HK1155131B - A compound spring - Google Patents

Description

Composite spring

The application is a divisional application, the parent application is an invention application with the application number of 200780039192.5, the invention name is 'control rod suitable for telex flight control system and connecting rod used therein', the application date is 8.8.2007, and the international publication number is WO 2009/020453.

Technical Field

The present invention relates generally to the field of control sticks (e.g., joysticks, side sticks, etc.) suitable for use in detecting and communicating manual operator commands to objects (e.g., wing surfaces, etc.) to be moved in response to such commands, to improved linkages for mounting such control sticks on suitable supports, and to improved compound springs particularly suitable for use therein. One particular application contemplates the transmission of pilot or copilot commands to various wing surfaces via fly-by-wire flight control systems.

Background

Joysticks are well known devices for transmitting pilot manually input commands to various aircraft flight control surfaces. In their earlier versions, the joystick was typically mounted on the floor of the cockpit between the legs of the driver. They are generally mounted so that the lever can make a compound pivotal movement about two mutually perpendicular axes representing the pitch and roll axes of the aircraft. However, the position and size of these levers often interfere with other devices and freedom and require considerable space to provide the allowable range of motion of the handle.

Initially, such joysticks were connected to various airfoil surfaces by mechanical linkages and cables. These couplings are unnecessarily heavy and bulky and do not readily allow for redundancy.

As the performance, control, and complexity of aircraft have increased, fly-by-wire systems have been developed. In these systems, the various manual inputs to the joystick handle are first converted to electrical signals, which are then transmitted along various redundant paths to one or more computers, and then to remotely located motors and drives that control the movement of various airfoil surfaces. Thus, the mechanical transmission from the joystick and the column wheel is replaced by an electrical transmission from the transducer associated with the lever.

In recent years, side rods have been developed. They are typically mounted in front of armrests on the outside of the driver and co-driver seats. The driver is usually seated in the left seat and the co-driver in the right seat. Thus, the driver's side bar is generally to the left and the co-driver's side bar is generally to the right. Thus, the driver will normally place his left arm on his left armrest and will control his side bar with his left hand, while the co-driver will normally place his right arm on his right armrest and will control his side bar with his right hand. In many cases, the tilt of the joystick about a suitable axis is detected as a function of position (see, e.g., U.S. Pat. Nos. 5,125,602 and 5,291,113). In other cases, it is detected as a function of force or moment (see, e.g., U.S. Pat. Nos. 6,028,409; 5,694,010 and 5,347,204).

Some of these side bars are mounted on a gimbal to allow omnidirectional or compound pivotal movement about the pitch and roll axes (see, e.g., U.S. Pat. Nos. 5,291,113 and 5,694,014).

The sidebars are generally considered to be "passive" or "active". A "passive" sidestick unit ("PSSU") detects the pitch and roll commands of the driver or co-driver as a function of the tilt displacement of the associated joystick about the appropriate axis. These instructions are then provided to one or more flight control computers, which in turn control the movement of the various wing surfaces to control the pitch and roll of the aircraft. The joystick may provide redundant command signals to the computer. Some of these devices use various springs to impart various force-feel gradients to the control lever handle to provide the rider and co-rider with tactile sensation and feel for various conditions (see, e.g., U.S. patent 5,125,602).

An "active" sidestick unit ("ASSU") is similar to the PSSU, but also incorporates a motor to couple the position of the sidesticks of the driver and co-driver. If the pilot is actively controlling the aircraft and the co-pilot's hand is off his joystick, the co-pilot's stick will be driven back to follow and repeat the various positional movements imparted to his stick by the pilot. Thereby, the driver's and co-driver's sticks will tilt simultaneously in parallel and in unison, as if slaved to each other. Conversely, if the co-pilot is actively controlling the aircraft and the pilot's hand is off his stick, the pilot's stick will follow and repeat the position command given to his stick by the co-pilot. This is sometimes referred to as "location re-replication" (see, e.g., U.S. Pat. No. 5,125,602), or "electronic cross-cockpit interconnect" (see, e.g., U.S. Pat. No. 5,456,428), or simply "cross-coupling" (see, e.g., U.S. Pat. No. 5,694,014).

