RU219077U1 - Servo - Google Patents

Abstract

The utility model relates to robotics, in particular to servo drives for driving the elements of a robotic arm. The servo drive contains an electric motor, a cycloidal reducer, a torque sensor and a drive ring. The servo drive is made with the possibility of placing a torque sensor in it, includes a concentrically mounted rim and a hub connected by means of ribs, and the stator is made with the possibility of rigid connection with the rim, and the pins are made with the possibility of rigid connection with the hub. The rotor of the electric motor is kinematically connected to the cycloidal reducer by means of a shaft. The cycloidal reducer includes at least one eccentric with a gear mounted on it, having holes for accommodating pins with clearance in them, and a gear wheel with internal gear meshing with the gear. The drive ring is connected to the gear wheel and rotates as the rotor rotates. The technical result is a reduction in the dimensions and weight of the servo drive, an increase in the load capacity of the device.

Description

The utility model relates to the field of robotics, in particular to devices for driving the elements of a robotic arm.

A servo drive is known from US9561585 used for a multi-axis drive mechanism such as a multi-axis manipulator, a robotic arm, etc. The servo drive includes a motor, a gearbox, a torque sensor driven relative to the motor stator and designed to measure the torque after the gearbox, as well as a ring output shaft connected to the outer peripheral part of the torque sensor. In this case, the output shaft ring is located at a distance from the torque sensor in the direction of the stator, so that the distance from the first end surface of the torque sensor to the engine is greater than the distance from the first end surface of the output shaft ring to the engine. The servo drive is characterized in that after the installation of the output shaft ring, the overall length of the servo in the direction of the output shaft does not change, and the space occupied by the servo does not increase. However, the servo drive still has rather large dimensions, and also does not contain means for controlling the engine speed and output shaft. Also, connecting a servo-driven device directly to a torque sensor is not always desirable.

US patent US 10500734 describes a robot control servo drive, which consists of a housing, motor units located inside the housing and including a hollow output shaft and a wave reducer, as well as a gear containing bearings for connecting them with the possibility of rotation. The first sensing element and the first source element together constitute a rotation sensor for detecting rotation of the output element. The servo drive has a compact structure and small size, which directly affects its size and weight. However, this servo drive uses a gearbox of complex design, and there are no means of controlling the torque and speeds of the motor and gearbox shafts.

U.S. Patent US8291788 describes variants of servos, which are a rotary actuator assembly that is designed to actuate a robot's upper arm. The slewing drive assembly includes a cylindrical carrier frame, a motor mounted coaxially with the frame, a gear connected to the motor and placed inside the frame, a torsion spring, and an output shaft. One end of the torsion spring is rotatably connected to the output of the gear train, while the torsion spring is placed inside the frame. The assembly also contains two absolute position sensors to determine, respectively, the angular position of the gear train relative to the frame and the angular position of the output shaft relative to the frame.

RF patent RU185774 describes a robotic servo used in mobile robotics. SUBSTANCE: robotic servo drive contains a housing with a gearbox attached to it and located in it, an output shaft connected to the gearbox by means of a screw connection, an absolute encoder connected to the gearbox output shaft through a gear, an electric motor with a shaft with a gear wheel connected to the gearbox by means of a gear, a control board located in the housing on the side of the electric motor and fastened by means of a screw connection to one of the walls of the housing. It also contains an electric motor shaft blocker installed near the shaft gear wheel and fastened to the servo drive housing by means of a screw connection on the gearbox side. The technical result is a significant energy saving under static loads, simplification of the development of new robotic solutions.

The main disadvantage of the known servo drives is their compactness due to the exclusion of torque measuring instruments from the design, and if they are present, increased dimensions, which is essential for the use of a servo drive in robotic manipulators.

Thus, there is a problem of providing such a servo drive which has a compact structure and at the same time is capable of accommodating monitoring means, such as, first of all, means for measuring torque and, in addition, means for measuring the rotational speed of the rotor and the output drive element, and also provides high torque transmission.

