rotation between the input member and the output member, and characterized by comprising a first intermediate member (<NUM>), a second intermediate member (<NUM>), and a third intermediate member (<NUM>),
wherein the epicyclical gear arrangement (<NUM>) interconnects the input member (<NUM>) to the output member (<NUM>) and the first intermediate member (<NUM>),
wherein the second intermediate member (<NUM>), the hydraulic pump/motor set (<NUM>), and the third intermediate member (<NUM>) couple the first intermediate member (<NUM>) to the output member (<NUM>) such that the overrunning clutch (<NUM>) is between the hydraulic pump/motor set (<NUM>) and the epicyclical gear arrangement (<NUM>),
wherein the epicyclical gear arrangement (<NUM>) includes a pinion gear (<NUM>), a plurality of planetary gears (<NUM>), a planetary gear carrier (<NUM>), and a ring gear (<NUM>), the pinion gear (<NUM>) is fixed relative to the input member (<NUM>), the planetary gear carrier (<NUM>) is fixed relative to the output member (<NUM>), the planetary gears (<NUM>) are each supported for rotation relative to the planetary gear carrier (<NUM>) and are intermeshed between the pinion gear (<NUM>) and the ring gear (<NUM>), the ring gear (<NUM>) is fixed relative to the first intermediate member (<NUM>); and
wherein the over-running clutch (<NUM>) includes a drive member (<NUM>), a driven member (<NUM>), and a latch feature (<NUM>), the drive member (<NUM>) is fixed in rotation relative to the first intermediate member (<NUM>) and is connected by the first intermediate member (<NUM>) to the ring gear (<NUM>).