Compact high-power-density electric linear driving mechanism

Abstract

According to the compact high-power-density electric linear driving mechanism, by optimizing a supporting and connecting structure, the space occupied by the stator, the rotor and the lead screw and the mass proportion of the stator, the rotor and the lead screw are enlarged as much as possible, and the purpose of ultrahigh power density is achieved. The electric linear driving mechanism comprises a shell, a motor stator, a motor rotor, a driving module and a lead screw pair, wherein the motor stator, the motor rotor and the driving module are arranged in the shell; the lead screw pair consists of a lead screw nut and a lead screw; an opening in one end of the shell is in butt joint with a bearing end cover, and a driving module is installed in the bearing end cover and used for driving a motor rotor. An opening in the other end of the shell is a lead screw extending end; the motor rotor is of a hollow structure, and one end is directly connected with the lead screw nut and used for driving the lead screw nut to rotate. The lead screw nut is supported in the shell through a bearing. The motor stator coaxially sleeves the motor rotor and is fixedly connected with the shell; the lead screw is arranged in the motor rotor and is connected with the guide unit arranged in the motor rotor; the guide unit is used for guiding linear motion of the lead screw.

Description

Technical Field

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

[0002] The existing linear drive technology has problems such as low space utilization and poor heat dissipation, resulting in low power density and low speed, which makes it difficult to meet the needs of emerging industries such as humanoid robots. The traditional linear drive mechanism uses a solution in which the lead screw rotates and the nut drives the push rod to extend and retract. The lead screw rotation will cause bending instability and cannot withstand high input speeds, which restricts the power density. For example, the currently known integrated linear electric drive mechanism has a diameter of 90mm and a thrust of 10KN, but the maximum speed is only about 300mm / s, which greatly restricts the movement speed of products such as robots. Summary of the invention

[0003] In view of this, the present invention proposes a compact high-power density electric linear drive mechanism, which can effectively shorten the length of the linear drive mechanism by optimizing the support and connection structure; maximize the space and mass ratio occupied by the stator, rotor and lead screw to achieve the purpose of ultra-high power density; and has good heat dissipation effect, simple process and high reliability.

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

[0005] The opening at one end of the housing is connected to the bearing end cover, and a driving module is installed inside the bearing end cover to drive the motor rotor; the opening at the other end of the housing is the extension end of the lead screw;

[0006] The motor rotor is a hollow structure, one end of which is directly connected to the lead screw nut for driving the lead screw nut to rotate; the lead screw nut is supported in the housing by a bearing;

[0007] The motor stator is coaxially sleeved outside the motor rotor and fixedly connected to the housing;

[0008] The lead screw is arranged inside the motor rotor and connected to a guide unit arranged inside the motor rotor; the guide unit is used for guiding the linear motion of the lead screw;

[0009] The outer surface of the shell is provided with a heat sink.

[0010] As a preferred embodiment of the present invention: the guide unit comprises: a guide rail bracket and a slider;

[0011] One end of the guide rail bracket is located inside the motor rotor, and the other end extends out of the motor rotor and is fixedly connected to the housing through a plurality of radial support bars;

[0012] The part of the guide rail bracket located inside the motor rotor is provided with a guide rail parallel to the lead screw, and the guide rail is provided with a slider that slides with it or a guide wheel that rolls with it; the slider or guide wheel is connected to the end of the lead screw.

[0013] As a preferred embodiment of the present invention: a displacement sensor is arranged inside the guide rail bracket, and a monitoring end of the displacement sensor monitors the displacement of the lead screw by monitoring the displacement of the slider.

[0014] As a preferred embodiment of the present invention: a retractable rubber sheath is provided at the protruding end of the lead screw on the housing, one end of the rubber sheath is fixedly connected to the housing, and the other end is connected to the lead screw; when the lead screw is retracted, the rubber sheath is driven to retract;

[0015] The outer coaxial sleeve of the lead screw is provided with a spiral oil scraper.

[0016] As a preferred embodiment of the present invention: a plurality of ventilation windows equipped with filter cotton are arranged on the bearing end cover, and a spiral weight-reducing groove is opened on the motor rotor, which cooperates with the heat sink on the shell to form a heat dissipation system.

[0017] As a preferred embodiment of the present invention: the housing is a hollow cylindrical structure with openings at both ends, and the opening at one end is butted against the bearing end cover;

[0018] The end of the bearing end cover that is butted against the housing is cylindrical, and the other end is rectangular;

[0019] The cylindrical end of the bearing end cover extends into the interior of the housing and is threadedly connected thereto.

