A high-precision compact robot joint

Abstract

This invention discloses a high-precision compact robot joint, comprising a reducer, a joint motor, a joint housing, a reducer housing, and a grating encoder. The joint motor is fixedly mounted inside the joint housing, and the load output flange of the reducer is fixedly connected to the joint housing. The output shaft of the joint motor is connected to the input shaft of the reducer. The grating encoder is correspondingly disposed between the joint housing and the reducer housing. This invention eliminates the commonly used feed shaft structure in the prior art, directly fixing the grating encoder to the relatively rotating reducer housing and the joint housing, avoiding the accuracy loss caused by feed shaft wear and coaxiality deviation. After long-term load operation, the position feedback error is ≤10 arcseconds, improving accuracy by more than 50%. At the same time, the axial dimension is significantly reduced to meet the requirements of compact installation, while the assembly process is simplified and maintenance costs are reduced by 30%.

Description

Technical Field

[0001] This invention relates to the field of robotics, and more specifically to a high-precision, compact robot joint. Background Technology

[0002] Existing robot joint module structures typically include a reducer, a frameless torque motor, a motor rotor connecting cylinder, a motor-side encoder, a joint-side encoder, a power-off brake, a joint housing, and a feed shaft. In traditional designs, the joint-side encoder is mounted on the rear side of the joint, and the angle from the reducer's output is fed back to the joint-side encoder via the feed shaft connected to the reducer's output. This existing structural design suffers from low position feedback accuracy and high maintenance costs.

[0003] To ensure high-precision position output of the joint, traditional structures have extremely high requirements for the machining accuracy, coaxiality, bearing selection, and assembly process of the feed shaft. After long-term operation under heavy loads, structural wear is prone to occur, leading to a decrease in coaxiality and thus reducing the accuracy of joint position feedback. The high-precision requirements of the feed shaft and related components also increase production and assembly costs, and frequent maintenance and calibration are required after wear.

[0004] In view of the above-mentioned defects, the inventors of this invention have finally obtained this invention after a long period of research and practice. Summary of the Invention

[0005] To address the aforementioned technical deficiencies, the present invention provides a high-precision, compact robot joint, comprising a reducer, a joint motor, a joint housing, a reducer housing, and an optical encoder. The joint motor is fixedly disposed within the joint housing, and the load output flange of the reducer is fixedly connected to the joint housing. The output shaft of the joint motor is connected to the input shaft of the reducer, and the optical encoder is correspondingly disposed between the joint housing and the reducer housing.

[0006] Preferably, an annular gap is provided between the joint housing and the reducer housing, and the grating encoder is correspondingly disposed within the annular gap.

[0007] Preferably, the grating encoder includes a code disk, a reader head, and a mounting base. The code disk has a circular structure and is fixedly disposed within the annular gap via the mounting base. The mounting base is fixedly connected to the reducer housing, and the code disk and the reducer housing are coaxially disposed. The reader head is fixedly disposed on the joint housing corresponding to the code disk.

[0008] Preferably, the read head is disposed on the end face of the joint housing corresponding to the annular gap, and the code disk is disposed between the read head and the load output flange.

[0009] Preferably, the mounting end face of the reading head on the joint housing, the code disk, the reducer housing, the load output flange, the output shaft of the joint motor, and the input shaft of the reducer are all coaxially arranged.

[0010] Preferably, the coaxiality error between the reducer axis and the joint housing is ≤0.01mm, and the axial distance between the code disk and the reading head is 0.2mm, with a coaxiality error ≤0.01mm.

[0011] Preferably, the rotor inner cylinder of the joint motor is also provided with a power failure brake.

[0012] Preferably, the power failure brake includes a magnetic yoke, an excitation coil, a spring, and a brake disc. The magnetic yoke is fixedly disposed on the stator end face of the joint motor, and a coil groove is annularly disposed on the end face of the magnetic yoke corresponding to the rotor inner cylinder. The excitation coil is disposed in the coil groove corresponding to the brake disc, and one end face of the annular brake disc is connected to the magnetic yoke through the spring, and the other end face is configured as a braking contact surface that cooperates with the rotor inner cylinder.

[0013] Preferably, the braking contact surface and the inner cylinder of the rotor are respectively provided with locking teeth and tooth grooves, and the locking teeth and tooth grooves are configured to cooperate with each other.

