A gear box arrangement for a robot joint

Abstract

This invention relates to the technical field of gearbox structures, specifically a gearbox device for robot joints. It includes upper and lower gearbox housings, input and output shafts, and meshing high- and low-speed helical gears. A semi-circular annular plate is installed within the gear housing cavity, and a positioning box is rotatably mounted thereon. A counterweight is provided at the bottom of the positioning box to maintain its vertical orientation under gravity. An oil delivery assembly and a control assembly are integrated within the positioning box. The oil delivery assembly includes an infusion pump, an input pipe, and an output pipe. The input pipe extends to the bottom of the cavity, and the output pipe faces the meshing area of ​​the high-speed gear. The control assembly includes a gravity sensor switch for detecting the device's orientation. When the gearbox rotates with the joint to a vertical position, causing the high-speed gear to detach from the liquid surface, the gravity sensor switch triggers the infusion pump to start, forcibly delivering lubricating oil from the bottom to the high-speed gear. This invention solves the problem of insufficient lubrication and wear of the high-speed gear due to orientation changes, achieving adaptive active lubrication, with a compact structure and reliable operation.

Description

Technical Field

[0001] This invention relates to the technical field of gearbox structures, specifically a gearbox device for robot joints. Background Technology

[0002] As a core component of mechanical transmission systems, gearboxes are widely used in various applications requiring speed changes and torque transmission. In the field of robot joint drives, gearboxes typically employ splash lubrication or oil immersion lubrication to reduce friction and wear during gear meshing, thereby extending their service life. Specifically, a specific amount of lubricating oil or grease is pre-filled into the gear housing of the gearbox. When the gears rotate at high speed, the lubricating oil is agitated or carried to the meshing tooth surfaces, forming an oil film to bear the load and dissipate heat.

[0003] However, existing gearbox devices used in robot joints face unique challenges in actual operation. Unlike stationary industrial reducers, when robot joints perform multi-degree-of-freedom movements (such as arm pitch and wrist rotation), the gearbox's posture changes spatially, exhibiting various states such as horizontal, tilted, or vertical. In existing technologies, to avoid excessive resistance in gear churning that leads to heat generation and power loss, the amount of lubricating oil injected into the gearbox typically only submerges the bottom teeth of the low-speed gear. When the gearbox rotates with the joint to a vertical position with the high-speed gear above and the low-speed gear below, the smaller-diameter high-speed gear, due to its higher position, is completely detached from the fluid surface and cannot contact the lubricating oil at the bottom of the gear housing. If the robot joint needs to operate at high speed continuously for an extended period in this specific posture, the meshing area of ​​the high-speed gear will be in a state of insufficient or boundary lubrication, which can easily lead to a sharp increase in tooth surface temperature, accelerated wear, and even, in severe cases, galling failure, significantly reducing the service life and reliability of the gearbox. Therefore, there is an urgent need to develop a robot joint gearbox device that can adapt to posture changes and actively compensate for lubrication. Summary of the Invention

[0004] The purpose of this invention is to provide a gearbox device for robot joints to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A gearbox device for a robot joint includes a lower gearbox housing and an upper gearbox housing assembled together. A gear receiving cavity is formed together in the lower gearbox housing and the upper gearbox housing. An input shaft passes through one end of the lower gearbox housing and the upper gearbox housing. One end of the input shaft extends into the gear receiving cavity and is fitted with a high-speed helical gear. An output shaft passes through the front end of the lower gearbox housing and the upper gearbox housing. One end of the output shaft extends into the gear receiving cavity and is fitted with a low-speed helical gear. The high-speed helical gear and the low-speed helical gear are perpendicular to each other and mesh. The device also includes a semi-circular annular plate, a positioning box, an oil supply assembly, and a control assembly. The upper gearbox housing and the lower gearbox housing are fixedly installed on the rear inner walls of the upper gearbox housing and the lower gearbox housing. The positioning box is installed on the semi-circular annular plate. The semi-circular annular plate is provided with a semi-circular annular groove. Several rotating rods are evenly distributed around the rear circumference of the positioning box. A rotating wheel is installed at the rear end of the rotating rod. The rotating wheel is clamped and rolled in the semi-circular annular groove, so that the positioning box can rotate around the axis of the output shaft. The positioning box is circular and located at the center periphery of the output shaft. A counterweight is fixedly installed at the bottom of the positioning box so that the positioning box always maintains a fixed vertical posture under the action of gravity. The oil delivery assembly is installed inside the positioning box. The oil delivery assembly includes an infusion pump, an input pipe, and an output pipe. One end of the input pipe is connected to the infusion pump, and the other end extends to the bottom of the gear receiving cavity. One end of the output pipe is connected to the infusion pump, and the other end extends to the middle of the gear receiving cavity and faces the meshing area of ​​the high-speed helical gear. The control component is installed inside the positioning box and includes a control box and a gravity sensor switch installed on the control box. The control box is electrically connected to the infusion pump and is used to control the start and stop of the infusion pump according to the attitude detection signal of the gravity sensor switch.

