One-way self-locking motor for lifting table

Abstract

This utility model discloses a one-way self-locking motor for a height-adjustable desk, including a front cover (1) and a rear cover (2). A stator (10) is provided between the front cover (1) and the rear cover (2). The stator (10) has multiple circumferentially distributed coils (3). A rotor (11) is provided inside the stator (10). Multiple circumferentially distributed permanent magnets (4) are provided on the outside of the rotor (11). An axially movable rotating shaft (5) is provided on the axis of the rotor (11). The rear end of the rotating shaft (5) is rotatably connected to the rear cover (2). A friction plate (6) is provided at one end of the rotating shaft (5). The front end of the rotating shaft (5) extends out of the front cover (1) and forms a worm (7) by opening a threaded groove. A worm wheel (8) is provided on one side of the worm (7). The worm wheel (8) is connected to the front cover (1) through a bracket (9). The worm wheel (8) is rotatably connected to the bracket (9). This utility model has the advantages of convenient installation, low failure rate, low noise, and one-way self-locking function.

Description

Technical Field

[0001] This utility model belongs to the field of height-adjustable desk motors, and particularly relates to a one-way self-locking motor for height-adjustable desks. Background Technology

[0002] The lifting power of an adjustable desk comes from a motor. Currently, most motors used in adjustable desks are brushed motors. Their structure includes the motor body, within which coils are fixed to the rotor, permanent magnets are fixed to the stator, and a worm gear is located at the output end of the motor body. A bracket is mounted on the outer shell of the motor body, and a worm wheel that meshes with the worm gear rotates on the bracket. The motor body drives the worm gear to rotate, which in turn drives the worm wheel. The rotational force of the worm wheel is converted into a vertical force through another mechanism, thus raising or lowering the desk. Customers use a controller on the adjustable desk to start the motor and control the height adjustment range.

[0003] In practice, it has been found that existing motors, due to their compact structure and externally mounted drive boards, present inconvenience for installation. Brushed motors also generate significant brush friction noise during operation, typically around 56 dB. Furthermore, to increase the lifting speed of the table, the worm gear has a large helix angle, preventing self-locking between the worm and worm wheel. This results in low friction between them, causing relative movement even under heavy loads on the table. Consequently, the table height decreases unintentionally, altering the intended operating height and leading to poor performance. Utility Model Content

[0004] The purpose of this invention is to provide a one-way self-locking motor for height-adjustable desks. This invention has the advantages of easy installation, low failure rate, low noise, and a one-way self-locking function.

[0005] The technical solution of this utility model is as follows: A one-way self-locking motor for a height-adjustable desk includes a front cover and a rear cover. A stator is provided between the front cover and the rear cover. The stator has multiple circumferentially distributed coils. A rotor is provided inside the stator. Multiple circumferentially distributed permanent magnets are provided on the outside of the rotor. An axially movable shaft is provided on the axis of the rotor. The rear end of the shaft is rotatably connected to the rear cover. A friction plate is provided at one end of the shaft. The front end of the shaft extends out of the front cover and has a threaded groove to form a worm. A worm wheel is provided on one side of the worm. The worm wheel is connected to the front cover through a bracket. The worm wheel is rotatably connected to the bracket.

[0006] In the aforementioned unidirectional self-locking motor for lifting tables, the stator includes multiple stacked first steel sheets, and at least two channels are provided on the outer side of the stator. A screw is provided in the channel, and the screw passes through the rear cover and the channel in sequence and then connects to the front cover.

[0007] In the aforementioned one-way self-locking motor for lifting tables, the rotor includes multiple second steel plates stacked together and tightly fitted through by a rotating shaft. Multiple through slots are provided on the outer circumferential surface of the rotor, and permanent magnets are provided in the through slots.

[0008] In the aforementioned one-way self-locking motor for lifting tables, the inner diameter of the stator is 18-22mm, and multiple wire grooves are provided on the inner wall of the stator. Ribs are formed between adjacent wire grooves, and the coil is wound on the corresponding ribs.

