US2222886A - Servomotor control system for airplanes - Google Patents

Description

Nov. 26, 1940. vOIGT 2,222,886

- SERVOMOTOR CONTROL SYSTEM FOR AIRPLANES Filed Jan. 16, 1937 trol surfaces.

Patented Nov. 26, 1940 w UNITED STATES PATENT A OFFICE SERVOMOTOR- CONTROL SYSTEM FOR AIRPLANES Waldemar Voigt, Haunstetten, near Augsburg, Germany, assignor to Siemens Apparate und Maschinen (Gesellschaft mit beschriinkter Haftung), Berlin, Germany, a corporation of Germany Application January 16, 1937, Serial No. 120,888 In Germany January 16, 1936 5 Claims. (01. 244-48) This invention relates to airplanes and more Referring more particularly to the drawings, particularly to the operation of the control surin Fig. 1 a control lever 11., pivoted at a fixed faces wherein an auxiliary source of power is point on the airplane fuselage, carries at its employed .to assist the pilot in moving the conlower end, pivotally attached thereto, a rod consisting of two sections b and c. The outer end One of the objects of the present invention is of section 0 is pivotally connected to the'operatto provide a servomotor interconnected with the .ing lever d of the airplane elevator 10. Between manually controlled lever to assist the pilot in the control rod sections b and c is arranged the effectively moving the elements of an airplane valve means am such a manner that the casing while in flight. of the valve is pivotally connected to the inner In the preferred embodiment it is a further end of the rod section c while the inner end of object of this invention to interconnect the manrod section 1) passes through a guide 1 into the ually controlled lever with the servomotoi' in such valve casing where it is connected to a movable a manner as to effect a reaction on the former member 2, shown in detail in Fig. 2. Two conwhen the latter is operated. duits g and h lead from'each end of the valve It is a further object to provide an adjuste to" each end of the fluid operated servomotor able connection between the manually controlled cylinder 1' which is also pivoted at a fixed point lever and the servomotor by which the amount on the airplane fuselage. Cylinder i contains a of reaction on the former from the latter may sliding piston 7 which is pivotally attached, at a be varied. suitable point through the piston rod k,'to the It frequently happens that dangerous stresses control rod section 0. Fluid under pressure is and strains are built up in the airplane strucsupplied to the valve e through a conduit 1 from ture as for instance when recovering rapidly a pump m driven by the main power plant of the from a nose dive. Accordingly, it is a further airpla a d s ar conduit 0 leads from the object of this invention to provide a mechanism valve e back to the suction side of the pump. I

which will automatically and temporarily take If desired, a Pressure a or 1t may be inover the operation of the control surfaces of terconnected with the conduit 1. the plane in the event that such stresses and n F th V v 8 f Fl 1 and 3 iS- Shown strains are developed to an excessive degree durin Cress-Section and consists of a casing lll ing flight. ing on the inside small recessed ports 4 and 5.

These and other objects of the invention will Att hed t h center f "t as on pp become apparent from inspection of th followsite sides thereof, are conduits l and 0 which ing specification when read with reference to represent pe e y the fl et nd i the accompanying drawings wherein is illustrateharge- At h e d' of the casing,,oonduits 9 ed thepreferred embodiment of the invention. nd h lead to opposite ends of the servomotor It is to be expressly understood, however, that Cylinder 11 The piston Valve 2 is 'recessed as the drawings are for the purpose of illustration wn a 211 for cooperation with the p s 4 only and are not designed as a definition of the o 5 d is operated y eans of the control limits of the invention, reference being had to red Section The casing la is p v t y 0011- the appended claims for that purpose. nected to the inner end of control rod section 40 In the drawings; 0. Adjustable stop screws 8 and I, carried by Fig. 1 shows diagrammatically one form of the casing, serve to limit the piston travel. auxiliary w r t l for t application of The auxiliary control, diagrammatically illusfluid pressure for operating the elevator of an trated in Operates in the following manairplane; hell Fig 2 shows, i t t preferred form When the control lever a is moved in the diof the control valve diagrammatically illustrated motion indicated by the arrow, a force s transat e in Fig. 1; I mitted through the argi/section b to move the Fig. 3 shows diagrammatically the preferred V v 2 t h l ainst the adjustable stop form of the auxiliary power contro1; screw 6. This interconnects conduits Z and g Fig. 4 shows, in section, the control valve diathrough the recessed ports 2a and 4, thereby grammatically illustrated at e" in Fig. 3, and subjecting the right hand side of piston 1' to Fig. 5 shows, in section, the adjustable confluid pressure. The other side of the piston is nection diagrammatically illustrated at q in Fig. connected to the discharge through conduits h 3. and 0. As the piston 9' moves to the left under the action of fluid pressure, it draws the control rod section 6 with it by means of the piston rod is, thereby moving the elevator 11 in an upwardly direction. As the control rod section 0 moves to the left, the valve casing I0, being pivotally connected thereto, is also moved to the left and if the control rod section 'b is held stationary, valve 2 will thereby lap ports I and o.

