Variable speed motor and gear transmission system with overload protection function

Abstract

The variable speed gearbox of the prior art usually adopts a multi-stage gear rigid meshing transmission mode. The power output by the DC motor is transmitted to the output end through the tooth meshing between gears. This rigid connection mode has significant safety hazards: when the output end (such as the last gear) is blocked due to external resistance, the resistance will be directly transmitted to the DC motor in the opposite direction due to the rigidity of the transmission chain. This can easily cause the motor to burn out due to a sharp increase in current, or the internal gears of the gearbox (especially the tooth part) to break or plastically deform due to the huge stress.

Description

Technical Field

[0001] This invention relates to the field of motor drive technology, specifically to a variable speed motor with overload protection function, and more particularly to a gear transmission system that prevents gear stall damage. Background Technology

[0002] In existing variable-speed motors, the gearboxes typically employ a multi-stage, hard-meshing transmission method. The power of the DC motor is transmitted to the output end stage by stage through the meshing of the gear teeth. This rigid connection method presents significant safety hazards; when the output end (such as the last gear) stalls due to external resistance, this resistance is directly transmitted back to the DC motor due to the rigidity of the transmission chain. This can easily lead to the motor burning out due to a surge in current, or the inability to release torque causing the gears inside the gearbox (especially the toothed parts) to fracture or undergo plastic deformation due to immense stress. Summary of the Invention

[0003] To address the shortcomings of existing variable speed motors, which are prone to damage to the motor and gears when stalled due to rigid gear transmission, this invention provides a variable speed motor and its gear transmission system. The system aims to achieve power transmission through a non-rigid connection. When the load exceeds a preset threshold, the system can automatically cut off the rigid transmission to achieve idling protection, thereby improving the service life of the motor and gearbox.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A gear transmission system with overload protection includes a drive shaft (1) and a transmission gear (2) for transmitting power. Crucially, the drive shaft (1) and the transmission gear (2) are physically separate independent components, rather than being integrally formed or rigidly connected.

[0005] The contact surface between the drive shaft (1) and the drive gear (2) is set as an uneven, rough friction surface.

[0006] The system also includes a pressure member (3) for applying axial or radial pressure to the drive shaft (1) and / or the drive gear (2) to keep the rough contact surfaces of the drive shaft (1) and the drive gear (2) in close contact and generate a preset static friction force.

[0007] Its working principle and technical solution are extended as follows: First, when the drive motor is running, if the load is normal, the transmission gear (2) drives the transmission shaft (1) to rotate synchronously through the friction of the contact surface (or conversely, the transmission shaft (1) drives the transmission gear (2) to rotate), thus realizing power transmission.

[0008] Second, when the external load increases dramatically, causing the transmission gear (2) or transmission shaft (1) to stall, the torque transmitted by it increases sharply. When the tangential force generated by this actual torque is greater than the maximum static friction between the contact surfaces, the transmission gear (2) and the transmission shaft (1) will overcome the static friction and slide relative to each other, that is, the transmission gear (2) will rotate relative to the transmission shaft (1), and vice versa.

[0009] Third, this physical sliding cuts off the rigid transmission path, preventing motor stalling and gear damage.

[0010] Preferably, the pressure applied by the pressure member (3) is adjustable, thereby adjusting the threshold of the maximum static friction force to adapt to different load requirements. The adjustable pressure member (3) can be achieved by replacing different physical components or by adjusting the compression space of the same physical component.

[0011] The maximum static friction force F = uN described in this invention is where u is the dynamic friction factor between the drive shaft (1) and the drive gear (2). The rougher the contact surface, the larger the value of μ, and the larger the value of F. N is the pressure applied to the drive shaft (1) by the pressure member (3). When u = 0, it means that the connection between the drive shaft (1) and the drive gear (2) is smooth, and even if N is infinitely large, F is still equal to 0. Preferably, when u is fixed, replacing the pressure member (3) with one having a larger value of N can increase F.

[0012] This invention fundamentally solves the problem of stall damage by breaking down traditional rigid meshing gears into separate components that rely on frictional transmission. Compared to existing technologies, this invention can release stress through slippage when stall occurs, effectively protecting the motor and gearbox, and it also features a simple structure and high reliability. Attached Figure Description

[0013] Figure 1 and Figure 3 This is an exploded view of the gear transmission system of Embodiment 1 of the present invention.

[0014] Figure 2 and Figure 4 This is a cross-sectional view of the gear transmission system of Embodiment 1 of the present invention.

[0015] Figure 5 This is a cross-sectional view of a clutch gear assembly after assembly according to Embodiment 1 of the present invention. Detailed Implementation

[0016] like Figure 5As shown, the DC motor 500 rigidly drives the gear 501 through the central shaft 502. The gear 501 rigidly transmits the kinetic energy of the DC motor to the gear 504 through synchronous meshing gear 503 and gear 504. The gear 504 implements the transmission gear (2) of the present invention.

[0017] like Figure 5 As shown, 505a and 505b are a single physical component, and the drive shaft (1) implementing the present invention is collectively referred to here as drive shaft 505. The contact surface between the drive shaft 505 and the gear 504 is an uneven, rough friction surface.

[0018] like Figure 5 As shown, spring 507 implements the pressure member (3) of the present invention.

[0019] like Figure 5 As shown, housing 509 is used to fix the DC motor and all components inside the housing, so that these components interact and operate stably.

[0020] like Figure 5 As shown, the housing 508 is convex in the illustration of this embodiment. The purpose is to allow the pressure member (3) to have a more flexible adjustment range. In actual application, if the required pressure member is small enough, the housing 508 does not need to be convex, so that the housing 509 is smooth and more aesthetically pleasing.

[0021] The pressure component described in this embodiment acts directly on the transmission shaft. Similarly, the pressure component can also act directly on the transmission gear.

[0022] In this embodiment, the rotational speed output by the DC motor is rigidly transmitted to the gear 504, and the friction between the contact surface between the gear 504 and the transmission shaft 505 drives the transmission shaft 505 to rotate together, thereby outputting the rotational speed to the gear 506.

[0023] When gear 506 stops rotating due to external force, since the transmission shaft 505 and gear 506 are rigidly connected, the transmission shaft 505 also immediately stops rotating. However, the DC motor 500 does not stop rotating, so the speed output by the DC motor 500 still drives gear 504 to rotate. The torque of gear 504 increases sharply, while the maximum static friction force on the contact surface between gear 504 and transmission shaft 505 remains unchanged. Therefore, when the torque of gear 504 increases to a level greater than the maximum static friction force, gear 504 and transmission shaft 505 overcome the static friction and slide relative to each other.

Claims

1. A gear transmission system with overload protection function, characterized in that, It includes a drive shaft (1), a drive gear (2), and a pressure member (3); the drive shaft (1) and the drive gear (2) are physically separate components; the contact surface between the drive shaft (1) and the drive gear (2) is a friction surface; the pressure member (3) is used to press the contact surface between the drive shaft (1) and the drive gear (2) together so that the two transmit power through friction; when the force generated by the transmitted torque is greater than the maximum static friction force of the contact surface, the drive gear (2) and the drive shaft (1) rotate relative to each other.

2. The gear transmission system according to claim 1, characterized in that, The contact surface is an uneven, rough surface.

3. The gear transmission system according to claim 1, characterized in that, The pressure of the pressure member (3) is adjustable.

4. The gear transmission system according to claim 1, characterized in that, The pressure component (3) is a spring or an elastic gasket.

5. A variable speed motor, comprising a motor body and a gearbox, characterized in that, The gearbox includes a gear transmission system as described in any one of claims 1 to 4.

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