Multifunctional integrated robot joint module

Abstract

The multifunctional integrated robot joint module comprises a motor, a torque sensor and a speed reducer, the speed reducer comprises a wave generator, a flexible gear, a bearing inner ring and a bearing outer ring, the outer ring of the torque sensor is clamped and fixed between the bearing outer ring and a motor shell, and the inner ring of the torque sensor is fixed to the flexible gear; the wave generator is arranged in the flexible gear, one end of the rotating shaft penetrates through the torque sensor and the flexible gear and then is fixed to the wave generator, a gear ring is further arranged on the inner wall of one end of the bearing inner ring, and the bearing inner ring sleeves the flexible gear and is in staggered tooth transmission with the flexible gear; an end cover and a controller cover are arranged at the other end of the motor shell, a control circuit board is fixed in an accommodating space formed by the end cover and the controller cover, and a wire harness of the torque sensor penetrates through the end cover through the interior of the motor shell and then is connected with the control circuit board. The motion transmission precision is improved, and the installation error is reduced; the problem of pulling of the sensor wire harness is solved, so that the sensor is more accurate in sensing; and the whole movement is more flexible.

Description

Technical Field

[0001] The invention belongs to the technical field of robots, and in particular relates to a multifunctional integrated robot joint module. Background Art

[0002] As the application of robots increases, collaborative robots, as automated labor that works in collaboration with humans, have entered more light industrial production. The movement of each degree of freedom of a collaborative robot is generated by the joint module at each joint. The joint module consists of multiple key components, among which the harmonic reducer is one of the core components. As a sensing element, the torque sensor is usually installed at the output end of the harmonic reducer for torque data collection, but its connecting line is easily pulled to affect the accuracy and rotation angle.

[0003] In addition, since the existing joint module integrates many components such as motors, harmonic reducers and torque sensors, the overall volume is large, and the components cannot form an independent module, the assembly is cumbersome, and the disassembly and maintenance are inconvenient; and in general joint modules, in the event of a sudden power outage, the output end can move freely, which may pose a safety hazard. Summary of the invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a multifunctional integrated robot joint module, which has a higher degree of integration, is easy to assemble, and solves the problem of wire harness pulling.

[0005] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0006] A multifunctional integrated robot joint module comprises a motor, a torque sensor and a reducer, wherein the motor comprises a motor housing, a stator assembly, a rotor core and a rotating shaft, wherein the stator assembly is fixed to the inner wall of the motor housing, the rotor core is located inside the stator and is sleeved and fixed on the rotating shaft, and the rotating shaft is rotatably connected to the motor housing, the reducer comprises a wave generator, a flexible wheel, a bearing inner ring and a bearing outer ring, the outer ring of the torque sensor is clamped and fixed between the bearing outer ring and one end of the motor housing, the inner ring of the torque sensor is fixed to the flexible wheel, the wave generator is arranged in the flexible wheel and drives the flexible wheel to deform, one end of the rotating shaft passes through the torque sensor and the flexible wheel and is fixed to the wave generator, a gear ring is further provided on the inner wall of one end of the bearing inner ring, the bearing inner ring is sleeved outside the flexible wheel and is staggered with the flexible wheel for transmission; an end cover is provided at the other end of the motor housing, a controller cover is also fastened and fixed on the end cover, a control circuit board is fixed in the accommodation space formed by the end cover and the controller cover, and a wiring harness of the torque sensor passes through the end cover in the motor housing and is connected to the control circuit board.

[0007] As a preferred solution, it also includes a T-shaped wiring harness pipe fitting, the interior of the T-shaped wiring harness pipe fitting is hollow to form a wire hole, the T-shaped wiring harness pipe fitting passes through the wave generator and the rotating shaft, and a gap is left between the wave generator and the rotating shaft, one end of the T-shaped wiring harness pipe fitting is fixed to the inner ring of the bearing, and is rotatably connected to the wave generator through a support member, and the other end of the T-shaped wiring harness pipe fitting is rotatably connected to the rotating shaft through the support member.

[0008] As a preferred solution, a magnetic ring A is fixed to one end of the rotating shaft close to the control circuit board, and a magnetic sensor and a signal processor matching with the magnetic ring A are also provided on the control circuit board.

