electric brake

Abstract

The present invention is entitled "Electric Brake." In some examples, the present invention provides a brake assembly including an actuator assembly configured to cause translation of a piston to compress a disc stack. The actuator assembly is configured to generate a first torque about a motor axis using a motor and a second torque from the first torque using a harmonic drive. The actuator assembly can include a gear set configured to cause a linear actuator to translate the piston using the second torque. In some examples, the actuator is configured to translate the piston along a compression axis that is different from the motor axis.

Description

Technical Field

[0001] This disclosure relates to a brake assembly for a vehicle. Background Technology

[0002] Vehicles such as aircraft may use wheel brake assemblies that include multi-disc brake assemblies. For example, such a multi-disc brake assembly may include a stack of discs comprising multiple rotor discs engaged with the wheel and multiple stator discs interleaved with the rotor discs. The rotor discs and the wheel are configured to rotate about an axis, while the stator discs remain stationary. To decelerate the rotational motion of the rotating wheel, the brake assembly may displace a piston against a pressure plate to compress the rotating rotor discs engaged with the wheel against the stationary stator discs, thereby generating a torque that decelerates the rotational motion of the wheel. Summary of the Invention

[0003] In some examples, this disclosure describes articles, systems, and techniques related to brake assemblies for vehicles. The brake assembly includes a motor and a harmonic actuator configured to transmit torque generated by the motor to a brake disc stack. The brake assembly may include: a disc stack configured to reduce and / or prevent wheel rotation when the disc stack is compressed; a piston configured to apply a compressive force to the disc stack; and an actuator configured to linearly translate the piston using rotation of a motor shaft. The actuator may be configured to transmit torque generated by the motor to the linear actuator using the harmonic actuator. In some examples, the motor generates a rotational axis about a motor axis, and the linear actuator translates the piston along a compression axis different from the motor axis (e.g., displaced from the motor axis). The displacement between the motor axis and a separate compression axis allows for a more compact actuator configuration compared to an inline actuator where a single axis serves as both the motor axis and the compression axis.

[0004] In the example, a brake assembly includes: a brake disc stack; an actuator assembly including: an electric motor configured to generate a first rotational torque about a motor axis; a harmonic driver configured to generate a second rotational torque in response to the first rotational torque; a gear set including an output gear configured to rotate in response to the second rotational torque; and a linear actuator mechanically coupled to the gear set, wherein the linear actuator is configured to generate linear motion along a compression axis and cause a piston to compress the brake disc stack as the output gear rotates, wherein the compression axis is different from the motor axis.

[0005] In the example, a brake assembly includes: a disc stack; a piston configured to compress the disc stack; an electric motor including a motor housing and a motor shaft, wherein the electric motor is configured to cause the motor shaft to rotate about a motor axis at a first speed and in a first direction relative to the motor housing; a harmonic driver mechanically engaged with the motor shaft, wherein the harmonic driver is configured to cause a flexible spline to rotate about the motor axis at a rotational speed less than the first speed and in a second direction opposite to the first direction; an output gear configured to rotate about a compression axis, wherein the flexible spline is configured to cause rotation of the output gear; and a linear actuator including a driver and a screw, wherein the output gear is configured to cause rotation of the driver, and wherein rotation of the driver causes the screw to translate relative to the motor housing along the compression axis such that the piston compresses the disc stack.

[0006] In one example, one method includes: generating a first rotational torque using an electric motor about a motor axis; generating a second rotational torque using a harmonic driver in response to the first rotational torque; rotating an output gear of a gear set using the second rotational torque; and using the rotation of the output gear to cause a linear actuator to generate linear motion along a compression axis, wherein the compression axis is different from the motor axis; and using the linear motion of the linear actuator to cause a piston compression disc stack.

[0007] Details of one or more examples are set forth in the accompanying drawings and the following description. Other features, objects, and advantages will be apparent from the description and drawings, as well as from the claims. Attached Figure Description

[0008] Figure 1 This is a perspective view showing an exemplary wheel.

[0009] Figure 2 It includes Figure 1 A schematic cross-sectional view of an exemplary wheel and brake assembly.

[0010] Figure 3 This is a schematic diagram illustrating an exemplary actuator.

[0011] Figure 4 It is shown Figure 3 A schematic diagram of another view of an exemplary actuator.

[0012] Figure 5 This is a schematic diagram of an exemplary harmonic driver.

[0013] Figure 6A It is in the first configuration Figure 5 A schematic diagram of a harmonic driver.

[0014] Figure 6B It is in the second configuration Figure 5 and Figure 6A A schematic diagram of a harmonic driver.

[0015] Figure 6C It is in the third configuration Figure 5 , Figure 6A and Figure 6B A schematic diagram of a harmonic driver.

[0016] Figure 6D It is in the fourth configuration Figure 5 and Figures 6A to 6C A schematic diagram of a harmonic driver.

[0017] Figure 7 This is a schematic diagram illustrating an exemplary actuator and an exemplary linear actuator.

[0018] Figure 8 This is a flowchart illustrating an exemplary technique for compressing disk stacks. Detailed Implementation

[0019] This disclosure describes articles, systems, and techniques relating to a brake assembly for a vehicle, the brake assembly including a motor and a harmonic drive configured to transmit torque generated by the motor to a stack of brake discs. The brake assembly includes a disc stack comprising one or more rotor discs and one or more stator discs. For example, the disc stack may include a plurality of rotor discs interleaved with a plurality of stator discs. The rotor discs are rotatably coupled to a wheel of the vehicle such that rotation of the wheel about a wheel axis causes rotation of the rotor discs about the wheel axis. The stator discs are configured to remain substantially stationary relative to the wheel and the rotor discs. The brake assembly is configured to compress the disc stack to cause engagement of frictional surfaces on the rotating rotor discs and the stationary stator discs, thereby reducing the rotational speed of the rotor discs about the wheel axis. The rotor discs are configured to engage the wheel such that the reduction in the rotational speed of the rotor discs causes a reduction in the speed of the wheel.

[0020] The brake assembly includes an actuator assembly configured to cause compression of the disc stack when braking is required (e.g., in response to user input or more automated control). In some examples, the actuator assembly is configured to cause translation of a piston that applies a compressive force to the disc stack. The compressive force applied by the actuator assembly causes the rotor and stator discs to translate slidably (e.g., along the axial direction of the wheel) to induce engagement between the rotating rotor disc and the stationary stator disc, thereby generating and / or increasing braking force on the wheel. The actuator assembly is also configured to reduce and / or eliminate the compressive force on the disc stack to reduce engagement between the rotating rotor disc and the stationary stator disc, thereby reducing braking force on the wheel. For example, the actuator assembly may be configured to apply a compressive force to the disc stack to reduce and / or decrease wheel rotation, and may be configured to reduce and / or eliminate the compressive force to allow and / or increase wheel rotation.

[0021] The brake assembly may include control circuitry configured to cause the actuator assembly to compress the disc stack based on a braking signal. For example, the control circuitry may be configured to transmit a braking signal in response to actuation of a user input device (e.g., a foot switch) located remotely from the brake assembly (e.g., in the cockpit of an aircraft). In the examples described herein, the actuator assembly includes a motor (e.g., an electric motor) configured to generate rotational motion in response to the braking signal and to convert the rotational motion of the motor into linear translation to induce compression of the disc stack.

[0022] In the example, the motor is configured to induce rotational motion along a first direction of rotation (“first axial direction”) and a second direction of rotation (“second axial direction”) of the motor shaft, opposite to the first axial direction, based on, for example, a braking signal. An actuator assembly is configured to convert the rotational motion along the first axial direction into a linear translation along the first direction, to, for example, increase and / or induce a compressive force applied to the valve disc stack. The actuator assembly may be configured to convert the rotational motion along the second axial direction into a linear translation along the second direction, opposite to the first direction, to, for example, decrease and / or eliminate the compressive force applied to the disc stack. In the example, the motor defines a housing and is configured to generate rotational motion of the motor shaft relative to the housing. The housing may be substantially stationary relative to a portion of the brake assembly (such as a torque tube).

[0023] In the example, the actuator assembly is configured to generate a first rotational torque using a motor at a first rotational speed, a second rotational torque using a harmonic driver at a second rotational speed less than the first rotational speed, and to convert the second rotational torque into linear motion to translate a piston using a linear actuator. The piston may be configured to induce a compressive force on the disc stack. In the example, the motor is configured to generate the first rotational torque about a motor axis, and the linear actuator is configured to produce linear motion along a compression axis different from the motor axis. The harmonic driver is configured to receive the first rotational torque and provide the second rotational torque to a gear set. The gear set may be configured to receive the second rotational torque and cause an output gear to transmit at least a portion of the second rotational torque to the linear actuator, such that the linear actuator induces linear motion along the compression axis. The linear actuator may be configured to displace the piston substantially along the compression axis.

[0024] Therefore, in some examples, the actuator assembly is configured such that the motor generates a first rotational torque about the motor axis, and the linear actuator induces compression of the disc stack by displacing the piston along a compression axis different from the motor axis. Compared to inline actuators where a single axis serves as both the motor axis and the compression axis, the arrangement where the motor generates the first torque about the motor axis and the linear actuator translates the piston along a separate compression axis allows for a more compact actuator assembly configuration.

[0025] Actuator assemblies can be configured to substantially gradually reduce the rotational speed generated by the motor during braking operations, allowing for finer control of linear motion to increase or decrease the compressive force on the disc stack. This finer control of linear motion enables increased control over the compressive force applied to the disc stack, potentially improving the responsiveness and sensitivity of the braking system. In some examples, actuator assemblies use harmonic drives to gradually reduce the rotational speed generated by the motor. The use of harmonic drives reduces and / or eliminates gear backlash that can occur during motor speed changes in brake assemblies that primarily use meshing gearboxes to achieve gradual speed reduction. The relatively smooth operation of harmonic drives, compared to braking systems using gearboxes with input gears configured to rotate synchronously with the motor for gradual speed reduction, allows for increased braking operations per second.

[0026] In examples, the actuator assembly is configured to translate the piston when the linear actuator converts rotational motion generated by the motor into linear translation. For example, the actuator assembly may be configured to cause translation of the piston in a direction substantially parallel to the wheel axis. The piston is configured to translate to induce a compressive force on the disc stack (or eliminate a previously applied compressive force). In some examples, the actuator assembly includes an actuator body configured to be substantially stationary relative to a portion of the brake assembly (e.g., a torque tube), and the actuator assembly is configured to use linear translation to translate the piston relative to the actuator body. In some examples, the actuator assembly is configured to cause the piston to translate in a first direction (e.g., increase and / or induce a compressive force on the disc stack) when the motor generates rotational motion in a first axial direction, and is configured to cause the piston to translate in a second direction opposite to the first direction (e.g., to reduce and / or eliminate a compressive force on the disc stack) when the motor generates rotational motion in a second axial direction.

[0027] The harmonic driver of the actuator assembly is configured to receive a first rotational torque from the motor along a first rotational direction and at a first rotational speed, and to generate a second rotational torque using the first rotational torque. The harmonic driver is also configured to generate the second rotational torque along a second rotational direction opposite to the first rotational direction and at a second rotational speed less than the first rotational speed. In some examples, the harmonic driver includes a harmonic generator configured to receive the first rotational torque from the motor (e.g., the motor shaft) and rotate relative to the motor housing in the same rotational direction as the motor shaft rotates relative to the motor housing. For example, the harmonic driver may include a flexible spline configured such that when the harmonic generator rotates along the first rotational direction (e.g., under the influence of the first rotational torque), the flexible spline generates the second rotational torque along the second rotational direction. Therefore, the rotational direction of the motor shaft (e.g., along a first axial direction or a second axial direction) determines the first rotational direction of the first rotational torque, and thus the second rotational direction of the second rotational torque can be determined.

[0028] The motor can apply a first rotational torque to the harmonic driver in a first rotational direction by at least causing the motor shaft to rotate in a first or second axial direction. Therefore, as used herein, the first rotational direction refers to the direction of rotation of the first rotational torque applied by the motor to the harmonic driver, and not the direction of shaft rotation adopted by the motor to apply the first rotational torque. The second rotational direction refers to the direction of rotation of the second rotational torque generated by the harmonic driver using the first rotational torque, and not the direction of shaft rotation adopted by the motor when the harmonic driver generates the second rotational torque.

