阅读说明：本技术 用于自动折叠屏手机的折叠驱动装置 (Folding driving device for automatic folding screen mobile phone ) 是由 蔡慧玲 邬均文 朱卫东 黄超 白剑 贺景松 于 2019-09-23 设计创作，主要内容包括：本发明涉及用于自动折叠屏手机的折叠驱动装置,具有电机、减速箱、以及用于驱动手机屏幕折叠转轴转动的输出丝杆；电机的输出轴与减速箱的输入端传动连接；还包括用于将减速箱的输出端的扭矩传输至输出丝杆,并在扭矩过载时可让减速箱的输出端与输出丝杆发生周向打滑的过载保护装置。本发明能够在扭矩过载时通过过载保护装置实现打滑,从而尽量避免因扭矩过载而导致减速箱齿轮受损和折叠故障的问题。(The invention relates to a folding driving device for an automatic folding screen mobile phone, which is provided with a motor, a reduction box and an output screw rod for driving a folding rotating shaft of a mobile phone screen to rotate; the output shaft of the motor is in transmission connection with the input end of the reduction gearbox; the overload protection device is used for transmitting the torque of the output end of the reduction gearbox to the output screw rod and enabling the output end of the reduction gearbox and the output screw rod to slip circumferentially when the torque is overloaded. The invention can realize slipping through the overload protection device when the torque is overloaded, thereby avoiding the problems of gear damage and folding failure of the reduction gearbox caused by the overload of the torque as much as possible.)

1. The folding driving device for the automatic folding screen mobile phone is provided with a motor (1), a reduction box (2) and an output screw rod (3) for driving a folding rotating shaft of a mobile phone screen to rotate; the output shaft of the motor (1) is in transmission connection with the input end of the reduction gearbox (2); the method is characterized in that: the overload protection device is characterized by further comprising an overload protection device (4) which is used for transmitting the torque of the output end of the reduction gearbox (2) to the output screw rod (3) and can enable the output end of the reduction gearbox (2) and the output screw rod (3) to slip circumferentially when the torque is overloaded.

2. A folding drive for an automatic folding screen handset as claimed in claim 1, wherein: the overload protection device (4) comprises a first transmission part and a second transmission part; the first transmission part is in transmission connection with the output end of the reduction gearbox (2), and the second transmission part is in transmission connection with the input end of the output screw rod (3); the first output part is in transmission connection with the second transmission part, and the first transmission part and the second transmission part slip circumferentially when the torque is overloaded.

3. A folding drive for an automatic folding screen handset as claimed in claim 2, wherein: the first transmission part is a first cylinder (41), a mounting cavity coaxial with the first cylinder (41) is arranged on the first cylinder (41), and a connecting end coaxial with the axis of the first cylinder and in circumferential transmission fit with the output end of the reduction gearbox (2) is arranged at one end of the outer part of the first cylinder (41); a plurality of transmission grooves (411) are equidistantly distributed on the circumferential inner wall of the mounting cavity along the circumference of the first cylinder axis, and the transmission grooves (411) extend along the first cylinder axis;

the second transmission part comprises a central body (42), and a matching hole which can be matched with the output screw rod (3) in a circumferential transmission manner is formed in the central body (42); at least two arc-shaped cantilevers (43) are arranged on the central body (42), the arc-shaped cantilevers (43) are coaxially arranged with the first cylinder body (41), and a buffer area for the arc-shaped cantilevers (43) to be close to the central body (42) is formed between the arc-shaped cantilevers (43) and the central body (42); the arc cantilevers (43) are provided with transmission convex strips (431) which are matched with the transmission grooves (411) for transmission;

the first cylinder (41) is in circumferential transmission fit with the output end of the reduction gearbox (2) through the connecting end; the second transmission part is embedded in the mounting cavity of the first cylinder (41), and the transmission convex strip (431) is matched with the transmission groove (411) for transmission; the input end of the output screw rod (3) is matched with the matching hole of the central body (42) in a circumferential transmission way.

