Bidirectional self-locking motor for lifting table

Abstract

The invention discloses a bidirectional self-locking motor for a lifting table, and the motor comprises a front cover and a rear cover, a stator is arranged between the front cover and the rear cover, a plurality of coils which are distributed in the circumferential direction are arranged in the stator, a rotor is arranged in the stator, a plurality of permanent magnets are arranged on the outer side of the rotor, a rotating shaft is arranged on the axis of the rotor, and a first ball bearing is arranged between the rotating shaft and the rear cover. A spring washer and a friction plate are sequentially arranged on the rear side of the first ball bearing, a screw connected with the rear cover is arranged on the rear side of the friction plate, the front end of the rotating shaft extends out of the front cover and is provided with a spiral groove to form a worm, and a worm gear is arranged on one side of the worm, connected with the front cover through a support and rotationally connected with the support. The friction plate is tightly jacked by the screw, so that the spring washer is simultaneously contacted with the inner and outer rings of the first ball bearing, the rolling resistance of the first ball bearing is increased, and bidirectional self-locking of the motor is realized. The device has the advantages of being convenient to install, low in failure rate and low in noise and having a bidirectional self-locking function.

Description

Technical Field

[0001] The invention belongs to the field of motors for lifting tables, and in particular relates to a bidirectional self-locking motor for lifting tables. Background Art

[0002] The lifting power of a lift table comes from a motor. Currently, all motors used in lift tables on the market are brushed motors. Their structure consists of a brushed motor body, where coils are fixed to a rotor and permanent magnets are fixed to a stator. A worm is mounted on the motor's output end, and a bracket is mounted on the motor's outer shell. A worm gear rotates on the bracket, which mates with the worm. The motor drives the worm, which in turn drives the worm gear. The worm's rotational force is converted into vertical force through another mechanism, causing the lift table to rise or fall. Customers use the controller on the lift table to activate the motor and control the lift table's travel.

[0003] In practice, it has been found that in existing motors, due to their compact structure, the motor drive plate is external, which brings inconvenience to the installation of the motor; since there is brush friction noise during the operation of the brush motor, the noise is generally relatively high, about 56db; in order to increase the lifting speed of the lifting seat, the helix angle of the worm is relatively large, resulting in the inability to achieve self-locking between the worm and the worm wheel, and the friction between the worm and the worm wheel is relatively small. When the load on the desktop is large, relative movement will still occur between the worm and the worm wheel, causing the height of the lifting table to be reduced due to unintended human factors, changing the set height for use, resulting in poor use effect. In addition, in some cases, when moving the lifting table, since the worm and the worm wheel cannot self-lock, if the lifting part of the lifting seat is on the table top of the lifting table, movement will also occur between the worm and the worm wheel, causing the height of the lifting table to increase due to unintended human factors, and will also change the set height for use, resulting in poor use effect. Summary of the Invention

[0004] The present invention aims to provide a bidirectional self-locking motor for a lifting table, which has the advantages of easy installation, low failure rate, low noise and bidirectional self-locking function.

[0005] The technical solution of the present invention: A bidirectional self-locking motor for a lifting table includes a front cover and a rear cover, a stator is provided between the front cover and the rear cover, a plurality of circumferentially distributed coils are provided in the stator, a rotor is provided inside the stator, a plurality of permanent magnets are provided on the outside of the rotor, a rotating shaft is provided on the axis of the rotor, a first ball bearing is provided between the rotating shaft and the rear cover, a spring washer and a friction plate are provided in sequence on the rear side of the first ball bearing, a screw for connecting to the rear cover is provided on the rear side of the friction plate, a front end of the rotating shaft extends out of the front cover and a screw groove is provided 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, and the worm wheel is rotatably connected to the bracket; the friction plate is tightened by the screw so that the spring washer contacts the inner and outer rings of the first ball bearing at the same time, thereby increasing the rolling resistance of the first ball bearing and realizing bidirectional self-locking of the motor.

[0006] In the aforementioned bidirectional self-locking motor for the lifting table, the stator includes a plurality of stacked first steel sheets, at least two channels are provided on the outside of the stator, screws are provided in the channels, and the screws pass through the rear cover and the channels in sequence and then connect to the front cover.

[0007] In the aforementioned bidirectional self-locking motor for a lifting table, the rotor includes a plurality of second steel sheets stacked together and tightly passed through by the rotating shaft. A plurality of through slots are provided on the outer circumference of the rotor, and permanent magnets are provided in the through slots.

