(19)
(11)EP 2 743 665 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
06.05.2020 Bulletin 2020/19

(21)Application number: 13195804.3

(22)Date of filing:  05.12.2013
(51)Int. Cl.: 
G01L 5/28  (2006.01)
G01L 5/00  (2006.01)

(54)

Circular load cell strain sensor configuration

Konfiguration eines kreisförmigen Kraftmesszellenbelastungssensors

Configuration de capteur de contrainte de cellule de charge circulaire


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 11.12.2012 US 201213710973

(43)Date of publication of application:
18.06.2014 Bulletin 2014/25

(73)Proprietor: Goodrich Corporation
Charlotte, NC 28217-4578 (US)

(72)Inventor:
  • Freshour, Thomas
    Troy, OH 45373 (US)

(74)Representative: Dehns 
St. Bride's House 10 Salisbury Square
London EC4Y 8JD
London EC4Y 8JD (GB)


(56)References cited: : 
EP-A1- 0 504 676
DE-A1-102009 000 255
JP-A- 2010 159 548
US-A1- 2006 266 561
WO-A1-2012/035245
GB-A- 2 305 729
US-A- 5 824 917
US-B2- 7 683 274
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    BACKGROUND



    [0001] The present invention is related to electromechanical brake systems, and in particular to circular load cells for electric brake actuators.

    [0002] Electromechanical brakes for aircraft often comprise stator discs and rotor discs. The stator discs are coupled to an axle and do not rotate relative to the axle. The rotor discs are coupled to, and rotate with the wheel, relative to the axle. An electric brake actuator is utilized to apply force to one of the stator discs to compress the stator portion with the rotor portion of the brake. This creates friction that converts kinetic energy into thermal energy in order to slow the rotation of the wheel. In order to better control the actuator, it is desirable to know the force that is being applied to the stator disc by the actuator.

    [0003] In the past, load cells have been used to determine stresses and strains experienced by the actuator when applying force to the stator disc. These actuators are often circular in shape and thus measuring devices placed upon the outer diameter of the load cell to measure axial compression and tension will experience bending and hoop stresses, which can cause wear of the device over time. It is desirable to reduce the bending and hoop stresses experienced by the measuring devices implemented on circular load cells.

    [0004] In JP 20100159548 A, a pin-type load cell is disclosed. The pin-type load cell includes a circumferential groove. Strain sensors are placed on a curved, annular surface of the groove to measure forces upon the pin-type load cell.

    [0005] In WO 2012/035245 A1, a system for measuring the stresses within an aircraft turbojet engine suspension is disclosed. Strain sensors are implemented along tabs of a weight to measure forces within joints of the engine suspension.

    [0006] In GB 2305729 A, a strain transducer is disclosed that may be inserted into a work piece. The strain transducer includes a cylindrical outer body that is held in place using an interference fit within a hole of a work piece.

    [0007] In EP 0504676 A1, a sensor for an elongation measurement of a bore of a structure is disclosed, and in US 2006/266561 A1, a force-measurement cell for insertion into a bore of a pin is disclosed.

    [0008] In US5824917 is disclosed a force measuring device. The device has force sensor integrated into one of two measurement wedges joined by adjuster.

    SUMMARY



    [0009] According to the invention, there is provided a load cell as set forth in claim 1 and an electromechanical brake as set forth in claim 11.

    BRIEF DESCRIPTION OF THE DRAWINGS



    [0010] 

    FIG. 1 is a cross-section view illustrating an electromechanical brake system according to an embodiment of the present invention.

    FIG. 2 is a cross-section view illustrating an electric brake actuator for an electromechanical brake system according to an embodiment of the present invention.

    FIG. 3 is a front view illustrating a load cell for an electric brake actuator according to an embodiment of the present invention.

    FIG. 4 is a top view of a groove of a circular load cell according to an embodiment of the present invention.

    FIG. 5 is a circuit diagram illustrating a strain sensor configuration according to an embodiment of the present invention.


    DETAILED DESCRIPTION



    [0011] The present invention relates to reducing stress on strain sensors for circular load cells. An electric brake actuator is used to apply a force to a stator portion of a brake in order to compress the stator portion with the rotor portion of the brake. This creates friction to convert kinetic energy to thermal energy to slow down the rotation of the wheel. A load cell is implemented within the brake actuator to measure axial tension and compression to determine the load of the actuator while applying force to the stator portion of the brake. The load is a ring or toroid with an inner diameter depending on the application. The load cell includes eight strain sensors for measuring the axial strain on the load cell. Four of the strain sensors are principal sensors and four of the strain sensors are transverse sensors. Grooves are cut out of the outer diameter every ninety degrees circumferentially around the load cell. The grooves each contain two side walls and a flat surface between the two side walls. The principal strain sensors are positioned along the flat between the two side walls and oriented to measure strain in the axial direction. The transverse sensors are placed vertically upon one of the two side walls. The eight strain sensors are electrically connected in a wheatstone bridge configuration. The wheatstone bridge is connected to a data acquisition module. By placing the strain sensors on the flat surfaces of the grooves, the traditional bending and hoop stresses experienced on the outer diameter of the circular load cell are eliminated.

    [0012] FIG. 1 illustrates an electromechanical brake system 10, which includes electric brake actuator 12, rotor discs 14, stator disks 16, axle 18, wheel 20, bearings 22a and 22b, and data acquisition module 24. Wheel 20 rotates about axle 18 on bearings 22a and 22b. Electric brake actuator 12 is utilized to apply a force to the closest of stator discs 16. Stator discs 16 are coupled to, and do not rotate relative to axle 18. Rotor discs 14 are coupled to, and rotate with wheel 20. When force is applied by electric actuator 12 to stator discs 16, friction is generated between stator discs 16 and rotor discs 14, converting kinetic energy to thermal energy in order to slow down the rotation of wheel 20. Electric brake actuator 12 electrically measures and communicates the load it experiences to data acquisition module 24. Data acquisition module 24 is any module capable of receiving and storing electronic signals from electric brake actuator 12.