In the event of power failure, the manual effort applied to the lever a in the direction of the arrow, will move the elevator p in an upward direction since a linkage connection is formed by the lever a, control rod section b, valve 2, stop screw 6, casing l0 and control rod section a.

The area of piston a and the pressure of the fluid may be varied to exert any desired force, such as for example, a force less than that required to actuate the control surface p so that it will function merely as an assistor.

In Fig. 3 is shown, diagrammatically, the preferred embodiment of this invention and consists of parts similar to that of Fig. 1. The control rod a carries, just below its fixed pivot, an externally threaded, rotatable sleeve q which cooperates with an internally threaded non-rotatable ring l2, shown in detail in Fig. 5. This ring is connected to the servomotor cylinder casing through the rod T which is pivoted at each end.

A control valve e" is interposed in the inlet and discharge conduits Z and o and is interconnected with the conduits g and h by means of conduits g and h" respectively. This valve serves to control the fluid passing through the valve e in accordance with certain conditions referred to hereinafter.

In Fig. 4, the control valve e" of Fig. 3, is shown in cross-section and consists of a casing I0" firmly afiixed in a vertical position to the fuselage of the airplane. The piston valve 2" is provided on each side with annular recesses l4 and I6 formed between the smaller pistons l 8 and 20 which are connected to the main piston 2" through stems 22 and 24. Adjustable stops 6" and 1" are provided in each end of the casing. Normally the inlet conduit 1 is continuous through recess l4 while the discharge conduit 0 is continuous through recess l6. Conduits g" and h" interconnect with conduits g and h of the control valve e and are normally covered by the pistons 2 and I8 respectively. The piston valve is pressed against the upper stop by means of a spring 9.

The connections between the threaded sleeve q and the servomotor casing are preferably formed in such a manner that the first movement of the lever a actuates the valve e to energize the servomotor.

The force exerted by the servomotor 1' through the pivoted rod r and ring l2 on the sleeve q is less than the total force required to actuate the control surface 17 and therefore only assists the operator in moving the rod a clockwise. This assisting force may be increased or decreased as the operator desires by rotating the sleeve q and thereby adjusting the ring I2.

Normally the operation of Fig. 19a is similar to that of Fig. 1. Recesses l4 and IS in valve e" permit the flow of fluid to and from the valve 6 and servomotor i without interruption. When, however, the airplane is righted after a nose dive, the centrifugal acceleration which occurs, owing to the upward curvature of the flight path, will manifest itself in increased weight of all the various parts. This weight, if unduly increased, may endanger the airplane structure.