If the aircraft is provided with an autopilot, the autopilot may generate an electrical signal that is provided to motors associated with the pilot's and co-pilot's control sticks to drive both control sticks back.

It is also known to provide such sidebars with various feedback force sensations that simulate the "feel" of the resistance of the airfoil surface to various input commands, or transitions between various operating states, or even vibrations in an emergency. It is also known to dampen such control levers to prevent the lever from freely moving away from the manually commanded position in the event that the operator were to release the lever (see, e.g., U.S. Pat. Nos. 5,125,602; 6,459,228 and 4,069,720). The disclosure of each of the above patents is incorporated herein by reference in their entirety.

However, column wheels, joysticks and side sticks developed to date include various mechanical linkages and couplings that introduce friction, backlash (backlash) and the like into the motion of the control stick. These designs are considered heavy and bulky. They are believed to interfere with the continuous smooth transmission of the pilot's manual input signals from the control stick to the flight control computer, and the continuous smooth transmission of the various electrical signals used to drive the control stick back in accordance with electronically commanded movements and forces.

Thus, it is believed that there is a proven and long-felt need to: improved control sticks for use in both "passive" and "active" fly-by-wire flight control systems, improved linkages for use with such improved control sticks, and improved compound torsion springs that may be used therein are provided.

Disclosure of Invention

By referring to the corresponding parts, portions or surfaces of the disclosed embodiments for illustrative purposes only and not by way of limitation, the present invention generally provides an improved control lever 20, an improved linkage 27 for use in a control lever, and an improved compound spring 38.

In one aspect, the present invention provides an improvement to a control stick 20 mounted on a support 21 and adapted to control the movement of an object (not shown). The improvement substantially comprises: a support member 21; and a link 27 for mounting the handle 24 on the support so as to be about two mutually perpendicular axes x_u1～x_u1And x_u2～x_u2Selectively making compound pivotal movements to provide input to the control lever. This connecting rod includes: a first gimbal ring 22 mounted on the support; an upper member 23 mounted on the first gimbal, the upper member having a handle 24 disposed above the first gimbal and having a lower portion 25 disposed below the first gimbal; an intermediate member 26; a second gimbal 28 connecting the upper member and the intermediate member; and a lower member 29, one of the intermediate and lower members being movably mounted on the other of the intermediate and lower members to permit relative movement between the intermediate and lower members when the handle is moved relative to the support; a third gimbal 30 connecting the lower member to the support; and an elastic member 31, such as a column spring, provided to bias the direction of relative movement between the intermediate member and the lower member. The handleThe handle may be grasped and selectively moved relative to the support to provide input to the linkage.

The resilient member 31 may be arranged to apply a force that substantially eliminates all backlash from the linkage. The resilient member may urge the handle towards a null position relative to the support.

The improvement may also include an object to be moved (e.g., a wing surface and at least one transducer 32, 32, 32 mounted on the support to sense the position of a portion of the linkage and generate an electrical signal proportional to such sensed position.

The improvement may also include a plurality of springs 33, 33, 34, 34 acting between the support and the link. These springs have different force-deflection characteristics. At least one of these springs may be a compound spring 38.

In the improved control lever, the range of motion between the intermediate member and the lower member when the handle is moved off-null may be a function of the ratio of (a) the distance a between the axes of the first and second gimbals to (B) the distance B between the axes of the second and third gimbals when the handle is in its null position. (i) An off angle between a virtual line connecting the axes of the first and second gimbals and (ii) a virtual line connecting the axes of the second and third gimbals may be substantially equal to a sum of (a) an off angle of the upper member with respect to a virtual line connecting the axes of the first and third gimbals and (b) an off angle of the lower member with respect to a virtual line connecting the axes of the first and third gimbals.