    [0013] FIG. 2 illustrates electric brake actuator 12, which includes load cell 30, communications port 32, ram 34 and housing 36. The portion of electric brake actuator 12 within housing 36 extends to apply force to stator discs 16 of FIG. 1 through ram 34. Communications port 32 is utilized to communicate electrical signals between electric brake actuator 12 and other electrical systems such as, for example, a brake control unit or data acquisition module 24.

    [0014] Load cell 30 converts a mechanical load into an electrical output. When ram 34 applies a force to the first of stator discs 16 of FIG. 1, a reactive force is mechanically transmitted from ram 34 back to load cell 30. Load cell 30 provides an electrical signal representative of this reactive force to data acquisition module 24 of FIG. 1 through communications port 32.

    [0015] FIG. 3 illustrates load cell 30, which includes inner diameter 50 and outer diameter 52. Outer diameter 52 includes axial grooves 54a-54d. Each axial groove 54a-54d includes a principal strain sensor 56a-56d, and a transverse strain sensor 58a-58d respectively. Between inner diameter 50 and each groove 54a-54d, is a pad 60a-60d respectively. Each pad 60a-60d is attached to the surface of load cell 30 between inner diameter 50 and each groove 54a-54d in order to better transmit the load to principal strain sensors 56a-56d. Load cell 30 includes inner diameter 50, for example, in order to better fit within electric brake actuator 12 of FIGS. 1 and 2. The difference in diameter between inner diameter 50 and outer diameter 52 is any difference necessary to accommodate load cell 30 within electric brake actuator 12 or any other application such as, for example, one half inch (1.27 centimeters). The depth of each groove 54a-54d is any depth between outer diameter 52 and inner diameter 50 such as, for example, one-quarter inch (0.635 centimeters). Principal strain sensors 56a-56d are utilized to measure tension and compression in the axial direction of load cell 30. Transverse strain sensors 58a-58d are used to account for temperature changes and unexpected stresses on load cell 30.

    [0016] FIG. 4 illustrates a top view of load cell 30 showing groove 54a. Groove 54a includes base 70, side walls 72 and 74, principal sensor 56a, transverse sensor 58a, pads 60a and 62a, and is connected to circumferential wire groove 76 in the outer surface 52 of load cell 30. Groove 54a, principal sensor 56a, transverse sensor 58a, and pads 60a and 62a are representative of each of grooves 54a-54d, principal strain sensors 56a-56d, transverse strain sensors 58a-58d and pads 60a-60d of FIG. 3, respectively. Pad 62a is also representative of each of four pads that are associated with grooves 54a-54d and are not visible in FIG. 3.

    [0017] Principal sensor 56a is utilized to measure the tension and compression between pads 60a and 62a. Principal sensor 56a is any electric strain sensor such as, for example, a general purpose strain gage. In another embodiment, pad 62a may be omitted, and principal sensor 56a is only connected to pad 60a, while still measuring tension and compression in the same direction.

    [0018] Transverse sensor 58a is used to compensate for temperature changes and other unexpected stresses upon principal sensor 56a. Transverse sensor 58a is mounted to side wall 72 and is positioned perpendicular to principal sensor 56a. This is so transverse sensor 58a does not measure any of the compression and tension between pads 60a and 62a.

    [0019] FIG. 5 is a circuit diagram illustrating a bridge circuit 90 according to an embodiment of the present invention. Bridge circuit 90 includes positive power terminal 92, negative power terminal 94, positive signal terminal 96, and negative signal terminal 98. The locations of principal sensors 56a-56d and transverse sensors 58a-58d of FIG. 3 are shown in bridge circuit 90.

    [0020] Bridge 90 is a wheatstone bridge with two legs 100 and 102 having principal sensors and two legs 104 and 106 having transverse sensors. Power is provided to the strain sensors through the positive and negative power terminals 92,94. When a load is experienced by electric actuator 12, the resistances of principal sensors 56a-56d change, creating an electric potential across signal terminals 96 and 98. When no load is experienced, the potential at both signal terminals 96 and 98 are equal, creating no voltage across the terminals. This signal is representative of the axial stress on load cell 30 and may be trimmed or provided as is to data acquisition module 24 of FIG. 1. This signal does not change with temperature or other unexpected stresses due to the configuration of transverse strain sensors 58a-58d because the temperature change or stress will affect the resistances of all strain sensors 56a-56d and 58a-58d equally.

    [0021] The following are non-exclusive descriptions of possible embodiments of the present invention.

    [0022] A load cell extending in an axial direction having an outer surface including a first axial groove in the outer surface, the first axial groove defined by a first flat wall, a second flat wall perpendicular to the first flat wall and a third flat wall, the first flat wall being between the second flat wall and the third wall, and a first principal strain sensor positioned on the first flat wall of the first groove to measure tension and compression in the axial direction. The load cell is a ring including the outer surface and an inner diameter. A pad is positioned between the first flat wall of the first axial groove and the inner diameter, and connected to the first principal strain sensor.

    [0023] The load cell of the preceding paragraph can optionally include any one or more of the following features, configurations and/or additional components.

    [0024] A first transverse strain sensor may be positioned on the second flat wall perpendicular to the first principal strain sensor.

    [0025] The load cell may be included within an electric brake actuator of an aircraft landing gear.