[0020] As a preferred embodiment of the present invention: a lifting ring end cover is installed at the middle of the outer end surface of the bearing end cover, and a push-pull force strain sensor is arranged on the inner side of the lifting ring end cover.

[0021] As a preferred embodiment of the present invention, the motor rotor and the lead screw nut are an integrated structure.

[0022] As a preferred embodiment of the present invention: a four-point contact ball bearing is arranged between the outer circumference of the screw nut and the inner circumference of the housing;

[0023] The inner ring of the four-point contact ball bearing is connected to or integrally manufactured with the outer circle of the lead screw pair nut, and the outer ring is fixed in the housing;

[0024] The four-point contact ball bearing and the deep groove ball bearing that assists in supporting the motor rotor form a supporting structure for the motor rotor and the lead screw pair.

[0025] Beneficial effects:

[0026] (1) The electric linear drive mechanism provided by the present invention has a hollow motor rotor structure that can accommodate a lead screw, a displacement sensor, etc., and the motor rotor is directly connected to the nut of the lead screw pair, and the lead screw directly serves as a push rod; thus, the structure is compact and the length of the linear drive mechanism can be effectively shortened; and a lead screw pair with a standard structure can be used, avoiding the use of a reverse lead screw pair with high process difficulty; and the present invention adopts a structure in which the nut rotates and the lead screw translates, which can effectively overcome the bending instability effect of the lead screw rotation, can withstand a higher input speed, and effectively improve the power density.

[0027] (2) In the present invention, the displacement sensor is built into the guide rail bracket, which not only effectively bears the rotational torque between the lead screw and the housing, but also protects the displacement contacts, thereby improving reliability and life.

[0028] (3) In the present invention, a retractable rubber sheath is provided at the protruding end of the lead screw on the housing, so that when the lead screw is extended, the rubber sheath is extended so that the portion of the lead screw protruding from the housing is always located inside the rubber sheath, thereby preventing dust and other debris from falling into the spiral groove of the lead screw; the spiral oil scraper provided in conjunction can achieve double protection for the lead screw, and has high reliability.

[0029] (4) In the present invention, a spiral weight-reducing groove is provided on the motor rotor, which generates airflow during rotation. The direction of the airflow is consistent with the direction of the airflow generated by the extension and contraction of the lead screw and the rubber sleeve. The airflow can be exchanged with the outside through the air permeable window to dissipate heat inside the structure, thereby further improving the heat dissipation effect.

[0030] (5) In the present invention, the entire structure of the electric linear drive mechanism is a rectangular parallelepiped, which effectively utilizes the space of the usage scene while allowing the interior of the bearing end cover at one end to better adapt to the shape of electronic devices such as chips, thereby providing more effective space for the circuit board of the drive module. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the overall structure of the compact high power density electric linear drive mechanism of the present invention;

[0032] Figure 2 It is a schematic diagram of the internal structure of the compact high power density electric linear drive mechanism of the present invention;

[0033] Figure 3 It is a schematic diagram of the structure of the displacement sensor and its supporting components;

[0034] Figure 4 This is a schematic diagram of the internal structure of the electric linear drive mechanism after removing the displacement sensor and its supporting components;

[0035] Figure 5It is a schematic diagram of the structure of the heat sink;

[0036] Figure 6 A schematic diagram of the tail trunnion hole setting;

[0037] Figure 7 Set up the schematic for the head trunnion.

[0038] Among them: 1- push-pull force strain sensor; 2- encoder; 3- bearing end cover; 4- housing; 5- displacement sensor; 6- motor stator; 7- motor rotor; 8- rotor bearing A; 9- four-point contact ball bearing; 10- nut A; 11- lead screw nut; 12- full needle roller bearing; 13- nut B; 14- key; 15- spiral oil scraper; 16- lead screw; 17- rotor bearing B; 18- drive module; 19- power socket; 20- heat sink; 21- rubber sheath; 22- air window; 23- signal socket; 24- lifting ring end cover; 25- tail ear shaft hole; 26- head ear shaft; 27- guide rail bracket; 28- slider. DETAILED DESCRIPTION

[0039] 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.

[0040] 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.

[0041] 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.

[0042] This embodiment provides a compact high-power density electric linear drive mechanism with a compact overall structure. Compared with the prior art, the invention achieves higher power density and better heat dissipation effect with comparable process difficulty and cost.