[0009] As a preferred embodiment, a brake is also fixed in the accommodating space formed by the end cover and the controller cover, and the brake includes a base, a connecting flange, a moving plate, a friction plate and a sleeve. The base is annular, and the inner ring of the base is provided with a retaining edge, the connecting flange is located on one side of the retaining edge, the moving plate is fixed to the connecting flange after passing through the retaining edge by bolts, the friction plate is arranged between the moving plate and the retaining edge, and the friction plate is fixed to the rotating shaft through the sleeve; an annular groove is provided on the base, a magnetic pole is provided in the annular groove, and a spring is also provided between the magnetic pole and the connecting flange, and when the magnetic pole is energized, the connecting flange compresses the spring close to the retaining edge, thereby causing the moving plate to separate from the friction plate, thereby ensuring the normal rotation of the rotating shaft; after the magnetic pole is de-energized, the connecting flange is free from the retaining edge under the action of the spring, thereby causing the moving plate to press the friction plate against the retaining edge, thereby stopping the rotation of the rotating shaft.

[0010] As a preferred solution, a magnetic ring B is fixed to a side of the shaft sleeve close to the control circuit board, and a magnetic sensor and a signal processor matching with the magnetic ring B are also provided on the control circuit board.

[0011] As a preferred solution, the wave generator includes an elliptical hub and a flexible bearing sleeved outside the elliptical hub, the outer ring of the flexible bearing is embedded in the flexible wheel, and the elliptical hub is sleeved on the rotating shaft and driven by a spline.

[0012] As a preferred solution, two circles of limiting convex rings are also arranged on the rotating shaft at intervals along the axial direction, and the elliptical hub is located between the two circles of limiting convex rings.

[0013] As a preferred solution, a first sealing ring is provided between the bearing inner ring and the bearing outer ring, and a second sealing ring is further provided between the bearing outer ring and the torque sensor.

[0014] As a preferred solution, the signal processing circuit on the torque sensor is integrated on a control circuit board, and the signal processing circuit is connected to the strain gauge on the torque sensor via a wiring harness.

[0015] As a preferred embodiment, the T-shaped wiring harness pipe includes an intermediate tube and a connecting plate fixed at one end of the intermediate tube, the connecting plate is fixed to the inner ring of the bearing, the intermediate tube passes through the wave generator and the rotating shaft, and a gap is left between the wave generator and the rotating shaft, the two ends of the intermediate tube are respectively rotatably connected to the rotating shaft and the wave generator through bearings, the connecting plate is annular, the intermediate tube is hollow tubular, and one end of the intermediate tube is integrally formed with the connecting plate.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The harmonic reducer of the joint module of the present invention eliminates the rigid wheel, and sets a gear ring and a flexible wheel transmission on the inner ring of the bearing, which improves the transmission accuracy, reduces the weight, and reduces the installation error; and by fixing the torque sensor together with the motor, its function is not affected; at the same time, the sensor harness is directly inserted and fixed on the controller from the motor side, which permanently solves the problem of sensor harness pulling and makes the sensor sensing more accurate; at the same time, since the torque sensor is fixed, the entire joint module can realize multiple turns of rotation, and the movement is more flexible. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings in the specification, which constitute a part of the present application, are used to provide a further understanding of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute a limitation on the present application.

[0019] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0020] Figure 2 It is a schematic diagram of the cutaway structure of the present invention;

[0021] Figure 3 and Figure 4 It is a schematic diagram of the explosion structure of the present invention at two different angles.

[0022] The accompanying drawings are marked as follows: 11, motor housing; 12, stator assembly; 13, rotor core; 14, rotating shaft; 15, limiting cam; 21, elliptical hub; 22, flexible bearing; 23, flexible wheel; 24, bearing inner ring; 25, bearing outer ring; 26, first sealing ring; 3, torque sensor; 31, second sealing ring; 4, T-shaped wiring harness fitting; 40, wire hole; 41, support member; 42, magnetic ring A; 51, base; 52, connecting flange; 53, moving plate; 54, friction plate; 55, bushing; 56, magnetic ring B; 6, control circuit board; 7, controller cover. DETAILED DESCRIPTION

[0023] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0024] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0025] In addition, in the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0026] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more, unless otherwise clearly specified.

[0027] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0029] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0030] like Figures 1 to 4 As shown, a multifunctional integrated robot joint module includes a motor, a torque sensor 3 and a reducer. The motor includes a motor housing 11, a stator assembly 12, a rotor core 13 and a rotating shaft 14. The stator assembly 12 is fixed to the inner wall of the motor housing 11, the rotor core 13 is located on the inner side of the stator and is sleeved and fixed on the rotating shaft 14. The rotating shaft 14 is rotatably connected to the motor housing 11.