The improvement may also include a magnetic detent 35 which acts between the support and the linkage to require a force to be applied to the handle to move the handle off null.

The improvement may also include a damper 36 acting between the support and the link to damp the velocity of the handle. The damper may be an eddy current damper.

The improvement may also include a motor (not shown) acting between the support and the linkage to move the linkage as a function of a signal provided to the motor.

The improved control stick may be mounted on an aircraft having a fly-by-wire control system, and the improved control stick may be mounted on a pilot's station and a co-pilot's station. The control sticks of the driver and co-driver may be cross-coupled to move together. The aircraft may have an autopilot, and the pilot's and co-pilot's control sticks may be moved together in response to a signal provided by the autopilot.

In another aspect, the present invention provides an improvement to a control lever 20 adapted to control the movement of an object. This improvement piece includes: a support member 21; an upper member 23 pivotally mounted on the support, the upper member having a lower portion 25 disposed below its pivotal connection to the support; an intermediate member 26 having an upper portion pivotally connected to the lower portion of the upper member and having a lower portion; and a lower member 29 having a lower portion pivotably mounted on the support and having an upper portion; wherein the lower portion of the intermediate member is movably mounted on the upper portion of the lower member such that pivotal movement of the upper portion of the upper member relative to the support will result in pivotal movement of the intermediate and lower members relative to the support; and an elastic member 31 provided to bias a relative movement direction between the intermediate member and the lower member.

The upper member may be mounted on the support so as to be about an axis x located intermediate the length of the upper member_u1～x_u1Or x_u2～x_u2For pivotal movement, the upper member can have an upper portion disposed above the axis and configured to serve as a handle 24 that can be grasped and selectively manipulated to provide input to the linkage.

The upper member can be mounted with respect to the support about two mutually perpendicular axes x_u1～x_u1And x_u2～x_u2Making a compound pivoting motion.

The force exerted by the resilient member may urge the upper member to move toward a null position relative to the support. The resilient member may be arranged to apply a force that substantially eliminates all backlash from the linkage. The force exerted by the resilient member may be adjustable.

The range of motion between the intermediate member and the lower member when the upper member is moved off null may be a function of the ratio of (a) the distance a between the pivot axis between the upper member and the support and the pivot axis between the intermediate member and the support when the upper member is in its null position to (B) the distance B between the pivot axis between the intermediate member and the support and the pivot axis between the lower member and the support when the upper member is in its null position. (i) An angle of departure between a virtual line connecting the axes of the first and second gimbals and (ii) a virtual line connecting the axes of the second and third gimbals may be substantially equal to a sum of (a) an angle of departure of the upper member with respect to a virtual line connecting the pivot axis between the upper member and the support and the pivot axis between the lower member and the support and (b) an angle of departure of the lower member with respect to a virtual line connecting the pivot axis between the upper member and the support and the pivot axis between the lower member and the support.

The upper member and support may be connected by a universal joint, such as a gimbal mechanism 22.

The intermediate member 26 can be mounted with respect to the upper member about two perpendicular axes x_M1～x_M1And x_M2～x_M2Making a compound pivoting motion.

The upper and intermediate members may be connected by a universal joint, such as a gimbal mechanism 28.

The lower member 29 can be mounted with respect to the support about two mutually perpendicular axes x_L1～x_L1And x_L2～x_L2Making a compound pivoting motion.

The lower member and the support may be connected by a universal joint, such as a gimbal mechanism 30.

The lower portion of the intermediate member may be slidably received in the upper portion of the lower member.

The resilient member may contribute to the force-feel gradient of the grip portion.

The improvement may further comprise: at least one first position sensor 32, 32, 32 mounted on the support and engaging the lower portion of the upper member to provide a first output signal as a function of the position of the lower portion of the upper member about one of the axes; and possibly at least one second displacement sensor 32, 32, 32 mounted on the support and engaging the lower portion of the upper member to provide a second output signal as a function of the position of the lower portion of the upper member with respect to the other of the axes.