4. A folding drive for an automatic folding screen handset as claimed in claim 2, wherein: the overload protection device (4) comprises a first transmission part, a second transmission part and an elastic element (44) which are arranged in a shell;

the first transmission part is a second cylinder (45), a mounting cavity coaxial with the second cylinder (45) is arranged on the second cylinder (45), and a connecting end coaxial with the axis of the second cylinder and in circumferential transmission fit with the output end of the reduction gearbox (2) is arranged at one end of the outer part of the second cylinder (45); a plurality of first convex teeth (451) are distributed on the bottom surface of the mounting cavity at equal intervals along the circumference of the axis of the second cylinder;

the second transmission part comprises a connecting rod (46), one end of the connecting rod (46) is provided with a transmission connecting hole which can be inserted by the input end of the output screw rod (3) and forms circumferential transmission fit with the input end, the other end of the connecting rod (46) is provided with a connector (461), and a plurality of second convex teeth (461-1) are distributed on the plane of the bottom surface of the mounting cavity, which is just opposite to the connector (461), along the circumference of the axis of the second cylinder at equal intervals;

the elastic element (44) is sleeved on the connecting rod (46), and two ends of the elastic element (44) respectively act on the connecting head (461) and the shell;

the connecting end of the first transmission part is in circumferential transmission fit with the output end of the reduction gearbox (2); the second transmission part and the elastic element (44) are arranged in the mounting cavity; the second convex tooth (461-1) of the second transmission part is meshed with the first convex tooth (451) of the first transmission part and forms circumferential transmission fit; the input end of the output screw rod (3) is in circumferential transmission fit with the transmission connecting hole.

5. A folding drive for an automatic folding screen handset as claimed in claim 1, wherein: the overload protection device (4) comprises a coupler, and two ends of the coupler are respectively in circumferential transmission fit with the output end of the reduction gearbox (2) and the input end of the output screw rod (3); the coupler and the output end of the reduction box (2) form an interference fit with static friction force, or form an interference fit with the input end of the output screw rod (3) with static friction force.

6. The folding drive device for an automatic folding screen mobile phone according to claim 5, characterized in that: the coupling comprises a coupling cylinder (47) and a plurality of friction plates (48); the connecting shaft is characterized in that a mounting cavity is formed in the connecting shaft cylinder (47), a plurality of clamping strips (471) are distributed on the circumferential inner wall of the mounting cavity along the circumference of the axis of the connecting shaft cylinder, and the clamping strips (471) extend along the axis direction of the connecting shaft cylinder; the coupling cylinder (47) is provided with a transmission connecting hole which is in circumferential transmission fit with the input end of the output screw rod (3);

the center of the friction plate (48) is provided with a mounting hole in interference fit with the output end of the reduction gearbox (2); a plurality of clamping grooves (481) matched with the clamping strips (471) to form circumferential transmission fit are formed in the peripheral edge of the friction plate (48);

the coupling cylinder (47) is in circumferential transmission fit with the input end of the output screw rod (3) through the transmission connecting hole; a plurality of friction plates (48) are stacked in the mounting cavity of the coupling cylinder (47) along the axial direction of the coupling cylinder; the mounting holes of the friction plates (48) are in interference fit with the output end of the reduction gearbox (2), and when the torque exceeds the static friction force of the friction plates (48) and the output end of the reduction gearbox (2), the friction plates (48) and the output end of the reduction gearbox (2) slip.

7. The folding drive device for an automatic folding screen mobile phone according to claim 5, characterized in that: the coupler comprises a connecting body (49), one end of the connecting body (49) is in circumferential transmission fit with the output end of the reduction gearbox (2), and the other end of the connecting body is provided with a plurality of clamping jaws (491) which are distributed along the circumference of the axis of the connecting body; an installation area for inserting the input end of the output screw rod (3) is formed between the clamping claws (491); the circumferential surface of the connecting body (49) is provided with an external thread;

the coupler also comprises a fastening nut (5) sleeved outside the coupler; a through cavity is arranged in the fastening nut (5), and the through cavity is provided with a connecting cavity and a pressing cavity which are communicated; the inner wall of the connecting cavity is provided with an internal thread which can be matched with the external thread of the connecting body (49); the pressing cavity is in a cone frustum shape and gradually reduces towards the direction far away from the connecting cavity; the inner wall of the compaction cavity acts on the clamping jaw (491), and the clamping jaw (491) is urged to form interference fit with the output end of the output screw rod (3) along with the approach of the compaction cavity to the connecting body (49); when the torque exceeds the static friction force between the claw (491) and the input end of the output screw rod (3), the claw (491) and the input end of the output screw rod (3) slip.

