Patent ID: 12196277

DETAILED DESCRIPTION

This document describes systems and techniques for automatically locking and unlocking rotary actuators that have positive engagement. The described systems and techniques are not dependent upon a coefficient of friction, and do not require separate lock actuation solenoids. In general, a mechanical locking mechanism is integrated into an epicyclic gearbox, and is activated and deactivated automatically based on torques that are transmitted through the gearbox. In very general terms, when a rotary output is locked and effectively grounded, torque from a rotational input (e.g., a motor) gets transmitted to a rotating lock, rotating the lock into hard stop in a positon that permits unlocking. With the rotating lock effectively grounded at the unlocking position, torque from the rotational input gets transmitted to the unlocked rotary output.

FIG.1shows a longitudinal cross section view of an example locking rotary actuator assembly100in a locked configuration. The assembly100includes a motor101. In some embodiments, the motor101can be an electric motor, a fluid motor, or any other appropriate rotary input member or device that can provide torque and/or rotational motion. In the illustrated example, the motor101is connected directly to a sun gear assembly110by a shaft102, such that the motor can urge rotation of the sun gear assembly110. In some embodiments, the motor101can be indirectly coupled to the sun gear assembly110. For example, the motor101can drive the shaft102and/or the sun gear through a gearbox, a pulley system, a universal joint, a flex shaft, a rack and pinion assembly, or any other appropriate mechanism that can transmit torque, linear motion, and/or force to urge rotation of the sun gear assembly110.

The sun gear assembly110is mechanically coupled to a planet gear assembly120that includes a collection of planet gears122and a planet carrier124. For example, rotation of the sun gear assembly110can urge rotation of the planet gears122, or it can cause the planet gears122to orbit the sun gear assembly110and urge rotation of the planet carrier124, or a combination of both actions, as will be discussed in more detail below.

The planet gear assembly120is mechanically coupled to a ring gear assembly130. The ring gear assembly130is configured to rotate a lock rotor assembly131in response to action of the planet gear assembly120. The ring gear assembly is configured to rotate through a predetermined range of motion (e.g., a partial rotation), limited by hard stops (not shown) at a predetermined clockwise position and at a predetermined counterclockwise position. When at a limit of rotational motion, the ring gear assembly130effectively becomes grounded against further movement in that direction, and substantially all of the torque from the motor101is transmitted through the planet carrier124to a rotary output assembly140. Conversely, when the rotary output assembly140is grounded, substantially all of the torque from the motor101is transmitted through the planet gears122to the ring gear assembly130. When neither the rotary output assembly140nor the ring gear assembly130are grounded, torque from the motor101is shared between the rotary output assembly140and the ring gear assembly130urging rotation of both.

The assembly100includes a housing150. In some embodiments, the housing150is affixed to and substantially mechanically grounded relative to rotation of the sun gear assembly110and/or the rotary output assembly140. A housing cap assembly152is removably affixed to the housing150. The housing cap assembly152includes an endcap154and a key guide assembly156. In some embodiments, the endcap154can prevent intrusion by foreign objects (e.g., loose parts, debris, fingers) into the internal workings of the assembly100. The key guide assembly156will be discussed in more detail below.

The assembly100also includes a collection of lock keys160. The lock keys160are configured to move radially inward and outward relative to the rotary output assembly140to selectably lock and unlock the rotary output assembly140to selectably prevent and permit rotation of the rotary output assembly140. In the illustrated configuration, the lock keys160are recessed into a collection of recesses142defined in an outer surface144of the rotary output assembly140. The operation and configuration of the lock keys160will be discussed in more detail below. The epicyclic gearbox formed by the sun gear assembly110, the planet gear assembly120, the ring gear assembly130and the housing150combine to provide the functions a rotary lock assembly.

FIG.2shows an axial cross section view of the example locking rotary actuator assembly100in the example configuration shown inFIG.1. In the illustrated example, the lock keys160are retained within the recesses142defined in the outer surface144. Each of the recesses142is defined between a rotational recess face146and a rotational recess face148, and provides a space to accommodate partial radial insertion of the lock key160. The key guide assembly156includes a collection of guide slots158defined as radial slots or apertures (e.g., radial relative to the rotary output assembly140) configured to provide radial guidance for movement of the lock keys160. The guide slots158are sized to permit radial movement of the lock keys160, but prevent rotational or orbital movement of the lock keys160(e.g., about the rotary output assembly140).