[0008] In the aforementioned bidirectional self-locking motor for a lifting table, the inner hole diameter of the stator is 18-22 mm, and a plurality of wire grooves are provided on the inner hole wall of the stator. Ribs are formed between adjacent wire grooves, and the coils are wound on the corresponding ribs.

[0009] In the aforementioned bidirectional self-locking motor for the lifting table, the outer diameter of the rotor is 1.5-3.5 mm smaller than the inner hole diameter of the stator. A plurality of permanent magnets are provided on the outer peripheral surface of the rotor. The outer peripheral surface of the permanent magnet is composed of a bottom surface, a top surface and two closed 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 width of the bottom surface is 5.0-5.4 mm, the angle between the two side surfaces is 40-50°, the middle part of the top surface protrudes outward, the radius of the top surface is 5.5-7.2 mm, and the distance between the permanent magnet and the stator is 0.3-0.9 mm.

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

[0011] The outer diameter of the rotor is 17.5 mm, and eight permanent magnets are provided on the outer circumference of the rotor. The bottom width is 5.2 mm, the angle between the two side surfaces is 45 degrees, the radius of the top surface is 6.0-6.7 mm, the thickest part of the permanent magnet is 1.8 mm, and the distance between the permanent magnet and the stator is 0.6 mm.

[0012] In the aforementioned bidirectional self-locking motor for the lifting table, the middle part of the rear cover protrudes outward to form a mounting cavity, a first ball bearing is provided in the mounting cavity, the rear end of the rotating shaft is inserted into the first ball bearing, and a second ball bearing is provided between the front cover and the rotating shaft.

[0013] In the aforementioned bidirectional self-locking motor for the lifting table, an annular drive plate is fixed on the inner side of the front cover, the rotating shaft passes through the drive plate, and the drive plate is provided with a brushless motor drive circuit and a Hall integrated circuit, and the brushless motor drive circuit is connected to the coil.

[0014] In the aforementioned bidirectional self-locking motor for the lifting table, bidirectional self-locking of the motor is achieved and the rotational friction of the motor is reduced by changing the axial position of the screw on the back cover.

[0015] Compared with the prior art, the present invention mainly improves the existing motor as follows:

[0016] First, the change from a brushed motor to a brushless motor reduces the friction noise of the brushes. Since the brushless motor has the characteristic of large output torque, the axial dimensions of the rotor and stator of the present invention can be reduced while outputting the same 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 in the motor, reducing the installation steps of the drive ring on the lifting table, making the installation of the motor convenient. At the same time, the drive ring is better protected to avoid external collision damage and reduce the failure rate.

[0017] Second, the stator is located between the front cover and the rear cover, and the outer circumference of the stator can be aligned with the outer circumferences of the front and rear covers, which expands the radial size of the stator. On the premise of keeping the output torque of the motor unchanged, the axial size of the stator and the rotor can be further shortened, leaving more space inside the motor, making it easier to install the drive ring and having better heat dissipation performance. At the same time, the installed drive ring can be farther away from the rotor, reducing heat radiation and further reducing the failure rate of the motor.

[0018] Third, a spring washer and a friction plate are set on the bearing side of the rear cover. The friction plate is tightened by screws so that the spring washer contacts the inner and outer rings of the bearing at the same time, increasing the rotational resistance of the rotating shaft. The rotational resistance is superimposed on the friction between the worm gear to achieve two-way self-locking of the motor, preventing the lifting table from changing height under the action of external force, and improving the use effect.

[0019] Fourth, the specific cross-sectional shape of the permanent magnet is adopted to optimize the deformation of the airflow between the stator and the rotor, which has a better effect on reducing noise. When tested under the conditions of background noise of 36dB and a distance of 30cm, the motor noise is reduced to 45.4dB, with obvious noise reduction effect.

[0020] In summary, the present invention has the advantages of easy installation, low failure rate, low noise and bidirectional self-locking function. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural diagram of Example 1.

[0022] Figure 2 Schematic diagram of the wiring of the coil in Example 1.

[0023] Figure 3 It is a cross-sectional diagram of the rotor.

[0024] Figure 4 Schematic diagram of the cross-sectional dimensions of the permanent magnet of Example 1.