Technical Field

The invention relates to a part of a mobile phone, in particular to a folding driving device for an automatic folding screen mobile phone.

Background

Mobile phones have become indispensable electronic devices in daily life. With the continuous generation and innovation of technologies, people need to upgrade mobile phones. Among them, the innovation of the screen of the mobile phone is always one of the directions that people continuously seek breakthrough. People all want to have a larger screen when using the mobile phone, thereby improving the use experience. However, the too large screen will cause the volume of the mobile phone to be increased, and on the contrary, the mobile phone is inconvenient to use. To address this problem, with the advent of flexible screens, automatic folding screen handsets have emerged. The mobile phone with the automatically folded screen can meet the requirements of a large screen and a small size through folding, so that the mobile phone is popular with people.

The middle folding rotating shaft of the existing automatic folding screen mobile phone is of a mechanical structure, and after the folding screen device is driven by a motor, the output rotating speed of the motor is regulated by a gear box, so that the speed is stable and stable. Therefore, when the human body is not operated normally (i.e. receives a large reverse force), the internal gear rotates at a high speed due to the speed ratio relationship inside the gearbox, and the internal gear of the gearbox is easily damaged. Meanwhile, the internal motor has certain self-locking force, so that when the internal motor is stressed reversely, the resistance is higher, and the gear is easily damaged due to overlarge reverse external force. The existing folding scheme has the following defects when the received reverse force is too large (namely, the torque is overloaded):

1) the gear is damaged when the reverse stress is too large;

2) the damaged gear is locked in the mechanism, and the folding and closing functions cannot be realized;

3) the maintenance is inconvenient, the cost is high, and the whole electric drive system needs to be replaced;

4) the service life is reduced after improper operation.

Disclosure of Invention

The invention aims to provide a folding driving device for an automatic folding screen mobile phone, which can drive an output screw rod for driving a rotating shaft of the folding screen mobile phone to rotate and an output end of a reduction gearbox to slip when a large reverse outward force is applied, so that the function of overload protection is achieved, the damage degree of gears in the reduction gearbox is reduced to the maximum extent, and the problems of jamming and folding faults are effectively avoided.

The technical scheme for realizing the purpose of the invention is as follows: the invention is provided with a motor, a reduction box and an output screw rod for driving a folding rotating shaft of a mobile phone screen to rotate; the output shaft of the motor is in transmission connection with the input end of the reduction gearbox; the method is characterized in that: the overload protection device is used for transmitting the torque of the output end of the reduction gearbox to the output screw rod and enabling the output end of the reduction gearbox and the output screw rod to slip circumferentially when the torque is overloaded.

The overload protection device comprises a first transmission part and a second transmission part; the first transmission part is in transmission connection with the output end of the reduction gearbox, and the second transmission part is in transmission connection with the input end of the output screw rod; the first output part is in transmission connection with the second transmission part, and the first transmission part and the second transmission part slip circumferentially when the torque is overloaded.

As an optimized design, the first transmission part is a first cylinder body, an installation cavity coaxial with the first cylinder body is arranged on the first cylinder body, and a connecting end coaxial with the axis of the first cylinder body and in circumferential transmission fit with the output end of the reduction gearbox is arranged at one end of the outer part of the first cylinder body; a plurality of transmission grooves are equidistantly distributed on the circumferential inner wall of the mounting cavity along the circumference of the first cylinder axis, and the transmission grooves extend along the first cylinder axis;

the second transmission part comprises a central body, and a matching hole which can be matched with the output screw rod in a circumferential transmission way is formed in the central body; the central body is provided with at least two arc cantilevers, the arc cantilevers and the first cylinder body are coaxially arranged, and a buffer area for the arc cantilevers to be close to the central body is formed between the arc cantilevers and the central body; the arc cantilevers are provided with transmission convex strips which are matched with the transmission grooves for transmission; the second transmission part can be designed into a rubber part, and the arc-shaped cantilever can better realize slipping through the natural elasticity of the rubber part;

the first cylinder is in circumferential transmission fit with the output end of the reduction gearbox through the connecting end; the second transmission part is embedded in the mounting cavity of the first cylinder body, and the transmission convex strip is in matched transmission with the transmission groove; the input end of the output screw rod is matched with the matching hole of the central body in a circumferential transmission way.