[0009] The outer diameter of the rotor is 1.5-3.5 mm smaller than the inner diameter of the stator. Multiple permanent magnets are provided on the outer circumferential surface of the rotor. The outer circumferential surface of the permanent magnet is composed of a bottom surface, a top surface, and two side surfaces. The bottom surface and the two side surfaces are both planes. The bottom surface is located inside the rotor, and the top surface is located outside the rotor. The inner ends of the two side surfaces are connected through the bottom surface, and the outer ends of the two side surfaces are connected through the top surface. The bottom surface is 5.0-5.4 mm wide, and the included angle between the two side surfaces is 40-50°. The top surface protrudes outward in the middle, and the radius of the top surface is 5.5-7.2 mm. The distance between the permanent magnet and the stator is 0.3-0.9 mm.

[0010] In the aforementioned one-way self-locking motor for lifting table, there are six coils, the inner diameter of the stator is 20mm, and six wire slots are provided on the inner wall of the stator.

[0011] The rotor has an outer diameter of 17.5 mm, eight permanent magnets on its outer circumference, a bottom width of 5.2 mm, an included angle of 45° between the two sides, a top radius of 6.0-6.7 mm, a maximum thickness of 1.8 mm for the permanent magnets, and a distance of 0.6 mm between the permanent magnets and the stator.

[0012] In the aforementioned one-way self-locking motor for lifting tables, the screw groove rotates clockwise, the friction plate is located at the rear end of the rotating shaft, the middle of the rear cover protrudes outward into a bowl shape and forms an installation cavity, an oil-impregnated bearing is provided in the installation cavity, a limiting snap ring for connecting the rotating shaft is provided on the front side of the oil-impregnated bearing, the rear end of the rotating shaft is inserted into the oil-impregnated bearing, and a first ball bearing is provided between the front cover and the rotating shaft.

[0013] In the aforementioned one-way self-locking motor for lifting tables, the oil-impregnated bearing is ball-jointed with the rear cover, and a gap is formed between the oil-impregnated bearing and the bottom surface of the mounting cavity, with the friction plate located in the gap; an exhaust groove is provided on the side wall of the mounting cavity, with one end of the exhaust groove extending to the bottom surface of the mounting cavity.

[0014] In the aforementioned one-way self-locking motor for lifting tables, the screw groove rotates in the opposite direction, the friction plate is located at the front end of the rotating shaft, the bracket is provided with a blind hole to accommodate the friction plate, and the front end of the rotating shaft extends into the blind hole.

[0015] In the aforementioned one-way self-locking motor for height-adjustable desks, a first ball bearing is provided between the front cover and the rotating shaft, and a second ball bearing is provided between the rear cover and the rotating shaft.

[0016] In the aforementioned unidirectional self-locking motor for the height-adjustable table, an annular drive plate is fixed on the inner side of the front cover, and the rotating shaft passes through the drive plate. The drive plate is equipped with a brushless motor drive circuit and a Hall integrated circuit, and the brushless motor drive circuit is connected to a coil.

[0017] Compared with the prior art, the main improvements made by this utility model on the basis of existing motors include the following:

[0018] First, the change from a brushed motor to a brushless motor reduces the friction noise of the brushes. Since brushless motors have the characteristic of high output torque, the axial dimensions of the rotor and stator of this invention can be reduced while maintaining the same output torque. Under the premise of keeping the motor's external dimensions basically unchanged and not affecting the universal installation and use of the motor on the lifting table, a certain amount of space can be left inside the motor to realize the built-in drive ring. This reduces the installation steps of the drive ring on the lifting table, making the motor easier to install. At the same time, the drive ring is better protected to avoid external impact damage, thus reducing the failure rate.

[0019] Secondly, the stator is located between the front and rear covers, and the outer circumferential surface of the stator can be aligned with the outer circumferential surfaces of the front and rear covers, which increases the radial dimension of the stator. Under the premise of keeping the motor output torque unchanged, the axial dimensions of the stator and rotor can be further shortened, leaving more space inside the motor, making it easier to install the drive ring, and improving heat dissipation performance. At the same time, the installed drive ring can be further away from the rotor, reducing heat radiation and further reducing the failure rate of the motor.