[0006] As a further embodiment of the present invention: the gear receiving cavity is cylindrical, the outer diameter of the low-speed stage helical gear is adapted to the inner diameter of the gear receiving cavity, and the thickness of the high-speed stage helical gear is adapted to the axial thickness of the gear receiving cavity.

[0007] As a further embodiment of the present invention: a plurality of balls are evenly distributed around the outer periphery of the rotating wheel, and the rotating wheel forms rolling friction with the inner wall of the semi-circular groove through the balls.

[0008] As a further embodiment of the present invention: a rotary seal is provided between the rotating rod and the wall of the positioning box, and the rotating rod is rotatably connected to the positioning box in a sealed manner.

[0009] As a further aspect of the present invention: sealing rings or sealing fillers are provided at the points where the input pipe and output pipe penetrate the wall of the positioning box to maintain the sealing and waterproof performance of the interior of the positioning box.

[0010] As a further embodiment of the present invention: the infusion pump is fixedly mounted on the inner wall of the positioning box by a mounting bracket, and the mounting bracket is equipped with shock-absorbing pads.

[0011] As a further aspect of the present invention: the gravity sensing switch is a mercury switch or a microelectromechanical gyroscope sensor, used to detect the tilt angle of the gearbox device relative to the direction of gravity.

[0012] The present invention has the following advantages: 1. Achieving Adaptive Oriented Lubrication: This invention utilizes a positioning box that can rotate freely within a semi-circular groove, with a counterweight installed at the bottom of the positioning box. By leveraging the principle of gravity self-balancing, regardless of how the robot joints rotate the gearbox housing, the positioning box and its internal oil delivery components always maintain a vertically downward orientation relative to the ground. This ensures that the end of the input pipe is always submerged below the lubricating oil level at the bottom of the gear housing cavity, solving the problem of oil pump cavitation caused by changes in the box's orientation.

[0013] 2. Targeted Solution to High-Speed ​​Gear Lubrication and Wear Problems: Addressing the pain point of existing technologies where high-speed helical gears detach from the oil surface in a vertical gearbox posture and are prone to wear during long-term operation, this invention utilizes a gravity-sensing switch to detect specific dangerous postures of the gearbox (such as prolonged vertical operation) and actively activates the lubrication pump. Through the output pipe, bottom lubricating oil is forcibly delivered and sprayed to the meshing area of ​​the high-speed helical gears located at a higher position, achieving active compensation lubrication for high-risk gear pairs with insufficient oil. This significantly reduces the risk of tooth surface wear and extends the maintenance cycle and service life of the robot joints.

[0014] 3. Compact structure without affecting transmission efficiency: The oil delivery component and control component of this invention are integrated into a ring-shaped positioning box. The positioning box cleverly utilizes the unused space around the output shaft without increasing the axial or radial dimensions of the gearbox, meeting the design requirements of lightweight and miniaturized robot joints. Furthermore, the infusion pump does not operate under normal splash lubrication conditions when the device is laid flat, avoiding energy loss and oil temperature rise caused by continuous oil supply, thus balancing lubrication reliability and transmission efficiency.

[0015] 4. Stable and reliable operation: The positioning box and the semi-circular ring plate are connected by a ball bearing wheel, which minimizes rotational friction and ensures that the counterweight can respond sensitively to changes in gravity. All pipelines and shaft connections are equipped with sealing structures to prevent lubricating oil from leaking into the positioning box and damaging electrical components, thus ensuring long-term stable operation of the device under complex working conditions. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall external structure of an embodiment of the present invention.