As a variant design, the overload protection device comprises a first transmission part, a second transmission part and an elastic element which are arranged in a shell;

the first transmission part is a second cylinder body, a mounting cavity coaxial with the second cylinder body is arranged on the second cylinder body, and a connecting end coaxial with the axis of the second cylinder body and in circumferential transmission fit with the output end of the reduction gearbox is arranged at one end of the outer part of the second cylinder body; a plurality of first convex teeth are distributed on the bottom surface of the mounting cavity at equal intervals along the circumference of the axis of the second cylinder;

the second transmission part comprises a connecting rod, one end of the connecting rod is provided with a transmission connecting hole which can be inserted by the input end of the output screw rod and forms circumferential transmission fit with the input end of the output screw rod, the other end of the connecting rod is provided with a connector, and a plurality of second convex teeth are distributed on the plane of the connector, which is over against the bottom surface of the installation cavity, along the circumference of the axis of the second cylinder at equal intervals;

the elastic element is sleeved on the connecting rod, and two ends of the elastic element respectively act on the connector and the shell; the elastic element may be a compression spring, a rubber sleeve, or the like.

The connecting end of the first transmission part is in circumferential transmission fit with the output end of the reduction gearbox; the second transmission part and the elastic element are arranged in the mounting cavity; the second convex teeth of the second transmission part are meshed with the first convex teeth of the first transmission part to form circumferential transmission fit; the input end of the output screw rod is in circumferential transmission fit with the transmission connecting hole.

As a deformation design, the overload protection device comprises a coupler, and two ends of the coupler are respectively in circumferential transmission fit with the output end of the reduction gearbox and the input end of the output screw rod; the coupler and the output end of the reduction box form interference fit with static friction force, or form interference fit with the input end of the output screw rod with static friction force.

As a variant design, the coupling comprises a coupling cylinder and a plurality of friction plates; the shaft coupling barrel is provided with an installation cavity, a plurality of clamping strips are distributed on the circumferential inner wall of the installation cavity along the circumference of the axis of the shaft coupling barrel, and the clamping strips extend along the axis direction of the shaft coupling barrel; the coupling cylinder is provided with a transmission connecting hole which is in circumferential transmission fit with the input end of the output screw rod;

the center of the friction plate is provided with a mounting hole in interference fit with the output end of the reduction gearbox; a plurality of clamping grooves matched with the clamping strips to form circumferential transmission matching are formed in the peripheral edge of the friction plate;

the coupling cylinder is in circumferential transmission fit with the input end of the output screw rod through the transmission connecting hole; a plurality of friction plates are stacked in the mounting cavity of the coupling cylinder along the axial direction of the coupling cylinder; the mounting holes of the friction plates are in interference fit with the output end of the reduction gearbox, and the friction plates and the output end of the reduction gearbox slip when the torque exceeds the static friction force of the friction plates and the output end of the reduction gearbox.

As a deformation design, the coupler comprises a connecting body, one end of the connecting body is in circumferential transmission fit with the output end of the reduction gearbox, and the other end of the connecting body is provided with a plurality of clamping jaws which are distributed along the circumference of the axis of the connecting body; an installation area for inserting the input end of the output screw rod is formed between the clamping jaws; the circumferential surface of the connecting body is provided with external threads;

the fastening nut is sleeved outside the coupler; a through cavity is arranged in the fastening nut and is provided with a connecting cavity and a pressing cavity which are communicated; the inner wall of the connecting cavity is provided with an internal thread which can be matched with the external thread of the connecting body; the pressing cavity is in a cone frustum shape and gradually reduces towards the direction far away from the connecting cavity; the inner wall of the compaction cavity acts on the clamping jaw and causes the clamping jaw to form interference fit with the output end of the output screw rod along with the approach of the compaction cavity to the connector; and when the torque exceeds the static friction force between the clamping jaw and the input end of the output screw rod, the clamping jaw and the input end of the output screw rod slip.