[0031] The reducer includes a wave generator, a flexible wheel 23, a bearing inner ring 24 and a bearing outer ring 25. The outer ring of the torque sensor 3 is clamped and fixed between the bearing outer ring 25 and one end of the motor housing 11. The inner ring of the torque sensor 3 is fixed to the flexible wheel 23. The wave generator is arranged in the flexible wheel 22 and drives the flexible wheel 22 to deform. One end of the rotating shaft 14 passes through the torque sensor 3 and the flexible wheel 22 and is fixed to the wave generator. A gear ring is also provided on the inner wall of one end of the bearing inner ring 24. The bearing inner ring 24 is sleeved outside the flexible wheel 22 and is staggered with the flexible wheel 22 for transmission. The other end of the motor housing 11 is provided with an end cover, and a controller cover 7 is also fastened and fixed on the end cover. A control circuit board 6 is fixed in the accommodation space formed by the end cover and the controller cover 7. The wiring harness of the torque sensor 3 passes through the end cover in the motor housing 11 and is connected to the control circuit board 6.

[0032] The wave generator includes an elliptical hub 21 and a flexible bearing 22 sleeved on the outside of the elliptical hub 21, the outer ring 22 of the flexible bearing is embedded in the flexible wheel 23, and the elliptical hub 21 is sleeved on the rotating shaft 14 and driven by a spline. The wave generator of the harmonic reducer is connected to the rotating shaft by a spline, which can meet the requirements of disassembly and assembly and reduce the space occupied by bolts. Two circles of limiting convex rings 15 are also arranged on the rotating shaft 14 at intervals along the axial direction, and the elliptical hub 21 is located between the two circles of limiting convex rings 15. The above structure makes the torque sensor and the harmonic reducer modularly designed, and realizes the replaceable design of the force-controlled joint and the non-force-controlled joint.

[0033] A first sealing ring 26 is provided between the bearing inner ring 24 and the bearing outer ring 25, and a second sealing ring 31 is provided between the bearing outer ring 25 and the torque sensor 3. The signal processing circuit on the torque sensor 3 is integrated on the control circuit board 6, and the signal processing circuit is connected to the strain gauge on the torque sensor 3 through a wiring harness. The above structure enables the torque sensor to realize an external amplifier, reduce the rigid part of the sensor, and shorten the overall shutdown module.

[0034] In the harmonic reducer in the joint module of the present invention, the steel wheel and the inner ring of the bearing are integrated, and the inner ring of the bearing is used as the output end to achieve a speed ratio of 101:1; at the same time, the flexible wheel is fixed to the motor housing through a torque sensor, and the sensor harness is directly inserted and fixed on the controller from the motor side, which permanently solves the problem of sensor harness pulling and makes the sensor sensing more accurate; at the same time, since the torque sensor is fixed, the entire joint module can achieve multiple turns of rotation, and the movement is more flexible.

[0035] A brake is also fixed in the accommodation space formed by the end cover and the controller cover 7. The brake includes a base 51, a connecting flange 52, a moving plate 53, a friction plate 54 and a sleeve 55. The base 51 is annular, and the inner ring of the base 51 is provided with a retaining edge. The connecting flange 52 is located on one side of the retaining edge. The moving plate 53 is fixed to the connecting flange 52 after passing through the retaining edge by bolts. The friction plate 54 is arranged between the moving plate 53 and the retaining edge, and the friction plate 54 is fixed to the rotating shaft 14 through the sleeve 55. An annular groove is provided on the base 51, and a magnetic pole is provided in the annular groove. A spring is also provided between the magnetic pole and the connecting flange 52. When the magnetic pole is energized, the connecting flange 52 compresses the spring close to the retaining edge, thereby causing the moving plate 53 to separate from the friction plate 54, thereby ensuring the normal rotation of the rotating shaft 14. When the magnetic pole is de-energized, the connecting flange 52 is not in contact with the retaining edge under the action of the spring, thereby causing the moving plate 53 to press the friction plate 54 on the retaining edge, thereby stopping the rotation of the rotating shaft 14. The above structure enables the joint module to achieve the power-off locking function, thereby improving safety.

