Disc spring providing linear axial motion

1. A servo control system for controlling a flight control surface in an aircraft, the servo control system comprising:

a pressure transducer containing a force sensing element, the force sensing element comprising a disc spring having a unitary body that circumscribes a central axis and has a repeating pattern that is symmetrical relative to the central axis, the disc spring being configured to provide linear axial motion while minimizing a radial load, wherein the disc spring is uniformly deflectable along the central axis in response to force acting on the disc spring;

a servo controller in communication with the pressure transducer, wherein the servo controller is configured to receive an output signal from the pressure transducer when the disc spring is deflected;

a flow control valve in communication with the servo controller, wherein the servo controller is configured to control the flow valve in response to the output signal; and

an actuator in communication with the flow control valve and the flight control surface, wherein the actuator is configured to control the flight control surface in response to the flow control valve.

2. The servo control system according to claim 1 , wherein the disc spring has a plurality of spirals that are continuous with each other and extend radially outwardly from the central axis, the plurality of spirals including nested symmetrical flights having walls with a non-uniform thickness.

3. The servo control system according to claim 2 , wherein the disc spring has a non-linearity of less than one percent.

4. The servo control system according to claim 2 , wherein the nested symmetrical flights are helical.

5. The servo control system according to claim 2 , wherein the disc spring has an inner diameter and an outer diameter, and the symmetrical flights have inner ends proximate the inner diameter and outer ends that are distally opposite the inner ends and proximate the outer diameter.

6. The servo control system according to claim 5 , wherein the inner ends of the symmetrical flights are equidistantly spaced from each other along the inner diameter and the outer ends of the symmetrical flights are equidistantly spaced from each other along the outer diameter.

7. The servo control system according to claim 5 , wherein the unitary body is continuous between each of the inner ends and between each of the outer ends.

8. The servo control system according to claim 2 , wherein the disc spring has at least two spirals, the nested symmetrical flights including a first symmetrical flight having a first inner end and a second symmetrical flight having a second inner end, wherein the first inner end and the second inner end are oriented 180 degrees from each other, and wherein the first symmetrical flight has a first outer end and the second symmetrical flight has a second outer end, and the first outer end and the second outer end are oriented 180 degrees from each other.

9. The servo control system according to claim 2 , wherein the disc spring has at least three spirals, wherein each of the at least three spirals has a symmetrical flight with an inner end and an outer end, wherein the inner ends are oriented 120 degrees from each other and the outer ends are oriented 120 degrees from each other.

10. The servo control system according to claim 1 , wherein the non-uniform thickness of the walls increases radially outwardly from the central axis.

11. The servo control system according to claim 10 , wherein the non-uniform thickness of the walls increases at a constant rate.

12. The servo control system according to claim 1 , wherein the disc spring has an extended position and a retracted position in which the disc spring is flat, the disc spring being axially moveable along the central axis between the extended position and the retracted position.

13. The servo control system according to claim 12 , wherein the disc spring has a first extended position and a second extended position, the disc spring being axially moveable in a first direction from the retracted position towards the first extended position and in a second direction from the retracted position towards the second extended position, the second direction being directly opposite the first direction.

14. The servo control system according to claim 13 , wherein a distance between the retracted position and the first extended position is equal to a distance between the retracted position and the second extended position.

15. The servo control system according to claim 1 , wherein the pressure transducer further includes a linear variable differential transducer and a piston that is moveable by the disc spring.

16. A force sensing element comprising:

a disc spring having a unitary body that circumscribes a central axis and has a repeating pattern that is symmetrical relative to the central axis, the disc spring being configured to provide linear axial motion while minimizing a radial load, wherein the disc spring is uniformly deflectable along the central axis in response to force acting on the disc spring, wherein the disc spring is configured for bidirectional movement along the central axis, wherein the disc spring has a first extended position and a second extended position, the disc spring being axially moveable in a first direction from the retracted position towards the first extended position when loaded and in a second direction from the retracted position towards the second extended position when loaded, the second direction being directly opposite the first direction.