The improvement may further comprise: a first upper spring 33, such as a compound spring, acting between the upper member and the support to influence the force required to move the handle about one of the axes; and possibly a second upper spring 33, such as a compound spring, acting between the upper member and the support to influence the force required to move the handle about the other of the axes.

The improvement may further comprise: a first intermediate spring 34, such as a compound spring, acting between the intermediate member and the support to influence the force required to move the handle about one of the axes; and possibly a second intermediate spring 34, such as a compound spring, acting between the intermediate member and the support to influence the force required to move the handle about the other of the axes. The first intermediate spring provides a significant change in force-feel gradient to alert the operator to changes in handle displacement.

The improvement may also include a resistance device 35 for exerting a small force on the intermediate member, wherein the force is the force that the operator must overcome to grip the handle out of the zero position. The obstruction means may comprise a plurality of magnets mounted on the support and intermediate member.

The improvement may also include a damper 36 acting on the lower member to damp the velocity of the handle. The damper may be an eddy current damper.

In another aspect, the present invention provides a control lever 20 generally comprising: a support member 21; a link 27 having a handle 24 and mounted on the support; and a plurality of position sensors 32, 32, 32 mounted on the support and engaging the links at different positions of the links, each of the position sensors being adapted to produce an output signal as a function of the position of the link relative to the support; a plurality of springs 33, 33, 34, 34 acting between the support and the link to influence the force-feel characteristics of the link; a magnetic brake 35 acting between the support and the linkage to require the operator to apply a force to the handle to move the handle away from the null position; and a damper 36 acting between the support and the link to damp the velocity of the handle.

Each of the springs may have its own individual force-deflection characteristic, and the force-feel characteristic of the linkage may be a function of the individual force-deflection characteristics of the springs. In a preferred embodiment, the force-feel characteristic of the linkage is a function of the sum of the various individual force-deflection characteristics of the springs and the geometry of the linkage.

The springs may urge the handle to move towards a null position relative to the support, and one of the springs may be arranged to apply a force which substantially removes all backlash from the linkage.

In yet another aspect, the present invention provides a compound spring 38 generally comprising: a first tubular portion 40 having a first wall extending between a first end 41 and a second end 42; at least one first slot 43 extending through the first wall and defined between opposing slot walls such that upon relative rotation of the first and second ends, the spring will have one force-displacement characteristic when the slot walls are spaced apart from one another and another force-displacement characteristic when the slot walls are in contact with one another; and a third force-displacement characteristic when the first and second ends are bent relative to each other in a common plane.

The first slot may be elongated in a direction parallel to the longitudinal axis of the first tubular portion. There may be a plurality of first slots, and the slots may be circumferentially spaced from one another about the first tubular portion.

The spring may also include a second tubular portion 44 disposed within the first tubular portion and having a second wall extending between the second end 42 and a third end 45. The second tubular portion may have at least one second slot 46 extending through the second wall and defined between opposing slotted walls. The second slot may be elongated in a direction parallel to a longitudinal axis of the second tubular portion, and the plurality of second slots may be circumferentially spaced from one another about the second tubular portion.

The third end 45 may be disposed near the first end 41.

It is therefore a general object of the present invention to provide an improved control stick.

Another object is to provide an improved linkage for use in a control stick.

It is a further object to provide an improved compound spring which is particularly suitable for use in a control lever.

These and other objects and advantages will become apparent from the foregoing and ongoing written specification, the drawings and the appended claims.

Drawings

FIG. 1 is a schematic view of one form of mechanical linkage of the improved control lever, this view showing the positions of the upper, intermediate and lower members when the handle is in its null position relative to the support;

FIG. 2 is a schematic view of the arrangement shown in FIG. 1, but showing the positions of the upper, middle and lower members when the handle has been moved to a non-zero position;

FIG. 3 is a simplified schematic diagram showing the angles between the various link members when the handle has been moved to a non-zero position;

FIG. 4 is a simplified schematic diagram showing the forces and moments acting on the various link members when the handle has moved to a non-zero position;

