High-power-density electric linear driving mechanism

Abstract

According to the high-power-density electric linear driving mechanism, an integrated electric cylinder with the small diameter can achieve the higher power density and the better heat dissipation effect through the structural layout. The linear driving mechanism comprises a shell, a motor stator, a motor rotor, a driving module and a lead screw pair composed of a lead screw nut and a lead screw. One end of the motor stator is coaxially butted with the shell, and the other end is fixedly connected with the sleeve through a bearing end cover; the motor rotor is coaxially arranged in the motor stator, and the lead screw is coaxially arranged in the motor rotor and is directly connected with the motor rotor; the tail part of the lead screw is supported on the shell through a bearing; the tail opening of the shell is sealed by a blind nut; a lifting ring in which a lifting ring bearing is mounted is arranged on the outer end surface of the blind nut; the head of the motor rotor is supported on the bearing end cover through a rotor bearing; the lead screw nut is located in the sleeve and coaxially connected with the push rod. The driving module is installed on the inner surface of the sleeve, and an encoder is installed in the shell. Cooling fins are arranged on the outer surface of the motor stator.

Description

Technical Field

[0001] The invention relates to a linear drive mechanism, in particular to a high-power density electric linear drive mechanism, and belongs to the technical field of electric linear actuators. Background Art

[0002] In the current field of industrial automation and robotics, linear drive technology is widely used because it can provide direct linear motion. However, existing linear drive technology has some limitations, especially in terms of space utilization, heat dissipation and power density; traditional linear drive mechanisms often occupy a large space due to their complex mechanical structure, which is particularly inconvenient in space-constrained applications. These problems are particularly prominent in products with a diameter of less than 50mm, resulting in low power density and low speed, which is difficult to meet the needs of emerging industries such as humanoid robots. Summary of the invention

[0003] In view of this, the present invention proposes a high power density electric linear drive mechanism, which can achieve higher power density and better heat dissipation effect for an integrated electric cylinder with a smaller diameter (less than 50 mm in diameter) by optimizing the structural layout.

[0004] The technical solution of the present invention is: a high power density electric linear drive mechanism, comprising: a housing, a motor stator, a motor rotor, a drive module and a lead screw pair consisting of a lead screw nut and a lead screw;

[0005] One end of the motor stator is coaxially connected to the housing, and the other end is fixedly connected to the sleeve through a bearing end cover;

[0006] The motor rotor is coaxially arranged inside the motor stator, and the lead screw is coaxially arranged inside the motor rotor and directly connected to the motor rotor for driving the lead screw to rotate; the tail of the lead screw is supported on the housing through a bearing; the tail opening of the housing is closed by a screw cover, and a lifting ring with a lifting ring bearing installed inside is arranged on the outer end surface of the screw cover;

[0007] One end of the motor rotor is supported on the bearing end cover through a rotor bearing;

[0008] The lead screw nut is located in the sleeve and is coaxially connected to the push rod. The push rod is the actuating end of the linear drive mechanism, extends out of the head of the sleeve, and is connected to a lifting ring with a lifting ring bearing installed inside.

[0009] The driving module is installed on the inner surface of the sleeve, and an encoder is installed inside the shell;

[0010] The outer surface of the motor stator is provided with a heat sink.

[0011] As a preferred embodiment of the present invention: a guide unit is provided in the sleeve;

[0012] The guide unit comprises: a guide fixing seat and a plurality of guide wheels arranged on the guide fixing seat;

[0013] The guide fixing seat is arranged at the head opening of the sleeve, and a plurality of guide wheels are evenly distributed along the circumferential direction on the inner circumferential surface of the central circular hole of the guide fixing seat, and guide grooves corresponding to the guide wheels and rollingly matched are evenly distributed along the circumferential direction on the outer circumferential surface of the push rod.

[0014] As a preferred embodiment of the present invention: a displacement sensor is provided on the guide fixing seat, and a monitoring end of the displacement sensor is used to monitor the displacement of the push rod.

[0015] As a preferred embodiment of the present invention: a retractable rubber sheath is provided at the extended end of the push rod, one end of the rubber sheath is fixedly connected to the guide fixing seat shell, and the other end is connected to the push rod; when the push rod is retracted, the rubber sheath is driven to retract;

[0016] Spiral oil scrapers are arranged on the inner circumferences of both ends of the lead screw nut.

[0017] As a preferred embodiment of the present invention: a plurality of air-permeable windows equipped with filter cotton are arranged on the end surface of the screw cover.