[0014] Preferably, the brake disc, the magnetic yoke, and the stator and rotor of the joint motor are all coaxially arranged, and the excitation coil and the spring are evenly distributed in a ring around the axis of the magnetic yoke.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: By eliminating the feed shaft structure commonly used in the prior art, the present invention directly fixes the grating encoder to the relatively rotating reducer housing and the joint housing, avoiding the accuracy loss caused by feed shaft wear and coaxiality deviation. After long-term load operation, the position feedback error is ≤10 arcseconds, and the accuracy is improved by more than 50%. At the same time, the axial dimension is greatly reduced to meet the requirements of compact installation, and the assembly process is simplified, reducing maintenance costs by 30%. Attached Figure Description

[0016] Figure 1 This is a structural view of the joint of the high-precision compact robot; Figure 2 This is a cross-sectional view of the joint of the high-precision compact robot. The numbers in the image represent: 1-Reducer; 2-Joint motor; 3-Joint housing; 4-Reducer housing; 5-Raster encoder; 6-Power failure brake; 7-Input shaft; 12-Load output flange; 21-Rotor inner cylinder; 51-Code disc; 52-Reader head; 53-Mounting base; 61-Magnetic yoke; 62-Excitation coil; 63-Spring; 64-Brake disc. Detailed Implementation

[0017] The above-mentioned and other technical features and advantages of the present invention will be described in more detail below with reference to the accompanying drawings. Example

[0018] like Figure 1 and Figure 2 As shown, Figure 1 This is a structural view of the joint of the high-precision compact robot; Figure 2 This is a cross-sectional view of the joint of the high-precision compact robot.

[0019] The high-precision compact robot joint of the present invention includes a reducer 1, a joint motor 2, a joint housing 3, a reducer housing 4, an optical encoder 5, and a power-off brake 6. The joint motor 2 is fixedly installed inside the joint housing 3, and the load output flange 12 of the reducer 1 is fixedly connected to the joint housing 3. The output shaft of the joint motor 2 is connected to the input shaft 7 of the reducer 1. By setting the output end of the reducer 1 (i.e., the load output flange 12) and the input end (i.e., the end of the input shaft 7) on the same side of the reducer 1 near the joint housing 3, the joint housing 3 serves as the joint stator, and the reducer housing 4 serves as the joint rotor to form a rotary joint structure, thereby eliminating the need for the feed shaft structure in the prior art. The optical encoder 5 is correspondingly installed between the joint housing 3 and the reducer housing 4 to collect the rotation angle signal of the output end of the reducer 1 without the need for feed shaft transmission. The power-off brake 6 is fixedly installed inside the joint motor 2 to perform the braking function of the joint motor 2.

[0020] Preferably, an annular gap is provided between the joint housing 3 and the reducer housing 4, and the grating encoder 5 is correspondingly disposed within the annular gap to reduce the overall axial design length.

[0021] Specifically, the grating encoder 5 includes a code disk 51, a read head 52, and a mounting base 53. The code disk 51 has a circular structure and is fixedly installed in the annular gap via the mounting base 53. The mounting base 53 is fixedly connected to the reducer housing 4, and the code disk 51 and the reducer housing 4 are coaxially arranged. The read head 52 is fixedly installed on the joint housing 3 corresponding to the code disk 51. The read head 52 reads the rotation angle of the code disk 51 as it rotates relative to the reducer housing 4 and the load output flange 12, thereby realizing real-time reading of the angle signal.

[0022] Generally, the reading head 52 is disposed on the end face of the joint housing 3 corresponding to the annular gap, and the code disk 51 is disposed between the reading head 52 and the load output flange 12, so as to make full use of the space of the annular gap and reduce the overall axial design length.

[0023] The mounting end face of the reading head 52 on the joint housing 3, the code disk 51, the reducer housing 4, the load output flange 12, the output shaft of the joint motor 2 and the input shaft 7 of the reducer 1 are all coaxially arranged to ensure that each component is on the same rotation axis and achieves stable rotational connection and data monitoring.

[0024] Generally, the coaxiality error between the axis of the reducer 1 and the joint housing 3 is ≤0.01mm, and the axial distance between the code disk 51 and the reading head 52 is 0.2mm, with a coaxiality error ≤0.01mm.

[0025] The power failure brake 6 is installed inside the rotor inner cylinder 21 of the joint motor 2, thereby reducing the overall axial design length.

[0026] Preferably, the power failure brake 6 includes a magnetic yoke 61, an excitation coil 62, a spring 63, and a brake disc 64. The magnetic yoke 61 is fixedly disposed on the stator end face of the joint motor 2, and a coil groove is provided annularly on the end face of the magnetic yoke 61 corresponding to the rotor inner cylinder 21. The excitation coil 62 is disposed in the coil groove corresponding to the brake disc 64. One end face of the annular brake disc 64 is connected to the magnetic yoke 61 through the spring 63, and the other end face is configured as a braking contact surface that cooperates with the rotor inner cylinder 21.

[0027] Generally, the braking contact surface and the rotor inner cylinder 21 are respectively provided with locking teeth and tooth grooves. The locking teeth and tooth grooves are configured to engage when the braking contact surface and the rotor inner cylinder 21 are in contact and fit together, thereby increasing friction and achieving braking.

[0028] The stator and rotor of the brake disc 64, the magnetic yoke 61, and the joint motor 2 are all coaxially arranged. The excitation coil 62 and the spring 63 are respectively evenly distributed in a ring around the axis of the magnetic yoke 61 to provide a stable axial force and realize the relative axial movement of the brake disc 64 and the magnetic yoke 61.

