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EP-4234400-B1 - ELECTROMECHANICAL ACTUATOR PUMP

EP4234400B1EP 4234400 B1EP4234400 B1EP 4234400B1EP-4234400-B1

Inventors

  • ALLEN, Jason Bradley

Dates

Publication Date
20260513
Application Date
20201109

Claims (5)

  1. An electromechanical actuator for steering a nose landing gear system, comprising: an electric motor (440); a gearbox (442) connected to the electric motor; and a clutch (444) configured to mechanically couple the gearbox to a steering collar, characterised in that the electric motor is coupled to, and configured to drive, a hydraulic pump (450), the hydraulic pump fluidly coupled with an accumulator (466), wherein the hydraulic pump is a check valve-type hydraulic pump enabling an output flow from a fluid outlet of the hydraulic pump regardless of the direction the electric motor is turning; and in that the electromechanical actuator further comprises a clutch control valve (441) fluidly coupled to the clutch and configured to receive a pressurized hydraulic fluid from the accumulator to engage or disengage the clutch with or from the steering collar.
  2. A nose landing gear system, comprising: an electromechanical actuator as claimed in claim 1.
  3. A method of operating a nose landing gear system using an electromechanical actuator as claimed in claim 1, the method comprising: driving the electric motor (440); circulating the pressurized hydraulic fluid within a recirculation hydraulic circuit via the hydraulic pump; and steering a nose landing gear assembly via the gearbox and the clutch (444); wherein circulating the hydraulic fluid within the recirculation hydraulic circuit includes circulating the hydraulic fluid through a fluid return provided by a directional control valve in a neutral position; the method further comprising: pressurizing the accumulator to a specified pressure that is sufficient to engage or disengage the clutch, mechanically coupled to the gearbox and to the nose landing gear assembly via a steering collar.
  4. The method of claim 3, further comprising disengaging the clutch, switching the directional control valve to a stowed position and stowing the nose landing gear assembly via the hydraulic pump.
  5. The method of claim 3, further comprising disengaging the clutch, switching the directional control valve to a deployed position and deploying the nose landing gear assembly via the hydraulic pump.

Description

FIELD The present disclosure relates generally to nose landing gear systems and, more particularly, to electromechanical actuators for steering nose landing gear systems. BACKGROUND Aircraft often contain numerous hydraulic systems including, for example, hydraulic systems typically used for the nose and main landing gear systems. The hydraulic pumps for such systems are typically centralized and located aft of the nose region. Transporting pressurized hydraulic fluid from the aft portions of the aircraft to the nose region often involves long networks of hydraulic tubes. The tubes run from near the engines, where pumps provide hydraulic fluid flow using engine power or electrical power provided from an auxiliary source, to the nose of the aircraft, where the pressurized fluid is used to power and steer the nose landing gear. As a result of the long tubing networks of centralized hydraulic systems, the aircraft carries a large volume of hydraulic fluid to fill the hydraulic tubes used for both supply and return. Carrying extra fluid equates to carrying extra weight and thereby decreases aircraft efficiency. Additionally, the hydraulic tubes occasionally develop leaks over the life of the aircraft. Leaks in the tubing are fixed using labor intensive processes to locate the leak, access the tubing, and replace the tubing. Reducing the potential for leak points is therefore desirable. With regard to the landing gear actuation systems, centralized hydraulic systems are relatively inefficient since the hydraulic systems and components must be sized to provide a relatively large pressurized flow rate for the landing gear actuation systems for short periods of time in addition to continually providing flow to other systems. Landing gear actuation systems generally operate only twice during a flight cycle, that is, before landing and after take-off. Attempts to reduce hydraulic tubing and therefore potential leak points include utilizing electric components in lieu of hydraulic components. One way this is accomplished is by generating hydraulic power locally via an electric motor-driven pump located within the nose landing gear bay. This hydraulic power is fed to a local independent hydraulic system within the nose landing gear bay that can drive a nose wheel steering motor as well as a nose landing gear door and uplock, downlock and retraction/extension actuators. Other attempts utilize a rotary electro-mechanical actuator (EMA) nose wheel steering unit in lieu of a hydraulic motor. Some attempts utilize an EMA for nose landing gear retraction/extension and other landing gear functions. However, use of an EMA as described may exhibit disadvantages. For example, the EMA does not handle over-running loads as easily as hydraulic actuators, and jamming failure modes are not easily addressed. Also, these concepts require more equipment (e.g., two motors) than optimally required. Document US 2016/0101849 A1 discloses an aircraft landing gear equipped with a steering device for orienting the wheels, the steering device comprising a body in which is incorporated an electromechanical actuator. The electromechanical actuator comprises an electric motor, a gearing device, a harmonic transmission device, clutch means, a pinion and a gearwheel that rotates as one with the steering tube. SUMMARY An electromechanical actuator for steering a nose landing gear system is providedas defined by claim 1. In various embodiments, the clutch is disposed between the gearbox and the steering collar. In various embodiments, a directional control valve is fluidly coupled to the hydraulic pump and to the retract actuator. In various embodiments, the directional control valve is configured to provide a recirculation hydraulic circuit when in a neutral position. In various embodiments, the recirculation hydraulic circuit is configured to fluidly couple a fluid outlet to a fluid inlet of the hydraulic pump via the directional control valve. In various embodiments, the fluid outlet of the hydraulic pump is fluidly coupled to a clutch control valve configured to engage and disengage the clutch and to the directional control valve. A method of operating a nose landing gear system is provided as defined by claim 3. In various embodiments, circulating the hydraulic fluid within the recirculation hydraulic circuit includes circulating the hydraulic fluid through a fluid return provided by a directional control valve in a neutral position. In various embodiments, the method includes disengaging the clutch, switching the directional control valve to a stowed position and stowing the nose landing gear assembly via the hydraulic pump. In various embodiments, the method includes disengaging the clutch, switching the directional control valve to a deployed position and deploying the nose landing gear assembly via the hydraulic pump. In various embodiments, the nose landing gear assembly steering collar is mechanically coupled to the gearbox via the clutch.