    [0026] A second axial groove may be provided in the outer surface, the second groove defined by a first flat wall, a second flat wall and a third wall, the first flat wall being between the second flat wall and the third wall, and a second principal strain sensor positioned on the first flat wall of the second axial groove to measure tension and compression in the axial direction. A third axial groove may be provided in the outer surface, the third axial groove defined by a first flat wall, a second flat wall and a third wall, the first flat wall being between the second flat wall and the third wall, and a third principal strain sensor positioned on the first flat wall of the third axial groove to measure tension and compression in the axial direction. A fourth axial groove may be provided in the outer surface, the fourth axial groove defined by a first flat wall, a second flat wall and a third wall, the first flat wall being between the second flat wall and the third wall, and a fourth principal strain sensor positioned on the first flat wall of the fourth axial groove to measure tension and compression in the axial direction.

    [0027] The first axial groove, second axial groove, third axial groove and fourth axial groove may be circumferentially spaced 90° apart around the outer surface.

    [0028] A first transverse strain sensor may be positioned on the second flat wall of the first axial groove perpendicular to the first principal strain sensor, a second transverse strain sensor positioned on the second flat wall of the second axial groove perpendicular to the second principal strain sensor, a third transverse strain sensor positioned on the second flat wall of the third axial groove perpendicular to the third principal strain sensor, and a fourth transverse strain sensor positioned on the second flat wall of the fourth axial groove perpendicular to the fourth principal strain sensor.

    [0029] The first, second, third and fourth strain sensors and the first, second, third, and fourth transverse sensors may be configured in a wheatstone bridge with a power input, and a signal output.

    [0030] The wheatstone bridge may include a first leg that includes the first and second principal strain sensors, a second leg that includes the first and second transverse strain sensors, a third leg that includes the third and fourth principal strain sensors, and a fourth leg that includes the third and fourth transverse strain sensors.

    [0031] The signal output may be connected to a data acquisition module that calculates the load of the electric actuator based upon the signal output.

    [0032] A circumferential groove may be provided in the outer surface to hold wires for connecting the first, second, third and fourth principal strain sensors.

    [0033] An electromechanical brake system including an electric actuator that applies force to a stator disc of a brake, a load cell that measures load of the electric actuator, the load cell including a first axial groove in an outer surface of the load cell, the first axial groove defined by a first flat surface, a second flat surface perpendicular to the first flat surface and a third surface, the first flat surface being between the second flat surface and the third surface and a first principal strain sensor on the first flat surface of the first axial groove. The load cell is a ring including the outer surface and an inner diameter. The load cell is a ring including the outer surface and an inner diameter. The load cell further includes a pad positioned between the first flat surface and the inner diameter, the pad being connected to the first principal strain sensor.

    [0034] The system of the preceding paragraph can optionally include any one or more of the following features, configurations and/or additional components.

    [0035] The load cell may further comprise a first transverse strain sensor on the second flat surface of the first axial groove.

    [0036] A second axial groove may be provided in the outer surface, the second axial groove defined by a first flat wall, a second flat wall and a third wall, the first flat wall being between the second flat wall and the third wall, and a second principal strain sensor positioned on the first flat wall of the second groove to measure tension and compression in the axial direction. A third axial groove may be provided in the outer surface, the third axial groove defined by a first flat wall, a second flat wall and a third wall, the first flat wall being between the second flat wall and the third wall, a third principal strain sensor positioned on the first flat wall of the third axial groove to measure tension and compression in the axial direction. A fourth axial groove may be provided in the outer surface, the fourth axial groove defined by a first flat wall, a second flat wall and a third wall, the first flat wall being between the second flat wall and the third wall, and a fourth principal strain sensor positioned on the first flat wall of the fourth axial groove to measure tension and compression in the axial direction.

    [0037] The first, second, third, and fourth axial grooves may be circumferentially spaced 90° apart around the outer surface.

    [0038] A first transverse strain sensor may be positioned on the second flat wall of the first axial groove perpendicular to the first principal strain sensor, a second transverse strain sensor positioned on the second flat wall of the second axial groove perpendicular to the second principal strain sensor, a third transverse strain sensor positioned on the second flat wall of the third axial groove perpendicular to the third principal strain sensor, and a fourth transverse strain sensor positioned on the second flat wall of the fourth axial groove perpendicular to the fourth principal strain sensor.

    [0039] The first, second, third, and fourth principal strain sensors and the first, second, third, and fourth transverse strain sensors may be configured in a wheatstone bridge with a power input, and a signal output.

    [0040] The wheatstone bridge may include a first leg that includes first and second of the four principal strain sensors, a second leg that includes first and second of the four transverse strain sensors, a third leg that includes third and fourth of the four principal strain sensors, and a fourth leg that includes third and fourth of the four transverse strain sensors.


    Claims

    1. A load cell (30) extending in an axial direction having an outer surface (52), wherein in that the load cell is a ring including the outer surface (52) and an inner diameter (50) and comprises:

    a first axial groove (54a) in the outer surface (52), the first axial groove (54a) defined by a first flat wall (70), a second flat wall (72) perpendicular to the first flat wall (70) and a third wall (74), the first flat wall (70) being between the second flat wall (72) and the third wall (74);

    a first principal strain sensor (56a) positioned on the first flat wall (70) of the first groove (54a) to measure tension and compression in the axial direction; characterised in that, that

    a pad (60a) is positioned between the first flat wall (70) of the first groove (54a) and the inner diameter (50), wherein the pad (60a) is connected to the first principal strain sensor (56a).


     
    2. The load cell of claim 1, further comprising:
    a first transverse strain sensor (58a) positioned on the second flat wall (72) perpendicular to the first principal strain sensor (56a).
     
    3. The load cell of claim 1 or 2, wherein the load cell (30) is included within an electric brake actuator of an aircraft landing gear.
     