[0020] Third, a friction plate is installed at one end of the rotating shaft. When the motor is not running, and the load of the lifting table acts on the worm through the worm gear, the rotating shaft moves to the side of the friction plate. The friction plate increases the rotational resistance of the rotating shaft, preventing the rotating shaft from rotating and thus preventing the lifting table from descending. It has a one-way self-locking function.

[0021] Fourth, by adopting a specific cross-sectional shape of the permanent magnet, the airflow deformation pattern between the stator and rotor is optimized, which has a better effect on noise reduction. Under the condition of background noise of 36dB and distance of 30cm, the motor noise is reduced to 45.1dB, and the noise reduction effect is obvious.

[0022] In summary, this utility model has the advantages of convenient installation, low failure rate, low noise, and one-way self-locking function. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of Example 1.

[0024] Figure 2 This is a wiring diagram of the coil in Example 1.

[0025] Figure 3 This is a cross-sectional schematic diagram of the rotor.

[0026] Figure 4 This is a structural diagram of the back cover.

[0027] Figure 5 This is a schematic diagram of the cross-sectional dimensions of the permanent magnet in Example 1.

[0028] Figure 6 This is a schematic diagram of the cross-sectional dimensions of the permanent magnet in Example 5.

[0029] Figure 7 This is a structural schematic diagram of Example 6.

[0030] The labels in the attached diagram are as follows: 1-Front cover, 2-Rear cover, 3-Coil, 4-Permanent magnet, 5-Shaft, 6-Friction plate, 7-Worm, 8-Worm wheel, 9-Bracket, 10-Stator, 11-Rotor, 12-Channel, 13-Screw, 14-Through slot, 15-Rib plate, 16-Mounting cavity, 17-Oil-impregnated bearing, 18-First ball bearing, 19-Exhaust groove, 20-Blind hole, 21-Second ball bearing, 22-Drive plate. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.

[0032] Example 1: A one-way self-locking motor for a height-adjustable desk, such as... Figures 1 to 6 As shown, it includes a front cover 1 and a rear cover 2, with a stator 10 between the front cover 1 and the rear cover 2, and six circumferentially distributed coils 3 in the stator 10.

[0033] The stator 10 has a rotor 11 inside, and eight circumferentially distributed permanent magnets 4 are provided on the outside of the rotor 11. An axially movable rotating shaft 5 is provided on the axis of the rotor 11. The rear end of the rotating shaft 5 is rotatably connected to the rear cover 2. A friction plate 6 is provided at the rear end of the rotating shaft 5. The front end of the rotating shaft 5 extends out of the front cover 1 and forms a worm 7 by opening a spiral groove. A worm wheel 8 is provided at the rear of the worm 7. The worm wheel 8 is connected to the front cover 1 through a bracket 9. The worm wheel 8 is rotatably connected to the bracket 9.

[0034] The stator 10 includes multiple stacked first steel sheets, the first steel sheets are made of silicon steel, and the outer side of the stator 10 is provided with at least two channels 12. The channels 12 can be through holes or slots. A screw 13 is provided in the channel 12. The screw 13 passes through the rear cover 2 and the channel 12 in sequence and then connects to the front cover 1.

[0035] The rotor 11 includes multiple second steel sheets stacked together and tightly fitted through the rotating shaft 5. The second steel sheets are made of silicon steel. Multiple through slots 14 are provided on the outer circumferential surface of the rotor 11, and permanent magnets 4 are provided in the through slots 14.

[0036] The stator 10 has an inner diameter of 20 mm. Six slots are formed on the inner wall of the stator 10, with ribs 15 forming between adjacent slots. The coil 3 is wound around the corresponding ribs 15. The rotor 11 has an outer diameter of 17.5 mm. The outer periphery of the permanent magnet 4 is composed of a bottom surface, a top surface, and two side surfaces. The bottom surface and the two side surfaces are planar. The bottom surface is located inside the rotor 11, and the top surface is located outside the rotor 11. The inner ends of the two side surfaces are connected through the bottom surface, and the outer ends of the two side surfaces are connected through the top surface. The bottom surface is 5.2 mm wide, and the included angle between the two side surfaces is 45°. The top surface protrudes outwards in the middle, with a radius of 6.35 mm. The thickest part of the permanent magnet 4 is 1.8 mm, and the distance between the permanent magnet 4 and the stator 10 is 0.6 mm.