[0036] The present invention also includes a T-shaped wiring harness pipe 4, which is hollow inside to form a wire hole 40. The T-shaped wiring harness pipe 4 passes through the wave generator and the rotating shaft 14, and a gap is left between the wave generator and the rotating shaft 14. One end of the T-shaped wiring harness pipe 4 is fixed to the bearing inner ring 24 and is rotatably connected to the wave generator through a support 41. The other end of the T-shaped wiring harness pipe 4 is rotatably connected to the rotating shaft 14 through the support 41.

[0037] The T-shaped wiring harness pipe 4 includes an intermediate tube and a connecting plate fixed at one end of the intermediate tube, the connecting plate is fixed to the inner ring 24 of the bearing, the intermediate tube passes through the wave generator and the rotating shaft 14, and a gap is left between the wave generator and the rotating shaft 14, the two ends of the intermediate tube are rotatably connected to the rotating shaft 14 and the wave generator through bearing shells respectively, the connecting plate is annular, the intermediate tube is hollow tubular, and one end of the intermediate tube is integrally formed with the connecting plate.

[0038] A magnetic ring A42 is also fixed to one end of the rotating shaft 14 close to the control circuit board 6, and a magnetic sensor and a signal processor that match the magnetic ring A42 are also provided on the control circuit board 6. A magnetic ring B56 is also fixed to one side of the sleeve 55 close to the control circuit board 6, and a magnetic sensor and a signal processor that match the magnetic ring B56 are also provided on the control circuit board 6.

[0039] The input and output of the present invention are controlled by dual encoders to achieve high-precision control; the encoder is integrated with the output shaft and the input shaft, the magnetic part of the encoder (magnetic ring A, magnetic ring B) is glued to the end of the shaft, the magnetic ring seat is eliminated, and the stainless steel support of the magnetic encoder is reduced, thereby reducing assembly errors and dimensional errors and improving accuracy; at the same time, the control circuit board 6 of the present invention is a single control board and meets the EtherCAT communication requirements.

[0040] The above-mentioned magnetic ring A and magnetic ring B can also be arranged concentrically, and the dual encoders in the controller cover are arranged concentrically inside and outside and side by side, meeting the requirements of arranging encoders at the output end and the input end respectively, so that the axial space of the overall joint module is saved by more than 5mm, and the reading control accuracy of the encoder is improved.

[0041] The present invention satisfies the requirements that the output and input ends are accurately and directly fixed on the reducer; the sensor and the reducer are installed to form a module assembly; finally, the module is installed to one end of the motor. Such a structure enables the stator part of the motor to be separately heat-fitted; for replacement of parts and disassembly and assembly, the housing components will not be damaged, and the replaceability is high; the assembly and disassembly are more convenient.

[0042] The joint module of the present invention integrates a motor, a controller, a brake, a torque sensor, a harmonic reducer, and a dual encoder, and has high density, high precision integration and a high degree of product modularization. In addition, the joint module of the present invention has a wide range of uses and high replaceability. The reducer of the above structure can be installed in a joint module that does not require a sensor only by changing the cup-type flexible wheel to a top-hat-type flexible wheel.

[0043] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0044] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A multifunctional integrated robot joint module, comprising a motor, a torque sensor (3) and a reducer, wherein the motor comprises a motor housing (11), a stator assembly (12), a rotor core (13) and a rotating shaft (14), wherein the stator assembly (12) is fixed to the inner wall of the motor housing (11), the rotor core (13) is located inside the stator and is sleeved and fixed on the rotating shaft (14), and the rotating shaft (14) is rotatably connected to the motor housing (11), characterized in that: The reducer comprises a wave generator, a flexible wheel (23), a bearing inner ring (24) and a bearing outer ring (25); the outer ring of the torque sensor (3) is clamped and fixed between the bearing outer ring (25) and one end of the motor housing (11); the inner ring of the torque sensor (3) is fixed to the flexible wheel (23); the wave generator is arranged in the flexible wheel (22) and drives the flexible wheel (22) to deform; one end of the rotating shaft (14) passes through the torque sensor (3) and the flexible wheel (22) and is fixed to the wave generator A gear ring is also provided on the inner wall of one end of the bearing inner ring (24), and the bearing inner ring (24) is sleeved outside the flexible wheel (22) and is driven by staggered teeth with the flexible wheel (22); an end cover is provided at the other end of the motor housing (11), and a controller cover (7) is also fastened and fixed on the end cover, and a control circuit board (6) is fixed in the accommodation space formed by the end cover and the controller cover (7), and the wiring harness of the torque sensor (3) passes through the end cover in the motor housing (11) and is connected to the control circuit board (6).