[0029] Similarly, the flexible spline of the harmonic driver can rotate along a first spline direction or a second spline direction opposite to the first spline direction to generate a second rotational torque in a second rotational direction opposite to the first rotational direction. In some examples, the motor shaft and the flexible spline rotate about a common axis (e.g., the motor axis), and the motor shaft and the flexible spline are configured to rotate about the common axis in opposite rotational directions.

[0030] In some examples, the harmonic driver, which may be referred to as a harmonic reducer, has any suitable configuration. In some examples, the harmonic driver includes: a fixed spline configured to remain substantially stationary relative to the motor housing; and a flexible spline. The flexible spline defines external gear teeth configured to mesh with internal gear teeth defined by the fixed spline to generate a second rotational torque along a second rotational direction and at a second speed. In some examples, the fixed spline defines a substantially circular (e.g., circular or nearly circular within manufacturing tolerances) pitch circle, and the harmonic generator is configured such that the flexible spline defines a substantially elliptical pitch circle. In some of these examples, the harmonic driver is configured such that the external teeth of the flexible spline mesh with the internal teeth of the circular spline at a point substantially along the major axis of the substantially elliptical pitch circle to generate the second rotational torque. The harmonic driver is configured to cause a speed reduction from the first rotational torque to the second rotational torque based on a reduction ratio that depends on the number of teeth (e.g., the number of teeth) of the flexible spline and the number of teeth of the fixed spline. In the example, the fixed spline has more teeth than the flexible spline.

[0031] A harmonic actuator (e.g., a flexible spline of a harmonic actuator) may be configured to apply a second rotational torque to the input gear of a gear set to cause rotation of the input gear. For example, the harmonic actuator may be configured to cause rotation of the input gear based on a second rotational direction of the second rotational torque. In some examples, the gear set includes an output gear, and the input gear is configured to cause rotation of the output gear when the harmonic actuator causes rotation of the input gear. The gear set may be configured such that the rotational direction of the input gear (e.g., by the harmonic actuator) substantially determines the rotational direction of the output gear (“output gear direction”). Therefore, the actuator assembly may be configured such that when the motor shaft applies a first rotational torque to the harmonic actuator in a first rotational direction, and the harmonic actuator uses the first rotational torque to apply a second rotational torque to the input gear in a second rotational direction, the output gear direction is determined by the rotational direction of the motor shaft.

[0032] In some examples, the actuator assembly is configured such that rotation of the motor shaft along a first axial direction causes the output gear to rotate along a first output gear direction, and rotation of the motor shaft along a second axial direction causes the output gear to rotate along a second output gear direction opposite to the first output gear direction.

[0033] In some examples, the linear actuator is configured to generate linear motion directly or indirectly using the rotation of the output gear. For example, the actuator assembly may be configured such that rotation of the output gear in a first output gear direction causes the linear actuator to generate linear motion in a first direction, and rotation of the output gear in a second output gear direction causes the linear actuator to generate linear motion in a second direction. Thus, the actuator assembly may be configured such that when the motor shaft rotates in a first axial direction causing the output gear to rotate in the first output gear direction, the linear actuator displaces the piston in the first direction to increase and / or induce compressive forces on the disc stack, and when the motor shaft rotates in the second axial direction causing the output gear to rotate in the second output gear direction, the linear actuator displaces the piston in the second direction to decrease and / or eliminate compressive forces on the disc stack.

[0034] In some examples, the linear actuator includes a driver configured to cause the screw to translate linearly when the driver rotates relative to the screw. An output gear may be configured to cause the driver to rotate when a motor (e.g., via a harmonic driver) causes the output gear to rotate. The linear actuator may be configured such that the driver determines the direction of the linear translation of the screw (e.g., a first direction or a second direction) about the direction of rotation of the screw. Therefore, the linear actuator may be configured to generate linear motion based on the direction of rotational motion received from the gear set. In some examples, the driver is a ball nut, and the screw is a ball screw. The linear actuator may be configured to cause a plurality of ball bearings between the ball nut and the ball screw to transmit force to the ball screw as the ball nut rotates relative to the ball screw.

[0035] Therefore, the brake assembly described herein is configured to apply compressive force on a disc stack using an actuator assembly to control the braking force applied to the wheel. The actuator assembly is configured to generate a first rotational torque (e.g., about a motor axis defined by the motor) using a motor at a first rotational speed and a second rotational torque using a harmonic actuator at a second rotational speed. The actuator assembly can be configured to use the second rotational torque to translate the piston along a compression axis different from the motor axis. Compared to an inline actuator where a single axis serves as both a motor axis and a compression axis, the arrangement where the motor generates the first torque about a motor axis and the linear actuator translates the piston over a separate compression axis allows for a more compact actuator assembly. Compared to braking systems that primarily use meshing gearboxes to achieve gradual speed reduction, the use of a harmonic actuator reduces and / or eliminates gear backlash during motor speed changes and allows for increased braking operations per second.

[0036] Figure 1This is a perspective view showing an exemplary wheel 10. In some examples, wheel 10 is part of an aircraft vehicle. In other examples, wheel 10 may be part of any other vehicle, such as any land vehicle or other vehicle. Figure 1 In the example shown, wheel 10 includes a wheel rim 12 defining an outer surface 14 and an inner surface 16. Wheel rim 12 includes a manhole 18 and a wheel hub 20. In some examples, the inner surface 16 may include the inner diameter of the manhole 18 of wheel 10. For example, in some cases, the inner surface 16 may be referred to as the inner diameter surface of wheel 10. The inner surface 16 and wheel hub 20 may define a wheel cavity 22 (e.g., volume) between the inner surface 16 and the wheel hub 20. In some examples, a tire (not shown) may be mounted on the outer surface 14 of rim 12. Wheel 10 may include an inner bead seat 24 and an outer bead seat 26 configured to retain the tire on the outer surface 14 of rim 12. In the example, wheel 10 may include an inner section 28 (e.g., including the inner bead seat 24) and an outer section 30 (e.g., including the outer bead seat 26). Wheel 10 is configured to rotate about an axis of rotation A. The axial direction A1 of wheel 10 is parallel to the axis of rotation A. The axial direction A2 of wheel 10 is parallel to the axis of rotation A and opposite to the direction A1.

[0037] The wheel 10 includes a plurality of rotor drive keys 32, such as rotor drive keys 34 and rotor drive keys 36, on an inner surface 16 of the wheel 10. In some examples, each of the plurality of rotor drive keys 32 extends in an axial direction A1 of the wheel 10 (e.g., in a direction parallel to the axis of rotation A). The plurality of rotor drive keys 32 (“rotor drive keys 32”) and the inner surface 16 are configured to be substantially stationary relative to each other, such that when the wheel 10 (and the inner surface 16) rotates about the axis of rotation A, each of the rotor drive keys (e.g., rotor drive keys 34, 36) translates in a closed path about the axis of rotation A. Therefore, when the wheel 10, the inner surface 16, and the rotor drive keys 32 rotate about the axis of rotation A, a force acting in the opposite direction to the rotation on one or more of the rotor drive keys 32 acts to slow down or stop the rotation. The rotor drive keys 32 may be configured to extend from a brake assembly ( Figure 2 The brake assembly 40 shown (or other brake assembly) receives torque and is configured to reduce and / or stop the rotation of the wheel 10. The rotor drive key 32 may be integrally formed with the inner surface 16, or may be separable from the inner surface 16 and mechanically attached to it.

[0038] Figure 2This is a schematic cross-sectional view showing the wheel 10 and the exemplary brake assembly 40. The wheel 10 includes a wheel rim 12, an outer surface 14, an inner surface 16, a wheel cavity 22, a wheel hub 20, an inner bead seat 24, an outer bead seat 26, an inner section 28, an outer section 30, and a rotor drive key 34. Figure 2 A wheel rim 12 is shown as a split rim wheel, wherein lug bolts 42 and lug nuts 44 connect the inner section 28 and the outer section 30; however, in other examples, the wheel rim 12 may utilize other configurations (e.g., a solid rim). A wheel 10 and brake assembly 40 are shown and described to provide an environment for the exemplary drive bushing described herein. However, in other examples, the drive bushing described herein may be used with any suitable wheel and brake assembly.

[0039] Wheel 10 is configured to rotate about a wheel axis A extending through axial assembly 46. Axial assembly 46 is configured to support wheel 10 while allowing wheel 10 to rotate about wheel axis A using bearings 48 and 50. For example, bearings 48 and 50 may define a substantially circular track around axial assembly 46. Torque tube 52 is coupled to axial assembly 46 (e.g., via bolts 54 and 56) such that torque tube 52 remains substantially stationary as wheel 10 rotates about axial assembly 46 and wheel axis A. Torque tube 52 may at least partially surround the exterior of axial assembly 46. Axial assembly 46 may be mechanically coupled to a structure attached to a vehicle (e.g., a strut).

[0040] exist Figure 2In the example shown, this portion of the depicted brake assembly 40 is shown positioned within the wheel 10 and configured to engage the torque tube 52 and the rotor drive key 34. The brake assembly 40 is configured to generate torque to counteract rotation of the wheel 10 about wheel axis A and transmit this torque to the rotor drive key 34, thereby reducing and / or eliminating rotation of the wheel 10 about wheel axis A. The brake assembly 40 includes a disc stack 58 comprising one or more rotor discs (e.g., rotor discs 60, 61, 62, 63) and one or more stator discs (e.g., stator discs 64, 65, 66). The rotor discs 60, 61, 62, 63 and / or the stator discs 64, 65, 66 can have any suitable configuration. For example, the rotor discs 60, 61, 62, 63 and / or the stator discs 64, 65, 66 can each be a substantially annular disc surrounding the axial assembly 46. Stator disks 64, 65, and 66 are connected to torque tube 52 via spline 68 and remain stationary relative to torque tube 52 (and axial assembly 46) as wheel 10 rotates. Rotor disks 60, 61, 62, and 63 are rotatably connected to rotor drive key 34 and inner surface 16 and rotate substantially synchronously with wheel 10 about axis A. For example, rotor drive key 34 may be configured to extend through drive slots on the periphery of one or more rotor disks 60, 61, 62, and 63 to cause rotor disks 60, 61, 62, and 63 to rotate substantially synchronously with wheel 10. Disk stack 58 may include any number of rotor disks and stator disks.

[0041] Rotor disks 60, 61, 62, 63 and / or stator disks 64, 65, 66 may be configured to provide opposing friction surfaces for braking vehicles such as aircraft. Compression of the disk stack 58 (e.g., between pressure plate 70 and backing plate 72) brings the opposing friction surfaces into contact, thereby generating a shear force between the rotor disks rotating substantially synchronously with the wheel 10 and the stator disks remaining substantially stationary relative to the torque tube 52. The shear force can cause the rotor disks (e.g., rotor disks 60, 61, 62, 63) engaging with the rotor drive key 34 to apply a torque opposite to the rotation of the wheel 10 on the rotor drive key 34. The rotor disks may apply a reverse torque to the rotor drive key 34 using drive slots extending through it.

[0042] Actuator assembly 73, including actuator body 77, is configured to cause piston 82 to translate relative to actuator body 77 to induce compression of disc stack 58. Actuator assembly 73 may be configured to cause piston 82 to translate along directions A1 and A2. For example, actuator assembly 73 may be configured to cause piston 82 to compress disc stack 58 when piston 82 translates substantially along direction A1, and to cause piston 82 to reduce (e.g., reduce and / or eliminate) compression when piston 82 translates substantially along direction A2. Brake assembly 40 may be configured such that compression of disc stack 58 (e.g., by causing piston 82 to translate substantially along direction A1) induces engagement between the friction surfaces of rotor discs 60, 61, 62, 63 and stator discs 64, 65, 66, thereby generating braking force to reduce and / or substantially prevent rotation of wheel 10. The brake assembly 40 may be configured to reduce and / or eliminate the compression of the disc stack 58 (e.g., by causing the piston 82 to translate substantially in the direction A2) to reduce and / or eliminate the engagement of the rotor discs 60, 61, 62, 63 and the stator discs 64, 65, 66, thereby reducing and / or eliminating the braking force on the wheel 10.