[0018] As a preferred embodiment of the present invention: the cross-section of the sleeve is rectangular, and the outer circumferential surface of the motor stator is provided with heat sinks, and the outer dimensions do not exceed the end dimensions of the rectangular cross-section of the sleeve; the diameter of the shell does not exceed the diameter of the motor stator; the entire structural shape of the electric linear drive mechanism formed thereby is a rectangular parallelepiped.

[0019] As a preferred embodiment of the present invention: the lead screw is supported on the housing by a four-point contact ball bearing;

[0020] The four-point contact ball bearing and the rotor bearing that assists in supporting the motor rotor form a supporting structure for the motor rotor and the lead screw pair.

[0021] Beneficial effects:

[0022] (1) In the present invention, the motor stator, encoder, sleeve, drive module, etc. are arranged at positions not subject to axial force, thereby reducing the thickness of the structural parts; and because the motor stator and sleeve are not subject to push-pull forces, the electronic stator can adopt a semi-exposed design, thereby improving the effective utilization of space.

[0023] This structural form maximizes the space and mass ratio occupied by the motor stator, motor rotor, and lead screw by optimizing the support and connection structure, and can achieve ultra-high power density at ultra-fine diameters. It has simple processes, high reliability, and low costs.

[0024] (2) In the present invention, the drive module is arranged on the inner surface of the sleeve, and the rotor shaft and the screw are integrated with the outer periphery of the screw pair nut, which can achieve optimal space utilization under a slender structure.

[0025] (3) In the present invention, the entire structure is in the shape of a rectangular parallelepiped, which effectively utilizes the space of the usage scene while allowing the inside of the sleeve to better adapt to the shape of electronic devices such as chips, thereby providing more effective space for the drive module circuit board.

[0026] (4) In the present invention, a full bridge of strain gauges is attached to the inner side of the sleeve, and the sleeve is subjected to a torsional moment (i.e., a torque signal of the screw rotation sensed by the sleeve), which is then converted into a push-pull force signal. This arrangement can save volume. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the overall structure of the high power density electric linear drive mechanism of the present invention;

[0028] Figure 2 It is a schematic diagram of the internal structure of the high power density electric linear drive mechanism of the present invention;

[0029] Figure 3 Schematic diagram of the installation of the guide unit and displacement sensor structure.

[0030] Among them: 1-encoder; 2-housing; 3-four-point contact ball bearing; 4-motor stator; 5-motor rotor; 6-rotor bearing; 7-bearing end cover; 8-strain gauge; 9-screw nut; 10-displacement sensor; 11-eye bearing; 12-drive module; 13-screw; 14-threaded sleeve; 15-spiral oil scraper; 17-screw cover; 18-ventilation window; 19-heat sink; 20-power socket; 21-sleeve; 22-signal socket; 23-rubber sheath; 24-push rod; 25-guide wheel; 26-guide holder. DETAILED DESCRIPTION

[0031] The present invention is described in detail below in conjunction with the accompanying drawings and preferred embodiments, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0032] The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0033] In the description of the embodiment of the present invention, it should be noted that the terms "left", "right", "front" and "rear" used herein refer to the orientation for the driver, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance. In the description of the embodiment of the present invention, "multiple" represents at least 2. In the description of the embodiment of the present invention, it should also be noted that unless otherwise clearly specified and limited, if the terms "set", "install", and "connect" appear, they 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 directly connected, or indirectly connected through an intermediate medium, or it can be a connection between the two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] This embodiment provides an ultra-thin high-power density electric linear drive mechanism, which, compared with the prior art, can enable an integrated electric cylinder with a thinner diameter (less than 50 mm in diameter) to achieve higher power density and better heat dissipation effect while maintaining comparable process difficulty and cost.

[0035] like Figure 1 and Figure 2 As shown, the electric linear drive mechanism is an integrated structure, including: a housing 2 , a motor stator 4 , a motor rotor 5 , a drive module 12 , and a screw pair consisting of a screw nut 9 and a screw 13 .

[0036] The shell 3 is a hollow cylindrical structure with two ends open. One end of the motor stator 4 is coaxially connected to the shell 3, and the other end is fixed to the sleeve 21 through the bearing end cover 7 (for the convenience of description, the end where the shell 3 is located is the tail of the linear drive mechanism, and the end where the sleeve 21 is located is its head); the cross-section of the sleeve 21 is rectangular; in order to make the linear drive mechanism have a good heat dissipation effect, the outer circumferential surface of the motor stator 4 is evenly spaced along the circumferential direction with square heat sinks 19 (the square heat sinks 19 are in a state of radiating outward), which effectively increases the heat dissipation area and improves the continuous operation time; as an example, the heat sinks 19 are arranged at the corresponding positions of the outer circumference of the motor stator 4 and the four corners of the sleeve 21 (thereby making full use of the gap between the circle and the square, the motor stator 4 is round, the sleeve 21 is square, and the four corners after docking). The outer circumferential surface of the motor stator 4 is provided with heat sink 19, and the outer dimension does not exceed the rectangular cross-sectional end dimension of the sleeve 21; the diameter of the housing 3 does not exceed the diameter of the motor stator 4; the entire structural shape of the electric linear drive mechanism thus formed is a rectangular parallelepiped, which effectively utilizes the space of the usage scene while enabling the interior of the sleeve 21 to better adapt to the shape of electronic devices such as chips, providing more effective space for the drive module circuit board, and square heat sinks 19 are designed at the four corners of the outer circle to effectively increase the heat dissipation area and improve the continuous operation time.