[0043] like Figure 1 and Figure 2 As shown, the electric linear drive mechanism is an integrated structure, including: a housing 4, a motor stator 6, a motor rotor 7, a drive module 18, and a screw pair consisting of a screw nut 11 and a screw 16 arranged inside the housing 4;

[0044] The entire structure of the electric linear drive mechanism is a rectangular parallelepiped, which effectively utilizes the space of the usage scene while allowing the interior of the bearing end cover 3 at one end to better adapt to the shape of electronic devices such as chips, thereby providing more effective space for the circuit board of the drive module 18.

[0045] The shell 4 is a hollow cylindrical structure with two ends open (after the heat sink 20 is arranged on the outer circumference of the shell 4, the whole structure is a rectangular parallelepiped structure, such as Figure 6 As shown in FIG. 1 , one end of the housing 4 is connected to the bearing end cover 3 (in this solution, the bearing end cover and the housing for installing the drive module 18 are designed as one piece); the end of the bearing end cover 3 and the housing 4 is cylindrical, and the other end has a rectangular cross section; the cylindrical end of the bearing end cover 3 extends into the housing 4 and is threadedly connected thereto. The drive module 18 is installed inside the bearing end cover 3 to drive the motor rotor 7. The other end of the housing 4 is opened as the protruding end of the lead screw 6, that is, in this solution, the lead screw 16 is directly used as the push rod of the linear drive mechanism.

[0046] The motor rotor 7 is a hollow structure, one end of which is directly connected to the screw nut 11, and is used to drive the screw nut 11 to rotate; as an example, the motor rotor 7 and the screw nut 11 are an integral structure; as another example, a coaxial sleeve is provided at the butt end of the screw nut 11 and the motor rotor 7, and the butt end of the motor rotor 7 is coaxially sleeved on the outer circumference of the sleeve, and is connected to the sleeve key through the key 14 on the outer circumference of the sleeve. A four-point contact ball bearing 9 is provided between the outer circumference of the screw nut 11 and the inner circumference of the housing 4, and the axial force and radial force of the screw 16 are borne by the four-point contact ball bearing 9 outside the screw nut 11. The outer ring and inner ring of the four-point contact ball bearing 9 are axially limited by nuts A10 and B13 respectively.

[0047] In this solution, the hollow structure of the motor rotor 7 can be connected to the screw nut 11, and a screw pair with a standard structure can be used, avoiding the use of a reversing screw pair with high process difficulty. The screw pair in this solution adopts a structure in which the nut rotates and the screw translates, which can effectively overcome the bending instability effect of the screw rotation, can withstand a higher input speed, and effectively improve the power density.

[0048] The motor rotor 7 with a hollow structure can accommodate the lead screw 16 and the displacement sensor 5, that is, the displacement sensor 5 and the lead screw 16 threadedly matched with the lead screw nut 11 are arranged inside the motor rotor 7 with a hollow structure; Figure 3 and Figure 4 As shown, a guide unit for guiding the lead screw 16 is also provided inside the motor rotor 7, and the guide unit includes: a guide rail bracket 27 and a slider 28; one end of the guide rail bracket 27 is located inside the motor rotor 7, and the other end extends out of the motor rotor 7 and is fixed to the housing 4 through a plurality of radial support bars, thereby realizing the installation of the guide rail bracket 27 inside the motor rotor 7. The part of the guide rail bracket 27 located inside the motor rotor 7 is provided with a guide rail parallel to the lead screw 16, and a slider 28 (or a roller) that is slidably matched with the lead screw 16 is provided on the guide rail; the slider 28 (or roller) is connected to the end of the lead screw 16, so that when the lead screw nut 11 rotates, the lead screw 16 moves linearly along its own axis, and during the linear motion, the slider 28 and the guide rail cooperate to guide its linear motion. The displacement sensor 5 is arranged inside the guide rail bracket 27, and its monitoring end monitors the displacement of the lead screw 16 by monitoring the displacement of the slider 28. The displacement sensor 5 is built into the guide rail bracket 27, which not only effectively bears the rotational torque between the lead screw 16 and the housing 4, but also protects the displacement contacts and improves the reliability of the displacement signal.

[0049] The head of the lead screw 16 extending out of the cylindrical end of the housing 4 is equipped with a ball head lifting ring, and a full needle roller bearing 12 is arranged inside the ball head lifting ring. A lifting ring end cover 24 is installed in the middle of the outer end surface of the bearing end cover 3, and a push-pull force strain sensor 1 (such as a strain gauge) is pasted on the inner side of the lifting ring end cover 24 to generate a push-pull force signal, which is small in size and low in cost.