[0017] Figure 2 This is a schematic diagram of the structure of the lower gearbox housing in an embodiment of the present invention.

[0018] Figure 3 This is a top view of the internal structure of the lower gearbox housing in an embodiment of the present invention.

[0019] Figure 4 This is a front view of the internal structure of the positioning box in an embodiment of the present invention.

[0020] Figure 5 for Figure 3 Enlarged diagram of part A in the image.

[0021] In the diagram: 1. Lower gearbox housing; 2. Upper gearbox housing; 3. Input shaft; 4. Output shaft; 5. Gear housing cavity; 6. High-speed stage helical gear; 7. Low-speed stage helical gear; 8. Semi-circular ring plate; 9. Positioning box; 10. Oil delivery assembly; 11. Control assembly; 12. Semi-circular ring groove; 13. Rotating shaft; 14. Rotating wheel; 15. Ball bearing; 16. Mounting bracket; 17. Oil pump; 18. Input pipe; 19. Output pipe; 20. Control box; 21. Gravity sensor switch; 22. Counterweight. Detailed Implementation

[0022] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0023] The technical solution of the present invention will be further described in detail below with reference to specific embodiments.

[0024] Please see Figures 1 to 5A gearbox device for robot joints includes a lower gearbox housing 1 and an upper gearbox housing 2 assembled together. A gear receiving cavity 5 is formed within both the lower and upper gearbox housings 1 and 2. An input shaft 3 passes through one end of each of the lower and upper gearbox housings 1 and 2 via bearings. One end of the input shaft 3 extends into the gear receiving cavity 5 and is connected to a high-speed helical gear 6 via a key. An output shaft 4 passes through the front end of each of the lower and upper gearbox housings 1 and 2 via bearings. One end of the output shaft 4 extends into the gear receiving cavity 5 and is connected to a low-speed helical gear 7 via a key. The high-speed helical gear 6 and the low-speed helical gear 7 are perpendicular to each other and mesh. The device is characterized by further including a semi-circular annular plate 8, a positioning box 9, an oil supply assembly 10, and a control assembly 11. The upper gearbox housing 2 and the lower gearbox housing 1 are fixedly installed on their rear inner walls by screws or integral casting. The positioning box 9 is installed on the semi-circular annular plate 8. The semi-circular annular plate 8 is provided with a semi-circular annular groove 12. Several rotating rods 13 are evenly distributed around the rear circumference of the positioning box 9. The rear end of the rotating rods 13 is fitted with a rotating wheel 14 by thread or interference fit. The rotating wheel 14 is clamped and rolled in the semi-circular annular groove 12, so that the positioning box 9 can rotate around the axis of the output shaft 4. The positioning box 9 is circular and located at the center periphery of the output shaft 4. A gap is left between the positioning box 9 and the output shaft 4 to avoid mutual interference. A counterweight 22 is fixedly installed at the bottom of the positioning box 9 by bolts or integral molding. The counterweight 22 is made of high-density metal material, such as lead or tungsten alloy, so that the positioning box 9 always maintains a fixed vertical posture under the action of gravity. The oil delivery assembly 10 is installed inside the positioning box 9. The oil delivery assembly 10 includes an infusion pump 17, an input pipe 18, and an output pipe 19. One end of the input pipe 18 is connected to the oil inlet of the infusion pump 17, and the other end extends to the bottom of the gear receiving cavity 5. A filter screen is installed at this end to prevent impurities from entering the pump body. One end of the output pipe 19 is connected to the oil outlet of the infusion pump 17, and the other end extends to the middle of the gear receiving cavity 5 and faces the meshing area of ​​the high-speed helical gear 6. A nozzle is installed at the end of the output pipe 19 for accurately spraying lubricating oil onto the meshing tooth surface. The control component 11 is installed inside the positioning box 9, including a control box 20 and a gravity sensor switch 21 installed on the control box 20. The control box 20 is equipped with a power supply and a controller. The control box 20 is electrically connected to the infusion pump 17 and is used to control the start and stop of the infusion pump 17 according to the attitude detection signal of the gravity sensor switch 21.