[0037] The motor rotor 5 is coaxially arranged inside the motor stator 4, and the lead screw 13 of the lead screw pair is coaxially arranged inside the motor rotor 5 and directly connected to the motor rotor 5 (i.e., the rotor shaft and the lead screw are integrated), and is used to drive the lead screw 13 to rotate; the tail of the lead screw 13 is supported on the housing 2 through a four-point contact ball bearing 3, and the axial force and radial force of the lead screw 13 are borne by the four-point contact ball bearing 3. In addition, an encoder 1 is installed inside the housing 2; the tail opening of the housing 3 is closed by a screw cover 17, and a lifting ring with a lifting ring bearing 11 installed inside is set at the center of the outer end surface of the screw cover 17.

[0038] One end of the motor rotor 5 is supported on the bearing end cover 7 through a rotor bearing 6 .

[0039] The lead screw nut 9 which is threadably matched with the lead screw 13 is located in the sleeve 21 and is coaxially connected to the push rod 24; therefore, when the motor rotor 5 drives the lead screw 13 to rotate, the lead screw nut 9 moves along its axis on the lead screw 13, thereby driving the push rod 24 to move linearly; the push rod 24 is the actuating end of the linear drive mechanism, extending out of the head of the sleeve 21 and connected to a lifting ring with a lifting ring bearing 11 installed inside.

[0040] The drive module 12 is installed on the inner surface of the sleeve 21, that is, the rotor shaft and the screw are integrated inside the sleeve 21, and the circuit board of the drive module 12 is arranged in the outer space of the screw nut 9, which can achieve optimal space utilization under a slender structure.

[0041] like Figure 3As shown, in order to guide the linear motion of the push rod 24, a guide unit is arranged in the sleeve 21, and the guide unit includes: a guide fixing seat 26 and a plurality of guide wheels 25 arranged on the guide fixing seat 26; the guide fixing seat 26 is arranged at the head opening of the sleeve 21 (that is, the protruding end of the push rod 24), and the guide fixing seat 26 has a central circular hole, and a plurality of guide wheels 25 are evenly distributed along the circumferential direction on the inner circumferential surface of the central circular hole, and guide grooves corresponding to the guide wheels 25 are evenly distributed along the circumferential direction on the outer circumferential surface of the push rod 24, and the guide wheels 25 are located in the corresponding guide grooves and roll with them; therefore, when the push rod 24 moves linearly, the guide wheels 25 roll in the corresponding guide grooves.

[0042] The displacement sensor 10 is disposed on the guide fixing seat 26 , and the monitoring end thereof is used to monitor the displacement of the push rod 24 .

[0043] In addition, a strain gauge 8 is attached to the inner side of the sleeve 21 to sense the torque signal of the screw rotation, which can be converted into a push-pull force signal through calculation and calibration (in this solution, since the end cover and the circuit board are not on the same side, if the traditional strain gauge installation method is adopted, the wiring will be long and the electromagnetic compatibility will be poor. Therefore, in this solution, the strain gauge 8 is set on the inner side of the sleeve 21 to sense the torque and then convert it into a push-pull force signal).

[0044] In order to protect the lead screw 13 and the push rod 24, a spiral oil scraper 15 and a retractable rubber sheath 23 are provided; specifically: spiral oil scrapers 15 are provided on the inner circumference of both ends of the lead screw nut 9; a retractable rubber sheath 23 is provided on the protruding end of the push rod 24 on the sleeve 21, one end of the rubber sheath 23 is fixedly connected to the guide fixing seat 26, and the other end is connected to the push rod 24, so that when the push rod 24 is extended, the rubber sheath 23 is driven to extend, so that the part of the push rod 24 extending out of the sleeve 21 is always located inside the rubber sheath 23.

[0045] A plurality of air-permeable windows 18 with filter cottons are arranged on the end surface of the screw cover 17, which can filter dust and other debris while ventilating. The air-permeable windows 18 are detachably connected to the screw cover 17, and are easy to replace. They can be replaced into fully enclosed cover plates in occasions with waterproof requirements.

