FORCE-SENSING DEVICE FOR VEHICLE RUNNING GEARS

Abstract

In a measuring device for the measurement of forces in a vehicle undercarriage, more particularly of the brake torque on a vehicle undercarriage, e.g. an aircraft landing gear, a sensor is introduced into a hollow connecting element that is transversally loaded by said forces, which sensor produces a measuring signal in function of a deformation of said connecting element. Distance measuring elements which detect the distance of the inner wall of said connecting element from said sensor are used as measuring elements.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be further explained by means of an exemplary embodiment and with reference to figures.

FIG. 1 schematic illustration of an aircraft landing gear (bogie);

FIG. 2 longitudinal section of a connecting element comprising a sensor of the invention;

FIG. 3 cross-section according to III-III in FIG. 2, connecting element in the unstressed condition;

FIG. 4 as FIG. 3 but connecting element loaded by brake torque;

FIG. 5 block diagram; and

FIG. 6 block diagram of a variant of the circuit of FIG. 5.

Claims

1. Device for measuring a force in a vehicle undercarriage, more particularly the brake torque, said force being transmitted to said vehicle undercarriage by a bar-shaped member and said bar-shaped member being loaded transversally by said force, wherein at least one sensor is arranged in the interior of said bar-shaped member and measures the deformation of said bar-shaped member that is due to said transversal load.

2. The device of claim 1, wherein said sensor includes at least one measuring element, said measuring element is arranged at a distance from a surface of said bar-shaped member, and said sensor is configured to generate a measuring signal in function of said distance.

3. The device of claim 1, wherein said measuring element includes at least two measuring means that are configured to measure radially directed deformations in said bar-shaped member that are essentially orthogonal to one another in order to be able to distinguish different types of deformations of said bar-shaped member.

4. A sensor for use in a device of claim 1, wherein said sensor has an enclosure that is attachable to said bar-shaped member, wherein a measuring element is arranged in said enclosure, and wherein said measuring element is configured to measure signals in function of the distance of said measuring element from a surface of said bar-shaped member.

5. The sensor of claim 4, wherein said measuring element is an inductive or capacitive distance measuring element or one based on eddy current effects.

6. The sensor of claim 5, wherein said sensor comprises at least one inductive distance measuring element and said enclosure of said sensor has a low or no magnetic permeability such that said sensor enclosure is essentially unrestrictedly permeable by the magnetic field of the inductive distance measuring element.

7. The sensor of claim 4, wherein on the outside of said enclosure, elastically deformable locating means are provided and said enclosure is essentially undeformable such that said sensor is maintained essentially centered and undeformed in the interior of said bar-shaped member by said locating means even when said bar-shaped member is deformed.

8. The sensor of claim 7, wherein said locating means are rings of a rubber-elastic material.

9. The sensor of claim 6, wherein said measuring element includes at least one coil on a core that extends essentially transversally through said enclosure and said enclosure is sufficiently permeable to a magnetic field such that a magnetic field can be generated which extends outside of said sensor enclosure and whose strength can be influenced by the spatial proximity of a magnetically conductive material.

10. The sensor of claim 4, wherein two measuring elements are provided which are arranged essentially orthogonally to each other in order to allow distinction of deformation types of a bar-shaped member surrounding said sensor.

11. The sensor of claim 4, wherein it comprises a circuit for driving said measuring element and/or conditioning its output signal.

12. A hollow bolt of a landing gear of an aircraft, and the sensor of claim 4 disposed in said hollow bolt, wherein said hollow bolt is loaded transversally by said forces.

13. The device of claim 1 which is operable for measuring the brake torque in a landing gear of an aircraft.

14. A circuit for a sensor of claim 5, wherein said circuit comprises: an arrangement for applying an alternating voltage or an alternating current to said measuring elements;an arrangement for determining the essentially purely capacitive or inductive component as the useful component of the signal delivered by said measuring element.

15. The circuit for a sensor of claim 10, wherein said circuit comprises: an arrangement for applying an alternating voltage or an alternating current to said measuring elements;an arrangement for determining the essentially purely capacitive or inductive component as the useful component of the signal delivered by said measuring element;an arrangement for computing the quotient between the difference of the capacitive or inductive components of the two orthogonally arranged measuring elements and the sum of the two components, the two components being essentially proportional with equal factors to the reciprocal value of the sum respectively the difference of a no-load value d0 and a deformation value.

16. The circuit for a sensor of claim 10, comprising: an arrangement for applying an alternating voltage or an alternating current to said measuring elements;an arrangement for determining the essentially purely capacitive or inductive component as the useful component of the signal delivered by said measuring element;an amplitude control input of said oscillator arrangement for adjusting the amplitude of said alternating voltage or current;an arrangement for forming the sum of the useful components of the signals of said measuring elements;a comparator arrangement for comparing the sum of the useful components to a predetermined value and generating an output signal at an output connected to said amplitude control input of said oscillator arrangement in order to keep the sum of the useful components constant.

17. The circuit of claim 16, wherein a measuring arrangement forms the difference of the useful components of the signals delivered by said measuring elements.