The technical result of the claimed utility model is to reduce the size and weight of the servo while increasing the load capacity of the device.

The problem is solved, and the claimed technical result is achieved in a servo drive containing an electric motor, a cycloidal gearbox and a drive ring. The servo drive is made with the possibility of placing a torque sensor in it, including a concentrically mounted rim and a hub connected by means of ribs, the stator being able to be rigidly connected to the rim, and the pins being made to be rigidly connected to the hub. The electric motor has a stator, which is configured to be connected to the rim of the torque sensor, and a rotor kinematically connected by a cycloidal reducer by means of a shaft. The cycloidal reducer includes at least one eccentric with a gear mounted on it, having holes for accommodating pins with a clearance in them, and a gear wheel with internal gear meshing with the gear. The drive ring is connected to the gear wheel and rotates as the rotor rotates.

In the claimed servo drive, a cycloidal gearbox is used, which, on the one hand, can withstand heavy loads due to the fact that approximately 40% of the gear teeth and the gear wheel are simultaneously engaged, which is several times higher than this figure for conventional gear, worm and planetary gearboxes. On the other hand, this type of gearbox is quite reliable and simple in comparison with the wave gearbox, and also occupies a small volume. Reducing the occupied volume and increasing the value of the transmitted torque made it possible to place a compact torque sensor in the servo drive, consisting of a rim and a hub connected by ribs, while not being a servo drive element that transmits rotation to an external device driven by a servo drive.

The problem is solved, and the claimed technical result is also achieved in preferred embodiments of the utility model, according to one of which the number of gear teeth is one less than the number of gear teeth, which ensures the maximum gear ratio and the maximum transmitted torque of the cycloidal gearbox without changing its dimensions.

Preferably, the cycloidal reducer includes two eccentrics and two gears, with the gear wheel meshing with the two gears and the pins placed in the holes made in the two gears. This makes it possible to increase the transmitted moment, as well as to balance the dynamic loads and reduce the bending forces exerted on the gearbox. In this case, the eccentrics are mounted on the shaft in such a way that the gears are turned 180° relative to each other and their eccentricities are diametrically opposed.

It is also preferred if the servo uses a combined tapered bearing on which the drive ring is mounted. Such a bearing includes bearing inner races, bearing outer races and rollers, the rollers being arranged alternately rotated by 90° relative to each other. The tapered bearing ensures the compactness of the servo drive due to its integration into the design, the ability to perceive both radial and axial loads, and makes it easy to eliminate backlash.

For the purposes of monitoring the rotational speed and determining the current position of the rotor and the drive ring, the servo drive may further comprise, respectively, a rotor speed sensor and a drive ring speed sensor. Wherein, the rotor speed sensor gear and the drive ring speed sensor gear are preferably mounted on the rear cover connected to the gear wheel.

In the following, the utility model and some possible embodiments of it are explained in more detail with reference to the figures, which show:

in fig. 1 - General view of the embodiment of the claimed servo;

in fig. 2 is a simplified sectional view of a servo drive version;

in fig. 3 - drawing of the servo drive version (main view), area A - enlarged view of the annular bearing, section B-B - enlarged view of the rollers of the annular bearing.

Reference numerals in the figures indicate:

1 - servo drive;

2 - front cover;

3 - torque sensor;

4 - drive ring;

5 - gear wheel;

6 - back cover;

7, 8 - mounting holes;

9 - electric motor;

10 - stator;

11 - rotor;

12 - shaft;

13 - eccentric;

14 - gear;

15 - bearing;

16 - gear holes;

17 - pin;

18 - ring bearing;

19 - hub;

20 - rim;

21.1, 21.2 - outer rings;

22.1, 22.2 - inner rings;

23 - roller;

24 - adjusting washer;

25 - drive ring speed sensor;

26 - rotor speed sensor;

27 - drive gear of the speed sensor of the drive ring;

28 - gear wheel of the speed sensor of the drive ring;

29 - magnet of the speed sensor of the drive ring;

30 - drive gear of the rotor speed sensor;

31 - gear wheel of the rotor speed sensor;

32 - rotor speed sensor magnet.