The invention has the positive effects that: (1) the invention can realize slipping through the overload protection device when the torque is overloaded, thereby avoiding the problems of gear damage and folding failure of the reduction gearbox caused by the overload of the torque as much as possible.

(2) According to the invention, through the transmission fit of the arc-shaped cantilever and the cylinder body, the circumferential transmission fit can be ensured, and the second transmission part and the first transmission part can slip through the deformation of the arc-shaped cantilever when the torque is overloaded, so that the overload protection effect is realized.

(3) According to the invention, through the elasticity of the elastic element, the circumferential transmission effect of the first transmission part and the second transmission part can be effectively ensured when the torque is not overloaded, and the first transmission part and the second transmission part can be slipped when the torque is overloaded, so that the overload protection effect is realized.

(4) The invention can effectively ensure the circumferential transmission matching effect when the torque is not overloaded through the friction plates, can set the torque overload value through controlling the number of the friction plates, and can send slip with the output end of the reduction box when the torque exceeds the static friction force generated by the friction plates due to improper manual operation, thereby playing the role of overload protection.

(5) The invention can effectively ensure the circumferential transmission effect through the gripping force of the jaws on the output screw rod, and can set the torque overload value by adjusting the fastening nut.

Drawings

In order that the present disclosure may be more readily and clearly understood, reference is now made to the following detailed description of the present disclosure taken in conjunction with the accompanying drawings, in which

FIG. 1 is a schematic structural view of example 1 of the present invention;

FIG. 2 is a sectional view of example 1 of the present invention;

fig. 3 is a schematic structural view of a first transmission unit in embodiment 1 of the present invention;

fig. 4 is a schematic structural diagram of a second transmission unit in embodiment 1 of the present invention;

FIG. 5 is a schematic structural view of example 2 of the present invention;

fig. 6 is a schematic structural view of a first transmission part in embodiment 2 of the present invention;

fig. 7 is a schematic structural diagram of a second transmission unit in embodiment 2 of the present invention;

FIG. 8 is a schematic structural view of example 3 of the present invention;

fig. 9 is a schematic structural view of a coupling cylinder in embodiment 3 of the present invention;

FIG. 10 is a schematic structural view of a friction plate in embodiment 3 of the present invention;

FIG. 11 is a schematic structural view of example 4 of the present invention;

fig. 12 is a schematic structural view of a coupling in embodiment 4 of the present invention;

fig. 13 is a schematic structural view of a fastening nut in embodiment 4 of the present invention.

Detailed Description

(example 1)

Referring to fig. 1 to 4, the invention is provided with a motor 1, a reduction box 2 and an output screw rod 3 for driving a folding rotating shaft of a mobile phone screen to rotate; the output shaft of the motor 1 is in transmission connection with the input end of the reduction box 2; the overload protection device is characterized by further comprising an overload protection device 4 which is used for transmitting the torque of the output end of the reduction gearbox 2 to the output screw rod 3 and enabling the output end of the reduction gearbox 2 and the output screw rod 3 to slip circumferentially when the torque is overloaded.

The overload protection device 4 comprises a first transmission part and a second transmission part;

the first transmission part is a first cylinder 41, an installation cavity coaxial with the first cylinder 41 is arranged on the first cylinder 41, and a connecting end coaxial with the axis of the first cylinder and in circumferential transmission fit with the output end of the reduction gearbox 2 is arranged at one end of the outer part of the first cylinder 41; a plurality of transmission grooves 411 are equidistantly distributed on the circumferential inner wall of the mounting cavity along the circumference of the first cylinder axis, and the transmission grooves 411 extend along the first cylinder axis;

the second transmission part comprises a central body 42, and a matching hole which can be matched with the output screw rod 3 in a circumferential transmission way is formed in the central body 42; at least two arc cantilevers 43 are arranged on the central body 42, the arc cantilevers 43 are coaxially arranged with the first cylinder 41, and a buffer area for the arc cantilevers 43 to approach the central body 42 is formed between the arc cantilevers 43 and the central body 42; the arc cantilevers 43 are provided with transmission convex strips 431 which are matched with the transmission grooves 411 for transmission;

the first cylinder 41 is in circumferential transmission fit with the output end of the reduction gearbox 2 through the connecting end; the second transmission part is embedded in the installation cavity of the first cylinder 41, and the transmission convex strip 431 is matched with the transmission groove 411 for transmission; the input end of the output screw 3 is in circumferential transmission fit with the matching hole of the central body 42.