    4. The load cell of any preceding claim, further comprising:

    a second axial groove (54c) in the outer surface (52), the second axial groove (54c) defined by a first flat wall (70), a second flat wall (72) and a third wall (74), the first flat wall (70) being between the second flat wall (72) and the third wall (74);

    a second principal strain sensor (56c) positioned on the first flat wall (70) of the second axial groove (54c) to measure tension and compression in the axial direction;

    a third axial groove (54b) in the outer surface (52), the third axial groove (54b) defined by a first flat wall (70), a second flat wall (72) and a third wall (74), the first flat wall (70) being between the second flat wall (72) and the third wall (74);

    a third principal strain sensor (56b) positioned on the first flat wall (70) of the third axial groove (54c) to measure tension and compression in the axial direction;

    a fourth axial groove (54d) in the outer surface (52), the fourth axial groove (54d) defined by a first flat wall (70), a second flat wall (72) and a third wall (74), the first flat wall (70) being between the second flat wall (72) and the third wall (74); and

    a fourth principal strain sensor (56d) positioned on the first flat wall (70) of the fourth groove (54d) to measure tension and compression in the axial direction.


     
    5. The load cell of claim 4, wherein the first axial groove (54a), second axial groove (54c), third axial groove (54b) and fourth axial groove (54d) are circumferentially spaced 90° apart around the outer surface.
     
    6. The load cell of claim 4 or 5, further comprising:

    a first transverse strain sensor (58a) positioned on the second flat wall (72) of the first axial groove (54a) perpendicular to the first principal strain sensor (56a);

    a second transverse strain sensor (58c) positioned on the second flat wall (72) of the second axial groove (54c) perpendicular to the second principal strain sensor (56c);

    a third transverse strain sensor (58b) positioned on the second flat wall (72) of the third axial groove (54b) perpendicular to the third principal strain sensor (56b); and

    a fourth transverse strain sensor (58d) positioned on the second flat wall (72) of the fourth axial groove (54d) perpendicular to the fourth principal strain sensor (56d).


     
    7. The load cell of claim 6, wherein the first, second, third and fourth principal strain sensors (56a...56d) and the first, second, third, and fourth transverse sensors (58a...58d) are configured in a wheatstone bridge (90) with a power input, and a signal output.
     
    8. The load cell of claim 7, wherein the wheatstone bridge (90) comprises:

    a first leg (100) that includes the first and second principal strain sensors (56a,56c);

    a second leg (104) that includes the first and second transverse strain sensors (58a,58c);

    a third leg (102) that includes the third and fourth principal strain sensors (56b,56d); and

    a fourth leg (106) that includes the third and fourth transverse strain sensors (58b,58d).


     
    9. The load cell of claim 7 or 8, wherein the signal output is connected to a data acquisition module (24) that calculates the load of an electric actuator based upon the signal output.
     
    10. The load cell of any of claims 4 to 9, further comprising a circumferential groove (76) in the outer surface that holds wires for connecting the first, second, third and fourth principal strain sensors (56a...56d).
     
    11. An electromechanical brake system comprising:

    an electric actuator (12) that applies force to a stator disc of a brake;

    a load cell (30) that measures load of the electric actuator (12), characterised in that the load cell (30) is a ring including an outer surface (52) and an inner diameter (50) comprising:

    a first axial groove (54a) in the outer surface (52) of the load cell (30), the first axial groove (54a) defined by a first flat surface (70), a second flat surface (72) perpendicular to the first flat surface (70) and a third surface (74), the first flat surface (70) being between the second flat surface (72) and the third flat surface (74);

    a first principal strain sensor (56a) on the first flat surface (70) of the first axial groove (54a); and

    a pad (60a) positioned between the first flat wall (70) of the first axial groove (54a) and the inner diameter (50), wherein the pad (60a) is connected to the first principal strain sensor (56a).


     
    12. The electromechanical brake system of claim 11, wherein the load cell (30) further comprises a first transverse strain sensor (58a) on the second flat surface (72) of the first axial groove (54a).
     
    13. The electromechanical brake system of claim 11 or 12, wherein the load cell further comprises:

    a second axial groove (54c) in the outer surface (52), the second axial groove (54c) defined by a first flat wall (70), a second flat wall (72) and a third flat wall (74), the first flat wall (70) being between the second flat wall (72) and the third wall (74);

    a second principal strain sensor (56c) positioned on the first flat wall (70) of the second axial groove (54c) to measure tension and compression in the axial direction;

    a third axial groove (54b) in the outer surface (52), the third axial groove (54b) defined by a first flat wall (70), a second flat wall (72) and a third wall (74), the first flat wall (70) being between the second flat wall (72) and the third wall (74);

    a third principal strain sensor (56b) positioned on the first flat wall (70) of the third axial groove (54b) to measure tension and compression in the axial direction;

    a fourth axial groove (54d) in the outer surface (52), the fourth axial groove (54d) defined by a first flat wall (70), a second flat wall (72) and a third wall (74), the first flat wall (70) being between the second flat wall (72) and the third wall (74); and

    a fourth principal strain sensor (56d) positioned on the first flat wall (70) of the fourth axial groove (54d) to measure tension and compression in the axial direction.


     
    14. The electromechanical brake system of claim 13, wherein the first, second, third, and fourth grooves (54a...54d) are circumferentially spaced 90° apart around the outer surface.
     