[0037] The rear cover 2 protrudes outward in a bowl shape at the center, forming a mounting cavity 16. An oil-impregnated bearing 17 made of grinding metallurgy material is installed inside the mounting cavity 16. The rear end of the rotating shaft 5 is inserted into the oil-impregnated bearing 17, with a clearance fit between the rotating shaft 5 and the oil-impregnated bearing 17. A first ball bearing 18 is provided between the front cover 1 and the rotating shaft 5, with a clearance fit between the rotating shaft 5 and the first ball bearing 18. Snap rings connecting the rotating shaft 5 are provided on both sides of the first ball bearing 18 to limit the axial movement of the rotating shaft 5. A stroke of 0.1-0.2 mm is sufficient to meet the requirements. When the rotating shaft 5 moves axially, the rotor 11 will also move along with it.

[0038] The oil-impregnated bearing 17 is ball-jointed to the rear cover 2, and a gap is formed between the oil-impregnated bearing 17 and the bottom surface of the mounting cavity 16, with the friction plate 6 located within the gap. Four circumferentially distributed venting grooves 19 are provided on the side wall of the mounting cavity 16, with one end of each venting groove extending to the bottom surface of the mounting cavity 16. When the shaft is inserted into the oil-impregnated bearing 17, air in the oil-impregnated bearing 17 can be discharged through the venting grooves 19, making shaft insertion easier and improving assembly speed.

[0039] An annular drive plate 22 is fixed to the inner side of the front cover 1. The rotating shaft 5 passes through the drive plate 22. The drive plate 22 is equipped with a brushless motor drive circuit (existing circuit) and a Hall integrated circuit (existing circuit). The brushless motor drive circuit is connected to the coil 3. The motor in Embodiment 1 is a brushless motor, driven by the brushless motor drive circuit. The Hall integrated circuit is used to detect the motor's speed and direction, which can be fed back to the original controller of the lifting platform. The controller can know the motor's operating status and thus the lifting stroke of the lifting platform. After reaching the set height, the motor stops. The method for the Hall integrated circuit to detect the motor's direction and speed is described in patent application document No. 202411299088.1. The external wiring harness of the brushless motor drive circuit and the external wiring harness of the Hall integrated circuit are combined and extend out of the front cover 1 to connect to the controller of the lifting table.

[0040] In the working principle of Example 1, the load of the lifting table is applied to the worm 7 through the worm wheel 8. Due to the positive rotation of the screw groove, the worm 7 moves backward, and the rotating shaft 5 contacts the friction plate 6. The rotating shaft 5 obtains frictional torque through the friction plate 6, which prevents the rotating shaft 5 from rotating, so the lifting table will not decrease in height.

[0041] The main differences between Example 1 and existing motors are as follows:

[0042] First, replace the brushed motor with a brushless motor.

[0043] Second, the motor is built into the drive board 22.

[0044] Third, friction plates are used to achieve one-way self-locking.

[0045] Example 2: Compared with Example 1, the drive board 22 is located outside the motor.

[0046] Example 3: Compared with Example 1, the Hall integrated circuit on the driver board 22 is removed. In this case, the controller can be removed from the lifting table, and a switch is used to control the motor start-up state and forward and reverse rotation state.

[0047] Example 4: Compared to Example 1, the driver board 22 is equipped with an XH2.54 (1x5p) socket. The brushless motor drive circuit and Hall effect integrated circuit are both connected to the XH2.54 (1x5p) socket. This socket is small in size and suitable for use in confined spaces. It includes five pins: 29V, GND, 5V, serial port Tx, and serial port Rx. The controller has an MX4.2 (2x3p) socket, and the wiring harness connects the X4.2 (2x3p) socket and the XH2.54 (1x5p) socket.