[0025] The gear receiving cavity 5 is cylindrical, and the outer diameter of the low-speed helical gear 7 is adapted to the inner diameter of the gear receiving cavity 5, so that the low-speed helical gear 7 can agitate the lubricating oil at the bottom of the cavity when rotating. The thickness of the high-speed helical gear 6 is adapted to the axial thickness of the gear receiving cavity 5.

[0026] A plurality of balls 15 are evenly distributed around the outer periphery of the rotating wheel 14. The rotating wheel 14 forms rolling friction with the inner wall of the semi-circular groove 12 through the balls 15. The balls 15 are made of bearing steel.

[0027] A rotary seal is provided between the rotating rod 13 and the wall of the positioning box 9. The rotary seal is a skeleton oil seal or an O-ring. The rotating rod 13 is rotatably connected to the positioning box 9 in a sealed manner.

[0028] Both the input pipe 18 and the output pipe 19 are equipped with sealing rings or sealing fillers at the points where they penetrate the wall of the positioning box 9, in order to maintain the sealing and waterproof performance of the interior of the positioning box 9 and prevent lubricating oil from seeping into the interior of the positioning box 9 and corroding the electrical components.

[0029] The infusion pump 17 is fixedly mounted on the inner wall of the positioning box 9 by a mounting bracket 16. The mounting bracket 16 is connected to the inner wall of the positioning box 9 by screws. The mounting bracket 16 has a shock-absorbing pad made of rubber, which is used to absorb the micro-vibrations when the infusion pump 17 is working.

[0030] The gravity sensing switch 21 is a mercury switch or a microelectromechanical gyroscope sensor, used to detect the tilt angle of the gearbox device relative to the direction of gravity. When the gearbox device is detected to be in an upright state for a duration exceeding a preset threshold, a trigger signal is output.

[0031] Working principle: This invention aims to solve the lubrication failure problem of robot joint gearboxes during posture changes. Initially, the bottom of the gear housing 5 is filled with an appropriate amount of lubricating oil. When the robot joint is in a normal posture (such as lying flat or tilted), the rotation of the low-speed helical gear 7 allows it to be partially immersed in the oil. Through splash lubrication, the lubricating oil is thrown onto the inner wall of the gearbox and the meshing surface of the high-speed helical gear 6, meeting basic lubrication requirements. At this time, the gravity sensor switch 21 does not detect a dangerous posture of continuous oil shortage, and the infusion pump 17 is in standby mode to save energy.

[0032] When the robot joints perform a large-scale rotational movement, causing the lower gearbox housing 1 and the upper gearbox housing 2 to rotate as a whole to a vertical position with the low-speed helical gear 7 facing down and the high-speed helical gear 6 facing up, the lubricating oil in the gear receiving cavity 5 accumulates at the bottom due to gravity, only submerging the lower tooth root of the low-speed helical gear 7. At this time, the high-speed helical gear 6, which has a smaller diameter and is positioned higher, is completely detached from the oil surface. In this posture, the gravity sensor switch 21 detects that the gravity vector direction of the gearbox device has continuously changed relative to its own coordinate system (i.e., it remains in a vertical state for a long time), and the internal circuit is turned on, sending an electrical signal to the controller in the control box 20. After receiving the signal and confirming that the duration exceeds the preset safety threshold, the controller immediately starts the infusion pump 17. Because the positioning box 9 relies on the gravity adaptive effect of the bottom counterweight 22 and the rolling cooperation between the rotating wheel 14 and the semi-circular groove 12, it always maintains its vertical posture and does not rotate with the gearbox housing during the rotation of the gearbox housing. Therefore, the end of the input pipe 18 always faces down and is submerged in the lubricating oil at the bottom of the gear receiving cavity 5. After the infusion pump 17 starts working, lubricating oil is drawn in after being filtered through the filter screen at the end of the inlet pipe 18. After being pressurized, it is forcibly sprayed into the meshing area of ​​the high-speed helical gear 6 through the outlet pipe 19 and the nozzle at the end, forming forced lubrication. This effectively avoids dry friction and severe wear of the high-speed gear pair under long-term vertical working conditions. When the robot joint posture returns to the tilted or flat position, the gravity sensor switch 21 is turned off, the controller shuts off the infusion pump 17 after a delay, and the system returns to the normal working mode with splash lubrication as the main method.