In the illustrated “locked” configuration, radial movement of the lock keys160away from the rotary output assembly140and escapement of the lock keys160from the recesses142is prevented by the lock rotor assembly131, which concentrically surrounds the key guide assembly156. Rotation of the rotary output assembly140is prevented, as such rotation would cause mechanical interference between the lock keys160and the rotational recess faces146and/or148. Since the lock keys160are substantially unable to move in the illustrated configuration, rotation of the rotary output assembly140is substantially prevented (e.g., locked).

FIGS.3and4show a longitudinal cross section and an axial cross section, respectively, of the example locking rotary actuator assembly100during an example unlocking process. During unlocking, the motor101is energized to urge rotation of the shaft102and the sun gear assembly110.

Since the rotary output assembly140is substantially locked at the start of the unlocking process, and the planet carrier124is coupled to the rotary output assembly140, the planet carrier124is substantially grounded in this configuration as well. With the planet carrier124grounded, rotation of the sun gear assembly110urges rotation (e.g., but not orbit) of the planet gears122.

Rotation of the planet gears122urges rotation of the lock rotor assembly131. The lock rotor assembly131includes a collection of recesses132. The recesses132are defined in an inner surface134of the lock rotor assembly131. Each of the recesses132is defined between a rotational recess face136and a rotational recess face138, and provides a space to accommodate partial radial insertion of the lock key160.

Rotation of the lock rotor assembly131rotates the recesses132into radial alignment with the guide slots158and the lock keys160. A lock rotor stop (not shown) is configured to stop rotation of the lock rotor assembly131at the point of alignment (e.g., an unlocked lock rotor configuration). In some embodiments, the lock rotor assembly131can be configured to have a predetermined amount of angular travel relative to the housing (e.g., about 15 degrees). Another lock rotor stop (not shown) is configured to stop rotation of the lock rotor assembly131in a locked lock rotor configuration in which the recesses132are not aligned with the guide slots158. In some embodiments, when the lock rotor assembly131is hard stopped in an unlocked lock rotor configuration, the ring gear assembly130becomes substantially grounded in that direction, substantially preventing static rotation of the planet gears122and urging rotation of the planet carrier124, which in turn urges rotation of the rotary output assembly140.

With the recesses in alignment with the guide slots158, the lock keys160are provided with additional space in which they can move radially away from the rotary output assembly140. The mechanical contact between the lock keys160and the rotational recess faces146,148that initially prevented further rotation of the rotary output assembly140(e.g., because the lock keys160were previously prevented from moving radially), can now urge radial displacement of the lock keys160out of the recesses132and into the recesses142. The rotational recess faces146,148are ramped or angled to urge the lock keys160radially outwards thus completing the unlocking action. As the lock keys160escape the recesses142, the rotary output assembly140is permitted to rotate further.

FIGS.5and6show a longitudinal cross section and an axial cross section, respectively, of the example locking rotary actuator assembly100in an example unlocked configuration. In the illustrated configuration, lock keys160have been radially displaced from the locked configuration (e.g., as shown inFIGS.1-2) to an unlocked configuration. In the illustrated configuration, the lock keys160are unable to provide substantial mechanical interference with the recesses142, which allows the rotary output assembly140to rotate (e.g., based on torque provided by the motor101and transferred through the sun gear assembly110and the planet carrier124). In some embodiments, if one or more of the lock keys160were to exhibit inadvertent radially inward movement, then rotation of the rotary output assembly140would push the lock keys radially outward again.

Locking of the locking rotary actuator assembly100can be accomplished by substantially reversing the direction of the motor101, which in turn can cause a reversal of the unlocking operations. The lock rotor assembly131can be rotated back toward the example configuration shown inFIGS.1-2. As the ring gear rotates, radially angled ramps on the lock key crown match angled ramps on the inner diameter of the lock rotor assembly131, and the lock keys160are urged out of the recesses132, radially inward toward the rotary output assembly140and into the recesses142. In some embodiments, a bias member (e.g., a torsion spring) can be configured to bias rotation of the ring gear assembly130and the lock rotor assembly131toward the locked configuration. With the lock keys160in the example positions shown inFIGS.1-2, the lock rotor assembly131can rotate into the locked lock rotor configuration (e.g., against a lock hard stop) with the recesses132out of alignment with the guide slots158, preventing radial escapement of the lock keys from the recesses142and maintaining mechanical interference against rotation of the rotary output assembly140.