FIG. 5 is a simplified schematic diagram of the control lever linkage showing various springs, sensors and dampers acting between the support and various components;

FIG. 6 is a set of graphs of the base spring, soft stop and differential functions of the secondary spring, force (ordinate) Vs rotation angle (abscissa) characteristics of the column spring, and further illustrating the additive or superimposed function of all of the springs described above;

FIG. 7 is an isometric view of one form of the improved composite torsion spring;

FIG. 8 is a side view of the spring shown in FIG. 7;

FIG. 9 is a horizontal cross-sectional view taken generally on line 9-9 of FIG. 8;

FIG. 10 is an isometric view of a commercial version of the improved control lever with the handle shown already tilted to a non-zero position, showing the compactness of the packaging of this particular embodiment.

Detailed Description

It should first be clearly recognized that: throughout the several figures, like reference numerals are used to identify like structural elements, portions or surfaces that themselves may be further described or explained by the entire written description, of which this detailed description is an integral part. Unless otherwise indicated, the drawings are intended to be read (e.g., cross-hatching, arrangement of parts, proportion, angle, etc.) together with the specification, and are to be considered a portion of the entire written description of this invention. In the following description, the terms "horizontal," "vertical," "left," "right," "up" and "down," as well as adjectival and adverbial derivatives thereof (e.g., "horizontally," "rightwardly," "upwardly," etc.) merely refer to the orientation of the illustrated structure as the particular drawing figure faces the reader. Similarly, the terms "inwardly" and "outwardly" generally refer to the orientation of a surface relative to its axis of extension or rotation (as the case may be).

Referring now to the drawings, the present invention provides certain improvements to control sticks. Such a control stick may be a joystick, a side stick, or some other type of control device for remotely controlling an object. In the drawings, the improved control stick is depicted as a side stick for an aircraft to control various wing surfaces on the aircraft. This is, however, merely an illustration and does not limit the scope of the appended claims.

One form of mechanical linkage for the improved control lever is generally shown in fig. 1, 2 and 5.

Referring now to fig. 1 and 2, an improved control stick, generally indicated at 20, is shown mounted on a suitable support, generally indicated at 21. In an aircraft environment, the control stick 20 will typically be mounted in an aircraft cockpit for controlling the movement of remote objects such as flaps, rudders, ailerons, and the like.

The configuration shown in fig. 1 and 2 schematically depicts a link (27) comprising a three gimbal mechanism. A "gimbal" herein is a device that: the device has two rings which are mounted at right angles to each other so that the object can remain suspended therein, irrespective of the movement of the support on which the object is mounted. It is a special type of joint and connection of a large class that allows compound pivotal movement about two mutually perpendicular axes. Other joints and connectors within this general category include universal joints, ball and socket joints that allow for omnidirectional pivotal movement of one member relative to another, and the like. More specifically, the improved connecting rod generally includes a first or upper balancing ring 22. The upper member 23 is mounted on a first gimbal, first plateThe weighing ring being mounted on the support and intended to be rotated about mutually perpendicular axes x_u1～x_u1And x_u2～x_u2A compound pivoting motion. The upper member has a handle 24 disposed above the first gimbal and has a lower portion 25 disposed below the first gimbal. The link is shown further comprising an intermediate member 26 and a second gimbal 28, the second gimbal 28 connecting an upper marginal end portion of the intermediate member and a lower marginal end portion of the upper member and being adapted to be mounted about mutually perpendicular axes x_M1～x_M1And x_M2～x_M2A compound pivoting motion. The device is also shown with a lower member 29. One of the lower member and the intermediate member is movably mounted on the other of the intermediate member and the lower member. In the illustrated construction, the lower marginal end portion of the intermediate member 26 is slidably and telescopically received in the lower member 29, but the construction may be reversed if desired. The lower edge end of the lower member 29 is mounted on the support by means of a third balancing ring 30 for the axis x perpendicular to each other_L1～x_L1And x_L2～x_L2A compound pivoting motion. A helical spring 31 is arranged to act between the lower member and the intermediate member. The spring is constantly compressed and continuously urges the intermediate member downward relative to the lower member. The net effect of this is to eliminate substantially all backlash from the three-member linkage.

