Downlock-pin actuator apparatus

[0002] This application claims benefit to U.S. provisional application 60/143,782 filed Jul. 14, 1999.

[0003] The present invention relates to latch and lock mechanisms, and lock control devices used with aircraft as a lock pin for their bombay doors.

[0004] In aircraft having bombay doors traveling at high speeds, it has become extremely important to limit the time that the bombay doors are open due to aerodynamic changes produced by the surfaces which are opened and/or because of alterations in the radar imaging of the aircraft.

[0005] It therefore has become imperative to attempt to open and close bombay doors and/or other control surfaces of aircraft in a rapid and rigid manner. Therefore, the actuators which move the surfaces must work in conjunction with locking pins which will position and ensure the stability of the doors or surfaces when they are in the open or closed position.

[0006] Locking mechanisms are known, some of which are employed in aircraft, and are disclosed in the following patents:

[0007] For example, Cairelli discloses a latching mechanism having gears and a cam which coact under the effect of a clock escapement mechanism to be held in position by a control pin.

[0008] However, none of the references identified above disclose or suggest a downlock-pin actuator apparatus according to the present invention.

[0009] It is an object of the present invention to provide a reliable downlock-pin actuator apparatus to securely lock bombay doors of aircraft.

[0010] It is another object of the present invention to provide a downlock-pin actuator consisting of a motor and flywheel for coaction with a clutch to drive a gear and linkage system for optimum storage of energy.

[0011] It is another object of the present invention to provide a downlock-pin actuator adapted for automatic actuation to control transfer movement of a pin of the actuator after a preselected period of time has elapsed.

[0012] It is another object of the present invention to provide a downlock-pin actuator of relatively compact size and light weight, i.e. approximately 2 pounds to be mounted in the confined spaces of an aircraft compartment.

[0013] It is another object of the present invention to provide a downlock-pin actuator having adjustable position sensing micro-switches to generate signals for the insertion and extraction position of the lock pin.

[0014] It is another object of the present invention to provide a downlock-pin actuator which operates at a relatively high speed and produces a relatively high amount of torque for its size.

[0015] It is another object of the present invention to provide a downlock-pin actuator which operates at relatively high speed, is relatively durable, and which is relatively reliable.

[0016] The downlock-pin actuator apparatus according to the present invention includes a motor which drives a single revolution clutch which drives a gear train through one half cycle in order to insert a lock pin of the apparatus and to retain the lock pin in the locked position. The apparatus of the present invention completes another revolution to extract the pin from the locked position to unlock the mechanism.

[0017] For a more complete understanding of the present invention, reference may be had to the following description of exemplary embodiments of the present invention considered in connection with the accompanying drawings, of which:

[0018] FIGS. 1 and 2 are schematic diagrams of elements of the downlock-pin actuator according to the present invention;

[0019] FIG. 3 is an exploded view of the downlock-pin actuator elements according to the present invention;

[0020] FIG. 4 is a view of the housing for the present invention; and

[0021] FIG. 5 is an electrical schematic of a system used in the present invention.

[0022] Referring to FIGS. 1-4, the downlock-pin actuator according to the present invention is shown generally at 10 and includes a flywheel 1 mounted to a motor 2 to actuate a gear 3 which coacts with another gear 4 to engage a clutch 5. A clamp 5A interconnects the clutch 5 with the gear 6 which meshes with the gear 7. The gear 7 is provided with an eccentrically positioned actuating cam 8. The actuating cam 8 is free to move in the fork 9A of lock pin 9 during the quick rotation of the gear 7. The cam will drive the sidewall of fork 9A to force the lock pin 9 in a quick powerful action in the direction of the arrow during the first phase of the actuation to project the locking pin 9.

[0023] After a predetermined time interval, the actuation cycle will repeat so that the actuating cam 8 will drive the lock pin 9 in a direction opposite to that of the arrow shown in FIG. 3.

[0024] The downlock pin actuating mechanism is driven by a motor gear train through a single revolution clutch. The single revolution clutch drives through one half cycle to insert the lock pin, and to retain the pin in the locked position. To extract the lock pin, the single revolution clutch is actuated to take another revolution to complete the lock cycle.

[0025] The single revolution clutch is shown schematically and includes a finger 5B which will engage a retractable pin from the clutch. The gear 6 which is driven by the clutch is half the pitch of gear 7 for the final gear stage. Therefore, a single rotation of gear 6 will produce half the rotation in gear 7 which will then displace the ram between the extend or retract position.