[0043] exist Figure 2 In the example shown, piston 82 defines piston surface 80, which is configured to establish contact pressure on pressure plate 70 when actuator assembly 73 translates piston 82 in direction A1. Actuator assembly 73 is configured to increase the contact pressure by causing piston 82 to translate in direction A1, thereby increasing the braking force generated on wheel 10 by the friction surfaces of rotor disks 60, 61, 62, 63 and stator disks 64, 65, 66. Actuator assembly 73 is configured to decrease the contact pressure by causing piston 82 to translate in direction A2, thereby decreasing the braking force generated on wheel 10 by the friction surfaces of rotor disks 60, 61, 62, 63 and stator disks 64, 65, 66.

[0044] In the example, actuator assembly 73 is configured to cause piston 82 to translate using motion (e.g., rotational motion) generated by an electric motor. Actuator assembly 73 may be configured to convert the rotational motion of the electric motor into linear motion to cause translation of piston 82 along direction A1 and / or direction A2. In some examples, actuator assembly 73 is configured to generate a first rotational torque using the electric motor at a first speed, and to convert the first rotational torque into a second rotational torque at a second speed less than the first speed. Actuator assembly 73 may be configured to rotate a portion of the linear actuator using the second rotational torque to cause translation of piston 82 along directions A1 and A2.

[0045] In the example, actuator assembly 73 also includes a harmonic reducer configured to receive a first rotational torque at a first speed and generate a second rotational torque at a second speed. In some examples, actuator assembly 73 further includes a gear set configured such that the electric motor generates the first rotational torque about a motor axis, and the piston 82 compresses the compression disc stack 58 along a compression axis, wherein the motor axis is different from the compression axis (e.g., displaced from the compression axis).

[0046] Wheel 10 and brake assembly 40 can be used with any kind of private, commercial, or military aircraft or other type of vehicle. Wheel 10 can be mounted to the vehicle via, for example, axial assembly 46 or some other suitable arrangement that allows wheel 10 to rotate about wheel axis A. Axis assembly 46 can be mounted on struts of landing gear (not shown) or other suitable components of the vehicle to connect wheel 10 to the vehicle. Wheel 10 can rotate about wheel axis A and axial assembly 46 to apply motion to the vehicle. Wheel 10 has been shown and described to provide context for the brake assembly described herein; however, in other examples, the brake assembly described herein can be used with any suitable wheel assembly.

[0047] Figure 3 This is a conceptual diagram of an exemplary actuator assembly 74, and a portion of the actuator assembly 74 is shown in cross-sectional and functional block diagram form with reference to the illustrated xyz axes. The actuator assembly 74 includes an actuator body 78. The actuator assembly 74 is an example of an actuator assembly 73, and the actuator body 78 is an example of an actuator body 77 (…). Figure 2 Examples of ). Figure 4 Another view of actuator assembly 74 is shown and includes Figure 3 The xyz axes are provided for reference. Actuator assembly 74 includes a motor 84, a harmonic driver 86, a gear set 88, and a linear actuator 90. The portion of the harmonic driver 86 is... Figure 4 The axes A1 and A2 are shown as dashed lines. Figure 3 and 4 As shown, axial direction A1 exits from the page, while axial direction A2 enters. Figure 4 The page in the middle.

[0048] Actuator assembly 74 is configured to use piston 82 to cause compression of disc stack 58 when braking is required. Actuator assembly 74 is configured to translate piston 82 in a first direction (e.g., axial direction A1) to cause compressive force on disc stack 58 (e.g., via pressure plate 70), thereby generating and / or increasing the braking force on wheel 10. Figure 1The actuator assembly 74 is configured to translate the piston 82 in a second direction substantially opposite to the first direction (e.g., axial direction A2) to reduce and / or eliminate the compressive force on the disc stack 58, thereby reducing and / or substantially eliminating the braking force on the wheel 10. Figure 3 and Figure 4 In the example shown, the actuator body 78 is configured to be substantially stationary relative to a portion of the brake assembly 40 (e.g., torque tube 52 or some other part). In some examples, the actuator assembly 74 is configured to translate the piston 82 relative to the actuator body 78.

[0049] Actuator assembly 74 is configured to convert the rotational motion generated by motor 84 into linear translation of piston 82 to control the braking assembly 40. Figure 2 The braking force generated on wheel 10. Figure 3 and Figure 4 In the example shown, motor 84 includes a motor housing 92 and a motor shaft 94, and motor 84 is configured to generate rotational motion by at least causing rotation of motor shaft 94 relative to motor housing 92. Motor housing 92 may be configured to be substantially stationary relative to actuator body 78. Motor 84 may be configured to cause rotation of motor shaft 94 about a motor axis MA defined by motor shaft 94. In this example, motor 84 is configured to cause rotation of motor shaft 94 along a first axial direction R1 (e.g., clockwise about motor axis MA) and along a second axial direction R2 (e.g., counterclockwise about motor axis MA) substantially opposite to the first axial direction R1. Motor housing 92 may be configured to be substantially stationary relative to actuator body 78. Furthermore, the first axial direction R1 and the second axial direction R2 are shown only as examples. In other examples, the first axial direction R1 may be counterclockwise and the second axial direction R2 may be clockwise about motor axis MA, or the first axial directions R1 and R2 may have some other arrangement relative to actuator assembly 74.

[0050] In some examples, the actuator assembly 74 is configured such that rotational movement of the motor shaft 94 along the first axial direction R1 causes the piston 82 to increase and / or induce compressive force on the disc stack 58, thereby increasing the braking force transmitted from the brake assembly 40 to the wheel 10 (e.g., via rotor drive keys 32, 34, 36). Figure 1 and Figure 2Additionally, actuator assembly 74 may be configured such that rotational movement of motor shaft 94 along the second axial direction R2 causes piston 82 to reduce and / or substantially eliminate compressive forces on disc stack 58, thereby reducing braking force transmitted from brake assembly 40 to wheel 10. In the example, actuator assembly 74 is configured to convert rotational movement of motor shaft 94 along the first axial direction R1 into linear translation of piston 82 along a first direction (e.g., axial direction A1), and to convert rotational movement of motor shaft 94 along the second axial direction R2 into linear translation of piston 82 along a second direction (e.g., axial direction A2).

[0051] Control circuitry 96 is configured to control actuator assembly 74. For example, control circuitry 96 may be configured to transmit a braking signal to actuator assembly 74 to cause actuator assembly 74 to translate piston 82. In an example, control circuitry 96 is configured to transmit the braking signal using communication link 98. Motor 84 may be configured to generate rotational motion in response to the braking signal. In some examples, control circuitry 96 is configured to receive user input from input device 102 (e.g., a foot switch in the cockpit and / or an anti-lock braking system (ABS)) and transmit a braking signal to actuator assembly 74 based on the user input. Input device 102 may use communication link 104 to transmit the braking signal to control circuitry 96. In the example, the control circuit 96 is configured to receive a first user input (e.g., an indication that braking needs to be increased) and transmit a braking signal to the actuator assembly 74, thereby causing the motor 84 to generate rotational motion along the first axial direction R1, and is further configured to receive a second user input (e.g., an indication that braking needs to be reduced) and transmit a braking signal to the actuator assembly 74, thereby causing the motor 84 to generate rotational motion along the second axial direction R2.

[0052] Actuator assembly 74 is configured to generate a first rotational torque using motor 84 at a first rotational speed. In an example, actuator assembly 74 generates the first rotational torque using rotation of motor shaft 94. Actuator assembly 74 can generate the first rotational torque along a first rotational direction. In an example, the first rotational direction of the first rotational torque is determined by the rotational direction of motor shaft 94. When motor shaft 94 rotates along a first axial direction R1 or a second axial direction R2, motor shaft 94 can generate a first rotational torque having a first rotational direction. Therefore, in some examples, the first rotational direction of the first rotational torque has the same rotational direction as the first axial direction R1 (e.g., T1-A). Figure 4 As shown in the figure), and in other examples, the first rotational direction of the first rotational torque has the same rotational direction as the second axial direction R2 (such as T1-B). Figure 4(as shown in the diagram). In some examples, actuator assembly 74 is configured such that the first rotational torque acts about motor axis MA. Alternatively, in some examples, actuator assembly 74 is configured such that the first rotational torque acts about motor axis 94.

[0053] Actuator assembly 74 is configured to gradually reduce a first rotational speed by using at least a first rotational torque to generate a second rotational speed having a second rotational speed less than the first rotational speed. In the example, the first rotational speed depends on or is substantially equal to the rotational speed of motor shaft 94. Gradually reducing the first rotational speed allows motor 84 to be a relatively high-speed motor, configured to generate rotation at a higher shaft speed, which may be desirable for other components of actuator assembly 74 (e.g., gear set 88 and / or linear actuator 90). Furthermore, the first rotational torque generated by motor 84 may be lower than the torque required for operation of actuator assembly 74. Gradually reducing the first rotational speed to the second rotational speed causes the generated second rotational torque to exceed the first rotational torque, such that the remaining components of actuator assembly 74 (e.g., gear set 88 and / or linear actuator 90) can be operated with a torque exceeding the torque generated by motor 84. Therefore, in the example, the actuator assembly 74 is configured to use a first rotational torque generated by the motor 84 at a first rotational speed to generate a second rotational torque at a second rotational speed, wherein the second rotational torque is greater than the first rotational torque and the second rotational speed is less than the first rotational speed.

[0054] The harmonic driver 86 is configured to receive a first rotational torque (e.g., T1-A or T1-B) from the motor 84 and generate a second rotational torque at a second rotational speed in response to the first rotational torque. In some examples, the second rotational speed is less than the first rotational speed. In some examples, the second rotational torque is greater than the first rotational torque. In some examples, the first rotational torque has a first rotational direction, and the harmonic driver 86 is configured to generate the second rotational torque in a second rotational direction opposite to the first rotational direction. For example, the harmonic driver 86 may be configured to receive the first rotational torque T1-A ( Figure 4The first rotational torque has a first rotational direction, which is clockwise about the motor axis MA (or some other axis); and generates a second rotational torque T2-A, which has a second rotational direction, which is counterclockwise about the motor axis MA (or another axis). The harmonic driver 86 may be configured to: receive the first rotational torque T1-B, which has a first rotational direction, which is counterclockwise about the motor axis MA (or some other axis); and generate the second rotational torque T2-B, which has a second rotational direction, which is clockwise about the motor axis MA (or another axis).

[0055] Therefore, the harmonic driver 86 is configured to generate a second rotational torque when the motor shaft 94 rotates along a first axial direction R1 or a second axial direction R2, the second rotational torque having a second rotational direction opposite to the first rotational direction. In the example, when the motor shaft 94 rotates about the motor axis MA along the first axial direction R1, the first rotational direction of the first rotational torque (e.g., T1-A) is substantially the same as the first axial direction R1, and the second rotational direction of the second rotational torque (e.g., T2-A) is substantially the same as the second axial direction R2. In the example, when the motor shaft 94 rotates about the motor axis MA along the second axial direction R2, the first rotational direction of the first rotational torque (e.g., T1-B) is substantially the same as the second axial direction R2, and the second rotational direction of the second rotational torque (e.g., T2-B) is substantially the same as the first axial direction R1.

[0056] The harmonic driver 86 can be configured in any suitable way. In some examples, such as... Figure 3 As shown, the harmonic driver 86 includes a harmonic generator 106, a flexible spline 108, and a fixed spline 110. Figure 3 Harmonic generator 106 is configured to rotate about an axis (e.g., motor axis MA) when it receives a first rotational torque from motor 84. Fixed spline 110 is configured to be substantially stationary relative to actuator body 78 and / or motor housing 92. Flexible spline 108 engages both harmonic generator 106 and fixed spline 110. In this example, flexible spline 108 is positioned between harmonic generator 106 and fixed spline 110. Harmonic driver 86 is configured to cause flexible spline 108 to generate a second rotational torque in a second rotational direction when harmonic generator 106 receives the first rotational torque in a first rotational direction (e.g., from motor 84).