The working principle of the invention is as follows:

due to the transmission matching of the transmission groove 411 and the transmission convex strip 431, the torque of the output end of the reduction gearbox 2 can be effectively transmitted to the output screw rod 3.

When the torque is overloaded due to the reverse force, the torque overcomes the elastic variable of the arc-shaped cantilever 43, so that the transmission convex strip 431 on the arc-shaped cantilever 43 is promoted to be separated from the transmission groove 411 which is matched with the current transmission groove and enter the other transmission groove 411, and the circumferential transmission is continued after the torque returns to the normal value.

(example 2)

Referring to fig. 5 to 7, the invention is provided with a motor 1, a reduction box 2 and an output screw rod 3 for driving a folding rotating shaft of a mobile phone screen to rotate; the output shaft of the motor 1 is in transmission connection with the input end of the reduction box 2; the method is characterized in that: the overload protection device is characterized by further comprising an overload protection device 4 which is used for transmitting the torque of the output end of the reduction gearbox 2 to the output screw rod 3 and enabling the output end of the reduction gearbox 2 and the output screw rod 3 to slip circumferentially when the torque is overloaded.

The overload protection device 4 comprises a first transmission part, a second transmission part and an elastic element 44 which are arranged in a shell;

the first transmission part is a second cylinder 45, a mounting cavity coaxial with the second cylinder 45 is arranged on the second cylinder 45, and a connecting end coaxial with the axis of the second cylinder and in circumferential transmission fit with the output end of the reduction gearbox 2 is arranged at one end of the outer part of the second cylinder 45; a plurality of first convex teeth 451 are distributed on the bottom surface of the mounting cavity along the circumference of the axis of the second cylinder at equal intervals;

the second transmission part comprises a connecting rod 46, one end of the connecting rod 46 is provided with a transmission connecting hole which can be inserted by the input end of the output screw rod 3 and forms circumferential transmission fit with the input end, the other end of the connecting rod 46 is provided with a connecting head 461, and a plurality of second convex teeth 461-1 are distributed on the plane of the connecting head 461, which is just opposite to the bottom surface of the installation cavity, at equal intervals along the circumference of the second cylinder axis;

the elastic element 44 is sleeved on the connecting rod 46, and two ends of the elastic element 44 respectively act on the connecting head 461 and the shell; the elastic member 44 is a rubber sleeve.

The connecting end of the first transmission part is in circumferential transmission fit with the output end of the reduction gearbox 2; the second transmission portion and the elastic member 44 are disposed in the mounting cavity; the second teeth 461-1 of the second transmission part are meshed with the first teeth 451 of the first transmission part and form circumferential transmission fit; the input end of the output screw rod 3 is in circumferential transmission fit with the transmission connecting hole.

The working principle of the invention is as follows:

under the action of the elastic element 44, the second convex tooth 461-1 of the second transmission part is meshed with the first convex tooth 451 of the first transmission part to form circumferential transmission fit, so that the torque at the output end of the reduction gearbox 2 can be effectively transmitted to the output screw rod 3.

When the torque is overloaded due to the reverse force, the torque overcomes the pressing force of the elastic element 44, so as to force the second convex tooth 461-1 to be disengaged from the first convex tooth 451 which is currently engaged with the second convex tooth, and to be engaged with other first convex teeth 451, and to reciprocate in sequence, until the torque returns to the normal value, the circumferential transmission is continued.

(example 3)

Referring to fig. 8 to 10, the invention is provided with a motor 1, a reduction box 2 and an output screw rod 3 for driving a folding rotating shaft of a mobile phone screen to rotate; the output shaft of the motor 1 is in transmission connection with the input end of the reduction box 2; the method is characterized in that: the overload protection device is characterized by further comprising an overload protection device 4 which is used for transmitting the torque of the output end of the reduction gearbox 2 to the output screw rod 3 and enabling the output end of the reduction gearbox 2 and the output screw rod 3 to slip circumferentially when the torque is overloaded.