    15. The electromechanical brake system of claim 13 or 14; further comprising:

    a first transverse strain sensor (58a) positioned on the second flat wall (72) of the first axial groove (54a) perpendicular to the first principal strain sensor (56a);

    a second transverse strain sensor (58c) positioned on the second flat wall (72) of the second axial groove (54c) perpendicular to the second principal strain sensor (56c);

    a third transverse strain sensor (58b) positioned on the second flat wall (72) of the third axial groove (54b) perpendicular to the third principal strain sensor (56b); and

    a fourth transverse strain sensor (58d) positioned on the second flat wall (72) of the fourth axial groove (54d) perpendicular to the fourth principal strain sensor (56d),

    wherein the first, second, third, and fourth principal strain sensors (56a...56d) and the first, second, third, and fourth transverse strain sensors (58a...58d) are optionally configured in a wheatstone bridge (90) with a power input, and a signal output, the wheatstone bridge optionally comprising:

    a first leg (100) that includes first and second of the four principal strain sensors (56a,56c);

    a second leg (104) that includes first and second of the four transverse strain sensors (58a,58c);

    a third leg (102) that includes third and fourth of the four principal strain sensors (56b,56d); and

    a fourth leg (106) that includes third and fourth of the four transverse strain sensors (58b,58d).


     


    Ansprüche

    1. Kraftmesszelle (30), die sich in einer axialen Richtung erstreckt, mit einer Außenfläche (52), wobei die Kraftmesszelle ein Ring ist, der die Außenfläche (52) und einen Innendurchmesser (50) beinhaltet und Folgendes umfasst:

    eine erste axiale Nut (54a) in der Außenfläche (52), wobei die erste axiale Nut (54a) durch eine erste glatte Wand (70), eine zweite glatte Wand (72) senkrecht zur ersten glatten Wand (70) und eine dritte Wand (74) definiert ist, wobei die erste glatte Wand (70) zwischen der zweiten glatten Wand (72) und der dritten Wand (74) liegt;

    einen ersten Hauptbelastungssensor (56a), der an der ersten glatten Wand (70) der ersten Nut (54a) positioniert ist, um Zugspannung und Kompression in der axialen Richtung zu messen; dadurch gekennzeichnet, dass eine Auflage (60a) zwischen der ersten glatten Wand (70) der ersten Nut (54a) und dem Innendurchmesser (50) positioniert ist, wobei die Auflage (60a) mit dem ersten Hauptbelastungssensor (56a) verbunden ist.


     
    2. Kraftmesszelle nach Anspruch 1, ferner umfassend:
    einen ersten Querbelastungssensor (58a), der an der zweiten glatten Wand (72) senkrecht zu dem ersten Hauptbelastungssensor (56a) positioniert ist.
     
    3. Kraftmesszelle nach Anspruch 1 oder 2, wobei die Kraftmesszelle (30) innerhalb eines elektrischen Bremsaktors eine Flugzeugfahrwerks beinhaltet ist.
     
    4. Kraftmesszelle nach einem der vorstehenden Ansprüche, ferner umfassend:

    eine zweite axiale Nut (54c) in der Außenfläche (52), wobei die zweite axiale Nut (54c) durch eine erste glatte Wand (70), eine zweite glatte Wand (72) und eine dritte Wand (74) definiert ist, wobei die erste glatte Wand (70) zwischen der zweiten glatten Wand (72) und der dritten Wand (74) liegt;

    einen zweiten Hauptbelastungssensor (56c), der an der ersten glatten Wand (70) der zweiten axialen Nut (54c) positioniert ist, um Zugspannung und Kompression in der axialen Richtung zu messen;

    eine dritte axiale Nut (54b) in der Außenfläche (52), wobei die dritte axiale Nut (54b) durch eine erste glatte Wand (70), eine zweite glatte Wand (72) und eine dritte Wand (74) definiert ist, wobei die erste glatte Wand (70) zwischen der zweiten glatten Wand (72) und der dritten Wand (74) liegt;

    einen dritten Hauptbelastungssensor (56b), der an der ersten glatten Wand (70) der dritten axialen Nut (54c) positioniert ist, um Zugspannung und Kompression in der axialen Richtung zu messen;

    eine vierte axiale Nut (54d) in der Außenfläche (52), wobei die vierte axiale Nut (54d) durch eine erste glatte Wand (70), eine zweite glatte Wand (72) und eine dritte Wand (74) definiert ist, wobei die erste glatte Wand (70) zwischen der zweiten glatten Wand (72) und der dritten Wand (74) liegt; und

    einen vierten Hauptbelastungssensor (56d), der an der ersten glatten Wand (70) der vierten Nut (54d) positioniert ist, um Zugspannung und Kompression in der axialen Richtung zu messen.


     
    5. Kraftmesszelle nach Anspruch 4, wobei die erste axiale Nut (54a), die zweite axiale Nut (54c), die dritte axiale Nut (54b) und die vierte axiale Nut (54d) in Umfangsrichtung um 90° um die Außenfläche beabstandet sind.
     
    6. Kraftmesszelle nach Anspruch 4 oder 5, ferner umfassend:

    einen ersten Querbelastungssensor (58a), der an der zweiten glatten Wand (72) der ersten axialen Nut (54a) senkrecht zu dem ersten Hauptbelastungssensor (56a) positioniert ist;

    einen zweiten Querbelastungssensor (58c), der an der zweiten glatten Wand (72) der zweiten axialen Nut (54c) senkrecht zu dem zweiten Hauptbelastungssensor (56c) positioniert ist;

    einen dritten Querbelastungssensor (58b), der an der zweiten glatten Wand (72) der dritten axialen Nut (54b) senkrecht zu dem dritten Hauptbelastungssensor (56b) positioniert ist; und

    einen vierten Querbelastungssensor (58d), der an der zweiten glatten Wand (72) der vierten axialen Nut (54d) senkrecht zu dem vierten Hauptbelastungssensor (56d) positioniert ist.


     
    7. Kraftmesszelle nach Anspruch 6, wobei der erste, zweite, dritte und vierte Hauptbelastungssensor (56a...56d) und der erste, zweite, dritte und vierte Quersensor (58a...58d) in einer Wheatstone-Brücke (90) mit einem Leistungseingang und einem Signalausgang konfiguriert sind.
     