[0033] All components of this invention are general standard parts or parts known to those skilled in the art. Their structure and principles are readily known to those skilled in the art through technical manuals or conventional experimental methods. It is obvious to those skilled in the art that this invention is not limited to the details of the above exemplary embodiments, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of this invention is defined by the appended claims rather than the foregoing description, and thus all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0034] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A gearbox device for a robot joint, comprising a lower gearbox housing (1) and an upper gearbox housing (2) assembled together, wherein a gear receiving cavity (5) is formed together in the lower gearbox housing (1) and the upper gearbox housing (2), an input shaft (3) is provided through one end of the lower gearbox housing (1) and the upper gearbox housing (2), one end of the input shaft (3) extends into the gear receiving cavity (5) and is fitted with a high-speed helical gear (6), an output shaft (4) is provided through the front end of the lower gearbox housing (1) and the upper gearbox housing (2), one end of the output shaft (4) extends into the gear receiving cavity (5) and is fitted with a low-speed helical gear (7), wherein the high-speed helical gear (6) and the low-speed helical gear (7) are perpendicular to each other and mesh, characterized in that: It also includes a semi-circular ring plate (8), a positioning box (9), an oil delivery assembly (10), and a control assembly (11); The upper gearbox housing (2) and the lower gearbox housing (1) are fixedly installed with the semi-circular annular plate (8) on their rear inner walls. The positioning box (9) is installed on the semi-circular annular plate (8). The semi-circular annular plate (8) is provided with a semi-circular annular groove (12). Several rotating rods (13) are evenly distributed around the rear circumference of the positioning box (9). A rotating wheel (14) is installed at the rear end of the rotating rod (13). The rotating wheel (14) is clamped and rolled in the semi-circular annular groove (12), so that the positioning box (9) can rotate around the axis of the output shaft (4). The positioning box (9) is circular and located in the middle periphery of the output shaft (4). A counterweight (22) is fixedly installed at the bottom of the positioning box (9) so that the positioning box (9) always maintains a fixed vertical posture under the action of gravity. The oil delivery assembly (10) is installed in the positioning box (9). The oil delivery assembly (10) includes an infusion pump (17), an input pipe (18), and an output pipe (19). One end of the input pipe (18) is connected to the infusion pump (17), and the other end extends to the bottom of the gear receiving cavity (5). One end of the output pipe (19) is connected to the infusion pump (17), and the other end extends to the middle of the gear receiving cavity (5) and faces the meshing area of ​​the high-speed helical gear (6). The control component (11) is installed in the positioning box (9) and includes a control box (20) and a gravity sensor switch (21) installed on the control box (20). The control box (20) is electrically connected to the infusion pump (17) and is used to control the start and stop of the infusion pump (17) according to the attitude detection signal of the gravity sensor switch (21).

2. A gearbox device for a robot joint according to claim 1, characterized in that: The gear receiving cavity (5) is cylindrical, the outer diameter of the low-speed helical gear (7) is adapted to the inner diameter of the gear receiving cavity (5), and the thickness of the high-speed helical gear (6) is adapted to the axial thickness of the gear receiving cavity (5).

3. A gearbox device for a robot joint according to claim 1, characterized in that: A number of balls (15) are evenly distributed around the outer periphery of the wheel (14), and the wheel (14) forms rolling friction with the inner wall of the semi-circular groove (12) through the balls (15).

4. A gearbox device for a robot joint according to claim 1, characterized in that: A rotary seal is provided between the rotating rod (13) and the wall of the positioning box (9), and the rotating rod (13) and the positioning box (9) are connected in a sealed rotational manner.

5. A gearbox device for a robot joint according to claim 1, characterized in that: Both the input pipe (18) and the output pipe (19) are provided with sealing rings or sealing fillers at the points where they penetrate the wall of the positioning box (9) to maintain the sealing and waterproof performance of the interior of the positioning box (9).

6. A gearbox device for a robot joint according to claim 1, characterized in that: The infusion pump (17) is fixedly mounted on the inner wall of the positioning box (9) by a mounting bracket (16), which has a shock-absorbing pad.

7. A gearbox device for a robot joint according to claim 1, characterized in that: The gravity sensing switch (21) is a mercury switch or a microelectromechanical gyroscope sensor, used to detect the tilt angle of the gearbox device relative to the direction of gravity.

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