The tension of spring 9 is so adjusted that excess centrifugal acceleration will force the valve piston 2" downwards. In this new position, the inlet conduit l and the discharge conduit 0 will be closed off by the pistons 2" and 20. By closing off the normal inlet and discharge conduits, the conduits g" and h" will be uncovered and the flow of fluid will then be through the conduit 1, recess I 4, conduit 71." into the left-hand side of servomotor 2'; The discharge on the right-hand side of the cylinder will be through conduits g, g, recess l6 and conduit 0.. This .will cause the piston a to move to the right and through the piston rod is and control rod section 0 the elevator 1: will be moved in a clockwise direction, thereby reducing the upward path of the airplane. When this upward path has been modified so that centrifugal action no longer affects the piston valve, the spring 9 will push it up to its normal position thereby reestablishing the fiow of fluid as in normal flight.

This auxiliary valve e may be designed so that it can be made entirely ineffective in extreme emergency cases where the altitude of the airplane is insuflicient to permit a safe path of acceleration.

It is obvious that the invention disclosed includes within its scope the actuation of other elements or objects aside from those mentioned herein, which require the use of auxiliary power for their operation.

While one illustrated embodiment of the invention has been described in detail, it is not my intention to limit its scope to that embodiment or otherwise than by the terms of the appended claims.

What is claimed is:

1. In an-airplane having a controlled member, a controlling lever connected thereto for directly actuating the same, means including a servomotor having a connection. with said controlled member for moving the latter by power, said servomotor having relatively movable elements, one element thereof connected to the controlled member for moving the latter in either of two directions, means connecting the other element to said controlling lever, an adjustable coupling forming a part of said connecting means, control mechanism for governing the energization of said servomotor, said mechanism including a movable device connected with said controlling lever whereby movement of the latter in opposite directions serves to energize said servomotor in opposite directions, and means responsive to centrifugalforce developed in the airplane travelling in a curved path during a sudden recovery from a dive for changing the energization of said servomotor. V

2. In anairplane having a controlled element, a controlling member, means including a power actuator having a connection with said controlled element for moving the latter by power, control mechanism for governing the energization of said power actuator, said mechanism comprising a pair of valves separate from each other, the first of which is cooperatively associated with the said controlling member for governing the energize.- tion of said power actuator, the second of which is cooperatively associated with said first valve and with said power actuator for energizing the power actuator independently of said first valve when the latter is in one position.

3. In an airplane having a controlled member,

a controlling member, means including a power actuatorhaving a connection with said controlled member for moving the latter by power, control mechanism for governing the energization of said power actuator, said mechanism including a movable device connected with said controlling member whereby movement of the latter in opposite directions serves to energize said actuator in opposite directions, additional means separate from said mechanism cooperatively associated with said movable device and with said power actuator, said means including a member subjected to the action of centrifugal force developed in the airplane travelling in a curved path by a sudden recovery from a dive for changing the energization of said power actuator when said movable device is in one position.

4. In an airplane having a controlled member,

'a controlling lever connected thereto for directly actuating the same, means including a servomotor having a connection with said controlled member for moving the latter by power, said servomotor having relatively movable elements, one element thereof connected to the controlled member for moving the latter, the other element thereof connected to said controlling lever, control mechanism for governing the energization of said servomotor, said mechanism comprising a pair of valves, the first of which is cooperatively associated with the said controlling lever for governing the energization of said servomotor, the second of which is cooperatively associated with said first valve and with said servomotor for energizing the servomotor independently of said first valve when the latter is in one position.

5. In an airplane having a controlled element,

.a controlling lever connected thereto for directly actuating the same, means including a servomotor having a connection with said controlled element for moving the latter by power, control mechanism for governing the energization of said servomotor, said mechanism including a control valve connected with said controlling lever whereby movement of the latter in opposite directions serves to energize said servomotor in opposite directions, a pilot valve cooperatively associated with said control valve and with said servomotor, said pilot valve comprising a resiliently supported piston normally controlling the supply of pressure fluid to the control valve, said piston being responsive to the action of centrifugal force developed by the airplane travelling in a curved path in response to a sudden recovery from a dive for closing the flow of pressure fluid to said control valve and opening the flow of pressure fluid to said servomotor whereby the latter is energized independently of the control valve, when the control valve is in one position.

WALDEMAR VOIGT.

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