    8. Kraftmesszelle nach Anspruch 7, wobei die Wheatstone-Brücke (90) umfasst:

    einen ersten Zweig (100), der den ersten und zweiten Hauptbelastungssensor (56a, 56c) beinhaltet;

    einen zweiten Zweig (104), der den ersten und zweiten Querbelastungssensor (58a, 58c) beinhaltet;

    einen dritten Zweig (102), der den dritten und vierten Hauptbelastungssensor (56b, 56d) beinhaltet; und

    einen vierten Zweig (106), der den dritten und vierten Querbelastungssensor (58b, 58d) beinhaltet.


     
    9. Kraftmesszelle nach Anspruch 7 oder 8, wobei der Signalausgang mit einem Datenerhebungsmodul (24) verbunden ist, das die Last eines elektrischen Aktors auf Grundlage des Signalausgangs berechnet.
     
    10. Kraftmesszelle nach einem der Ansprüche 4 bis 9, ferner umfassend eine Umfangsnut (76) in der Außenfläche, die Drähte zum Verbinden des ersten, zweiten, dritten und vierten Hauptbelastungssensors (56a...56d) hält.
     
    11. Elektromechanisches Bremssystem, umfassend:

    einen elektrischen Aktor (12), der eine Kraft auf eine Statorscheibe einer Bremse aufbringt;

    eine Kraftmesszelle (30), die eine Last des elektrischen Aktors (12) misst, dadurch gekennzeichnet, dass die Kraftmesszelle (30) ein Ring ist, der eine Außenfläche (52) und einen Innendurchmesser (50) beinhaltet und Folgendes umfasst:

    eine erste axiale Nut (54a) in der Außenfläche (52) der Kraftmesszelle (30), wobei die erste axiale Nut (54a) durch eine erste glatte Fläche (70), eine zweite glatte Fläche (72) senkrecht zur ersten glatten Fläche (70) und eine dritte Fläche (74) definiert ist, wobei die erste glatte Fläche (70) zwischen der zweiten glatten Fläche (72) und der dritten Fläche (74) liegt;

    einen ersten Hauptbelastungssensor (56a) an der ersten glatten Fläche (70) der ersten axialen Nut (54a); und

    eine Auflage (60a), die zwischen der ersten glatten Fläche (70) der ersten axialen Nut (54a) und dem Innendurchmesser (50) positioniert ist, wobei die Auflage (60a) mit dem ersten Hauptbelastungssensor (56a) verbunden ist.


     
    12. Elektromechanisches Bremssystem nach Anspruch 11, wobei die Kraftmesszelle (30) ferner einen ersten Querbelastungssensor (58a) an der zweiten glatten Fläche (72) der ersten axialen Nut (54a) umfasst.
     
    13. Elektromechanisches Bremssystem nach Anspruch 11 oder 12, wobei die Kraftmesszelle ferner umfasst:

    eine zweite axiale Nut (54c) in der Außenfläche (52), wobei die zweite axiale Nut (54c) durch eine erste glatte Wand (70), eine zweite glatte Wand (72) und eine dritte glatte Wand (74) definiert ist, wobei die erste glatte Wand (70) zwischen der zweiten glatten Wand (72) und der dritten Wand (74) liegt;

    einen zweiten Hauptbelastungssensor (56c), der an der ersten glatten Wand (70) der zweiten axialen Nut (54c) positioniert ist, um Zugspannung und Kompression in der axialen Richtung zu messen;

    eine dritte axiale Nut (54b) in der Außenfläche (52), wobei die dritte axiale Nut (54b) durch eine erste glatte Wand (70), eine zweite glatte Wand (72) und eine dritte Wand (74) definiert ist, wobei die erste glatte Wand (70) zwischen der zweiten glatten Wand (72) und der dritten Wand (74) liegt;

    einen dritten Hauptbelastungssensor (56b), der an der ersten glatten Wand (70) der dritten axialen Nut (54b) positioniert ist, um Zugspannung und Kompression in der axialen Richtung zu messen;

    eine vierte axiale Nut (54d) in der Außenfläche (52), wobei die vierte axiale Nut (54d) durch eine erste glatte Wand (70), eine zweite glatte Wand (72) und eine dritte Wand (74) definiert ist, wobei die erste glatte Wand (70) zwischen der zweiten glatten Wand (72) und der dritten Wand (74) liegt; und

    einen vierten Hauptbelastungssensor (56d), der an der ersten glatten Wand (70) der vierten axialen Nut (54d) positioniert ist, um Zugspannung und Kompression in der axialen Richtung zu messen.


     
    14. Elektromechanisches Bremssystem nach Anspruch 13, wobei die erste, zweite, dritte und vierte Nut (54a...54d) in Umfangsrichtung um 90° um die Außenfläche beabstandet sind.
     
    15. Elektromechanisches Bremssystem nach Anspruch 13 oder 14, ferner umfassend:

    einen ersten Querbelastungssensor (58a), der an der zweiten glatten Wand (72) der ersten axialen Nut (54a) senkrecht zu dem ersten Hauptbelastungssensor (56a) positioniert ist;

    einen zweiten Querbelastungssensor (58c), der an der zweiten glatten Wand (72) der zweiten axialen Nut (54c) senkrecht zu dem zweiten Hauptbelastungssensor (56c) positioniert ist;

    einen dritten Querbelastungssensor (58b), der an der zweiten glatten Wand (72) der dritten axialen Nut (54b) senkrecht zu dem dritten Hauptbelastungssensor (56b) positioniert ist; und

    einen vierten Querbelastungssensor (58d), der an der zweiten glatten Wand (72) der vierten axialen Nut (54d) senkrecht zu dem vierten Hauptbelastungssensor (56d) positioniert ist,