[0048] The MX4.2 (2x3p) is used in many height-adjustable desk controllers, but it hasn't been used in conjunction with the XH2.54 yet, mainly due to concerns about potentially excessive current draw. This application uses it in conjunction with the XH2.54 because the motor in this application is a brushless motor. This interface is used as an input for brushless motors, while it's used as an output for brushed motors. For example, if the input is 29V 2A, and the output voltage is only 14.5V, a 4A output is required. The output voltage will vary depending on the motor speed, while the input voltage is fixed. When used with a brushed motor, the 4A current draw of the XH2.54 is too high, while with a brushless motor, the 2A current draw of the XH2.54 is not excessive. By using the XH2.54, the number of interface positions on the driver board 22 is reduced, better meeting the needs of confined spaces.

[0049] The power line (29V) and 5V, Tx, Rx are separated by GND, which isolates the power supply and signal, improving anti-interference and EMC performance.

[0050] Example 4 primarily addresses the challenge of integrating the driver board 22 into the motor while maintaining a similar size and output torque to existing motors. Integrating the driver board 22 within the motor provides better protection and reduces installation difficulty. The primary goal is to reduce the size of the driver board 22, which can be achieved through methods such as using an XH2.54 socket, external power supply, using a pre-driven chip in the brushless motor drive circuit, employing a single-resistor sampling algorithm, and implementing sensorless control. Considering heat dissipation in a confined environment, the drive power supply and 5V MCU power supply included on the driver board 22 can be externally powered, and larger MOSFETs (TO-252) can be used to reduce losses and increase heat dissipation.

[0051] Example 5: Compared with Example 1, the cross-sectional dimensions of the permanent magnet are changed as follows. Figure 6 As shown.

[0052] Noise tests were conducted on Examples 1 and 5 under the following conditions: ambient noise level of 36 dB and a distance of 30 cm from the motor. Example 5 produced a noise level of 50 dB, while Example 1 produced a noise level of 45.1 dB. Both are quieter than existing motors, with Example 1 being superior.

[0053] In other comparative experiments, one or more cross-sectional dimensions of the permanent magnet were adjusted multiple times, and the final test results showed that Example 1 had the best noise reduction effect.

[0054] Example 6: As Figure 7As shown, compared with Embodiment 1, the differences are as follows: the screw groove rotates in the opposite direction, the friction plate 6 is located at the front end of the rotating shaft 5, the bracket 9 is provided with a blind hole 20 to accommodate the friction plate 6, and the front end of the rotating shaft 5 extends into the blind hole 20. A first ball bearing 18 is provided between the front cover 1 and the rotating shaft 5, and a second ball bearing 21 is provided between the rear cover 2 and the rotating shaft 5. The drive plate 22 is externally mounted.

[0055] The working principle of Example 6 is as follows: when the load of the lifting table is applied to the worm 7 through the worm wheel 8, the worm 7 moves forward due to the reverse rotation of the screw groove. The rotating shaft 5 contacts the friction plate 6, and the rotating shaft 5 obtains frictional torque through the friction plate 6, which prevents the rotating shaft 5 from rotating and thus the lifting table will not descend in height.

[0056] In the description of this utility model, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

Claims

1. A one-way self-locking motor for a height-adjustable desk, characterized in that: The device includes a front cover (1) and a rear cover (2). A stator (10) is provided between the front cover (1) and the rear cover (2). The stator (10) has multiple circumferentially distributed coils (3). The stator (10) has a rotor (11) inside. The rotor (11) has multiple circumferentially distributed permanent magnets (4) on its outer side. The rotor (11) has an axially movable shaft (5). The rear end of the shaft (5) is rotatably connected to the rear cover (2). One end of the shaft (5) has a friction plate (6). The front end of the shaft (5) extends out of the front cover (1) and forms a worm (7) by opening a screw groove. A worm wheel (8) is provided on one side of the worm (7). The worm wheel (8) is connected to the front cover (1) through a bracket (9). The worm wheel (8) is rotatably connected to the bracket (9).

2. The one-way self-locking motor for a height-adjustable desk according to claim 1, characterized in that: The stator (10) includes multiple stacked first steel sheets. At least two channels (12) are provided on the outside of the stator (10). A screw (13) is provided in the channel (12). The screw (13) passes through the rear cover (2) and the channel (12) in sequence and then connects to the front cover (1).