In FIG. 1 shows a general view of the servo drive 1, the overall dimensions of which are essentially determined by the front cover 2, on which the power supply and control board of the servo drive 1 can be placed, the outer surface of the torque sensor 3, the outer surface of the drive ring 4, through which the torque is transmitted to the moving elements of the external driven device, the outer surface of the gear wheel 5 with internal gearing and the back cover 6.

According to the design of the servo drive 1, the front cover 2 and the torque sensor 3 are relatively fixed and can be mounted on the driven device by means of, for example, screws, for which mounting holes 7 can be made on the outer surface of the torque sensor 3. Drive ring 4, gear wheel 5 and the back cover 6 are connected together, made rotating relative to the front cover 2 and the torque sensor 3 and can be attached to the movable elements of the driven device by means of, for example, screws, for which mating mounting holes 8 can be made on the drive ring 4. Others are possible. options for attaching the elements of the servo 1 to the controlled device and its movable elements.

In FIG. 2 shows a simplified sectional view of a variant of the claimed servo drive 1. The servo drive 1 is configured to accommodate a torque sensor 3, an electric motor 9 with a stator 10 and a rotor 11, a shaft 12 connected to the rotor 11, mounted in a housing on bearings and on which, in turn, a cycloidal gearbox is installed. It is preferable that the shaft 12 be made in a composite manner, as shown in FIG. 3.

The cycloidal gearbox generally includes the following components: at least one eccentric 13 mounted on the shaft 12; gear 14 mounted on the eccentric 13 through the bearing 15, while in the gear 14 holes 16 of the gear are made (see Fig. 3); a gear wheel 5, which engages with its internal teeth with the external teeth of the gear 14; pins 17 that pass through the holes 16 of the gear, and the diameter of the holes 16 of the gear is greater than the diameter of the pins 17.

When the rotor 11 is brought into rotation, the eccentric 13 mounted on the shaft 12 begins to rotate, causing a plane-parallel movement of the gear 14 in its plane, determined by the eccentricity of the eccentric 13. In turn, such a movement of the gear 14 leads to the rotation of the gear wheel 5 and the drive ring connected to it 4 mounted on an annular bearing 18, thereby rotating the movable element of the driven device (not shown in the figures). The gear ratio of such a gearbox is determined by the ratio of the number of teeth of the gear 14 and the gear wheel 5, and it is maximum if the number of teeth of the gear 14 is less than the number of teeth of the gear wheel 5 by one.

Pins 17 are rigidly fixed in the annular bearing 18. In this case, the annular bearing 18 itself is connected to the hub 19 of the torque sensor 3, and the rim 20 of the specified sensor 3 is connected to the front cover 2 (see Fig. 3). Between themselves, the hub 19 and the rim 20 are connected by ribs (not shown in the figures). Deformation sensors placed on the ribs, such as strain gauges or capacitive sensors (not shown in the figures), can determine the amount of deformation of the ribs. This design of the torque sensor 3 is quite compact, and its placement according to the present invention allows you to easily control the amount of torque transmitted by the servo. The torque is transmitted through the gear 14 to the pins 17, and from the pins 17 to the hub 19. In this case, the deformation of the ribs with a certain flexibility occurs, which is fixed by strain sensors, and the transmitted torque is determined by its value.

In the preferred embodiment of the utility model, two eccentrics 13 are used and, accordingly, two gears 14 mounted on them through two bearings 15, as shown in FIG. 2, 3. In this case, the eccentrics 13 are mounted on the shaft 12 in such a way that the gears 14 are turned 180° relative to each other, and their eccentricities are diametrically opposed. This allows you to further increase the maximum value of the transmitted torque, balance the dynamic loads and reduce the bending forces exerted on the elements of the cycloidal gearbox.

