Horizontal stabilizer trim actuator assembly

Abstract

An assembly for manual control of an HSTA for controlling the position of a moveable surface, the assembly comprising a user-operated manual control element (1′) e.g. a trim wheel in the cockpit, a first motor and a first resolver connected to the manual control element and a second motor and a second resolver arranged to communicate with the first motor and the first resolver and to cause corresponding movement of the actuator, in use.

Claims

1. An assembly for controlling movement of a movable surface comprising: an actuator in engagement with the moveable surface; and an assembly for controlling the actuator, the assembly for controlling the actuator comprising: a horizontal stabilizer trim actuator (HSTA) of an aircraft in engagement with the moveable surface and an assembly for manual control of the HSTA for controlling a position of the moveable surface, the assembly for manual control of the HSTA comprising: a user-operated trim wheel, and transfer means configured to translate movement of the user-operated trim wheel to movement of the HTSA, the transfer means comprising: a first motor and a first resolver connected to the trim wheel and a second motor and a second resolver arranged to communicate with the first motor and the first resolver and to cause corresponding movement of the HTSA; wherein rotation of the trim wheel is detected by the first resolver, via the first motor, and is converted to an angle command, and wherein the second motor receives the angle command and drives the HSTA according to the angle command to cause a corresponding movement of the moveable surface, and wherein the second resolver detects the angular position of the moveable surface and provides an output indicative of mechanical input angle, the assembly further comprising a comparator arranged to compare the angle command with the mechanical input angle to provide a command to the second motor (7), based on the difference between the angle command and the mechanical input angle, to drive the HSTA responsive to the command; the assembly for controlling the actuator further comprising means for providing a feedback signal from the second resolver to the first motor indicative of the position of the HSTA, whereby the feedback signal causes corresponding movement of the trim wheel; the assembly for manual control of an actuator for controlling the position of a moveable surface further comprising: an automatic control arrangement for automatic control of the actuator via a control computer, and wherein operation of the assembly for manual control overrides operation of the automatic control arrangement; wherein the arrangement for automatic control of the actuator comprises a plurality of motors providing communication between the control computer and the actuator, and wherein, when the manual control overrides the automatic control, one of said plurality of motors operates as said second motor and the remaining of the plurality of motors is/are disconnected.

2. The assembly of claim 1, wherein the trim wheel is configured such that the user moves it by an amount or degree corresponding to or proportional to the desired movement of the movable surface.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Preferred embodiments will now be described with reference to the drawings, wherein:

(2) FIG. 1 is a schematic view of a conventional manual trim control system;

(3) FIG. 2 is a schematic of a modified manual trim according to the disclosure; and

(4) FIG. 3 is a schematic of a preferred arrangement according to the disclosure.

DETAILED DESCRIPTION

(5) A conventional manual trim will now be briefly described with reference to FIG. 1. The description relates to the control of a horizontal stabilizer, but the same principles also apply to other moveable surfaces, flaps etc. driven by an actuator.

(6) A trim wheel 1 is provided in the cockpit e.g. in the cockpit central panel to be easily accessible to the pilot. For manual control of the HSTA, the pilot turns the trim wheel by an amount corresponding to the amount that the tail stabilizer 3 or other moveable surface is to be adjusted. Rotation of the trim wheel 1 is translated by a linkage 4 comprising links, cables and pulleys, to the actuator 2, and corresponding movement of the actuator drives the moveable surface 3 as commanded. The pilot is informed by the rotary position of the trim wheel 1 of the position of the moveable surface 3. The rotary position of the trim wheel 1 also informs the pilot of the position of the moveable surface 3 when it has been driven automatically, as the trim wheel 1 is back driven by the linkage 4 responsive to movement of the HSTA.

(7) As mentioned above, the linkage in such systems is complex and bulky and position feedback is not highly accurate due to the long transfer chain.

(8) In the system of the present disclosure, described with reference to FIG. 2, a motor 5 and a resolver 6 are installed at the trim wheel 1′. In addition, the mechanical input to the HSTA is replaced by a motor 7 and a resolver 8. Thus, the complex, bulky linkage 4 is replaced. This will simplify maintenance.

(9) When a pilot wishes to take manual control of the HSTA, he turns the trim wheel 1. The rotation is detected by the first resolver 6, via the first motor 5, and is converted to an angle command θ.sub.TRIM. The angle command is received by the second motor 7 connected to the HSTA 20 to drive the HSTA 20 to cause a corresponding movement of the moveable surface 30.

(10) In the preferred arrangement, the second resolver 8, at the HSTA, provides position feedback as part of the control. The resolver 8 detects the angular position of the moveable surface 30 (or the drive position of the HSTA 2). This provides an output indicative of mechanical input angle θ.sub.MI. When an angle command is sent from the trim wheel resolver 6, this is compared e.g. at comparator or summer 9 with the mechanical input angle from the HSTA resolver 8 and a command is sent to the HSTA based on the difference in the commanded position and the actual position. This command is sent to the motor 7 of the HSTA.

(11) Feedback of the mechanical input angle, indicative of the position of the moveable surface, can also be fed back, from the HSTA resolver 8 mechanical input angle θ.sub.MI, to the trim wheel motor 5, via comparator 11, to turn the trim wheel 1′ (via first motor 5) so that its rotary position corresponds to the position of the moveable surface so that, even when the HSTA is controlled automatically, via the FCC (not shown) the pilot has a visual indication—the trim wheel 1′ position—as to the current position of the moveable surface.

(12) In a preferred embodiment, the system is also arranged such that if a pilot provides a manual command to the HSTA, as described above, this overrides the automatic FCC control by means of an override circuit 10.

(13) A conventional HSTA architecture includes three electrical motors connected to the FCC for the automatic control, as well as a manual input (as shown in FIG. 1) for the pilot. When the pilot takes control by means of the trim wheel 1′ an override mechanism de-clutches the electrical motors to give priority to the manual pilot operation.

(14) With reference to FIG. 3, during automatic control, control commands I.sub.SM are provided from the FCC (not shown) to control three electric motors 12,12′ which drive the actuator (not shown) by signals ELAC1, ELAC2 via mechanical stops 14. In one preferred embodiment of the system of this disclosure described above in relation to FIG. 2, one of the three electric motors 12′ usually used for the automatic FCC control can also be used as the HSTA motor 7 for the manual control. This also avoids the need for a mechanical overriding system, as the overriding function can be performed electrically.

(15) As shown in, and described above in relation to, FIG. 2, once the trim wheel 1′ is operated for the pilot to take manual control, this is compared with the FCC command, at 10. If the trim wheel command supersedes the FCC control, the electrical motors 12 are overridden—i.e. disconnected. In the preferred embodiment, when the manual operation takes over, two of the three motors 12 are disconnected e.g. by switches 11. The third motor 12′, however, is used as an input motor 7 in the manual control architecture of FIG. 2.

(16) As the motors and resolvers communicate via electric signals, the mechanical input and linkage is removed.

(17) Using this preferred architecture, there is no need for a separate mechanical manual input to the HSTA, thus greatly simplifying the system and providing a simpler, smaller, lighter system that is easier to maintain and that is more responsive, thus improving position feedback accuracy.