3. The one-way self-locking motor for a height-adjustable desk according to claim 2, characterized in that: The rotor (11) includes multiple second steel plates stacked together and tightly fitted through by the rotating shaft (5). Multiple through slots (14) are provided on the outer circumferential surface of the rotor (11), and permanent magnets (4) are provided in the through slots (14).

4. The one-way self-locking motor for a height-adjustable desk according to claim 3, characterized in that: The inner diameter of the stator (10) is 18-22mm. Multiple wire grooves are provided on the inner wall of the stator (10), and ribs (15) are formed between adjacent wire grooves. The coil (3) is wound on the corresponding ribs (15). The outer diameter of the rotor (11) is 1.5-3.5 mm smaller than the inner diameter of the stator (10). Multiple permanent magnets (4) are provided on the outer circumferential surface of the rotor (11). The outer circumferential surface of the permanent magnet (4) is composed of a bottom surface, a top surface and two side surfaces. The bottom surface and the two side surfaces are both planes. The bottom surface is located inside the rotor (11) and the top surface is located outside the rotor (11). The inner ends of the two side surfaces are connected through the bottom surface and the outer ends of the two side surfaces are connected through the top surface. The bottom surface is 5.0-5.4 mm wide and the included angle between the two side surfaces is 40-50°. The top surface protrudes outward in the middle and has a radius of 5.5-7.2 mm. The distance between the permanent magnet (4) and the stator (10) is 0.3-0.9 mm.

5. The one-way self-locking motor for a height-adjustable desk according to claim 4, characterized in that: There are six coils (3), the inner diameter of the stator (10) is 20mm, and the inner wall of the stator (10) is provided with six wire slots. The rotor (11) has an outer diameter of 17.5 mm, eight permanent magnets (4) are provided on the outer circumference of the rotor (11), the bottom width is 5.2 mm, the included angle between the two sides is 45°, the radius of the top surface is 6.0-6.7 mm, the thickest part of the permanent magnet (4) is 1.8 mm, and the distance between the permanent magnet (4) and the stator (10) is 0.6 mm.

6. The one-way self-locking motor for a height-adjustable desk according to claim 4, characterized in that: The screw groove rotates in the forward direction, the friction plate (6) is located at the rear end of the rotating shaft (5), the middle part of the rear cover (2) protrudes outward into a bowl shape and forms an installation cavity (16), an oil-impregnated bearing (17) is provided in the installation cavity (16), the rear end of the rotating shaft (5) is inserted into the oil-impregnated bearing (17), and a first ball bearing (18) is provided between the front cover (1) and the rotating shaft (5).

7. The one-way self-locking motor for a height-adjustable desk according to claim 6, characterized in that: The oil-impregnated bearing (17) is ball-jointed with the rear cover (2), and a gap is formed between the oil-impregnated bearing (17) and the bottom surface of the mounting cavity (16), with the friction plate (6) located in the gap; an exhaust groove (19) is provided on the side wall of the mounting cavity (16), and one end of the exhaust groove (19) extends to the bottom surface of the mounting cavity (16).

8. The one-way self-locking motor for a height-adjustable desk according to claim 4, characterized in that: The screw groove rotates in the opposite direction, the friction plate (6) is located at the front end of the rotating shaft (5), and the bracket (9) is provided with a blind hole (20) to accommodate the friction plate (6), and the front end of the rotating shaft (5) extends into the blind hole (20).

9. The one-way self-locking motor for a height-adjustable desk according to claim 8, characterized in that: A first ball bearing (18) is provided between the front cover (1) and the rotating shaft (5), and a second ball bearing (21) is provided between the rear cover (2) and the rotating shaft (5).

10. The one-way self-locking motor for a height-adjustable desk according to any one of claims 1 to 9, characterized in that: An annular drive plate (22) is fixed on the inner side of the front cover (1), and the rotating shaft (5) passes through the drive plate (22). The drive plate (22) is provided with a brushless motor drive circuit and a Hall integrated circuit. The brushless motor drive circuit is connected to the coil (3).

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