    wobei der erste, zweite, dritte und vierte Hauptbelastungssensor (56a...56d) und der erste, zweite, dritte und vierte Querbelastungssensor (58a...58d) optional in einer Wheatstone-Brücke (90) mit einem Leistungseingang und einem Signalausgang konfiguriert sind, wobei die Wheatstone-Brücke optional Folgendes umfasst:

    einen ersten Zweig (100), der den ersten und zweiten der vier Hauptbelastungssensoren (56a, 56c) beinhaltet;

    einen zweiten Zweig (104), der den ersten und zweiten der vier Querbelastungssensoren (58a, 58c) beinhaltet;

    einen dritten Zweig (102), der den dritten und vierten der vier Hauptbelastungssensoren (56b, 56d) beinhaltet; und

    einen vierten Zweig (106), der den dritten und vierten der vier Querbelastungssensoren (58b, 58d) beinhaltet.


     


    Revendications

    1. Cellule de charge (30) s'étendant dans une direction axiale ayant une surface externe (52), dans laquelle dans cette cellule de charge se trouve un anneau comportant la surface externe (52) et un diamètre interne (50) et comprend :

    une première rainure axiale (54a) dans la surface externe (52), la première rainure axiale (54a) étant définie par une première paroi plate (70), une deuxième paroi plate (72) perpendiculaire à la première paroi plate (70) et une troisième paroi (74), la première paroi plate (70) se trouvant entre la deuxième paroi plate (72) et la troisième paroi (74) ;

    un premier capteur de contrainte principal (56a) positionné sur la première paroi plate (70) de la première rainure (54a) pour mesurer la tension et la compression dans la direction axiale ; caractérisée en ce que,

    un tampon (60a) est positionné entre la première paroi plate (70) de la première rainure (54a) et le diamètre interne (50), dans laquelle le tampon (60a) est relié au premier capteur de contrainte principal (56a).


     
    2. Cellule de charge selon la revendication 1, comprenant en outre :
    un premier capteur de contrainte transversal (58a) positionné sur la deuxième paroi plate (72) perpendiculairement au premier capteur de contrainte principal (56a).
     
    3. Cellule de charge selon la revendication 1 ou 2, dans laquelle la cellule de charge (30) est incluse à l'intérieur d'un actionneur de frein électrique d'un train d'atterrissage d'aéronef.
     
    4. Cellule de charge selon une quelconque revendication précédente, comprenant en outre :

    une deuxième rainure axiale (54c) dans la surface externe (52), la deuxième rainure axiale (54c) étant définie par une première paroi plate (70), une deuxième paroi plate (72) et une troisième paroi (74), la première paroi plate (70) se trouvant entre la deuxième paroi plate (72) et la troisième paroi (74) ;

    un deuxième capteur de contrainte principal (56c) positionné sur la première paroi plate (70) de la deuxième rainure axiale (54c) pour mesurer la tension et la compression dans la direction axiale ;

    une troisième rainure axiale (54b) dans la surface externe (52), la troisième rainure axiale (54b) étant définie par une première paroi plate (70), une deuxième paroi plate (72) et une troisième paroi (74), la première paroi plate (70) se trouvant entre la deuxième paroi plate (72) et la troisième paroi (74) ;

    un troisième capteur de contrainte principal (56b) positionné sur la première paroi plate (70) de la troisième rainure axiale (54c) pour mesurer la tension et la compression dans la direction axiale ;

    une quatrième rainure axiale (54d) dans la surface externe (52), la quatrième rainure axiale (54d) étant définie par une première paroi plate (70), une deuxième paroi plate (72) et une troisième paroi (74), la première paroi plate (70) se trouvant entre la deuxième paroi plate (72) et la troisième paroi (74) ; et

    un quatrième capteur de contrainte principal (56d) positionné sur la première paroi plate (70) de la quatrième rainure (54d) pour mesurer la tension et la compression dans la direction axiale.


     
    5. Cellule de charge selon la revendication 4, dans laquelle la première rainure axiale (54a), la deuxième rainure axiale (54c), la troisième rainure axiale (54b) et la quatrième rainure axiale (54d) sont espacées circonférentiellement de 90° autour de la surface externe.
     
    6. Cellule de charge selon la revendication 4 ou 5, comprenant en outre :

    un premier capteur de contrainte transversal (58a) positionné sur la deuxième paroi plate (72) de la première rainure axiale (54a) perpendiculairement au premier capteur de contrainte principal (56a) ;

    un deuxième capteur de contrainte transversal (58c) positionné sur la deuxième paroi plate (72) de la deuxième rainure axiale (54c) perpendiculairement au deuxième capteur de contrainte principal (56c) ;

    un troisième capteur de contrainte transversal (58b) positionné sur la deuxième paroi plate (72) de la troisième rainure axiale (54b) perpendiculairement au troisième capteur de contrainte principal (56b) ; et

    un quatrième capteur de contrainte transversal (58d) positionné sur la deuxième paroi plate (72) de la quatrième rainure axiale (54d) perpendiculairement au quatrième capteur de contrainte principal (56d).


     
    7. Cellule de charge selon la revendication 6, dans laquelle les premier, deuxième, troisième et quatrième capteurs de contrainte principaux (56a...56d) et les premier, deuxième, troisième et quatrième capteurs transversaux (58a...58d) sont configurés dans un pont de Wheatstone (90) avec une entrée de puissance et une sortie de signal.
     
    8. Cellule de charge selon la revendication 7, dans laquelle le pont de Wheatstone (90) comprend :

    une première jambe (100) qui comporte les premier et deuxième capteurs de contrainte principaux (56a, 56c) ;

    une deuxième jambe (104) qui comporte les premier et deuxième capteurs de contrainte transversaux (58a, 58c) ;

    une troisième jambe (102) qui comporte les troisième et quatrième capteurs de contrainte principaux (56b, 56d) ; et

    une quatrième jambe (106) qui comporte les troisième et quatrième capteurs de contrainte transversaux (58b, 58d).


