Patent Application
20130315753
The subject matter disclosed herein generally pertains to the field of a control system for a pump that provides a fluid flow in an engine.
Engines require various fluid flows during operation, for purposes such as cooling, lubrication, and providing fuel for combustion. Fluid flows may be propelled by a pump through a network of pipes and valves on an engine. The flow rate and pressure of a fluid flow that is needed for an engine may vary based on the operation of the engine. Providing fluid flows tailored to engine operation with relative accuracy may require complex control hardware on the engine. Engine gearbox-driven pumping systems comprising a fixed gearbox may be used for various fluid flow applications in an engine. A gearbox pumping and control system transfers mechanical power from the engine to the pump via the gearbox to provide the fluid flow in the engine, and may deliver relatively accurate flows and pressures. However, a gearbox-driven pumping system may require additional air cooling or a return to tank path in order to maintain a target fluid temperature, as fuel recirculation around pump may generate extra heat in the pumping system that needs to be dissipated.
According to one aspect, a fluid pumping system for an engine includes a pump; a summing differential connected to the pump; a gearbox connected to the summing differential, wherein the gearbox causes the pump to rotate to provide a fluid flow in the engine via the summing differential; and a motor connected to the summing differential, wherein the motor adjusts a rotational speed of the pump via the summing differential.
According to another aspect, a method for speed control of a pump to provide a fluid flow in an engine includes powering the pump to rotate by a gearbox connected to a summing differential to provide the fluid flow in the engine; and adjusting a rotational speed of the pump by a motor connected to the summing differential.
Other aspects, features, and techniques of the invention will become more apparent from the following description taken in conjunction with the drawings.
Referring now to the drawings wherein like elements are numbered alike in the several FIGURES:
Embodiments of systems and methods for speed control of an engine pump via a summing differential are provided, with exemplary embodiments being discussed below in detail. A gearbox-driven pumping system may be used in conjunction with a summing differential and a motor to provide a fluid flow in an engine. The gearbox may provide the primary power source to the pump from the engine, while the motor may be used to increase or decrease the rotational speed of the pump in order to meet a target flow requirement (e.g., flow rate and pressure) for the fluid flow in the engine. The gearbox may be sized to input power to the pump from the engine to produce a base rotational pump speed that is determined based on the design of the pump and the requirements of the pumping application. The motor input to the differential may add or subtract rotational speed from the pump shaft in order to make adjustments in the pump speed, as the actual pump flow demand in the engine may vary. The motor may be controlled based on a flow sensor in the engine in order to meet a target flow requirement for the fluid flow. The flow sensor may be part of an electronic engine controller of the engine in some embodiments. In one embodiment, by matching the pumping to the flow requirement, less heat is created in the pumping system, eliminating the need to return fuel to the aircraft tank. This may eliminate the need for relatively complex plumbing and valve systems. The motor may also act as a back-up power source for the pump in the event of a failure in the power transmission path comprising the gearbox.
Embodiments of speed control of an engine pump via a summing differential may be used in conjunction with any appropriate type of engine, including but not limited to an aircraft engine, such as an airplane or helicopter engine, a ground vehicle, a relatively large industrial engine, or a ground-based electric generator. The pump that is powered via the summing differential may provide any appropriate fluid flow in the engine, including but not limited to fuel, oil, air, or glycol. The motor may comprise an electric motor, and may be powered by any appropriate power source, including but not limited to a power grid, an auxiliary power unit (APU), or the engine itself via a generator. The target flow requirement may be based on a current operating condition of the engine. For example, in embodiments where the engine comprises an aircraft engine, during ground idle or at the top of a descent the pump flow target may be low, so the motor may subtract speed from the pump by way of the summing differential to provide a desired flow in the engine. When the aircraft engine is at full power (for example, at takeoff), there is high flow demand, and the motor adds speed to the pump for increased flow. During straight and level flight (for example, during cruising), the motor may provide relatively little or no speed adjustment to the pump, and so that the motor requires relatively little power to maintain the flow at the desired level in the engine.
The technical effects and benefits of exemplary embodiments include reduction of complexity in a fluid pumping system for an engine while providing fluid flows that may relatively accurately meet engine requirements.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. While the description of the present invention has been presented for purposes of illustration and description, it is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications, variations, alterations, substitutions, or equivalent arrangement not hereto described will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. Additionally, while various embodiment of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