The overload protection device 4 comprises a coupling which comprises a coupling cylinder 47 and a plurality of friction plates 48; the coupling cylinder 47 is provided with an installation cavity, a plurality of clamping strips 471 are distributed on the circumferential inner wall of the installation cavity along the circumference of the axis of the coupling cylinder, and the clamping strips 471 extend along the direction of the axis of the coupling cylinder; the coupling cylinder 47 is provided with a transmission connecting hole which is in circumferential transmission fit with the input end of the output screw rod 3;

the center of the friction plate 48 is provided with a mounting hole which is in interference fit with the output end of the reduction gearbox 2; the peripheral edge of the friction plate 48 is provided with a plurality of clamping grooves 481 which are matched with the clamping strips 471 to form circumferential transmission matching;

the coupling cylinder 47 is in circumferential transmission fit with the input end of the output screw rod 3 through a transmission connecting hole; a plurality of friction plates 48 are stacked in the mounting cavity of the coupling cylinder 47 along the axial direction of the coupling cylinder; the mounting holes of each friction plate 48 are in interference fit with the output end of the reduction gearbox 2, and when the torque exceeds the static friction force of the friction plates 48 and the output end of the reduction gearbox 2, the friction plates 48 and the output end of the reduction gearbox 2 slip.

The working principle of the invention is as follows:

under the effect of friction disc 48 and the output end interference fit of reducing gear box 2, can effectively transmit the moment of torsion of the output end of reducing gear box 2 for output lead screw 3.

When the torque is overloaded due to the reverse force, the torque overcomes the static friction force between the friction plate 48 and the output end of the reduction gearbox 2, and the friction plate 48 and the output end of the reduction gearbox 2 are enabled to slip. And continuing circumferential transmission until the torque recovers to a normal value.

(example 4)

Referring to fig. 11 to 13, the invention has a motor 1, a reduction box 2, and an output screw rod 3 for driving the mobile phone screen folding spindle to rotate; the output shaft of the motor 1 is in transmission connection with the input end of the reduction box 2; the method is characterized in that: the overload protection device is characterized by further comprising an overload protection device 4 which is used for transmitting the torque of the output end of the reduction gearbox 2 to the output screw rod 3 and enabling the output end of the reduction gearbox 2 and the output screw rod 3 to slip circumferentially when the torque is overloaded.

The overload protection device 4 comprises a coupler; the coupler comprises a connecting body 49, one end of the connecting body 49 is in circumferential transmission fit with the output end of the reduction gearbox 2, and the other end of the connecting body 49 is provided with a plurality of clamping claws 491 which are distributed along the circumference of the axis of the connecting body; an installation area for inserting the input end of the output screw rod 3 is formed between the clamping claws 491; the circumferential surface of the connecting body 49 is provided with external threads;

the coupler also comprises a fastening nut 5 sleeved outside the coupler; a through cavity is arranged in the fastening nut 5 and is provided with a connecting cavity and a pressing cavity which are communicated; the inner wall of the connecting cavity is provided with an internal thread which can be matched with the external thread of the connecting body 49; the pressing cavity is in a cone frustum shape and gradually reduces towards the direction far away from the connecting cavity; the inner wall of the compaction cavity acts on the clamping jaw 491 and urges the clamping jaw 491 to form interference fit with the output end of the output screw rod 3 as the compaction cavity approaches the connecting body 49; when the torque exceeds the static friction force between the claws 491 and the input end of the output screw 3, the claws 491 slip with the input end of the output screw 3.

The working principle of the invention is as follows:

under the effect of the fastening nut 5, the claw 491 clamps the output screw rod 3, so that the torque of the output end of the reduction gearbox 2 can be effectively transmitted to the output screw rod 3.

When the torque is overloaded due to the reverse force, the torque gram claws 491 output the static friction force of the screw rod 3, so that the claws 491 output the screw rod 3 to slip. And continuing circumferential transmission until the torque recovers to a normal value.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.