Stiffness-variable joint actuator with motor-reducer integration

Abstract

The present invention discloses a stiffness-variable joint actuator with motor-reducer integration, and belongs to the field of robots. The stiffness-variable joint actuator includes: a torque motor, which includes a casing, a stator, a rotor, pin gears, and pin gear rollers; and a reducer core, which includes cycloidal gears, a planetary carrier, and an eccentric shaft. The motor is connected to a cycloidal-pin gear reducer, thereby achieving the technical effect of enhancing the impact resistance and reverse actuation capability of the actuator. The rotor is disposed outside the stator, the eccentric shaft is connected to the rotor, and the reducer is disposed inside the motor, thereby achieving the technical effect of integrating the motor and the reducer and reducing the axial dimension of the actuator. The cycloidal gears are provided with round holes and special-shaped holes, and the planetary carrier is provided with round dowel pins and special-shaped dowel pins; under a rated load, the round holes are in contact with the round dowel pins, and the special-shaped holes are not in contact with the special-shaped dowel pins; and under a load above the rated load, the round holes and the round dowel pins extrude each other to achieve an allowable deformation, and the special-shaped holes are in contact with the special-shaped dowel pins, thereby achieving the technical effect of changing the stiffness of the actuator.

Claims

1. A stiffness-variable joint actuator with motor-reducer integration, comprising: a torque motor (1), which comprises a casing (11), a stator (12), a rotor (13), pins (14) and pin rollers (15), wherein a feedback sensor (111) is fixed onto the casing (11), a coil (121) is wound on the stator (12), the rotor (13) is provided with a flange (131), permanent magnets (132) are embedded in the flange (131), and a magnetic element (133) is embedded in a shaft end of the rotor (13); and a reducer core (2), which comprises two identical cycloidal gears (21) arranged at a phase difference of 180, an eccentric shaft (22) and a planetary carrier (23), wherein flanks of the cycloidal gears (21) are provided with round holes (211) and non-circular holes (212), and the planetary carrier (23) is provided with round dowel pins (231) and non-circular dowel pins (232); wherein the stator (12) is fixedly connected to the casing (11) via bolts, the pins (14) are disposed between the stator (12) and the casing (11), and the pin rollers (15) are sleeved on the pins (14); a cavity is disposed outside the stator (12) and inside the casing (11), and the flange (131) and the permanent magnets (132) on the rotor (13) are accommodated in the cavity to enable placement of the rotor outside the stator; the shaft end of the rotor (13) is connected to the casing via a bearing; in the reducer core (2), a needle roller bearing is inserted into center holes of the two identical cycloidal gears (21) and sleeved on the eccentric shaft (22); the planetary carrier (23) is assembled by connecting upper and lower parts through bolts; the round dowel pins (231) and the non-circular dowel pins (232) on the planetary carrier (23) correspondingly pass through the round holes (211) and the non-circular holes (212) in the flanks of the cycloidal gears (21) respectively, and a center hole of the planetary carrier (23) is sleeved on the eccentric shaft (22) via a conical roller bearing; the cycloidal gears (21) of the reducer core (2) are meshed with the pin rollers (15) sleeved on the pins (14) inside the torque motor (1); the rotor (13) and the eccentric shaft (22) are centered via a hole and fixedly connected via a bolt, thereby transmitting a rotor rotation of the motor to the reducer core; wherein when the actuator is subject to a load below a rated load, the round dowel pins (231) on the planetary carrier (23) pass through and are in contact with the round holes (211) in the two cycloidal gears (21), and the non-circular dowel pins (232) on the planetary carrier pass through and are without contact with the non-circular holes (212) in the two cycloidal gears; wherein when the actuator is subject to a load above the rated load, the round dowel pins (231) on the planetary carrier (23) pass through and deform the round holes (211) in the cycloidal gears (21) to achieve an allowable deformation, and the non-circular dowel pins (232) on the planetary carrier pass through and start contacting the non-circular holes (212) in the two cycloidal gears; and wherein a stiffness of the actuator is varied by changing a contact mode between the dowel pins on the planetary carrier and the dowel pin holes in the flanks of the cycloidal gears.

2. The stiffness-variable joint actuator with motor-reducer integration according to claim 1, wherein the magnetic element (133) is fixedly connected to and embedded into the shaft end of the rotor (13) via bolts; and the feedback sensor (111) fixed to the casing (11) via a bolt can sense a rotation speed and a position of the magnetic element (133) to transmit motor information to a motor controller, thereby controlling the rotation of the motor.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) FIG. 1 is a schematic axonometric view of a stiffness-variable joint actuator with motor-reducer integration according to the present invention;

(2) FIG. 2 is a schematic diagram showing components and assembling of the stiffness-variable joint actuator with motor-reducer integration according to the present invention;

(3) FIG. 3 is a schematic axonometric view of an upper portion of a torque motor;

(4) FIG. 4 is a schematic axonometric view of a lower portion of a torque motor;

(5) FIG. 5 is a schematic diagram showing that cycloidal gears are meshed with pin gear rollers;

(6) FIG. 6 is a schematic axonometric view of a reducer core;

(7) FIG. 7 is a schematic axonometric view of a planetary carrier;

(8) FIG. 8 is a schematic axonometric view showing that dowel pins of the planetary carrier are matched with dowel pin holes in flanks of the cycloidal gears;

(9) FIG. 9 is a schematic diagram of the cycloidal gear.