The mechanical linkage is shown in figure 1 in a centered or zero position relative to the support. In this position, the longitudinal axes of all three members 23, 26 and 29 are vertically aligned. In fig. 2, the uppermost handle is shown tilted to the left relative to the support, with consequent rightward movement of the lower marginal end portion of the upper member. It is also noted that: the movement being about the axis x by means of the intermediate and lower members_L2～x_L2The axial movement of the intermediate member relative to the lower member and the additional compressive displacement of the spring 31.

As noted above, while the present invention is shown as being implemented in the form of a driver's and co-driver's side-stick, those skilled in the art will readily appreciate that such a mechanism may be implemented in the form of a joystick, or some other type of control stick for controlling an object. The object itself may be a wing surface of an aircraft, or some other object.

Figure 3 is a further simplified schematic of the linkage when the handle has moved out of the null position. Although the gimbal mechanism allows compound pivotal movement about two mutually perpendicular axes, the embodiment schematically illustrated in fig. 3 depicts movement about only one such axis for each gimbal. The upper pivot point of the first gimbal is defined by x_u2Indicating that the middle pivot point of the second gimbal is x_M2Indicating that the pivot point of the lower gimbal is x_L2Indicated, and thus consistent with the nomenclature above. At zero position, the intermediate pivot point x_M2And a lower pivot point x_L2The coupling between is indicated by reference numerals 26, 29 (which is the effective combined length of the intermediate and lower members) and by reference numerals 26 ', 29' when in the non-zero position shown.

When the handle is in its null position, the links are vertically aligned, which is more clearly shown in FIG. 1. In fig. 3, the distance between the upper and middle pivots 31, 32 is indicated by distance a, the middle and lower pivots x_M2、x_L2The distance between is indicated by distance B. When the handle is moved from the zero position to the non-zero position indicated at 24 ', the lower end of the upper member will swing to the position indicated at 25' and the intermediate and lower members will move to the alternative positions indicated at 26 ', 29'. Angle a represents the angle at which the moving handle is offset from the null position. Angle B represents the angle at which the axes of the intermediate and lower members 26 ', 29' are offset from null. Angle C is the sum of angles a and B. The dimension dx represents the extension of the intermediate member relative to the lower member as the intermediate and lower members move from the zero position to the non-zero position, which is provided by the further compression of the spring 31. The equations for angles B and C, and distance dx are as follows:

AngleC＝AngleA+AngleB

referring now to FIG. 4, the force F applied by the hand of the driver_uThe arm distance GRP through the handle will be about the upper pivot point X_u2Form an upper moment M_u. The force exerted at the second pivot point will be a function of the distances a and b. About an intermediate pivot axis x_M2Is calculable. Similarly, the force exerted at the intermediate pivot point is also calculable. These relationships are represented by the following equations:

M_M＝-F_M×(GRP+A)-F_M×A

M_M＝-F_U×[(GRP+A)+A]

thus, the range of motion between the intermediate member and the lower member as the handle moves off null is a function of the ratio of (a) the distance between the axes of the first and second gimbal and (b) the distance between the axes of the second and third gimbal. The offset angle between a virtual line joining the axes of the first and second gimbals and a virtual line joining the axes of the second and third gimbals is substantially equal to the offset angle of the upper member relative to the virtual line joining the axes of the first and third gimbals and the offset angle of the lower member relative to the virtual line joining the axes of the first and third gimbals when the handle is in its null position.