[0057] Actuator assembly 74 may be configured to cause gear set 88 to rotate in response to a second rotational torque. For example, harmonic driver 86 (e.g., flexible spline 108) may be configured to apply the second rotational torque to gear set 88 to induce rotation. Gear set 88 may include one or more gears (e.g., input gear 112 and output gear 118) configured to transmit rotational motion to linear actuator 90, causing linear actuator 90 to translate piston 82 in the axial direction A1 (e.g., to increase and / or induce compressive forces on disk stack 58) or in the axial direction A2 (e.g., to reduce and / or substantially eliminate compressive forces on disk stack 58).

[0058] The gear set 88 is configured such that the direction of rotation of the rotational motion transmitted to the linear actuator 90 depends on the second direction of rotation of the second rotational torque applied by the harmonic driver 86. The linear actuator 90 may be configured such that the direction of rotation of the rotational motion transmitted from the gear set 88 substantially determines the linear direction (e.g., axial direction A1 or axial direction A2) in which the linear actuator 90 translates the piston 82. Therefore, the actuator assembly 74 may be configured such that the direction of the linear translation generated by the linear actuator 90 depends on the direction of rotation of the motor shaft 94. For example, when the motor shaft 94 rotates in one direction (e.g., a first axial direction R1 or a second axial direction R2), the actuator assembly 74 may be configured such that the linear actuator 90 translates the piston 82 to increase and / or induce compressive forces on the disk stack 58; and when the motor shaft 94 rotates in another direction (e.g., the other of the first axial direction R1 or the second axial direction R2), the actuator assembly 74 may be configured such that the linear actuator 90 translates the piston 82 to reduce and / or substantially eliminate compressive forces on the disk stack 58.

[0059] In some examples, the harmonic driver 86 (e.g., flexible spline 108) is configured to apply a second rotational torque to the input gear 112 of the gear set 88 to cause rotation of the input gear 112. In these examples, the actuator assembly 74 is configured to cause rotation of the input gear 112 based on a second rotational direction of the second rotational torque. For example, when the harmonic driver 86 generates the second rotational torque T2-A, the actuator assembly 74 may be configured to cause rotation of the input gear 112 in a direction substantially the same as the second rotational torque T2-A. When the harmonic driver 86 generates the second rotational torque T2-B, the actuator assembly 74 may be configured to cause rotation of the input gear 112 in a direction substantially the same as the second rotational torque T2-B. In some examples, the actuator assembly 74 is configured to cause rotation of the input gear 112 in a direction opposite to the rotation of the motor shaft 94.

[0060] In some examples, the input gear 112 defines gear teeth 114 (“input gear teeth 114”) around its outer periphery 116. For example, the input gear 112 may define input gear teeth 114 around a pitch circle surrounding the gear axis of the input gear 112. In some examples, the input gear 112 is configured such that when a second rotational torque is applied to the input gear 112, the input gear teeth 114 rotate substantially about the motor axis MA. For example, the gear axis of the input gear 112 may be substantially parallel to or substantially coincident with the motor axis MA defined by the motor 84.

[0061] Gear set 88 further includes an output gear 118. Gear set 88 is configured such that rotation of input gear 112 causes a corresponding rotation of output gear 118. In the example, gear set 88 is configured such that the direction of rotation of input gear 112 substantially determines the output gear direction of output gear 118. Therefore, when motor shaft 94 applies a first rotational torque (e.g., T1-A or T1-B) to harmonic driver 86 in a first rotational direction, and harmonic driver 86 uses the first rotational torque to apply a second rotational torque (e.g., T2-A or T2-B) to input gear 112 in a second rotational direction, actuator assembly 74 can be configured such that the output gear direction of output gear 118 depends on the direction of rotation of motor shaft 94. In the example, actuator assembly 74 is configured such that rotation of motor shaft 94 in a first axial direction R1 causes output gear 118 to rotate in a first output gear direction (e.g., output gear direction R3). Figure 4 The rotation of the motor shaft 94 along the second axial direction R2 causes the output gear 118 to rotate along the second output gear direction, which is opposite to the first output gear direction (e.g., output gear direction R4). Figure 4 The output gear 118 can be configured to transmit rotational motion to the linear actuator 90 in the direction of the first output gear or the direction of the second output gear.

[0062] In some examples, the output gear 118 defines gear teeth 120 (“output gear teeth 120”) around the outer periphery 122 of the output gear 118, for example, around the pitch circle surrounding the gear axis of the output gear 118. In the examples, and as... Figure 3 and Figure 4As depicted, the output gear teeth 120 are configured to mesh with the input gear teeth 114, such that the input gear teeth 114 apply torque to the output gear teeth 120, thereby causing the output gear 118 to rotate about its axis. In the example, the actuator assembly 74 is configured such that the gear axis of the output gear 118 is displaced from the gear axis of the input gear 112. In the example, the actuator assembly 74 is configured such that the gear axis of the output gear 118 is substantially parallel to the gear axis of the input gear 112. The actuator assembly 74 may be configured such that the gear axis of the output gear 118 is substantially parallel to the motor axis MA defined by the motor 84 (e.g., parallel or nearly parallel within manufacturing tolerances).

[0063] The linear actuator 90 is configured to cause the piston 82 to translate substantially linearly along the compression axis CA. For example... Figure 3 As shown, in some examples, the compression axis CA is shifted from the motor axis MA, for example, along the y-axis (as shown) or along one or more other or additional axes. In examples, such as... Figure 3 As shown, gear set 88 is configured to convert rotational motion about the motor axis MA (e.g., from the flexible spline 108) into rotational motion about the compression axis CA. In the example, actuator assembly 74 is configured to cause input gear 112 to rotate about the motor axis MA and output gear 118 to rotate about the compression axis CA. In some examples, actuator assembly 74 is configured to cause motor 84 and / or harmonic driver 86 to rotate along one or more of the x, y, and z axes (e.g., the y-axis, as shown in the image). Figure 3 (As shown) Displaced from the compression axis CA. Actuator assembly 74 may be configured such that the linear actuator 90 is displaced along one or more of the x, y, and z axes (e.g., the y-axis, as shown). Figure 3 (As shown) Displaced from the motor axis MA. Therefore, compared to an inline actuator, actuator assembly 74 allows for flexibility in the relative positioning of the motor 84, harmonic driver 86, and / or linear actuator 90, which can be configured to rotate the motor shaft about the motor axis and cause the piston to translate on a compression axis that is substantially coincident with the motor axis.

[0064] A linear actuator 90 is configured to receive rotational motion from a gear set 88 and convert the rotational motion into a linear translation substantially along the compression axis CA. In an example, the linear actuator 90 includes a driver 124 configured to receive rotational motion from the gear set 88. The driver 124 may be configured to rotate (e.g., about the compression axis CA) when it receives rotational motion from the gear set 88. The linear actuator 90 may be configured to produce a linear translation substantially along the compression axis CA when the driver 124 rotates. In an example, an output gear 118 is configured to transmit rotational motion to the driver 124. The driver 124 may be configured to rotate in a first direction (“first driver direction”) when the output gear 118 transmits rotational motion to the driver 124 in a first output gear direction, and is configured to rotate in a second direction (“second driver direction”) opposite to the first driver direction when the output gear 118 transmits rotational motion to the driver 124 in a second output gear direction.

[0065] In some examples, the output gear 118 and the actuator 124 form a substantially rigid body (e.g., a substantially integral component) such that the actuator 124 and the output gear 118 rotate in the same direction of rotation. For example, the actuator assembly 74 may be configured such that when the output gear 118 rotates about the compression axis CA in direction R3, the actuator 124 rotates about the compression axis CA in direction R3. The actuator assembly 74 may be configured such that when the output gear 118 rotates about the compression axis CA in direction R4, the actuator 124 rotates about the compression axis CA in direction R4.

[0066] The actuator assembly 74 has any suitable configuration configured to cause the piston 82 to translate along an axial direction A1 or A2. In some examples, the actuator assembly 74 includes a screw 126 configured to translate linearly along a compression axis CA when the actuator 124 rotates, wherein the screw 126 is configured to cause the piston 82 to translate along an axial direction A1 or A2 when the screw 126 translates linearly. In an example, the screw 126 is configured to translate linearly along a first axial direction A1 when the actuator 124 rotates along a first actuator direction (e.g., direction R3). The screw 126 may be configured to translate linearly along a second axial direction A2 when the actuator 124 rotates along a second actuator direction (e.g., direction R4).

[0067] The screw 126 can be configured to increase and / or induce compressive forces on the disc stack 58 when the screw 126 linearly displaces the piston 82 in the axial direction A1. The screw 126 can also be configured to decrease and / or eliminate compressive forces on the disc stack 58 when the screw 126 linearly displaces the piston 82 in the axial direction A2. The direction of the linear translation of the screw 126 depends on the drive direction of the driver 124 and the output gear direction of the output gear 118, which depends on the second rotational direction of the second rotational torque (T2-A or T2-B) determined by the motor shaft 94. Therefore, the direction of the linear translation produced by the screw 126 can depend on the rotational direction of the motor shaft 94.

[0068] Therefore, actuator assembly 74 is configured to generate a first rotational torque (T1-A or T2-B) using motor 84 at a first rotational speed, generate a second rotational torque (T2-A or T2-B) using harmonic driver 86 at a second rotational speed less than the first rotational speed, and convert the second rotational torque into linear motion using linear actuator 90. Linear actuator 90 can cause piston 82 to translate in a direction dependent on the rotational direction of motor shaft 94. In the example, motor 84 is configured to generate the first rotational torque about motor axis MA, and linear actuator 90 is configured to produce linear motion along a compression axis CA different from motor axis MA. Therefore, compared to inline actuators, actuator assembly 74 allows for flexibility in the relative positioning of motor 84, harmonic driver 86, and / or linear actuator 90, which can be configured to rotate the motor shaft about the motor axis and cause piston translation on a compression axis substantially coincident with the motor axis.

[0069] Motor 84 is configured to receive electrical power (e.g., from an onboard generator system) and convert the power into rotation of motor shaft 94 relative to motor housing 92. Motor 84 may be configured to receive AC (alternating current) or DC (direct current) power. Motor 84 may include a rotor and a stator and may be configured to generate a rotational field on the stator to generate torque on the rotor. In some examples, motor 84 is a brushless DC (BLDC) motor, configured to receive DC power input and generate a rotational field on the stator via electronic commutation. Motor 84 may utilize multiple permanent magnets on the rotor to urge rotor torque in response to the rotating stator field. Motor shaft 94 may be coupled to the rotor such that rotation of the rotor in response to rotor torque causes motor shaft 94 to rotate about motor axis MA. In the example, motor 84 is configured to provide a rotational field or commutation field on the rotor to generate torque.

[0070] Control circuit 96 is configured to control the rotational direction of motor shaft 94 based on inputs, for example, from input device 102. Control circuit 96 may be configured to cause motor 84 to rotate motor shaft 94 along a first axial direction R1 or a second axial direction R2. In an example, control circuit 96 is configured to control the rotational speed of motor shaft 94 about motor axis MA. For example, control circuit 96 may be configured to increase or decrease the rotational speed of motor shaft 94 based on inputs from input device 102 to increase or decrease the speed of linear translation of piston 82 along compression axis CA. In some examples, control circuit 96 is configured to receive signals from sensor 128, which is configured to sense operating parameters of motor shaft 94, such as speed, position, and / or rotational direction. Control circuit 96 may be configured to use the sensed operating parameters to maintain or determine desired changes in the operation of motor 84 to achieve desired braking operation. Control circuit 96 may be configured to communicate with other control systems on the vehicle, such as anti-lock braking system (ABS), brake control unit (BCU), or other systems.