[0025] Figure 5 It is a schematic diagram of the cross-sectional dimensions of the permanent magnet of Example 5.

[0026] The marks in the accompanying drawings are: 1-front cover, 2-rear cover, 3-stator, 4-coil, 5-rotor, 6-permanent magnet, 7-rotating shaft, 8-first ball bearing, 9-spring washer, 10-friction plate, 11-screw, 12-worm, 13-worm wheel, 14-bracket, 15-screw, 16-rib plate, 17-mounting cavity, 18-second ball bearing, 19-drive plate. DETAILED DESCRIPTION

[0027] The present invention will be further described below with reference to the accompanying drawings and examples, but they are not intended to limit the present invention.

[0028] Example 1: Bidirectional self-locking motor for lifting table, such as Figures 1 to 4 As shown, it includes a front cover 1 and a rear cover 2 , a stator 3 is provided between the front cover 1 and the rear cover 2 , and six circumferentially distributed coils 4 are provided in the stator 3 .

[0029] A rotor 5 is provided inside the stator 3, and eight circumferentially distributed permanent magnets 6 are provided on the outside of the rotor 5. A rotating shaft 7 is provided on the axis of the rotor 5, and a first ball bearing 8 is provided between the rotating shaft 7 and the rear cover 2. The rear side of the first ball bearing 8 is provided with a spring washer 9 and a friction plate 10 (made of iron-based powder alloy) in sequence. The spring washer 9 has a trumpet-shaped cross-section, and the rear side of the friction plate 10 is provided with a screw 11 connected to the rear cover 2. The front end of the rotating shaft 7 extends out of the front cover 1 and is provided with a screw groove to form a worm 12. A worm gear 13 is provided on one side of the worm 12. The worm gear 13 is connected to the front cover 1 through a bracket 14, and the worm gear 13 is rotatably connected to the bracket 14.

[0030] The stator 3 includes a plurality of stacked first steel sheets, each of which is made of silicon steel. At least two channels are provided on the outside of the stator 3. The channels can be through holes or slots connected to the outer peripheral surface of the stator 3. A screw 15 is provided in the channel, which passes through the rear cover 2 and the channel in sequence and then connects to the front cover 1.

[0031] The rotor 5 includes a plurality of second steel sheets stacked together and tightly passed through by the rotating shaft 7. The second steel sheets are made of silicon steel. A plurality of through slots are provided on the outer peripheral surface of the rotor 5, and permanent magnets 6 are provided in the through slots.

[0032] The inner hole diameter of the stator 3 is 20 mm. Six wire slots are provided on the inner hole wall of the stator 3 . Ribs 16 are formed between adjacent wire slots, and the coils 4 are wound on the corresponding ribs 16 .

[0033] The outer diameter of the rotor 5 is 17.5 mm. The outer circumference of the permanent magnet 4 consists of a bottom surface, a top surface, and two closed side surfaces. The bottom surface and both side surfaces are flat. 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 by the bottom surface, and the outer ends of the two side surfaces are connected by the top surface. The bottom surface is 5.2 mm wide, the angle between the two side surfaces is 45°, the middle portion of the top surface is convex outward, and the radius of the top surface is 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.

[0034] The center of the rear cover 2 bulges outward to form a mounting cavity 17. A first ball bearing 8 is mounted in the mounting cavity 17. The rear end of the rotating shaft 7 is inserted into the first ball bearing 8. A second ball bearing 18 is positioned between the front cover 1 and the rotating shaft 7. Circlips are attached to the front of the first ball bearing 8 and to the front and rear sides of the second ball bearing 18, respectively, to restrict axial movement of the rotating shaft 5.

[0035] An annular drive plate 22 is fixed to the inner side of the front cover 1, and the rotating shaft 5 passes through the drive plate 22. A brushless motor drive circuit (existing circuit) and a Hall integrated circuit (existing circuit) are provided on the drive plate 22, and the brushless motor drive circuit is connected to the coil 3. The motor in Example 1 is a brushless motor, which is driven by a brushless motor drive circuit. The Hall integrated circuit is used to detect the speed and direction of the motor, which can be fed back to the original controller of the lifting seat. The controller can know the operating status of the motor, and then know the lifting stroke of the lifting seat, and stop the motor after reaching the set height. The method for detecting the direction and speed of the motor by the Hall integrated circuit refers to the patent application document with application number 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 extended out of the front cover 1 to be connected to the controller of the lifting table.