[0029] When the joint motor 2 starts, the power is transmitted to the reducer 1 through the input shaft 7. After the reducer 1 reduces speed and increases torque, the load output flange 12 of the reducer 1 drives the reducer housing 4 to rotate relative to the joint housing 3, thereby realizing joint movement. The code disk 51 of the grating encoder 5 rotates synchronously with the reducer housing 4. The reading head 52 collects the angle signal of the code disk 51 in real time and directly feeds back the position of the joint output end without the need for feed shaft transmission, ensuring high-precision feedback.

[0030] When the joint is energized, the excitation coil 62 of the de-energized brake 6 is energized, the brake disc 64 is attracted towards the excitation coil 62, the spring 63 is compressed, and a gap is generated between the brake disc 64 and the rotor inner cylinder 21, allowing the stator and rotor of the joint motor 2 to rotate normally relative to each other. When the joint is de-energized, the excitation coil 62 of the de-energized brake 6 is de-energized, the spring 63 pushes the brake disc 64 to fit against the rotor inner cylinder 21, generating a frictional torque to achieve braking. In the entire structure, the encoder is mounted on the same plane axially and the brake is integrated, which greatly shortens the axial length of the joint and achieves a compact layout.

[0031] This invention eliminates the commonly used feed shaft structure in the prior art, and directly fixes the grating encoder 5 to the relatively rotating reducer housing 4 and the joint housing 3, avoiding the accuracy loss caused by feed shaft wear and coaxiality deviation. After long-term load operation, the position feedback error is ≤10 arcseconds, and the accuracy is improved by more than 50%. At the same time, the axial dimension is greatly reduced to meet the requirements of compact installation, and the assembly process is simplified, reducing maintenance costs by 30%.

[0032] Furthermore, by integrating the power failure brake 6 into the rotor inner cylinder 21 of the joint motor 2, the axial length of the joint module is further shortened by 20mm, which is 15%~25% shorter than the traditional structure, thus meeting the requirements for compact installation.

[0033] This invention is compatible with mainstream reducers such as RV reducers and harmonic reducers, and can be widely used in scenarios with stringent requirements for precision and space, such as humanoid robots and industrial collaborative robots.

[0034] The above are merely preferred embodiments of the present invention and are illustrative in nature, not restrictive. Those skilled in the art will understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the present invention, all of which will fall within the protection scope of the present invention.

Claims

1. A high-precision, compact robot joint, characterized in that, The device includes a speed reducer, a joint motor, a joint housing, a speed reducer housing, and a grating encoder. The joint motor is fixedly installed inside the joint housing, and the load output flange of the speed reducer is fixedly connected to the joint housing. The output shaft of the joint motor is connected to the input shaft of the speed reducer. The grating encoder is correspondingly installed between the joint housing and the speed reducer housing.

2. The high-precision compact robot joint as described in claim 1, characterized in that, An annular gap is provided between the joint housing and the reducer housing, and the grating encoder is correspondingly disposed within the annular gap.

3. The high-precision compact robot joint as described in claim 2, characterized in that, The grating encoder includes a code disk, a reader head, and a mounting base. The code disk has a circular structure and is fixedly mounted in the annular gap via the mounting base. The mounting base is fixedly connected to the reducer housing, and the code disk and the reducer housing are coaxially arranged. The reader head is fixedly mounted on the joint housing corresponding to the code disk.

4. The high-precision compact robot joint as described in claim 3, characterized in that, The reading head is disposed on the end face of the joint housing corresponding to the annular gap, and the code disk is disposed between the reading head and the load output flange.

5. The high-precision compact robot joint as described in claim 4, characterized in that, The mounting end face of the reading head on the joint housing, the code disk, the reducer housing, the load output flange, the output shaft of the joint motor, and the input shaft of the reducer are all coaxially arranged.

6. The high-precision compact robot joint as described in claim 5, characterized in that, The coaxiality error between the reducer axis and the joint housing is ≤0.01mm, and the axial distance between the code disk and the reading head is 0.2mm, with a coaxiality error ≤0.01mm.

7. The high-precision compact robot joint as claimed in claim 1, characterized in that, The joint motor is also equipped with a power failure brake inside the rotor cylinder.

8. The high-precision compact robot joint as described in claim 7, characterized in that, The power failure brake includes a magnetic yoke, an excitation coil, a spring, and a brake disc. The magnetic yoke is fixedly mounted on the stator end face of the joint motor, and a coil groove is annularly arranged on the end face of the magnetic yoke corresponding to the inner cylinder of the rotor. The excitation coil is disposed in the coil groove corresponding to the brake disc, and one end face of the annular brake disc is connected to the magnetic yoke through the spring, while the other end face is configured as a braking contact surface that mates with the inner cylinder of the rotor.

9. The high-precision compact robot joint as described in claim 8, characterized in that, The braking contact surface and the inner cylinder of the rotor are respectively provided with locking teeth and tooth grooves, and the locking teeth and tooth grooves are configured to cooperate with each other.

10. The high-precision compact robot joint as described in claim 8, characterized in that, The brake disc, the magnetic yoke, and the stator and rotor of the joint motor are all coaxially arranged, and the excitation coil and the spring are respectively evenly distributed in a ring around the axis of the magnetic yoke.

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