[0050] The motor stator 6 is coaxially sleeved outside the motor rotor 7 and fixedly connected to the housing 4 .

[0051] In addition, one axial end of the motor rotor 7 (the end connected to the lead screw nut 11) is supported on the housing 4 through the rotor bearing A8, and the other axial end is supported on the bearing end cover 3 through the rotor bearing B17. When the motor rotor 7 and the lead screw nut 11 are an integrated structure, the rotor bearing A8 can be omitted. The rotor bearing A8 and the rotor bearing B17 are both deep groove ball bearings; the four-point contact ball bearing 9 and the rotor bearing A8 and the rotor bearing B17 that auxiliary support the motor rotor form the support structure of the motor rotor and the lead screw pair.

[0052] In this solution, the lead screw 16 moves linearly, extending or retracting into the housing 4. In order to protect the lead screw 16, a spiral oil scraper 15 and a retractable rubber sheath 21 are provided. Specifically, a spiral oil scraper 15 is provided on the inner circumference of the butt end of the lead screw nut 11 and the motor rotor 7 (when connected by a sleeve, it is provided on the inner circumference of the sleeve); a retractable rubber sheath 21 is provided on the extended end of the lead screw 16 on the housing 4. One end of the rubber sheath 21 is fixed to the housing 4, and the other end is connected to the lead screw 16. Therefore, when the lead screw 16 is extended, the rubber sheath 21 is extended, so that the part of the lead screw 16 extending out of the housing 4 is always located inside the rubber sheath 21, preventing dust and other debris from falling into the spiral groove of the lead screw 16. The spiral oil scraper 15 and the retractable rubber sheath 21 are used to provide double protection for the lead screw, which has high reliability.

[0053] In the electric linear drive mechanism, the output axial force transmission route of the structure is lead screw 16-lead screw nut 11-four-point contact ball bearing 9-housing 4-lifting ring end cover 24, and the motor stator 6, motor rotor 7, encoder 2, drive module 18, displacement sensor 5, etc. are arranged in a position not subject to axial force and are well protected.

[0054] In order to make the linear drive mechanism have a good heat dissipation effect, Figure 5 As shown, square heat sinks 20 are evenly spaced along the circumferential direction on the outer circumferential surface of the shell 4 (the square heat sinks 20 are in an outwardly radiating state), which effectively increases the heat dissipation area and improves the continuous operation time; the outer dimensions of the outer circumferential surface of the shell 4 after the heat sink 20 is arranged shall not exceed the dimensions of the rectangular cross-section end of the bearing end cover 3.

[0055] The bearing end cover 3 is provided with a plurality of ventilation windows 22 equipped with filter cotton, which can filter dust and other debris while ventilating. The ventilation window 22 is detachably connected to the bearing end cover 3, and is easy to replace. In occasions where waterproofing is required, it can be replaced with a fully enclosed cover.

[0056] As an example, a spiral weight-reducing groove is provided on the motor rotor 7, which generates airflow during rotation. The direction of the airflow is consistent with the direction of the airflow generated by the extension and contraction of the lead screw 16 and the rubber sheath 21. The airflow can be exchanged with the outside world through the air window 22 to dissipate heat inside the structure, thereby further improving the heat dissipation effect. The air window 22 and the spiral weight-reducing groove cooperate with the heat sink 20 on the shell to form a heat dissipation system.

[0057] In addition, an encoder 2 is installed in the bearing end cover 3.

[0058] Furthermore, a power socket 19 and a signal socket 23 are also provided on the outer end surface of the bearing end cover 3;

[0059] In the above structure, all bearings can use standard parts to reduce costs, and can obtain good matching results in terms of space, speed, strength, and life, achieving dual optimization of space utilization and equal strength design. When the inner hole of the standard bearing matches the shaft, adding a sleeve or a weight-reducing hole can obtain an optimized power-to-weight ratio. The axial positioning of the bearing avoids the use of structures such as end covers fixed by screws, but instead uses shaft (hole) shoulders and ring nuts to save space and weight. At the same time, the bearing end cover 3 and the housing 4 are directly screwed together through large-diameter fine-pitch threads to obtain higher reliability and convenient positioning and adjustment processes.

