ELECTROMECHANICAL ACTUATOR DRIVEN GOVERNOR FOR RAM AIR TURBINE
A ram air turbine governor includes a hub carrying multiple turbine blades. A sensor is configured to detect a parameter. A counterweight is coupled to at least one turbine blade and is configured to provide an input to the turbine blade in response to a centrifugal force to move the turbine blade from a first pitch position to a second pitch position. An electromechanical actuator is operatively coupled to the counterweight. A controller is in communication with the mechanical actuator and the sensor. The controller is configured to command the electromechanical actuator and move the turbine blade from the second pitch position to a third pitch position in response to the detected parameter.
This disclosure relates to a ram air turbine system. More particularly, the disclosure relates to a speed governor for the ram air turbine system.
A ram air turbine (RAT) system includes turbine having blades. A typical RAT has a governor that adjusts the pitch angle of the turbine blades over the speed range of the aircraft. The turbine blades control the output rotational speed delivered from the blades to an electrical generator and/or hydraulic pump that are designed to operate efficiently over a typical operating speed range.
One type of governor includes a set of springs which acts against a set of counterweights to set a desired blade pitch angle. The springs are often large and only operate on the principle of mechanical force balance with the counterweights. In these types of systems, there is no external mechanism to set the blade pitch. Other blade pitch control governors have been developed that entirely eliminate mechanical control systems that incorporate counterweights.
SUMMARYA ram air turbine governor includes a hub carrying multiple turbine blades. A sensor is configured to detect a parameter. A counterweight is coupled to at least one turbine blade and is configured to provide an input to the turbine blade in response to a centrifugal force to move the turbine blade from a first pitch position to a second pitch position. An electromechanical actuator is operatively coupled to the counterweight. A controller is in communication with the mechanical actuator and the sensor. The controller is configured to command the electromechanical actuator and move the turbine blade from the second pitch position to a third pitch position in response to the detected parameter.
The disclosure can be further understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:
An example RAT system 10 is illustrated in
A yolk plate assembly 34 cooperates with the counterweights 32. In particular, a cam follower 36 provided on the counterweights 32 is arranged between first and second spaced apart members 42, 44 of the yolk plate assembly 34. The yolk plate assembly 34 moves linearly along guide pins 38 with rotation of the blades 20. The yoke plate assembly 34 is affixed to a centrally located governor shaft 40.
A spring assembly 46 is arranged within a nose cone 48. The spring assembly 46, which includes a pair of concentric coil springs in the example, applies a spring force on the yolk plate assembly 34 to counteract the centrifugal force created by the counterweights 32. In this manner, the spring assembly 46 establishes a limit to the overspeed protection provided by the counterweights 32. Such an arrangement provides overspeed protection of about ±10-20% of an overspeed design limit.
An electromechanical actuator 52 is coupled to the governor shaft 40 to linearly move the yolk plate assembly 34, which changes the pitch of the blades 20 to a third pitch position. A coupling device 54 is used to mechanically interconnect the electromechanical actuator 52 and the governor shaft 40, if necessary. The electromechanical actuator 52 may be an acme screw, ball screw or other configuration that enables the use of a relatively small motor and prevents back-driving. The electromechanical actuator 52 may be powered by the generator 22, in one example.
The electromechanical actuator 52 communicates with one or more sensors and is used to increase (fine direction) or decrease (coarse direction) the pitch of the blades 20 in response to detected parameters from the sensors. For example, the electromechanical actuator 52 may refine the overspeed limit and/or manipulate the pitch of the blades 20 during other conditions, such as turbine start-up or blade vibrations.
A schematic of a RAT control system 56 is schematically illustrated in
A speed sensor 60, a condition sensor 62 and/or a vibration sensor 64, for example, are in communication with the controller 58. The speed sensor 60 may be indicative of air speed or the rotational speed of the turbine 18. In one example, the speed sensor 60 is provided by speed sensor integrated with the generator 22. The controller 58 is programmed to command the electromechanical actuator 52 to position the blades 20 such that the target overspeed limit is reached.
The condition sensor 62 may be a sensor that detects a turbine start-up condition, such as deployment of the RAT. In one example, the condition sensor may be a switch that initiates RAT deployment. The controller 58 is programmed to command the electromechanical actuator 52 to position the blades 20 initially to position in which the hub 19 rotates most rapidly up to desired operating speed.
The vibration sensor 64 is configured to detect undesired vibration in the RAT, for example, blade vibration. The controller 58 is programmed to command the electromechanical actuator 52 to position the blades 20 to a position that induces less vibration, for example, to a coarser blade pitch.
Another example RAT system 110 is illustrated in
Although an example embodiment has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of the claims. For that reason, the following claims should be studied to determine their true scope and content.
Claims
1. A ram air turbine governor comprising:
- a hub carrying multiple turbine blades;
- a sensor configured to detect a parameter;
- a counterweight coupled to at least one turbine blade and configured to provide a rotational input to the turbine blade in response to a centrifugal force to move the turbine blade from a first pitch position to a second pitch position;
- an electromechanical actuator operatively coupled to the counterweight; and
- a controller in communication with the electromechanical actuator and the sensor, the controller configured to command the electromechanical actuator and move the turbine blade from the second pitch position to a third pitch position in response to the detected parameter.
2. The ram air turbine governor according to claim 1, comprising a yoke plate assembly coupled to the counterweight and movable linearly with rotation of the blades.
3. The ram air turbine governor according to claim 2, comprising a governor spring cooperating with the yoke plate assembly and configured to provide a force counteracting the rotational input.
4. The ram air turbine governor according to claim 2, comprising a governor shaft affixed to the yoke plate assembly, and the electromechanical actuator coupled to the governor shaft and configured to move the yoke plate assembly in response to the command.
5. The ram air turbine governor according to claim 2, wherein the counterweight includes a cam follower coupled to the yoke plate assembly and configured to translate between linear and rotational movement of the yoke plate assembly and the blade, respectively.
6. The ram air turbine governor according to claim 1, wherein the sensor is a speed sensor, and the parameter corresponds to a rotational speed of the hub.
7. The ram air turbine governor according to claim 1, wherein the sensor is a start-up condition sensor, and the parameter is a start-up condition.
8. The ram air turbine governor according to claim 1, wherein the sensor is a vibration sensor, and the parameter is a vibration of the blade.
9. A ram air turbine governor comprising:
- a hub carrying multiple turbine blades;
- a sensor configured to detect a parameter, the parameter including at least one of a start-up condition and a vibration condition;
- an electromechanical actuator operatively coupled to the turbine blades; and
- a controller in communication with the electromechanical actuator and the sensor, the controller configured to command the electromechanical actuator and move the turbine blade between pitch positions in response to the detected parameter.
10. The ram air turbine governor according to claim 9, comprising a counterweight coupled to at least one turbine blade and configured to provide a rotational input to the turbine blade in response to a centrifugal force to move the turbine blade from a first pitch position to a second pitch position.
Type: Application
Filed: Jun 24, 2011
Publication Date: Dec 27, 2012
Inventors: William E. Soidel (Rockford, IL), Zaffir A. Chaudhry (S. Glastonbury, CT), Scott J. Marks (Oregon, IL)
Application Number: 13/167,801
International Classification: F01D 7/02 (20060101);