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EP-4407205-B1 - RESETTING AN ELECTROMECHANICAL DISCONNECT

EP4407205B1EP 4407205 B1EP4407205 B1EP 4407205B1EP-4407205-B1

Inventors

  • ANGHEL, CRISTIAN E.
  • MINKE, DAVID R.

Dates

Publication Date
20260506
Application Date
20240105

Claims (10)

  1. A method to reset an electromechanical disconnect, the method comprising: electrically disengaging a pawl (504) holding a second half (404) of a dog clutch (400), located between a starter-generator (104) and a main engine gear box (106), in a disengaged position; controllably energizing the starter-generator to produce a selected angle of rotational motion of a starter-generator shaft (408), wherein the selected angle is equal to 360 degrees divided by a number of teeth on a first half (402) of the dog clutch; and determining when the first half of the dog clutch is engaged with a second half of the dog clutch.
  2. The method of claim 1, wherein controllably energizing the starter-generator comprises providing a start current with a ramp from 0 to 5% for up to two seconds to the starter-generator.
  3. The method of claim 1, wherein controllably energizing the starter-generator comprises providing a start current in short, low bursts to cause the starter-generator shaft to rotate in small increments.
  4. The method of claim 1, wherein controllably energizing the starter-generator comprises applying current at a level to cause the starter-generator shaft to rotate slowly.
  5. The method of claim 1, wherein controllably energizing the starter-generator comprises pulsing the starter-generator for a period of time at high frequency to cause starter-generator shaft to rotate through the selected angle.
  6. A system (100), the system comprising: a starter-generator (104); a main engine gear box (106); a resettable electromechanical disconnect (102) coupled between the starter-generator and the main engine gear box; and a controller (108) coupled to the starter-generator and the resettable electromechanical disconnect, wherein the resettable electromechanical disconnect comprises: a dog clutch (400) having a first half (402) and a second half (404), the first half and second half of the dog clutch oriented along an axis (416), wherein the first half of the dog clutch is configured to engage with a shaft (406) of a main gear box (106) and the second half of the dog clutch is configured to engage with a drive shaft (408) of a starter-generator (104); a pawl (504) positioned to move between a first position and a second position, wherein the pawl is disengaged from the dog clutch in the first position and the pawl engages with the second half of the dog clutch in the second position; a solenoid (502) coupled to the pawl; and a control input configured to receive a control signal, wherein the control signal causes the solenoid to move the pawl between the first position and the second position; wherein when the control input receives the control signal to move the pawl to the first position, the pawl disengages with the second half of the dog clutch, the second half of the dog clutch translates toward the first half of the dog clutch via a spring (506), and the second half of the dog clutch is controllably rotated through a selected angle by a low torque from the starter-generator until the first half of the dog clutch engages with the second half of the dog clutch, wherein the selected angle is equal to 360 degrees divided by a number of teeth of a plurality of teeth (418, 430, 802, 804, 902, 904) on each half of the dog clutch.
  7. The system of claim 6, wherein the second half of the dog clutch includes the spring (506) in a shaft (508), wherein the spring applies a force on the second half of the dog clutch that causes the second half of the dog clutch to translate toward the first half of the dog clutch when the pawl is in the first position.
  8. The system of claim 6 or 7, wherein the teeth of the plurality of teeth are spaced apart to provide an opening (422, 434, 808, 908) between adjacent teeth in the plurality of teeth.
  9. The system of claim 6, 7 or 8, wherein a side (806, 810, 918, 924) of each tooth of the plurality of teeth of the first half of the dog clutch and the second half of the dog clutch is sloped at an angle to promote movement of the plurality of teeth into a meshed, engaged position.
  10. The system of any of claims 6 to 9, further comprising a proximity sensor (505) that is configured to detect when the first half of the dog clutch engages with the second half of the dog clutch.

Description

BACKGROUND During the last two decades there has been an increased demand for electrification in aerospace and other vehicles. Traditionally, aircraft engines have been started using compressed air or a DC starter. With the advent of More Electric Aircraft (MEA), the engine is started by using an AC generator already installed on the engine as a starter by employing power converters. During Engine Start Mode, the AC generator installed on the engine is operated as a motor and is fed from a variable voltage and variable frequency power source provided by the power converters. Once the engine attains a certain speed, the power converter is disconnected and the system transitions to power generation mode. What was previously named "generator" is now known as a "starter-generator" (SG). The SG is coupled with the engine typically via an accessory main engine gearbox (MEG). Besides the SG, this MEG drives other aircraft critical systems. Thus, the MEG needs to be protected in the event of failure in the SG. One approach to protect the MEG is to include a simple sheer section on a shaft between the SG and the MEG. However, because the SG usually operates in a 2:1 speed range, protection of the MEG cannot be reliably accommodated with a simple sheer section on the shaft. Therefore, another conventional approach to protect the MEG is to use a resettable electromechanical disconnect. Conventionally, resetting (or reengaging) the resettable electromechanical disconnect is performed when the engine is off. However, the engaging mechanism (which is typically a dog clutch that has high and low point features) needs to be properly aligned to achieve re-engagement. This alignment is completed by an operator physically accessing and rotating the SG shaft or rotor until alignment of the dog clutch is achieved. As a result, the production and operation cost of operating the resettable electromechanical disconnect are increased. Documents cited during prosecution include GB 1 145 950 A and DE 10 2020 212195 A1. SUMMARY Aspects and preferred embodiments of the invention are defined in the appended claims. Disclosed herein is a method to reset an electromechanical disconnect is provided. The method includes electrically disengaging a pawl holding a second half of a dog clutch, located between a starter-generator and a main engine gear box, in a disengaged position, controllably energizing the starter-generator to produce a selected angle of rotational motion of a starter-generator shaft, wherein the selected angle is equal to 360 degrees divided by a number of teeth on the first half of the dog clutch, and determining when the first half of the dog clutch is engaged with a second half of the dog clutch. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the present invention can be more easily understood and further advantages and uses thereof more readily apparent, when considered in view of the description of the preferred embodiments and the following figures in which: FIG. 1 is a block diagram of one embodiment of a system including a resettable electromechanical disconnect coupled between a starter-generator and a main engine gear box.FIG. 2 is one embodiment of a state transition diagram for the system of FIG. 1.FIG. 3 is a graph that illustrates one embodiment of a relationship between torque and speed of the starter-generator of FIG. 1 that enables re-engaging the resettable electromechanical disconnect.FIG. 4 is a perspective view of one embodiment of a dog clutch for use in one embodiment of the resettable electromechanical disconnect of FIG. 1.FIGs. 5, 6, and 7 are cross sectional views of functional components of one embodiment of a resettable electromechanical disconnect that can be used in the system of FIG. 1.FIG. 8A is a perspective view of an alternative embodiment of a dog clutch with teeth that are configured to promote engagement of the of a first half of the dog clutch with a second half of the dog clutch for use in a resettable electromechanical disconnect.FIG. 8B is a cross sectional view of teeth of the dog clutch of FIG. 8A.FIG. 9A is a perspective view of another alternative embodiment of a dog clutch with teeth that promote engagement of the first half of the dog clutch with the second half of the dog clutch for use in a resettable electromechanical disconnect.FIG. 9B is a cross sectional view of teeth of the dog clutch of FIG. 9A. In accordance with common practice, the various described features are not drawn to scale but are drawn to emphasize features relevant to the present invention. Reference characters denote like elements throughout figures and text. DETAILED DESCRIPTION In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of specific illustrative embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the inventi