[0071] Figure 5 A harmonic driver 86 comprising a harmonic generator 106, a flexible spline 108, and a fixed spline 110 is schematically depicted. Figures 6A to 6D The diagram depicts a harmonic driver 86 receiving a first rotational torque T1 on a harmonic generator 106 and using the first rotational torque T1 to generate a second rotational torque T2 on a flexible spline 108. Figures 6A to 6D In the context of the first rotational torque T1, when the second rotational torque T2 is equal to torque T2-A, the first rotational torque T1 can be equal to torque T1-A. Figure 4 Alternatively, when the second rotational torque T2 is torque T2-B, the first rotational torque T1 can be torque T1-B.

[0072] Motor shaft 94 is attached to harmonic generator 106 such that rotation of motor shaft 94 about motor axis MA causes rotation of harmonic generator 106 about motor axis MA. Harmonic generator 106 defines a substantially elliptical (e.g., elliptical or nearly elliptical within manufacturing tolerances) perimeter P about motor axis MA. Fixed spline 110 is configured to remain substantially stationary relative to actuator body 78 and includes internal teeth 130 around a substantially circular pitch circle. In this example, harmonic generator 106 includes a plurality of ball bearings 132, including ball bearings 133 and 134. Flexible spline 108 is positioned between harmonic generator 106 and fixed spline 110 and includes external teeth 136 configured to engage with internal teeth 130.

[0073] The harmonic driver 86 is configured such that the harmonic generator 106 and the flexible spline 108 can rotate asynchronously. For example, when the motor shaft 94 causes the harmonic generator 106 to rotate about the motor axis MA, the harmonic driver 86 can be configured such that the ball bearing 132 allows the harmonic generator 106 (and its periphery P) to slide substantially beneath the flexible spline 108 as the harmonic generator 106 rotates about the motor axis MA. The flexible spline 108 is configured to bend to substantially conform to the periphery P when the harmonic generator 106 rotates asynchronously relative to the flexible spline 108. The periphery P of the harmonic generator 106 causes the flexible spline 108 to define an elliptical pitch circle having a major axis AX1 and a minor axis AX2, wherein the length defined by the minor axis AX2 is less than that of the major axis AX1.

[0074] The harmonic driver 86 is configured such that when the periphery P of the harmonic generator 106 rotates about the motor axis MA, the flexible spline 108 bends (e.g., elastically deforms), causing the major axis AX1 and the minor axis AX2 to rotate at the same rotational speed as the harmonic generator 106. When the harmonic generator 106 slides under the flexible spline 108, the flexible spline 108 deforms into an elliptical shape and defines an elliptical pitch circle, thereby causing the outer tooth 136 to engage substantially along the major axis AX1 with the inner tooth 130. Furthermore, the elliptical pitch circle causes the outer tooth 136 to disengage substantially along the minor axis AX2 from the inner tooth 130. Therefore, the rotation of the motor shaft 94 about the motor axis MA causes the harmonic generator 106 to rotate about the motor axis MA, and the harmonic generator 106 causes the flexible spline 108 to bend, causing the major axis AX1 and the minor axis AX2 to rotate synchronously with the motor shaft 94 and the harmonic generator 106. The flexible spline 108 bends (e.g., deforms elastically) such that the outer tooth 136 engages with the inner tooth 130 along the long axis AX1, and when the long axis AX1 and the short axis AX2 rotate, the outer tooth 136 disengages from the inner tooth 130 along the short axis AX2.

[0075] The flexible spline 108 is configured to rotate about the motor axis MA in a direction of rotation opposite to that of the harmonic generator 106. In the example, the flexible spline 108 defines a plurality of external teeth 136, fewer in number than the number of internal teeth 130 defined by the fixed spline 110. In the example, the flexible spline 108 defines a plurality of external teeth 136, the number of which is at least two fewer than the number of internal teeth 130 (e.g., two, three, four, or more). Compared to the harmonic generator 106, the combination of the elliptical pitch circle of the fixed spline 110 and the reduced number of external teeth 136 causes the flexible spline 108 to rotate about the motor axis MA in the opposite direction. In the example, when the harmonic generator 106 (and the major axis AX1) rotates 180 degrees clockwise, the flexible spline 108 rotates one tooth of the internal tooth 130 counterclockwise relative to the fixed spline 110. For each complete clockwise rotation (360 degrees) of the harmonic generator 106, the flexible spline 108 can move two teeth of the internal gear 130 counterclockwise relative to the fixed spline 110. Therefore, when the motor shaft 94 applies a first torque (T1-A or T1-B) to the harmonic generator 106 in the first rotational direction, the harmonic driver 86 is configured to cause the flexible spline 108 to generate a second torque (T2-A or T2-B) in a second rotational direction opposite to the first rotational direction.

[0076] As an example, Figures 6A to 6D A harmonic drive 86 is depicted, in which a motor shaft 94 applies a first torque T1 to a harmonic generator 106. Figures 6A to 6D In the example, the first torque T1 causes the harmonic generator 106 to rotate counterclockwise. Relative to Figure 6A The first torque T1 has caused the harmonic generator 106 to... Figure 6B Rotate 90 degrees counterclockwise in the middle. Figure 6C Rotate 180 degrees counterclockwise in the middle, and Figure 6D Rotate 270 degrees counterclockwise.

[0077] A fixed point M is depicted on the flexible spline 108. The harmonic driver 86 is configured such that when the harmonic generator 106 rotates counterclockwise, the fixed point M on the flexible spline 108 rotates clockwise. For example, in Figure 6B In the process, a 90-degree counterclockwise rotation of the harmonic generator 106 causes the fixed point M to rotate clockwise over an angular displacement indicated by angle G1. Figure 6C In the process, the 180-degree counterclockwise rotation of the harmonic generator 106 has caused the fixed point M to rotate clockwise over an angular displacement indicated by angle G2, where angle G2 is greater than angle G1. Figure 6DIn the process, the 270-degree counterclockwise rotation of the harmonic generator 106 causes the fixed point M to rotate clockwise over an angular displacement indicated by angle G3, where angle G3 is greater than angle G2. The rotation of the flexible spline 108 (causing the rotation of the fixed point M) causes the flexible spline 108 to generate a second torque T2, which has a rotational direction opposite to the first torque T1.

[0078] In addition, such as Figures 6A to 6D As shown, the harmonic driver 86 provides a speed reduction from a first rotational speed to a second rotational speed of a first torque T1 to a second rotational speed of a second torque T2. In this example, the harmonic driver 86 generates the speed reduction from the first rotational speed to the second rotational speed based on the number of external teeth 136 and the number of internal teeth 130. In this example, the speed reduction is substantially equal to the number of external teeth 136 divided by the difference between the number of internal teeth 130 and the number of external teeth 136. In other words, the speed reduction can be substantially equal to N1 / (N2-N1), where N1 is the number of external teeth 136 and N2 is the number of internal teeth 130.

[0079] In some examples, the flexible spline 108 is essentially configured as a thin-walled steel cup, wherein the outer teeth 136 are machined to an outer surface near and / or adjacent to the open end of the cup (e.g., at the "top" of the cup). The flexible spline 108 may include a diaphragm at the end of the cup opposite the open end (e.g., at the "bottom" of the cup). The flexible spline 108 is configured to transmit a second rotational torque generated by the engagement of the outer teeth 136 and the inner teeth 130 to the diaphragm. In an example, the harmonic driver 86 is configured to use a diaphragm in gear set 88 (… Figure 3 , Figure 4 A second rotational torque is applied to the motor. In the example, the harmonic driver 86 is configured to apply a second rotational torque about the motor axis MA.

[0080] Input gear 112 ( Figure 3The input gear 112 can be configured to receive a second rotational torque from the diaphragm of the harmonic driver 86. The input gear 112 can define input gear teeth 114 about a pitch circle surrounding the input gear axis, such that torque on the input gear 112 about the input gear axis causes the input gear teeth 114 to rotate about the input gear axis. In the example, the input gear axis is substantially parallel or substantially coaxial with the motor axis MA. In the example, the input gear 112 is configured to receive a second rotational torque from the harmonic driver 86 and rotate about the input gear axis in a second direction of rotation of the second rotational torque. The input gear 112 can be configured to rotate in a second rotational direction when the motor shaft 94 rotates in a first rotational direction. In the example, the actuator assembly 74 is configured such that rotation of the motor shaft 94 about the motor axis MA in a first axial direction causes rotation of the input gear 112 in a second axial direction opposite to the first axial direction, and rotation of the shaft 94 about the motor axis MA in a second axial direction causes rotation of the input gear 112 in the first axial direction.

[0081] Gear set 88 is configured such that rotation of input gear 112 causes rotation of output gear 118. In the example, output gear 118 defines output gear teeth 120 about a pitch circle surrounding the output gear axis, such that rotation of output gear 118 about the output gear axis causes rotation of output gear teeth 120 about the output gear axis. In the example, the output gear axis of output gear 118 is displaced from (e.g., different from) the input gear axis of input gear 112. Therefore, gear set 88 can be configured to receive a second rotational torque to cause rotation of input gear 112 about the input gear axis, and to transmit at least a portion of the second rotational torque to output gear 118 to cause rotation of output gear 118 about an output gear axis different from the input gear axis. In the example, the input gear axis is substantially aligned with the motor axis MA (e.g., substantially coaxial). In the example, the output gear axis is substantially aligned with the compression axis CA (e.g., substantially coincident). Therefore, gear set 88 can be configured to transmit torque substantially from motor axis MA to compression axis CA, allowing for a more compact actuator assembly compared to an inline actuator where a single axis substantially coincides with both motor axis MA and compression axis CA.

[0082] In the example, gear set 88 is configured such that input gear teeth 114 mesh with output gear teeth 120 to cause rotation of output gear 118. In some examples, gear set 88 is configured such that input gear 112 drives rotation of output gear 118 without using one or more idler gears between input gear 112 and output gear 118. Gear set 88 may be configured such that the rotational speed of input gear 112 is greater than the rotational speed of output gear 118. In the example, input gear 112 defines a plurality of input gear teeth 114 and output gear 118 defines a plurality of output gear teeth 120, and the number of input gear teeth 114 is less than the number of output gear teeth 120. Gear set 88 may be configured such that the reduction factor of the rotational speed of output gear 118 from the rotational speed of input gear 112 is substantially equal to the number of input gear teeth 114 divided by the number of output gear teeth 120. In other words, the speed reduction from the input gear 112 to the output gear 118 can be substantially equal to N3 / N4, where N3 is the number of teeth 114 on the input gear and N4 is the number of teeth 120 on the output gear.

[0083] Therefore, actuator assembly 74 can be configured such that when motor 84 generates a first torque at a first rotational speed (e.g., T1-A or T1-B), harmonic driver 86 can cause a first speed reduction by using the first torque to generate a second torque at a second rotational speed less than the first rotational speed. The first speed reduction can be substantially equal to N1 / (N2-N1), where N1 is the number of external teeth 136 and N2 is the number of internal teeth 130. Actuator assembly 74 can be configured such that when gear set 88 receives the second rotational torque at the second rotational speed, and when gear set 88 uses the second rotational torque to generate rotation of output gear 118, gear set 88 causes a second speed reduction. The second speed reduction can be substantially equal to N3 / N4, where N3 is the number of input gear teeth 114 and N4 is the number of output gear teeth 120.

[0084] In the examples, actuator assembly 74 may be configured such that a first speed reduction and a second speed reduction cause an overall speed reduction of at least 80:1, and in some examples at least 150:1. Furthermore, actuator assembly 74 may be configured to cause an overall speed reduction without using one or more idler gears between input gear 112 and output gear 118, thereby reducing and / or eliminating gear backlash during changes in the speed and / or rotational direction of motor shaft 94. Moreover, using harmonic drive 86 and gear set 88 to achieve speed reduction without idler gears allows for a more compact actuator assembly compared to actuators configured to primarily use meshing gearboxes for gradual speed reduction.