2. A multifunctional integrated robot joint module according to claim 1, characterized in that: The invention also comprises a T-shaped wiring harness pipe (4), wherein the interior of the T-shaped wiring harness pipe (4) is hollow to form a wire hole (40), the T-shaped wiring harness pipe (4) passes through the wave generator and the rotating shaft (14), and a gap is left between the wave generator and the rotating shaft (14), one end of the T-shaped wiring harness pipe (4) is fixed to the inner ring of the bearing (24), and is rotatably connected to the wave generator via a support member (41), and the other end of the T-shaped wiring harness pipe (4) is rotatably connected to the rotating shaft (14) via the support member (41).

3. A multifunctional integrated robot joint module according to claim 1, characterized in that: A magnetic ring A (42) is also fixed to one end of the rotating shaft (14) close to the control circuit board (6), and a magnetic sensor and a signal processor that match the magnetic ring A (42) are also provided on the control circuit board (6).

4. The multifunctional integrated robot joint module according to claim 1, characterized in that: A brake is also fixed in the accommodation space formed by the end cover and the controller cover (7), and the brake comprises a base (51), a connecting flange (52), a moving plate (53), a friction plate (54) and a shaft sleeve (55). The base (51) is annular, and the inner ring of the base (51) is provided with a retaining edge. The connecting flange (52) is located on one side of the retaining edge. The moving plate (53) is fixed to the connecting flange (52) after passing through the retaining edge by bolts. The friction plate (54) is arranged between the moving plate (53) and the retaining edge, and the friction plate (54) is fixed to the connecting flange (52) by bolts. The shaft sleeve (55) is fixed on the rotating shaft (14); the base (51) is provided with an annular groove, a magnetic pole is provided in the annular groove, and a spring is provided between the magnetic pole and the connecting flange (52). When the magnetic pole is energized, the connecting flange (52) compresses the spring close to the stop edge, thereby causing the movable plate (53) to separate from the friction plate (54), thereby ensuring the normal rotation of the rotating shaft (14); when the magnetic pole is de-energized, the connecting flange (52) moves away from the stop edge under the action of the spring, thereby causing the movable plate (53) to press the friction plate (54) onto the stop edge, thereby stopping the rotation of the rotating shaft (14).

5. A multifunctional integrated robot joint module according to claim 4, characterized in that: A magnetic ring B (56) is also fixed to one side of the shaft sleeve (55) close to the control circuit board (6), and a magnetic sensor and a signal processor matching the magnetic ring B (56) are also provided on the control circuit board (6).

6. The multifunctional integrated robot joint module according to claim 1, characterized in that: The wave generator comprises an elliptical hub (21) and a flexible bearing (22) sleeved outside the elliptical hub (21); the outer ring (22) of the flexible bearing is embedded in the flexible wheel (23); the elliptical hub (21) is sleeved on the rotating shaft (14) and driven by a spline.

7. A multifunctional integrated robot joint module according to claim 6, characterized in that: Two circles of limiting convex rings (15) are also arranged on the rotating shaft (14) at intervals along the axial direction, and the elliptical wheel hub (21) is located between the two circles of limiting convex rings (15).

8. The multifunctional integrated robot joint module according to claim 1, characterized in that: A first sealing ring (26) is provided between the bearing inner ring (24) and the bearing outer ring (25), and a second sealing ring (31) is provided between the bearing outer ring (25) and the torque sensor (3).

9. The multifunctional integrated robot joint module according to claim 1, characterized in that: The signal processing circuit on the torque sensor (3) is integrated on a control circuit board (6), and the signal processing circuit is connected to the strain gauge on the torque sensor (3) via a wiring harness.

10. The multifunctional integrated robot joint module according to claim 1, characterized in that: The T-shaped wiring harness pipe (4) comprises an intermediate tube and a connecting plate fixed to one end of the intermediate tube, the connecting plate being fixed to the inner ring (24) of the bearing, the intermediate tube passing through the wave generator and the rotating shaft (14), and a gap being left between the intermediate tube and the wave generator and the rotating shaft (14), the two ends of the intermediate tube being rotatably connected to the rotating shaft (14) and the wave generator respectively through bearing bushes, the connecting plate being annular, the intermediate tube being hollow tubular, and one end of the intermediate tube being integrally formed with the connecting plate.

Images