(10) In the figures, reference signs are as follows: 1torque motor, 11casing, 111feedback sensor, 12stator, 121coil, 13rotor, 131flange, 132permanent magnet, 133magnetic element, 14pin gear, 15pin gear roller, 2reducer core, 21cycloidal gear, 211round hole, 212special-shaped hole, 22eccentric shaft, 23planetary carrier, 231round dowel pin, 232special-shaped dowel pin.

DETAILED DESCRIPTION OF THE INVENTION

(11) The present invention will be explained in details below in conjunction with the accompanying drawings.

(12) The present invention and the embodiments thereof are described in a non-limiting way below, and the actual embodiments are not limited thereto. In brief, those structure modes and embodiments which are similar to the present technical solution and are designed without inventiveness by those of ordinary skills in the art under the inspiration of the embodiment above without departing from the inventive principle of the present invention shall fall under the protection scope of the present invention.

(13) As shown in FIG. 1, a specific embodiment of the present invention discloses a stiffness-variable joint actuator with motor-reducer integration, which can be used in the field of robots and the like.

(14) In a preferred embodiment, an assembling relationship is shown in FIG. 2.

(15) A casing 11 is formed by connecting and splicing upper and lower portions via bolts. The stator 12 and the upper portion of the casing 11 are fixed via bolts, a coil 121 is wound on the stator 12, pin gears 14 are disposed between the stator 12 and the casing 11, pin gear roller 15 is sleeved outside the pin gear 14, as shown in the axonometric view in FIG. 3; and the rotor 13 is connected to the lower portion of the casing 11 via a bearing, as shown in the axonometric view in FIG. 4. After the coil of the stator is energized, the rotor may rotate relative to the stator; a magnetic element 133 is embedded in a shaft end of the rotor 13; a feedback sensor 111 fixed to the casing 11 can sense the rotation speed and position of the magnetic element 133, thereby transmitting motor information into a motor controller to control the rotation of the motor.

(16) The eccentric shaft 22 is connected to the rotor 13 via bolts, and the cycloidal gears 21 are meshed with the pin gear roller 15 in a pattern as shown in FIG. 5. The power can be transmitted into the reducer from the motor, such that the high degree of integration between the motor and the cycloidal gear reducer is achieved, the motor-reducer integration is achieved, and the axial dimension of the joint actuator is reduced.

(17) The axonometric view of the reducer core 2 is shown in FIG. 6; the cycloidal gears 21 are sleeved on the eccentric shaft 22 via a needle roller bearing; the upper and lower parts of the planetary carrier 23 are connected together via bolts, as shown in an axonometric view in FIG. 7; the planetary carrier 23 is sleeved on the eccentric shaft 22 via a conical roller; the dowel pins on the planetary carrier 23 pass through the corresponding dowel pint holes in the cycloidal gears 21, as shown in FIG. 8. After the cycloidal gears meshes with the pin gear rollers, the cycloidal gears undergoes self rotation to drive the plane carrier to rotate by means of the dowel pins.

(18) As shown in FIG. 7, the planetary carrier 23 is provided with four round dowel pins 231 and four special-shaped dowel pins 232. As shown in FIG. 9, the flanks of the cycloidal gears 21 are provided with four round holes 211 and four special-shaped holes 212. Moreover, the round profile of each round dowel pin and the round profile of each round hole are equidistant curves at a distance equal to the eccentric distance of the cycloidal gear; likewise, the profile of each special-shaped dowel pin and the profile of each special-shaped hole are also equidistant curves at a distance equal to the sum of the eccentric distance and the deformation amount of the round dowel pin under the rated load. During the operation of the joint actuator, in a case where a load is lower than the rated load, the special-shaped holes do not in contact with the special-shaped dowel pins, and the self rotation of the cycloidal gears are transmitted via the contact between the round holes 211 and the round dowel pins 231; in a case where a load is above the rated load, the round holes and the round dowel pins extrude each other to produce the maximum deformation (i.e., achieving the allowable deformation amount), the special-shaped holes and the special-shaped dowel pins then come into contact, and at this point, the torque of the motor is transmitted jointly by allowing for contact between the round holes and the round dowel pins and contact between the special-shaped holes and the special-shaped dowel pins. Under different load conditions, the dowel pins of the planetary carrier and the cycloidal gears contact in different ways, thereby changing the stiffness of the joint actuator.

(19) According to the present invention, the motor is connected to the cycloidal-pin gear reducer, allowing for a more compact structure of the joint actuator and increasing the impact resistance, transmission efficiency and reverse driving capability of the joint actuator. The rotor of the torque motor is disposed outside the stator, and the reducer is disposed in the torque motor, and the rotor of the motor is fixedly connected to the input shaft of the reducer, such that the axial dimension of the actuator is reduced, the need for an auxiliary spring encoder is eliminated, and the high degree of integration and enhanced power density are achieved for the joint actuator. In the cycloidal-pin gear reducer, the contact mode between the dowel pins of the planetary carrier and the dowel pin holes of the cycloidal gear can be adjusted according to the load torque as follows: during stable operation (i.e., a load is below the rated load), the round dowel pins and the round holes come into contact to transmit power; and under the action of an impact load (i.e., a load is above the rated load), the round dowel pins and the round holes extrude each other to achieve an allowable value, and the special-shaped dowel pins of the planetary carrier and the special-shaped holes of the cycloidal gear come into contact to start transmitting power. By adjusting the contact mode for the dowel pins, the stiffness of the reducer can be changed, which enhances the impact resistance of the joint actuator.