[0085] Gear set 88 is configured such that the rotational direction of input gear 112 substantially determines the output gear direction of output gear 118. Actuator assembly 74 is configured such that the rotational direction of motor shaft 94 (e.g., a first axial direction R1 or a second axial direction R2) substantially determines the rotational direction of input gear 112. Therefore, actuator assembly 74 is configured such that the rotational direction of motor shaft 94 determines the output gear direction of output gear 118. In the example, rotation of motor shaft 94 along the first axial direction R1 causes output gear 118 to rotate along the first output gear direction (e.g., output gear direction R3). Figure 4 The rotation of the motor shaft 94 along the second axial direction R2 causes the output gear 118 to rotate along the second output gear direction, which is opposite to the first output gear direction (e.g., output gear direction R4). Figure 4 Rotate.

[0086] Output gear 118 is configured to transmit rotational motion to linear actuator 90 along a first output gear direction or a second output gear direction. In an example, output gear 118 is configured to cause a portion of linear actuator 90 (e.g., driver 124) to rotate about a compression axis CA. Linear actuator 90 is configured to receive rotational motion from output gear 118 (along the first output gear direction or the second output gear direction) and convert the rotational motion into a linear translation substantially along the compression axis CA. In an example, linear actuator 90 is configured to produce a linear translation substantially along the compression axis CA when driver 124 rotates substantially about the compression axis CA. In an example, driver 124 is configured to rotate in a first driver direction when output gear 118 transmits rotational motion to driver 124 along the first output gear direction, and is configured to rotate in a second driver direction opposite to the first driver direction when output gear 118 transmits rotational motion to driver 124 along the second output gear direction.

[0087] In the example, screw 126 is configured to translate linearly along compression axis CA when actuator 124 rotates about compression axis CA. The linear actuator can be configured such that screw 126 translates axially in direction A1 when actuator 124 rotates in a first actuator direction, and translates axially in direction A2 when actuator 124 rotates in a second actuator direction. Therefore, actuator assembly 74 can be configured such that the direction of rotation of motor shaft 94 determines the direction of rotation of actuator 124 about compression axis CA, and thereby determines the direction of translation of screw 126. For example, in some examples, when motor 84 causes motor shaft 94 to rotate along a first axial direction R1, driver 124 causes screw 126 to translate linearly along direction A1 to increase and / or induce compressive force on the disk stack 58, and when motor 84 causes motor shaft 94 to rotate along a second axial direction R2, driver 124 causes screw 126 to translate linearly along direction A2 to decrease and / or substantially eliminate compressive force on the disk stack 58. In other examples, when motor 84 causes motor shaft 94 to rotate along a second axial direction R2, driver 124 causes screw 126 to translate linearly along direction A1 to increase and / or induce compressive force on the disk stack 58, and when motor 84 causes motor shaft 94 to rotate along the first axial direction R1, driver 124 causes screw 126 to translate linearly along direction A2 to decrease and / or substantially eliminate compressive force on the disk stack 58.

[0088] In the example, the actuator 124 is a ball nut, and the screw 126 is a ball screw. The linear actuator 90 may include multiple ball bearings 138 (“actuator ball bearings 138”), such as ball bearings 139 and 140 (…). Figure 3 In some of these examples, the linear actuator 90 is configured such that rotation of the driver 124 about the compression axis CA applies a force to the actuator ball bearing 138 in direction A1 or direction A2, and the actuator ball bearing 138 transmits this force to the screw 126, thereby causing the screw 126 to translate in direction A1 or A2, respectively. In the examples, such as Figure 3As shown, the actuator 124 defines a helical track 142 (“Actuator Helical Track 142”) surrounding the compression axis CA, and the screw 126 defines a helical track 144 (“Screw Helical Track 144”) surrounding the compression axis CA. The linear actuator 90 is configured to confine at least a portion or all of the actuator ball bearing 138 within the actuator helical track 142 and the screw helical track 144. In this example, the actuator 124 is configured to apply a force to the actuator ball bearing 138 using the actuator helical track 142, and the actuator ball bearing 138 is configured to transmit that force to the screw 126 using the screw helical track 144. In the example, the linear actuator 90 includes a ball returner 146 configured to allow the actuator ball bearing 138 to exit from and return to the driver helical track 142 and the screw helical track 144 as the screw 126 translates in direction A1 or direction A2.

[0089] Actuator assembly 74 may include anti-rotation member 148. Figure 3 The anti-rotation member 148 is configured to limit rotational movement of the screw 126 relative to the actuator body 78, the motor housing 92, or another part of the brake assembly 40 (e.g., torque tube 52). The anti-rotation member 148 may be configured to allow translation of the screw 126 in a linear direction (e.g., direction A1 or direction A2) while limiting rotational movement of the screw 126. In the example, the anti-rotation member 148 is configured to cause the screw 126 to substantially resist the torque applied to the screw 126 by the output gear 118 during rotation of the actuator 124. In the example, the anti-rotation member 148 is configured to remain substantially stationary relative to the actuator body 78. The actuator body 78 may mechanically support the anti-rotation member 148 such that the anti-rotation member 148 causes the screw 126 to resist the torque applied by the actuator 124.

[0090] The anti-rotation member 148 may include a linear bearing 150 configured to engage the screw 126 to keep the screw 126 substantially stationary relative to the driver 124. The linear bearing 150 may be configured such that when a torque is applied to the screw 126 about the compression axis CA, the linear bearing 150 applies a substantially equal and opposite reaction torque to the screw 126 to prevent rotation of the screw 126 about the compression axis CA. The linear bearing 150 may be configured to translate along a linear direction (e.g., direction A1 or direction A2) while limiting rotational movement of the screw 126. In the example, the linear bearing 150 includes a plurality of ball bearings 152 (“linear ball bearings 152”), such as ball bearings 153 and 154. In the example, the linear bearing 150 is configured such that if the rotation of the drive 124 about the compression axis CA applies torque to the screw 126, the linear ball bearing 152 transmits that torque to the anti-rotation member 148, thereby causing the linear bearing 150 to apply substantially equal and opposite reaction torques to the screw 126.

[0091] The linear bearing 150 is configured to allow the screw 126 to translate relative to the anti-rotation member 148 in a linear direction (e.g., direction A1 or direction A2). For example, when the actuator 124 rotates relative to the screw 126 to cause linear movement of the screw 126, the linear bearing 150 may be configured to provide limited or substantially no resistance to the linear movement, while substantially resisting any rotational movement of the screw 126 that may be caused by the torque applied to the screw 126 by the actuator 124. In the example, the anti-rotation member 148 defines a linear track 156, and the screw 126 defines a linear track 158 (“screw linear track 158”), and the anti-rotation member 148 is configured to confine the linear ball bearing 152 within the linear track 156 and the screw linear track 158. In the example, the linear track 156 and the screw linear track 158 are configured such that the linear ball bearing 152 defines a path substantially parallel to the compression axis CA. In the example, actuator assembly 74 is configured such that when driver 124 applies torque on screw 126 about compression axis CA, screw linear rail 158 transmits the torque to anti-rotation member 148 via linear ball bearing 152 and linear rail 156, and anti-rotation member 148 applies substantially equal and opposite reaction forces to screw 126 via linear rail 156 and linear ball bearing 152 to substantially limit the rotational movement of screw 126.

[0092] In the example, screw 126 defines a clearance 129 and can be configured such that anti-rotation member 148 is positioned within clearance 129. In the example, one of actuator 124 or anti-rotation member 148 is positioned within clearance 129 (e.g., substantially within screw 126), and the other of actuator 124 or anti-rotation member 148 is positioned outside clearance 129 (e.g., substantially outside screw 126). For example, in Figure 3 In the example, the anti-rotation member 148 is positioned within the gap 129, and the actuator 124 is positioned outside the gap 129. The screw 126 may include a substantially tubular section defining the gap 129. The piston 82 may be supported by the screw 126 at the end of the substantially tubular section.

[0093] The screw 126 includes an inner surface 160 (“screw inner surface 160”) that defines the boundary of the clearance 129. The anti-rotation member 148 includes an outer surface 162 (“anti-rotation outer surface 162”) configured to face the screw inner surface 160 when the anti-rotation member 148 is positioned in the clearance 129. In this example, the anti-rotation outer surface 162 defines a linear track 156, and the screw inner surface 160 defines a screw linear track 158. Figure 3 In one example and in other examples, the actuator 124 may be configured to substantially surround a portion of the screw 126, such that the actuator 124 is positioned outside the gap 129. The actuator 124 may include an inner surface 164 (“actuator inner surface 164”) configured to face the screw 126 when the actuator 124 substantially surrounds that portion of the screw 126. In one example, the screw 126 includes an outer surface 166 (“screw outer surface 166”) configured to face the actuator inner surface 164 when the actuator 124 substantially surrounds that portion of the screw 126. In one example, the actuator inner surface 164 defines an actuator helical track 142, and the screw outer surface 166 defines a screw helical track 144.

[0094] Figure 7 This is a conceptual diagram of another example actuator assembly 75, including actuator body 79, linear actuator 91, and anti-rotation member 149. Linear actuator 91 includes actuator 125 and screw 127 and defines a clearance 131. Linear actuator 91 is configured such that actuator 125 is positioned within clearance 131, and anti-rotation member 149 is positioned outside clearance 131 (e.g., partially and / or substantially surrounding screw 127). Figure 7Referring to the xyz axes shown, a portion of actuator assembly 75 is illustrated in cross-section and functional block diagram form. Actuator assembly 75 may be an example of actuator assemblies 73 and 74, actuator body 79 may be an example of actuator bodies 77 and 78, linear actuator 91 may be an example of linear actuator 90, driver 125 may be an example of driver 124, screw 127 may be an example of screw 126, and anti-rotation member 149 may be an example of anti-rotation member 148. Figure 2 The actuator assembly 75 further includes a motor 84, a motor shaft 94, a harmonic driver 86, an input gear 112, an output gear 118, a control circuit 96, and an input device 102.

[0095] Output gear 118 is configured to cause driver 125 to rotate within clearance 131 when output gear 118 rotates. Driver 125 is configured to rotate substantially within clearance 131 defined by screw 127 to cause linear translation of screw 127 in either axial direction A1 or axial direction A2. Linear actuator 91 includes anti-rotation member 149 surrounding screw 127 and configured to limit rotational movement of screw 127 as driver 125 rotates about screw 127. In the example, output gear 118 is configured to cause driver 125 to rotate about compression axis CA within clearance 131. Screw 127 may include a substantially tubular section defining clearance 131. Piston 82 may be supported by screw 127 at the end of the substantially tubular section. In the example, the output gear 118 is configured to cause the driver 125 to rotate in the first driver direction when the output gear 118 rotates in the first output gear direction, and is configured to cause the driver 125 to rotate in the second driver direction when the output gear 118 rotates in the second output gear direction.

[0096] The screw 127 is configured to translate linearly along the compression axis CA when the actuator 125 rotates about the compression axis CA. The linear actuator 91 can be configured such that when the actuator 125 rotates in a first actuator direction, the screw 127 translates in the axial direction A1, and such that when the actuator 125 rotates in a second actuator direction, the screw 127 translates in the axial direction A2. Therefore, the actuator assembly 75 can be configured such that the rotation direction of the motor shaft 94 determines the rotation direction of the actuator 125 about the compression axis CA, and thereby determines the translation direction of the screw 127.

[0097] In some examples, the actuator 125 is a ball nut, and the screw 127 is a ball screw. The linear actuator 91 can be configured such that rotation of the actuator 125 about the compression axis CA applies a force to the actuator ball bearing 138 in direction A1 or direction A2, and the actuator ball bearing 138 transmits this force to the screw 127, causing the screw 127 to translate in direction A1 or A2, respectively. In examples, such as... Figure 7 As shown, the actuator 125 defines a helical track 143 (“Actuator Helical Track 143”) surrounding the compression axis CA, and the screw 127 defines a helical track 145 (“Screw Helical Track 145”) surrounding the compression axis CA. The linear actuator 91 is configured to confine at least a portion or all of the actuator ball bearing 138 within the actuator helical track 143 and the screw helical track 145. The actuator 125 may be configured to apply a force to the actuator ball bearing 138 using the actuator helical track 143, and the actuator ball bearing 138 is configured to transmit that force to the screw 127 using the screw helical track 145. In the example, the linear actuator 91 includes a ball returner 147 configured to allow the actuator ball bearing 138 to exit from and return to the driver helical track 143 and the screw helical track 145 as the screw 127 translates in direction A1 or direction A2.