According to another preferred embodiment of the inventive servo drive 1, shown in detail in FIG. 3, the annular bearing 18 is made in the form of a combined tapered bearing, which includes outer rings 21.1, 21.2, inner rings 22.1, 22.2 and rollers 23 placed between them (see enlarged view A in Fig. 3). In this case, the rollers 23 are installed alternately with a rotation of 90° relative to each other (see section B-B in Fig. 3). Such an annular bearing 18 can accommodate radial and axial loads simultaneously, which typically requires the use of two bearings, resulting in an increase in the weight and dimensions of the device. In addition, the annular bearing 18 may include shims 24, which, with this design, can easily eliminate backlash. Thus, the use of such an annular bearing 18 makes it possible to reduce the dimensions and weight of the servo drive 1 while maintaining or even increasing its load capacity.

In addition, the servo drive 1 may include a drive ring speed sensor 25 and/or a rotor speed sensor 26 for monitoring the speed and current position of the drive ring 4 and rotor 11, respectively.

To measure the speed and determine the position of the drive ring 4, the drive gear 27 of the drive ring speed sensor is fixed on the pins 17, with which the gear 28 of the drive ring speed sensor is engaged with its teeth. In turn, the specified gear 28 is mounted on the back cover 6 through bearings with the possibility of rotation and contains a magnet 29 of the drive ring speed sensor. As mentioned above, the drive ring 4, the gear ring 5 and the back cover 6 are connected, so that the rotation of the drive ring 4 causes the back cover 6 to rotate. its axis, thereby making planetary motion. The movement of the magnet 29 of the sensor is fixed by the sensor 25 of the speed of the drive ring, and in this way the speed and position of the drive ring 4 is determined.

To measure the speed and determine the position of the rotor 11, a drive gear 30 of the rotor speed sensor is installed on the shaft 12, with which the gear 31 of the rotor speed sensor is engaged with its teeth. In turn, the specified gear 31 is mounted on the back cover 6 through bearings with the possibility of rotation and contains a magnet 32 of the rotor speed sensor. The rotation of the drive gear 30 mounted on the shaft 12 leads to the rotation of the gear 31 and, accordingly, the rotation of the magnet 32 relative to the rotor speed sensor 26. In this way, the rotational speed and position of the rotor 11 are determined.

The claimed servo drive is characterized by a compact and lightweight design, increased load capacity.

Claims (6)

1. A servo drive containing an electric motor having a stator and a rotor, a cycloidal gearbox kinematically connected to the rotor by means of a shaft and including at least one eccentric mounted on the shaft, a gear mounted on the eccentric, having holes for accommodating pins with clearance in them, and a gear wheel with internal gear, engaged with the gear, drive ring connected to the gear wheel and configured to rotate when the rotor rotates, the servo drive is configured to accommodate a torque sensor, including a concentrically mounted rim and a hub connected by means of ribs, and the stator made with the possibility of rigid connection with the rim, and the pins are made with the possibility of rigid connection with the hub. 2. The servo drive according to claim 1, wherein the number of gear teeth is one less than the number of gear teeth. 3. The servo drive according to claim 1 or 2, in which the cycloidal gearbox includes two eccentrics and two gears, while the gear is engaged with two gears, and the pins are placed in holes made in two gears, and the eccentrics are mounted on the shaft in this way that the gears are rotated 180° relative to each other and their eccentricities are diametrically opposed. 4. The servo drive according to claim 1, in which the drive ring is mounted on a combined tapered bearing, including inner bearing rings, outer bearing rings and rollers, and the rollers are installed alternately with a rotation of 90 ° relative to each other. 5. The servo drive according to claim 1, further comprising a rotor speed sensor, wherein the rotor speed sensor gear is rotatably mounted on a back cover connected to the gear. 6. The servo drive according to claim 1, further comprising a drive ring speed sensor, wherein the drive ring speed sensor gear is rotatably mounted on a back cover coupled to the gear.

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