[0046] Furthermore, a power socket 20 and a signal socket 22 are also provided on the outer surface of the sleeve 21 .

[0047] In the linear drive mechanism of this structure, the output axial force transmission route of the structure is screw cap 17-four-point contact ball bearing 3-screw 13-screw nut 9-sling ring connected to the push rod; the motor stator 4, encoder 1, sleeve 21, drive module 12 and displacement sensor 10 are arranged at a position not subject to axial force to reduce the thickness of the structural parts; and because the motor stator 4 and sleeve 21 do not bear push and pull forces, the electronic stator 5 can adopt a semi-exposed design to improve the effective utilization of space.

[0048] This structural form maximizes the space and mass ratio occupied by the motor stator, motor rotor, and screw by optimizing the supporting and connecting structures, optimizes the matching of motor and screw speed torque, strength, life, and heat dissipation, and achieves ultra-high power density at ultra-fine diameter, with simple process, high reliability, and low cost.

[0049] All bearings can be made of standard parts to reduce costs, and can be well matched in terms of space, speed, strength and life, achieving dual optimization of space utilization and equal strength design.

[0050] Using the above innovative structure, an electric linear drive mechanism designed for a robot has a volume of 241mm×45mm×45mm, a weight of 1.4Kg, and a heat dissipation area of ​​200cm 2 The output can reach 2KN / 800mm / s, and it has the advantages of high reliability, low cost and good use effect.

[0051] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high power density electric linear drive mechanism, comprising: A housing, a motor stator, a motor rotor, a drive module, and a lead screw pair consisting of a lead screw nut and a lead screw; One end of the motor stator is coaxially connected to the housing, and the other end is fixedly connected to the sleeve through a bearing end cover; The motor rotor is coaxially arranged inside the motor stator, and the lead screw is coaxially arranged inside the motor rotor and directly connected to the motor rotor for driving the lead screw to rotate; the tail of the lead screw is supported on the housing through a bearing; the tail opening of the housing is closed by a screw cover, and a lifting ring with a lifting ring bearing installed inside is arranged on the outer end surface of the screw cover; One end of the motor rotor is supported on the bearing end cover through a rotor bearing; The lead screw nut is located in the sleeve and is coaxially connected to the push rod. The push rod is the actuating end of the linear drive mechanism, extends out of the head of the sleeve, and is connected to a lifting ring with a lifting ring bearing installed inside. The driving module is installed on the inner surface of the sleeve, and an encoder is installed inside the shell; The outer surface of the motor stator is provided with a heat sink.

2. The high power density electric linear drive mechanism according to claim 1, characterized in that: A guide unit is arranged in the sleeve; The guide unit comprises: a guide fixing seat and a plurality of guide wheels arranged on the guide fixing seat; The guide fixing seat is arranged at the head opening of the sleeve, and a plurality of guide wheels are evenly distributed along the circumferential direction on the inner circumferential surface of the central circular hole of the guide fixing seat, and guide grooves corresponding to the guide wheels and rollingly matched are evenly distributed along the circumferential direction on the outer circumferential surface of the push rod.

3. The high power density electric linear drive mechanism according to claim 2, characterized in that: A displacement sensor is arranged on the guide fixing seat, and a monitoring end of the displacement sensor is used for monitoring the displacement of the push rod.

4. The high power density electric linear drive mechanism according to claim 2, characterized in that: The extended end of the push rod is provided with a retractable rubber sheath, one end of the rubber sheath is fixedly connected to the guide fixing seat shell, and the other end is connected to the push rod; when the push rod is extended or retracted, the rubber sheath is driven to extend or retract; Spiral oil scrapers are arranged on the inner circumferences of both ends of the lead screw nut.

5. The high power density electric linear drive mechanism according to claim 1, 2 or 3, characterized in that: A plurality of air-permeable windows equipped with filter cotton are arranged on the end surface of the screw cover.

6. The compact high power density electric linear drive mechanism according to claim 1, 2 or 3, characterized in that: The sleeve cross section is rectangular, and the outer circumferential surface of the motor stator is provided with heat sinks, and the outer dimensions do not exceed the end dimensions of the sleeve rectangular cross section; the diameter of the shell does not exceed the diameter of the motor stator; the entire structural shape of the electric linear drive mechanism formed thereby is a rectangular parallelepiped.

7. The compact high power density electric linear drive mechanism according to claim 1, 2 or 3, characterized in that: The lead screw is supported on the housing via a four-point contact ball bearing; The four-point contact ball bearing and the rotor bearing that assists in supporting the motor rotor form a supporting structure for the motor rotor and the lead screw pair.

Images