[0036] When screw 11 tightens friction plate 10, spring washer 9 simultaneously contacts the inner and outer races of first ball bearing 8, establishing a friction connection between the inner and outer races of first ball bearing 8. The tighter screw 11 is, the greater the friction, making it harder for first ball bearing 8 to roll, and shaft 7 to rotate. The rotational resistance of shaft 7 combined with the self-locking force of the worm gear achieves bidirectional self-locking of the motor. While ensuring the motor's self-locking function, avoid over-tightening screw 11 to prevent excessive rolling resistance of first ball bearing 8. The degree of tightening can be determined through simple experiments.

[0037] The differences between Example 1 and the existing motor are mainly as follows:

[0038] First, change the brushed motor to a brushless motor.

[0039] Second, the driving plate 22 is built into the motor.

[0040] Third, spring washers and friction plates are set to achieve bidirectional self-locking of the motor.

[0041] Embodiment 2: Compared with embodiment 1, the driving plate 22 is arranged outside the motor.

[0042] Example 3: Compared with Example 1, the Hall integrated circuit on the driving board 22 is removed. At this time, the controller on the lifting table can be removed, and a switch is used to control the motor starting state and forward and reverse rotation state.

[0043] 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 IC are both connected to the XH2.54 (1x5p) socket. This socket is small 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. A wiring harness connects the X4.2 (2x3p) socket and the XH2.54 (1x5p) socket.

[0044] MX4.2 (2x3p) is used in the controllers of many lifting tables, and it has not yet been used in conjunction with XH2.54. The main consideration is that the current passing through it may be too large. This application uses it in conjunction with other devices because the motor of this application is a brushless motor. The interface of the brushless motor is used as the input interface, while the brushed motor is used as the output interface. For example, if the input current is 29V 2A and the output voltage is only 14.5V, 4A needs to be output. The output voltage will vary with the motor speed, and the input voltage is fixed. When used on a brushed motor, the XH2.54 current of 4A is too large, while when used on a brushless motor, the XH2.54 current of 2A will not be too large. By using XH2.54, the interface position on the driver board 22 is reduced to better meet the needs of small spaces.

[0045] The power line (29V) and 5V, Tx, and Rx are connected by GND to separate the power and signal, thus improving anti-interference and EMC performance.

[0046] Example 4 mainly solves the problem of how to install the driver board 22 inside the motor when the motor size is basically the same as the existing motor size and the output torque is also basically the same. The driver board 22 is integrated inside the motor to better protect the driver board 22 and reduce the difficulty of motor installation. The first thing is to reduce the volume of the driver board 22, which can be achieved by using an XH2.54 socket, external power supply, using a chip with pre-drive on the brushless motor drive circuit to drive the motor, using a single resistor sampling algorithm, and adopting non-sensing control methods. Considering the heat dissipation in a closed environment, the driving power supply and 5VMCU power supply contained in the driver board 22 can be powered by external power, and the MOS tube uses a large volume (TO-252) to reduce loss and increase heat dissipation.

[0047] Example 5: Compared with Example 1, the cross-sectional dimensions of the permanent magnet are changed to Figure 5 As shown, the radius of the top surface is changed to 9.35 mm.

[0048] Noise tests were conducted on Examples 1 and 5 under the following conditions: an ambient noise level of 36dB and a distance of 30cm from the motor. The noise level of Example 5 was 50.6dB, while that of Example 1 was 45.4dB. Both were quieter than existing motors, with Example 1 being superior.

[0049] In other comparative experiments, one or more cross-sectional dimensions of the permanent magnet were adjusted multiple times. The final test found that Example 1 had the best noise reduction effect, and the factor that had the greatest impact on noise was the top surface radius. For example, when the top surface radius was changed to 20mm, 8.5mm, 7.2mm, and 5.5mm, the noise levels were 50.1db, 48.4db, and 48.2db, respectively. Excluding the noise reduction caused by switching from a brushed motor to a brushless motor, the top surface radius should actually be between 5.5-7.2mm to further reduce noise due to the improvement in the top surface radius.