FIG.7shows an example lock key700. In some embodiments, the lock key700can be the example lock key160ofFIGS.1-6. The lock key700includes a key body710and a key crown720.

The key body710includes radially angled ramps712. In some embodiments, the radically angled ramps712can be configured to substantially complement the angles of the rotational recess faces138and/or148of the recesses132and/or142. In some embodiments, the radically angled ramps722can have (or can average) about a angle. In some embodiments, the ramps138can be undercut (inverse) lobes having radial ramp angles (e.g., approximately 25 degrees) that can substantially complement the ramp angle on the key crown720.

The key crown720includes radially angled ramps722. In some embodiments, the radically angled ramps722can be configured to substantially complement the angles of the rotational recess faces136and/or146of the recesses132and/or142. In some embodiments, the radically angled ramps722can have (or can average) about a 30° angle.

FIG.8is flow chart that shows an example of a process800for unlocking an example locking actuator assembly. In some implementations, the process800can be performed by all or part of the example assembly100ofFIGS.1-6.

At810, torque is received at a sun gear assembly of an epicyclic gear assembly. For example, the motor101can urge rotation of the sun gear assembly110. In some implementations an electric motor can provide the torque at the sun gear assembly. For example, the motor101can be an electric motor.

At820, torque is transmitted from the sun gear assembly to a ring gear assembly of the epicyclic gear assembly through a collection of planet gears of a planet gear assembly of the epicyclic gear assembly. For example, rotation of the sun gear assembly110can urge rotation of the planet gears122and the ring gear assembly130.

At830, rotation of a lock rotor is urged based on rotation of the ring gear assembly. For example, as the ring gear assembly130rotates, the lock rotor assembly131also rotates.

In some implementations, the process800can include contacting, based on movement of the rotary output assembly, the lock key with an radial groove face of a groove defined in the rotary output assembly and configured to receive the lock key in the first lock key configuration, preventing rotary movement of the rotary output assembly based on interference between the lock key and the radial groove face, preventing rotation of the planet gear assembly based on the prevented rotary movement of the rotary output assembly, and transmitting substantially all torque received at the sun gear assembly to the ring gear assembly. For example, when the rotary output assembly140is locked, the lock keys160contact the rotational recess faces136,138,146, and/or148to prevent rotation of the rotary output assembly, which can cause substantially all of the torque provided by the motor101to be transmitted to the ring gear assembly130.

In some implementations, the process800can include rotating the lock rotor from a first lock rotor configuration to a second lock rotor configuration. For example, the lock rotor assembly131can be rotated from the example configuration shown inFIGS.1-2to the example configuration shown inFIGS.3-6. In some implementations, the first lock rotor configuration can be a first rotational position defined by a first lock rotor end stop configured to interfere with rotation of the lock rotor in a first direction, and the second lock rotor configuration can be a second rotational position defined by a second lock rotor end stop configured to interfere with rotation of the lock rotor in a second direction opposite the first direction.

In some implementations, the process800can include configuring the lock rotor to prevent radial displacement of a lock key from a first key configuration to a second key configuration in the first lock rotor configuration, and configuring the lock rotor to permit radial displacement of the lock key from the first key configuration to the second key configuration in the second lock rotor configuration.

At840, rotation of a planet carrier is urged by orbital motion of the planet gears about the sun gear assembly. For example, rotation of the sun gear assembly110can urge rotation of the planet carrier124.

At850, torque is transmitted from the planet carrier to a rotary output assembly. For example, rotation of the planet carrier124can urge rotation of the rotary output assembly140.

In some implementations, the process800can include urging radial displacement of a lock key from a first lock key configuration to a second lock key configuration based on rotary movement of the rotary output assembly. For example, in the example unlocked configuration ofFIGS.2-6, rotation of the rotary output member140can urge radial displacement of the lock keys160from the recesses142.

Although a few implementations have been described in detail above, other modifications are possible. For example, the logic flows depicted in the figures do not require the particular order shown, or sequential order, to achieve desirable results. In addition, other steps may be provided, or steps may be eliminated, from the described flows, and other components may be added to, or removed from, the described systems. Accordingly, other implementations are within the scope of the following claims.