     
    9. Cellule de charge selon la revendication 7 ou 8, dans laquelle la sortie de signal est reliée à un module d'acquisition de données (24) qui calcule la charge d'un actionneur électrique sur la base de la sortie de signal.
     
    10. Cellule de charge selon l'une quelconque des revendications 4 à 9, comprenant en outre une rainure circonférentielle (76) dans la surface externe qui contient des fils destinés à relier les premier, deuxième, troisième et quatrième capteurs de contrainte principaux (56a...56d).
     
    11. Système de freinage électromécanique comprenant :

    un actionneur électrique (12) qui applique une force à un disque de stator d'un frein ;

    une cellule de charge (30) qui mesure la charge de l'actionneur électrique (12), caractérisé en ce que la cellule de charge (30) est un anneau comportant une surface externe (52) et un diamètre interne (50) comprenant :

    une première rainure axiale (54a) dans la surface externe (52) de la cellule de charge (30), la première rainure axiale (54a) étant définie par une première surface plate (70), une deuxième surface plate (72) perpendiculaire à la première surface plate (70) et une troisième surface (74), la première surface plate (70) se trouvant entre la deuxième surface plate (72) et la troisième surface plate (74) ;

    un premier capteur de contrainte principal (56a) sur la première surface plate (70) de la première rainure axiale (54a) ; et

    un tampon (60a) positionné entre la première paroi plate (70) de la première rainure axiale (54a) et le diamètre interne (50), dans lequel le tampon (60a) est relié au premier capteur de contrainte principal (56a).


     
    12. Système de freinage électromécanique selon la revendication 11, dans lequel la cellule de charge (30) comprend en outre un premier capteur de contrainte transversal (58a) sur la deuxième surface plate (72) de la première rainure axiale (54a).
     
    13. Système de freinage électromécanique selon la revendication 11 ou 12, dans lequel la cellule de charge comprend en outre :

    une deuxième rainure axiale (54c) dans la surface externe (52), la deuxième rainure axiale (54c) étant définie par une première paroi plate (70), une deuxième paroi plate (72) et une troisième paroi plate (74), la première paroi plate (70) se trouvant entre la deuxième paroi plate (72) et la troisième paroi (74) ;

    un deuxième capteur de contrainte principal (56c) positionné sur la première paroi plate (70) de la deuxième rainure axiale (54c) pour mesurer la tension et la compression dans la direction axiale ;

    une troisième rainure axiale (54b) dans la surface externe (52), la troisième rainure axiale (54b) étant définie par une première paroi plate (70), une deuxième paroi plate (72) et une troisième paroi (74), la première paroi plate (70) se trouvant entre la deuxième paroi plate (72) et la troisième paroi (74) ;

    un troisième capteur de contrainte principal (56b) positionné sur la première paroi plate (70) de la troisième rainure axiale (54b) pour mesurer la tension et la compression dans la direction axiale ;

    une quatrième rainure axiale (54d) dans la surface externe (52), la quatrième rainure axiale (54d) définie par une première paroi plate (70), une deuxième paroi plate (72) et une troisième paroi (74), la première paroi plate (70) se trouvant entre la deuxième paroi plate (72) et la troisième paroi (74) ; et

    un quatrième capteur de contrainte principal (56d) positionné sur la première paroi plate (70) de la quatrième rainure axiale (54d) pour mesurer la tension et la compression dans la direction axiale.


     
    14. Système de freinage électromécanique selon la revendication 13, dans lequel les première, deuxième, troisième et quatrième rainures (54a...54d) sont espacées circonférentiellement de 90° autour de la surface externe.
     
    15. Système de freinage électromécanique selon la revendication 13 ou 14 ; comprenant en outre :

    un premier capteur de contrainte transversal (58a) positionné sur la deuxième paroi plate (72) de la première rainure axiale (54a) perpendiculairement au premier capteur de contrainte principal (56a) ;

    un deuxième capteur de contrainte transversal (58c) positionné sur la deuxième paroi plate (72) de la deuxième rainure axiale (54c) perpendiculairement au deuxième capteur de contrainte principal (56c) ;

    un troisième capteur de contrainte transversal (58b) positionné sur la deuxième paroi plate (72) de la troisième rainure axiale (54b) perpendiculairement au troisième capteur de contrainte principal (56b) ; et

    un quatrième capteur de contrainte transversal (58d) positionné sur la deuxième paroi plate (72) de la quatrième rainure axiale (54d) perpendiculairement au quatrième capteur de contrainte principal (56d),

    dans lequel les premier, deuxième, troisième et quatrième capteurs de contrainte principaux (56a...56d) et les premier, deuxième, troisième et quatrième capteurs de contrainte transversaux (58a...58d) sont éventuellement configurés dans un pont de Wheatstone (90) avec une entrée de puissance et une sortie de signal, le pont de Wheatstone comprenant éventuellement :

    une première jambe (100) qui comporte les premier et deuxième des quatre capteurs de contrainte principaux (56a, 56c) ;

    une deuxième jambe (104) qui comporte les premier et deuxième des quatre capteurs de contrainte transversaux (58a, 58c) ;

    une troisième jambe (102) qui comporte les troisième et quatrième des quatre capteurs de contrainte principaux (56b, 56d) ; et

    une quatrième jambe (106) qui comporte les troisième et quatrième des quatre capteurs de contrainte transversaux (58b, 58d) .


     




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    REFERENCES CITED IN THE DESCRIPTION



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    Patent documents cited in the description