[0050] In the description of the present invention, it should be understood that the terms "up", "down", "front", "back", "left", "right", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

Claims

1. Bidirectional self-locking motor for lifting table, characterized by: The invention comprises a front cover (1) and a rear cover (2), wherein a stator (3) is provided between the front cover (1) and the rear cover (2), a plurality of circumferentially distributed coils (4) are provided in the stator (3), a rotor (5) is provided inside the stator (3), a plurality of permanent magnets (6) are provided on the outer side of the rotor (5), a rotating shaft (7) is provided on the axis of the rotor (5), a first ball bearing (8) is provided between the rotating shaft (7) and the rear cover (2), a spring washer (9) and a friction plate (10) are provided on the rear side of the first ball bearing (8), and a friction plate (10) is provided on the rear side of the friction plate (10). A screw (11) is provided for connecting the rear cover (2); the front end of the rotating shaft (7) extends out of the front cover (1) and is provided with a screw groove to form a worm (12); a worm wheel (13) is provided on one side of the worm (12); the worm wheel (13) is connected to the front cover (1) through a bracket (14); the worm wheel (13) and the bracket (14) are rotatably connected; the friction plate (10) is pressed tightly by the screw (11), so that the spring washer (9) contacts the inner and outer rings of the first ball bearing (8) at the same time, thereby increasing the rolling resistance of the first ball bearing (8) and realizing bidirectional self-locking of the motor.

2. The bidirectional self-locking motor for a lifting table according to claim 1, characterized in that: The stator (3) comprises a plurality of stacked first steel sheets. At least two channels are provided on the outside of the stator (3). Screws (15) are provided in the channels. The screws (15) pass through the rear cover (2) and the channels in sequence and are then connected to the front cover (1).

3. The bidirectional self-locking motor for a lifting table according to claim 2, characterized in that: The rotor (5) comprises a plurality of second steel sheets stacked together and tightly fitted through by a rotating shaft (7). A plurality of through slots are provided on the outer peripheral surface of the rotor (5), and permanent magnets (6) are provided in the through slots.

4. The bidirectional self-locking motor for a lifting table according to claim 3, characterized in that: The inner hole diameter of the stator (3) is 18-22 mm. A plurality of wire slots are provided on the inner hole wall of the stator (3). Ribs (16) are formed between adjacent wire slots. The coil (4) is wound on the corresponding ribs (16).

5. The bidirectional self-locking motor for a lifting table according to claim 4, characterized in that: The outer diameter of the rotor (5) is 1.5-3.5 mm smaller than the inner diameter of the stator (3). A plurality of permanent magnets (6) are provided on the outer peripheral surface of the rotor (5). The outer peripheral surface of the permanent magnet (6) is composed of a bottom surface, a top surface and two closed side surfaces. The bottom surface and the two side surfaces are both planes. The bottom surface is located inside the rotor (5), and the top surface is located outside the rotor (5). 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 width of the bottom surface is 5.0-5.4 mm, the angle between the two side surfaces is 40-50 degrees, the middle part of the top surface is convex outward, the radius of the top surface is 5.5-7.2 mm, and the distance between the permanent magnet (6) and the stator (3) is 0.3-0.9 mm.

6. The bidirectional self-locking motor for a lifting table according to claim 5, characterized in that: There are six coils (4), the inner hole diameter of the stator (3) is 20 mm, and six wire slots are provided on the inner hole wall of the stator (3); The outer diameter of the rotor (5) is 17.5 mm, eight permanent magnets (6) are provided on the outer peripheral surface of the rotor (5), the bottom surface width is 5.2 mm, the angle between the two side surfaces is 45 degrees, the radius of the top surface is 6.0-6.7 mm, the thickest part of the permanent magnet (6) is 1.8 mm, and the distance between the permanent magnet (6) and the stator (3) is 0.6 mm.

7. The bidirectional self-locking motor for a lifting table according to claim 5, characterized in that: The middle portion of the rear cover (2) protrudes outward to form a mounting cavity (17), a first ball bearing (8) is provided in the mounting cavity (17), the rear end of the rotating shaft (7) is inserted into the first ball bearing (8), and a second ball bearing (18) is provided between the front cover (1) and the rotating shaft (7).

8. The bidirectional self-locking motor for a lifting table according to any one of claims 1 to 7, characterized in that: An annular drive plate (19) is fixed on the inner side of the front cover (1), and the rotating shaft (7) passes through the drive plate (19). A brushless motor drive circuit and a Hall integrated circuit are provided on the drive plate (19), and the brushless motor drive circuit is connected to the coil (4).

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