FIG. 5 is a schematic view of the improved control rod 20, but further illustrating the various springs, sensors and dampers attached thereto. In fig. 5, the link 27 is again shown to include an upper member 23 having an upper handle 24 and a lower arm 25, an intermediate member 26 and a lower member 29. The lower marginal end portion of the intermediate member is depicted as being telescopically received in the lower member 29. The coil spring 31 continuously urges the intermediate member to move downwardly relative to the lower member. In fig. 5, the links are shown mounted for movement in only one plane, for simplicity of illustration. The upper member 23 is mounted on the support 21 so as to be about the axis x_U2Making a pivoting movement. The upper marginal end portion of the intermediate member is pivotably connected to the lower marginal end portion of the upper member about an axis x_M2Making a pivoting movement. Finally, a lower member 29 is pivotably mounted on the support so as to be about the axis x_L2And (6) moving. It should be clearly understood that: the construction may include three gimbal rings, although the details of these gimbal rings are not fully shown.

In fig. 1, the movement of the upper member 23 is detected by three redundant position sensors, respectively indicated at 32. Three of these position sensors are arranged at diametrically opposed positions. There are three more position sensors on either side of the upper member in a plane away from the sheet. The function of these position sensors is to detect and determine the range of tilting motion of the upper member relative to the support. Triple redundancy is provided by three of these position sensors.

Within the position sensor there are a plurality of opposed compound torsion springs, indicated respectively at 33. Likewise, two opposing torsion springs are shown in fig. 5, and there are two other opposing springs in a plane away from the paper. The function of these springs is to provide some force-feel resistance to the tilting movement of the handle. The structure and operation of these compound torsion springs are shown in greater detail in fig. 7-9 and described below.

Additional torsion springs, indicated at 34, 34 act between the upper member and the intermediate member to provide some secondary spring function and soft stop. This configuration may also include a magnetic detent, indicated at 35, which would necessarily require the driver to apply some force to move the linkage away from the null position.

Still referring to fig. 5, opposed eddy current dampers, each indicated at 36, are provided to act between the support and the lower member to damp the rate of movement of the links. Likewise, there are actually four rate dampers disposed in opposing pairs.

FIG. 6 illustrates the individual functions of the various springs shown in FIG. 5, and graphically illustrates the net function due to their superposition. The basic spring function is depicted as a straight line between the ordinate (force) and the abscissa (degree of rotation). The second spring 34 provides a soft stop and differential (differential), as indicated in fig. 6. The column spring 31 has the shown force-displacement characteristic. The curve labeled "net function" is obtained by superimposing the other four curves shown in fig. 6. Figure 6 illustrates that the various springs can be carefully chosen so that their properties, when superimposed, can impart any net function desired.

Referring now to fig. 7-9, one of the compound torsion springs is generally indicated at 38. The spring is shown with a mounting flange 39 adapted to be attached to a suitable structure depending on its application. The spring also has a first tubular portion (indicated at 40) connected to the flange, having a first end 41 connected to the flange and extending rightwardly therefrom to a second end 42. The first tubular portion is shown with at least one longitudinal slot indicated at 43. In the illustrated form, the first tubular portion has a plurality of such slots, and the slots are circumferentially spaced relative to the first tubular portion.

The spring may also have a second tubular portion 44 within the first tubular portion 40. The second tubular portion is physically connected to the first tubular portion at the second end 42 and extends to the left within the first tubular portion to a third end 45. The second tubular portion 44 has at least one longitudinally extending slot 46. In the form shown there are a plurality of such slots and the slots are circumferentially spaced from one another about the second tubular portion. The purpose of these slots is to provide the following capabilities: one force-displacement characteristic is exhibited when a torsional force is applied to the spring between the first and third ends before the opposing grooved walls physically contact each other, and a second force-displacement characteristic is exhibited after such grooved walls contact each other. In practice, the two tubular portions are mechanically connected in series, although the second tubular portion is provided within the first tubular portion. The circumferential spacing between the opposing longitudinally extending walls of the slot may be the same or different for the two tubular portions, depending on the particular force-displacement characteristics required. In addition, one unique feature of the improved spring is that it is not a pure torsion spring. Conversely, it may act as a torsion spring, and may also bend in a plane (such as the plane of the paper). The various torsion springs shown in fig. 5 can be selectively designed to provide a particular force-displacement characteristic as desired to contribute to the overall net function of the device. Another unique feature of the compound spring is: by having the inner tube in an inverted position on the outer tube, the spring is made axially compact. This provides a number of advantages as it enables the control lever to be provided in a small package or housing, as shown in figure 10.