[0098] The screw 127 includes an inner surface 161 (“screw inner surface 161”) that defines the boundary of the clearance 131. In this example, the screw inner surface 161 defines a screw helical track 145. The actuator 125 may include an outer surface 169 (“actuator outer surface 169”) configured to face the screw 127 when the screw 127 is substantially the actuator 125. In this example, the actuator outer surface 169 defines an actuator helical track 143.

[0099] The anti-rotation member 149 is configured to limit rotational movement of the screw 127 relative to the actuator body 79, the motor housing 92, or another part of the brake assembly 40 (e.g., torque tube 52). The anti-rotation member 149 may be configured to allow translation of the screw 127 in a linear direction (e.g., direction A1 or direction A2) while limiting rotational movement of the screw 127. The anti-rotation member 149 may be configured to cause the screw 127 to substantially resist torque applied to the screw 127 by the output gear 118 during rotation of the actuator 125. In this example, the anti-rotation member 149 is configured to remain substantially stationary relative to the actuator body 79. The actuator body 79 may mechanically support the anti-rotation member 149 such that the anti-rotation member 149 causes the screw 127 to resist torque applied by the actuator 125.

[0100] The anti-rotation member 149 may include a linear bearing 151 configured to engage the screw 126 to keep the screw 126 substantially stationary relative to the actuator 124. The linear bearing 151 may be configured such that when a torque is applied to the screw 127 about the compression axis CA, the linear bearing 151 applies a substantially equal and opposite reaction torque to the screw 127 to prevent rotation of the screw 127 about the compression axis CA. The linear bearing 151 may be configured to translate along a linear direction (e.g., direction A1 or direction A2) while limiting rotational movement of the screw 127. The linear bearing 151 may include a linear ball bearing 152 configured such that if rotation of the actuator 125 about the compression axis CA applies torque to the screw 127, the linear ball bearing 152 transmits that torque to the anti-rotation member 149, thereby causing the linear bearing 151 to apply a substantially equal and opposite reaction torque to the screw 127.

[0101] Linear bearing 151 is configured to allow screw 127 to translate relative to anti-rotation member 149 in a linear direction (e.g., direction A1 or direction A2). For example, when actuator 125 rotates relative to screw 127 to cause linear movement of screw 127, linear bearing 151 may be configured to provide limited or substantially no resistance to linear movement while substantially resisting any rotational movement of screw 127 that may be caused by torque applied to screw 127 by actuator 125. In the example, anti-rotation member 149 defines linear track 157, and screw 127 defines linear track 159 (“screw linear track 159”), and anti-rotation member 149 is configured to confine linear ball bearing 152 within linear track 157 and screw linear track 159. In the example, linear track 157 and screw linear track 159 are configured such that linear ball bearing 152 defines a path substantially parallel to the compression axis CA. In the example, actuator assembly 75 is configured such that when the actuator 124 applies torque on the screw 127 about the compression axis CA, the screw linear rail 159 transmits the torque to the anti-rotation member 149 via the linear ball bearing 152 and the linear rail 157, and the anti-rotation member 149 applies substantially equal and opposite reaction torques to the screw 127 via the linear rail 157 and the linear ball bearing 152 to substantially limit the rotational movement of the screw 127.

[0102] The anti-rotation member 148 may include an inner surface 170 (“anti-rotation inner surface 170”) configured to face the outer surface 167 (“screw outer surface 167”) of the screw 127 when the anti-rotation member 149 is positioned in the gap 131. In the example, the anti-rotation inner surface 170 defines a linear track 157, and the screw outer surface 167 defines a screw linear track 159.

[0103] Brake assembly 40 may include any suitable number of actuators, such as actuator assemblies 73, 74, and / or 75, configured to apply and / or increase compressive forces on disc stack 58, and / or configured to decrease and / or eliminate compressive forces on disc stack 58. The actuators may be arranged within brake assembly 40 in any suitable configuration. In the example, brake assembly 40 includes a plurality of actuators arranged around a perimeter surrounding wheel axle A. Two or more actuators may be configured to translate their respective pistons substantially simultaneously based on commands issued by control circuitry 96 to the two or more actuators, and / or may be configured to translate their respective pistons substantially individually based on individual commands issued by control circuitry 96 to individual actuators.

[0104] The actuator assembly 74, wheel 10, brake assembly 40, and their components can be formed using any suitable technique. The actuator assembly 74, wheel 10, brake assembly 40, and their components can be forged, cast, manufactured, produced by additive manufacturing (e.g., 3D printing), extruded, stretched, or using other suitable methods. In some examples, the actuator assembly 74, wheel 10, brake assembly 40, and their components can be machined to define the configuration described herein. In other examples, the actuator assembly 74, wheel 10, brake assembly 40, and their components can be formed substantially without machining.

[0105] In some examples, wheel 10 may be finished from near-net-shaped forged aluminum and includes axial components and / or wheel rims for assembling brake assembly 40 and / or actuator assembly 74 onto wheel 10. In other examples, wheel 10 may be manufactured in a different manner. In still other examples, wheel 10 may be obtained rather than manufactured. Wheel 10 may be made of any suitable material. In some examples, wheel 10 includes metal or metal alloy. For example, wheel 10 may include aluminum, nickel alloy, steel alloy (e.g., stainless steel), titanium, carbon composite, or magnesium.

[0106] Control circuitry 96 may include a processor, memory, and (in some examples) input / output (I / O) peripherals. In examples, control circuitry 96 may include any one or more of the following: a microcontroller (MCU) (e.g., a computer on a single integrated circuit containing a processor core, memory, and programmable I / O peripherals), a microprocessor (μP) (e.g., a central processing unit (CPU) on a single integrated circuit (IC)), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a system-on-a-chip (SoC), or equivalent discrete or integrated logic circuitry. Control circuitry 96 may include integrated circuits, i.e., integrated control circuitry, and integrated control circuitry may be implemented as fixed hardware processing circuitry, programmable processing circuitry, and / or a combination of both. Memory may include any volatile or non-volatile medium, such as random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), electrically erasable programmable ROM (EEPROM), flash memory, etc. Furthermore, in some examples, memory or another memory may also store executable instructions for causing one or more controllers described herein to perform actions belonging to them.

[0107] Input device 102 may have any suitable configuration. For example, input device 102 may include a foot switch, a button or keypad, a speaker configured to receive voice commands from a user, or a display (such as a liquid crystal (LCD), a light-emitting diode (LED), or an organic light-emitting diode (OLED)). In some examples, input device 102 may include a touchscreen. Input device 102 is configured to receive user input (e.g., in the form of placing a foot switch in a specific position and / or pressing one or more buttons on a keypad or via a touchscreen), which may be user input selecting one or more actuators for actuation. In some examples, input device 102 is also configured to display information, such as one or more indications providing information about the actuation of brake assembly 40.

[0108] Communication links 98 and 104 may be hardwired and / or wireless communication links. In some examples, communication links 98 and 104 may include a portion of control circuitry 96. In some examples, communication links 98 and 104 include wired connections, wireless internet connections, direct wireless connections (such as wireless LAN), and Bluetooth. TM Wi-Fi TM And / or infrared connection. Communication links 98 and 104 can utilize any wireless or remote communication protocol.

[0109] The brake discs described herein (including rotor discs 60, 61, 62, 63 and stator discs 64, 65, 66) can be made of any suitable material. In some examples, the brake discs described herein can be made of metal or metal alloys (such as steel alloys). In some examples, the brake discs can be made of ceramic materials (such as ceramic composites). In some examples, the brake discs can be made of carbon-carbon composite materials. In some examples, the brake discs can be made of carbon-carbon composite materials with high thermal stability, high wear resistance, and / or stable frictional properties. The brake discs may include carbon materials having multiple carbon fibers and dense material. The carbon fibers may be arranged as a single layer or multiple layers in woven or nonwoven fabrics.

[0110] Figure 8 This is a flowchart illustrating an exemplary technique for compressing a stack of discs in a brake assembly. Although the technique is described herein with reference to the brake assembly 40 and wheel 10, it can be used with other exemplary components described herein.

[0111] The technology includes a motor 84 using actuator assemblies 73, 74, and 75 to generate a first rotational torque (e.g., T1-A, T1-B) (180). Actuator assemblies 73, 74, and 75 may include actuator bodies 77, 78, and 79 configured to remain substantially stationary relative to a portion of brake assembly 40 (such as torque tube 52). Motor 84 may include a motor housing 92 configured to remain substantially stationary relative to actuator bodies 77, 78, and 79. Motor 84 may be configured to generate the first rotational torque by rotating motor shaft 94 relative to motor housing 92. In this example, actuator assemblies 73, 74, and 75 are configured to generate the first rotational torque in response to a braking signal received from control circuitry 96. Control circuitry 96 may be configured to receive user input from input device 102 and transmit a braking signal to actuator assemblies 73, 74, and 75 based on the user input.

[0112] The technology may include generating a first rotational torque at a first rotational speed and in a first rotational direction. In an example, a motor housing 92 defines a motor axis MA, and a motor 84 is configured to generate the first rotational torque about the motor axis MA. The motor housing 92 may be configured to rotate the motor shaft 94 about the motor axis MA to generate the first rotational torque. The motor 84 may be configured to rotate the motor shaft 94 about the motor axis MA in a first axial direction R1 or in a second axial direction R2 opposite to the first axial direction R1 to generate the first rotational torque.

[0113] The technology includes using a harmonic driver 86 to generate a second rotational torque (182). The harmonic driver 86 may be configured to generate the second rotational torque using a first rotational torque generated by a motor 84. The harmonic driver 86 may generate the second rotational torque at a second rotational speed less than the first rotational speed and in a second rotational direction opposite to the first rotational direction.

[0114] In the example, the harmonic driver 86 includes a harmonic generator 106, a flexible spline 108 defining an outer tooth 136, and a fixed spline 110 defining an inner tooth 130. The fixed spline 110 may define a substantially circular pitch circle and may be configured to remain substantially stationary relative to another portion of the actuator body 78, the motor housing 92, and / or the brake assembly 40 (such as a torque tube 52). The harmonic generator 106 may be configured to cause the flexible spline 108 to define an elliptical pitch circle. The technique may include using a first rotational torque to cause rotation of the harmonic generator 106. The technique may include causing the outer tooth 136 to engage substantially with the inner tooth 130 at the major axis of the elliptical pitch circle as the harmonic generator 106 rotates. The technique may include using the flexible spline 108 to generate a second rotational torque. The flexible spline 108 may be configured to generate a second rotational torque about a motor axis MA. In the example, the technique includes using the harmonic driver to generate a second rotational torque at a second rotational speed using a first rotational torque at a first rotational speed, wherein the second rotational speed is less than the first rotational speed.

[0115] The technology may include rotating the output gear 118 of the gear set 88 using a second rotational torque. In an example, the harmonic driver 86 is configured to cause rotation of the input gear 112 to cause rotation of the output gear 118. The input gear 112 may define input gear teeth 114, and the output gear 118 may define output gear teeth 120. In an example, the input gear 112 is configured to mesh with the input gear teeth 114 and the output gear teeth 120. In an example, the gear set 88 is configured to rotate the input gear 112 about an input gear axis and to rotate the output gear 118 about an output gear axis that is displaced from (e.g., different from) the input gear axis.

[0116] The technique includes using a second rotational torque to translate a piston 82 (184). The technique may include causing linear actuators 90, 91 to generate linear motion to use the second rotational torque to translate the piston 82. In an example, an output gear 118 is configured to cause rotation of a driver 124 when the second rotational torque causes rotation of the output gear 118. Linear actuators 90, 91 may include screws 126, 127 configured to translate linearly when the drivers 124, 125 rotate. In an example, screws 126, 127 are configured to translate linearly along a compression axis CA. The compression axis CA may substantially coincide with the output gear axis of the output gear 118. In some examples, the driver 124 is configured to rotate substantially about a portion of the screw 126 to cause linear translation. In some examples, the driver 125 may be configured to rotate within a clearance 131 defined by the screw 127 to cause linear translation.