[0060] As an example, Figure 6 As shown, the lifting ring end cover 24 is not provided, but the tail ear shaft hole 25 is provided on the upper and lower opposite sides of the bearing end cover 3 to save axial space.

[0061] As an example, Figure 7 As shown, the eye end cover 24 is not provided, but the head ear shaft 26 is provided on the upper and lower opposite sides of the outer circumferential surface of the extended end of the lead screw 16 on the housing 4 to shorten the axial force transmission route and save axial space.

[0062] As an example, the weight of the shell can be reduced by designing rib-like structures at the four corners of the shell 4 to bear the axial force.

[0063] Using the above structure, an electric linear drive mechanism designed for a robot has a volume of 230mm×85mm×85mm, a weight of 4Kg, and a heat dissipation area of ​​700cm 2 The output can reach 12KN / 625mm / s, and it has the advantages of high reliability, low cost and good use effect.

[0064] 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 compact high power density electric linear drive mechanism, comprising: A housing, a motor stator and a motor rotor arranged inside the housing, a drive module, and a lead screw pair consisting of a lead screw nut and a lead screw; The opening at one end of the housing is connected to the bearing end cover, and a driving module is installed inside the bearing end cover to drive the motor rotor; the opening at the other end of the housing is the extension end of the lead screw; The motor rotor is a hollow structure, one end of which is directly connected to the lead screw nut and is used to drive the lead screw nut to rotate; The lead screw nut is supported in the housing via a bearing; The motor stator is coaxially sleeved outside the motor rotor and fixedly connected to the housing; The lead screw is arranged inside the motor rotor and connected to a guide unit arranged inside the motor rotor; the guide unit is used for guiding the linear motion of the lead screw; The outer surface of the shell is provided with a heat sink.

2. The compact high power density electric linear drive mechanism according to claim 1, characterized in that: The guide unit comprises: a guide rail bracket and a slider; One end of the guide rail bracket is located inside the motor rotor, and the other end extends out of the motor rotor and is fixedly connected to the housing through a plurality of radial support bars; The part of the guide rail bracket located inside the motor rotor is provided with a guide rail parallel to the lead screw, and the guide rail is provided with a slider that slides with it or a guide wheel that rolls with it; the slider or guide wheel is connected to the end of the lead screw.

3. The compact high power density electric linear drive mechanism according to claim 2, characterized in that: A displacement sensor is arranged inside the guide rail bracket, and a monitoring end of the displacement sensor monitors the displacement of the lead screw by monitoring the displacement of the slider.

4. The compact high power density electric linear drive mechanism according to claim 1, 2 or 3, characterized in that: A retractable rubber sheath is provided at the protruding end of the lead screw on the housing, one end of the rubber sheath is fixedly connected to the housing, and the other end is connected to the lead screw; when the lead screw is retracted, the rubber sheath is driven to retract; The outer coaxial sleeve of the lead screw is provided with a spiral oil scraper.

5. The compact high power density electric linear drive mechanism according to claim 1, 2 or 3, characterized in that: The bearing end cover is provided with a plurality of ventilation windows equipped with filter cotton, and the motor rotor is provided with spiral weight-reducing grooves, which cooperate with the heat sink on the shell to form a heat dissipation system.

6. The compact high power density electric linear drive mechanism according to claim 1, 2 or 3, characterized in that: The housing is a hollow cylindrical structure with openings at both ends, and one end of the opening is butted against the bearing end cover; The end of the bearing end cover that is butted against the housing is cylindrical, and the other end is rectangular; The cylindrical end of the bearing end cover extends into the interior of the housing and is threadedly connected thereto.

7. The compact high power density electric linear drive mechanism according to claim 1, 2 or 3, characterized in that: A lifting ring end cover is installed at the middle part of the outer end surface of the bearing end cover, and a push-pull force strain sensor is arranged on the inner side of the lifting ring end cover.

8. The compact high power density electric linear drive mechanism according to claim 1, 2 or 3, characterized in that: The motor rotor and the lead screw nut are an integrated structure.

9. The compact high power density electric linear drive mechanism according to claim 1, 2 or 3, characterized in that: A four-point contact ball bearing is arranged between the outer circumference of the screw nut and the inner circumference of the housing; The inner ring of the four-point contact ball bearing is connected to or integrally manufactured with the outer circle of the lead screw pair nut, and the outer ring is fixed in the housing; The four-point contact ball bearing and the deep groove ball bearing that assists in supporting the motor rotor form a supporting structure for the motor rotor and the lead screw pair.

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