Accordingly, the present invention provides an improved control lever, an improved linkage for use therein, and an improved compound spring.

Improvements in or relating to

The present invention contemplates that various changes and modifications may be made. For example, while one form utilizes a three gimbal mechanical linkage having various members, other types of linkages may alternatively be used. In fact, the connection may be simplified to a ball joint, a universal joint, or some other joint. Indeed, although the main advantage of these forms is that the joint and connector allow compound pivotal movement of the handle about mutually perpendicular axes, other types of links may be used in alternative configurations. In some cases, the links may be affected by the geometry of these couplings.

The column spring is believed to be particularly effective in eliminating substantially all backlash from the linkage. In effect, it continuously biases the linkage to eliminate backlash. However, while it is desirable to have such a column spring, it is not absolutely critical.

Different types of springs, sensors and dampers shown in fig. 6 may be associated with different parts of the linkage. Although the main spring 33 is associated with the upper member and the secondary spring is associated with the intermediate member, this configuration is not invariable, but may be varied. The position of the eddy current damper can also be changed. Similarly, the position of the disengagement detent 35 can also be changed and modified as desired.

The compound torsion spring is also considered unique. The spring is considered to be a compound spring that is operatively arranged to resist both torsion about its axis x-x and bending in a particular plane, such as (but not limited to) the plane of the paper. In its simplest form, the torsion spring has only one tubular portion, wherein the tubular portion is provided with at least one, but preferably a plurality of circumferentially spaced longitudinally extending slots. The function of these slots is that the spring will have one force-displacement characteristic when the second end is rotated relative to the first end and before the slot walls contact each other and a second, different force-displacement characteristic after the slot walls contact each other. By having the slots circumferentially spaced about the first tubular portion, the spring is more symmetrical and has similar resistance to bending in any particular direction. The spring may also have an inverted second portion within the first portion. Those skilled in the art will readily recognize that: the first and second portions, which are commonly connected at the second end, are mechanically connected to each other in series. However, the inverted interior or second portion allows for a compact construction, and this is believed to be particularly useful where the size of the housing is limited, such as in an aircraft.

Thus, while several simplified and progressively detailed embodiments of the invention have been shown and described, and several modifications and changes thereto discussed, those skilled in the art will readily appreciate that various additional changes and modifications may be made without departing from the spirit of the invention, which is defined and differentiated by the following claims.

Claims (8)

1. A compound spring, comprising:

a first tubular portion having a first wall extending between a first end and a second end;

at least one first slot extending through the first wall and defined between opposing slot walls such that upon application of a torsional force to the compound spring to rotate the first and second ends relative to each other, the compound spring will have one first force-displacement characteristic before the slot walls contact each other and a second force-displacement characteristic after the slot walls contact each other;

the compound spring has a third force-displacement characteristic when the first and second ends are bent relative to each other in a common plane in which the first and second ends lie.

2. The compound spring of claim 1, wherein said first slot is elongated in a direction parallel to a longitudinal axis of said first tubular portion.

3. The compound spring as defined in claim 1, further including a plurality of said first slots, said first slots being circumferentially spaced from one another about said first tubular portion.

4. The compound spring as defined in claim 1, further comprising a second tubular portion disposed within said first tubular portion and having a second wall extending between said second and third ends.

5. The compound spring as in claim 4, wherein said second tubular portion has at least one second slot extending through said second wall and defined between opposing slotted walls.

6. The compound spring of claim 5, wherein said second slot is elongated in a direction parallel to the longitudinal axis of said second tubular portion.

7. The compound spring as defined in claim 6, further comprising a plurality of said second slots, said second slots being circumferentially spaced from one another about said second tubular portion.

8. The compound spring as in claim 4, wherein said third end is disposed proximate said first end.