[0117] In this example, the technique includes causing screws 126 and 127 to initiate and / or increase compressive forces on the disk stack 58 when motor 84 rotates motor shaft 94 along a first axial direction R1. Actuator assemblies 73, 74, and 75 may be configured to cause output gear 118 to rotate about an output gear axis along a first output gear direction when motor 84 rotates motor shaft 94 along the first axial direction R1. Actuators may be configured to cause drivers 124 and 125 to rotate along a first driver direction when output gear 118 rotates along the first output gear direction. Drivers 124 and 125 may be configured to cause screw 126 to translate along a first axial direction A1 to initiate and / or increase compression on the disk stack 58 when drivers 124 and 125 rotate along the first driver direction. In this example, the technique includes causing screws 126 and 127 to decrease and / or substantially eliminate compressive forces on the disk stack 58 when motor 84 rotates motor shaft 94 along a second axial direction R2. Actuator assemblies 73, 74, and 75 may be configured such that when motor 84 rotates motor shaft 94 along a second axial direction R2, output gear 118 rotates in a second output gear direction opposite to the first output gear direction. Actuators may be configured such that when output gear 118 rotates along the second output gear direction, drivers 124 and 125 rotate in a second driver direction opposite to the first driver direction. Drivers 124 and 125 may be configured such that when drivers 124 and 125 rotate along the second driver direction, screws 126 and 127 translate along a second axial direction A2 to reduce and / or substantially eliminate compression on the disk stack 58.

[0118] This disclosure includes the following embodiments.

[0119] Example 1: A brake assembly comprising: a stack of brake discs; an actuator assembly comprising: an electric motor configured to generate a first rotational torque about a motor axis; a harmonic driver configured to generate a second rotational torque in response to the first rotational torque; a gear set including an output gear configured to rotate in response to the second rotational torque; and a linear actuator mechanically coupled to the gear set, wherein the linear actuator is configured to generate linear motion along a compression axis and cause a piston to compress the stack of brake discs when the output gear rotates, wherein the compression axis is different from the motor axis.

[0120] Example 2: The brake assembly according to Example 1, wherein the electric motor is configured to generate a first rotational torque at a first rotational speed and in a first rotational direction, and wherein the harmonic driver is configured to generate a second rotational torque at a second rotational speed and in a second rotational direction, wherein the second rotational speed is less than the first rotational speed and the second rotational direction is opposite to the first rotational direction.

[0121] Example 3: The brake assembly according to Example 1 or 2, wherein the output gear is configured to cause rotation of the linear actuator, and wherein the linear actuator is configured to generate linear motion when the output gear causes rotation.

[0122] Example 4: A brake assembly according to any one of Examples 1 to 3, wherein the linear actuator includes a screw and a driver, the screw being configured to translate and the driver being configured to rotate about the screw, wherein the rotation of the driver causes the screw to generate linear motion along the compression axis.

[0123] Example 5: The brake assembly according to Example 4, wherein the linear actuator includes a plurality of ball bearings, wherein the driver is configured to cause the ball bearings to apply force on the screw so that the screw generates linear motion along the compression axis.

[0124] Example 6: A brake assembly according to any one of Examples 1 to 5, wherein the gear set includes an input gear configured to rotate about a motor axis, wherein the harmonic driver is configured to cause rotation of the input gear, and wherein the output gear is configured to rotate about a compression axis when the input gear rotates about the motor axis.

[0125] Example 7: The brake assembly according to Example 6, wherein the output gear meshes with the input gear.

[0126] Example 8: The brake assembly according to Example 6 or 7, wherein a portion of the linear actuator is configured to rotate synchronously with the output gear.

[0127] Example 9: A brake assembly according to any one of Examples 1 to 8, wherein the harmonic driver includes a fixed spline defining an inner tooth and a flexible spline defining an outer tooth, wherein the flexible spline is configured to engage the outer tooth with the inner tooth to generate a second rotational torque.

[0128] Example 10: A brake assembly according to any one of Examples 1 to 9, wherein the harmonic driver includes a harmonic generator and a flexible spline, wherein an electric motor is configured to cause rotation of the harmonic generator using a first rotational torque, and wherein the harmonic generator is configured to cause the flexible spline to define an elliptical pitch circle in which the major axis is longer than the minor axis.

[0129] Example 11: A brake assembly according to any one of Examples 1 to 10, wherein the linear actuator is configured to prevent the piston from rotating about the compression axis when the linear actuator generates linear motion along the compression axis.

[0130] Example 12: A brake assembly according to any one of Examples 1 to 11, wherein: the harmonic driver includes a flexible spline and is configured to generate a second rotational torque using the flexible spline; the gear set includes an input gear meshing with an output gear, the input gear being configured to rotate synchronously with the flexible spline; and the linear actuator includes a driver configured to rotate synchronously with the output gear such that the screw of the linear actuator generates linear motion along the compression axis.

[0131] Example 13: A brake assembly according to any one of Examples 1 to 12, wherein: the electric motor includes a motor housing and a motor shaft, and the electric motor is configured to generate a first rotational torque by at least rotating the motor shaft relative to the motor housing; and the harmonic driver includes: a harmonic generator, wherein the motor shaft is configured to cause the harmonic generator to rotate synchronously with the motor shaft; a fixed spline configured to remain substantially stationary relative to the motor housing and define internal gear teeth around a substantially circular pitch circle; and a flexible spline between the harmonic generator and the fixed spline, wherein: the harmonic generator is configured to cause the flexible spline to define a substantially elliptical pitch circle with a major axis longer than a minor axis, the flexible spline defining external gear teeth above the elliptical pitch circle, and the flexible spline is configured to cause the external gear teeth to mesh with the internal gear teeth of the fixed spline such that the flexible spline generates a second rotational torque.

[0132] Example 14: A brake assembly according to any one of Examples 1 to 13, the brake assembly further comprising a torque tube, wherein the disc stack comprises one or more rotor discs and one or more stator discs, the one or more rotor discs being configured to rotate about the torque tube, the one or more stator discs being configured to remain rotationally stationary relative to the torque tube, and wherein the piston is configured to cause one or more rotor discs and one or more stator discs to translate over the torque tube when the piston compresses the disc stack.

[0133] Example 15: A brake assembly comprising: a disc stack; a piston configured to compress the disc stack; an electric motor including a motor housing and a motor shaft, wherein the electric motor is configured to cause the motor shaft to rotate about a motor axis at a first speed and in a first direction relative to the motor housing; a harmonic driver mechanically engaged with the motor shaft, wherein the harmonic driver is configured to cause a flexible spline to rotate about the motor axis at a rotational speed less than the first speed and in a second direction opposite to the first direction; an output gear configured to rotate about a compression axis, wherein the flexible spline is configured to cause rotation of the output gear; and a linear actuator including a driver and a screw, wherein the output gear is configured to cause rotation of the driver, and wherein rotation of the driver causes the screw to translate relative to the motor housing along the compression axis such that the piston compresses the disc stack.

[0134] Example 16: The brake assembly according to Example 15, wherein the output gear is configured to cause the driver to rotate about the compression axis.

[0135] Example 17: The brake assembly according to Example 15 or 16 further includes an input gear, wherein the input gear is configured to rotate synchronously with a flexible spline about a motor axis.

[0136] Example 18: The brake assembly according to Example 17, wherein the input gear meshes with the output gear.

[0137] Example 19: A method comprising: generating a first rotational torque using an electric motor about a motor axis; generating a second rotational torque using a harmonic driver in response to the first rotational torque; rotating an output gear of a gear set using the second rotational torque; and using the rotation of the output gear to cause a linear actuator to generate linear motion along a compression axis, wherein the compression axis is different from the motor axis; and using the linear motion of the linear actuator to cause piston compression discs to stack.

[0138] Example 20: According to the method of Example 19, the method further includes: using a second rotational torque to rotate an input gear about a motor axis; and using the input gear to rotate an output gear about a compression axis, wherein the input gear meshes with the output gear.

[0139] Various examples have been described. These and other examples are within the scope of the following claims.

Claims

1. A brake assembly, the brake assembly comprising: Brake discs stacked; Actuator assembly, the actuator assembly comprising: An electric motor, the electric motor being configured to generate a first rotational torque using a motor shaft about a motor axis; A harmonic driver, the harmonic driver being configured to receive the first rotational torque from the motor shaft and being configured to generate a second rotational torque in response to the first rotational torque; Gear set, the gear set comprising: An input gear, the input gear being configured to rotate about the motor axis in response to the second rotational torque; and An output gear meshes with the input gear, the output gear being configured to rotate about a compression axis different from the motor axis; A linear actuator, comprising a driver and a screw, The output gear is configured to cause the driver to rotate about the compression axis. The rotation of the drive causes the screw to translate along the compression axis, causing the piston to compress the brake disc stacks, and The linear actuator includes an anti-rotation component; and Multiple ball bearings between the anti-rotation member and the screw, and The plurality of ball bearings are configured to prevent the piston from rotating about the compression axis when the output gear causes the driver to rotate.

2. The brake assembly of claim 1, wherein the electric motor is configured to generate the first rotational torque at a first rotational speed and in a first rotational direction, and wherein the harmonic driver is configured to generate the second rotational torque at a second rotational speed and in a second rotational direction, wherein the second rotational speed is less than the first rotational speed and the second rotational direction is opposite to the first rotational direction.

3. The brake assembly of claim 1 or claim 2, wherein the linear actuator comprises a plurality of actuator ball bearings, wherein the driver is configured to cause one or more of the actuator ball bearings to apply a force on the screw to generate linear motion of the screw along the compression axis.

4. The brake assembly according to any one of claims 1 or 2, The motor shaft is configured to generate the first rotational torque at a first rotational speed and in a first rotational direction. The harmonic driver includes a harmonic generator, a fixed spline, and a flexible spline. The fixed spline is configured to remain stationary relative to the motor housing of the electric motor. The flexible spline is located between the harmonic generator and the fixed spline. The harmonic generator is configured to receive the first rotational torque at a first rotational speed and in a first rotational direction.

5. The brake assembly of claim 1 or claim 2, wherein the input gear is configured to receive the second rotational torque from the harmonic driver.

6. The brake assembly of claim 1 or claim 2, wherein a portion of the linear actuator is configured to rotate synchronously with the output gear.

7. The brake assembly according to claim 1 or claim 2, wherein: The harmonic driver includes a flexible spline and is configured to generate the second rotational torque using the flexible spline. The input gear is configured to rotate synchronously with the flexible spline, and The driver is configured to rotate synchronously with the output gear.

8. The brake assembly of claim 1 or claim 2, further comprising a torque tube, wherein the brake disc stack comprises one or more rotor discs and one or more stator discs, the one or more rotor discs being configured to rotate about the torque tube, the one or more stator discs being configured to remain rotationally stationary relative to the torque tube, and wherein the piston is configured to cause the one or more rotor discs and the one or more stator discs to translate over the torque tube when the piston compresses the brake disc stack.

9. The brake assembly of claim 1 or claim 2, wherein the screw includes an inner surface defining a boundary of a gap, and wherein one of the anti-rotation member or the actuator is positioned within the gap and the other of the anti-rotation member or the actuator is positioned outside the gap, such that the screw is positioned between the anti-rotation member and the gap.

10. A method for operating a stack of disks, the method comprising: The motor shaft of the electric motor generates the first rotational torque around the motor axis. A second rotational torque is generated using a harmonic driver in response to the first rotational torque, wherein the harmonic driver receives the first rotational torque from the motor shaft; The second rotational torque is used to rotate the input gear of the gear set around the motor axis. The output gear of the gear set is rotated about a compression axis different from the motor axis, wherein the output gear meshes with the input gear; as well as The rotation of the output gear causes the linear actuator, including the driver and the screw, to generate linear motion along the compression axis, at least by causing the driver to rotate about the compression axis. This causes the screw to translate along the compression axis, thereby causing the piston to compress the stack of discs; as well as Multiple ball bearings between the anti-rotation member and the screw prevent the piston from rotating about the compression axis when the output gear causes the driver to rotate.

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