[0026] In order to achieve high speed operation in a compact package, the actuator uses the potential energy of the motor and flywheel to drive a ram or pin end to either the extend or retract position within 0.5 seconds. The actuator operates in the following manner: Two seconds before the unit is commanded to extend or retract, the motor 2 is energized and comes up to speed within 0.01 seconds. The clutch 5 is then energized, engaging the inertia of the motor 2 and flywheel 1 to the final gear stage 6, 7, which drives the output ram 9 by means of a cam 8 which is on the final output gear 7. The eccentric cam 8 engages the fork 11 on the rear of the output ram 9 and drives the ram as the cam rotates 180 degrees with every pulse of the clutch.

[0027] Calculations of the speed for the clutch are shown below.

[0028] Two microswitches 12B, 12C are used to send a signal to indicate the actuators position either extend or retract and are driven by the two tabs 9B, 9C machined into the output fork or ram 9.

[0029] The electrical circuitry of the downlock pin actuator is shown in FIG. 5 and includes input 28F which comes from the aircraft to actuate the system. The linear regulator in turn applies the voltage to the under voltage lockout. Next to that is the current limiter. The current limiter ramps forward as the current starts rising, and limits the current so it does not go over the peak. This circuit is used to drive the motor.

[0030] As mentioned, time is an extremely important factor of the invention. One of the uses for this type of device could be for quick opening doors on an aircraft. When the doors are opened, it is necessary to ensure that they are locked in place. If the doors are going to be open for only a brief period of time, such as 2 second, it is necessary for the actuator to move extremely quickly from a retracted position to a locked position and then just as quickly back to a retracted position.

[0031] Calculation of Lock Pin insertion time after the clutch has been actuated.

[0032] Calculation of motor speed immediately upon clutching-in of the clutched-in inertia group.

[0033] The motor speed will be calculated by conservation of energy method.

[0034] KEo=KE1

[0035] KEo=Kinetic energy of the rotating system prior to clutching in the load inertia group.

[0036] KE1=Kinetic energy of the entire system immediately after clutching-in of the load inertia and prior to application of the load torque.

[0037] KEo=Jo*Wo{circumflex over ( )}2/2 in-oz

[0038] J1=Jm+Jenoz-in-sec{circumflex over ( )}2

[0039] Jm=polar inertia of motor (oz-in-sec{circumflex over ( )}2)

[0040] Jen=polar inertia connected permanently to motor/Flywheel (oz-in-sec*2)

[0041] Wo=No load speed of motor system (rad/sec)

[0042] KE1=J1*W1{circumflex over ( )}2/2 IN OZ

[0043] J1=Jo+Je1 oz-in-sec{circumflex over ( )}2

[0044] Jel=clutched-in polar inertia of the gear train (oz-in-sec{circumflex over ( )}2)

[0045] W1=(WO{circumflex over ( )}2*Jo/(Jo+Je1)){circumflex over ( )}0.5 rad/sec

[0046] Calculation of Reduced Motor Speed due to Load Torque

[0047] Motor speed reduction is calculated at the rate of every 10% increment.

[0048] The conservation of energy and work is used to calculate motor speed reduction when load torque is applied.

[0049] KE1−work=KE2

[0050] KE1=J1*W1{circumflex over ( )}2/2 oz-in

[0051] Work=Force * Distance oz in

[0052] Work=(T1/Rp)Rp*TETA1+T1*TETA1 OZ-IN

[0053] Rp=pitch radius of motor pinion (in)

[0054] T1=applied load torque (in-lb)

[0055] TETA1=Angle through which the load torque acts (rad)

[0056] KE2=J1*W2{circumflex over ( )}2/2 oz-in

[0057] W2=(W1{circumflex over ( )}2*(J1−2*T1*TETA1) /J1){circumflex over ( )}0.5 rad/sec

[0058] Calculation of Time required for the motor to rotate through each increment of stroke

[0059] TETA1=Wav*trad

[0060] t=TETAL/Wav sec

[0061] TETA1=rad increment angle through which the load torque acts

[0062] Wav=(W1+W2)/2 rad/sec

[0063] t=time increment for motor to rotate through the angle increment (sec)

[0064] Lock Pin Insertion Time

[0065] Insertion Time=0.07055 sec

[0066] Total Lock Pin Insertion Time

[0067] The clutch will engage the load within 0.030 sec.

[0068] It will be understood that the embodiments described herein are merely exemplary and that a person skilled in the art may make many variations and modifications without departing from the spirit and scope of the invention. All such modification and variations are intended to be included within the scope of the invention as defined in the claims herein.