Mechanical joint, mechanical arm and cleaning apparatus

Abstract

A mechanical joint (100), a mechanical arm (200) and a cleaning apparatus (300). The mechanical joint (100) comprises: a connecting frame (110) and a lifting assembly (120), wherein the connecting frame (110) is hinged to a base (211) of the mechanical arm (200); the lifting assembly (120) comprises a nut (121), a lead screw (122) and a driving part (123), wherein the nut (121) and the lead screw (122) are connected by means of non-self-locking threads and are hinged to the base (211), the driving part (123) is arranged on the connecting frame (110), a first end of the lead screw (122) is connected to the driving part (123), and a second end of the lead screw (122) passes through the nut (121); and the driving part (123) is configured to drive the lead screw (122) to rotate, such that the lead screw (122) and the nut (121) move relative to each other to drive the connecting frame (110) to be raised or lowered relative to the base (211).

Description

Mechanical joint, mechanical arm and cleaning device

[0001] Cross-reference to related applications

[0002] The present disclosure claims priority to Chinese Patent Application No. 202421845521.2, filed July 31, 2024, which is incorporated by reference herein in its entirety. TECHNICAL FIELD

[0003] The present application relates to the technical field of smart home, especially to a mechanical joint, a mechanical arm and a cleaning device. BACKGROUND

[0004] With the continuous development of science and technology and the continuous improvement of people's living standards, cleaning devices such as intelligent sweeping robots have continuously entered our daily life. In order to better realize the cleaning function, the current cleaning device will add a mechanical arm with a mechanical hand to realize the grabbing or moving of obstacles, objects and garbage by using the mechanical hand. SUMMARY

[0005] In a first aspect, the present application provides a mechanical joint for a mechanical arm, the mechanical joint comprising: a connecting frame and a lifting assembly, the connecting frame being hinged to a base of the mechanical arm, the lifting assembly comprising a nut, a lead screw and a driving part, the nut being hingedly connected to the base in a non-self-locking threaded connection with the lead screw, the driving part being arranged on the connecting frame, a first end of the lead screw being connected to the driving part, and a second end of the lead screw being arranged through the nut; wherein the driving part is configured to drive the lead screw to rotate, so that the lead screw and the nut move relative to each other to drive the connecting frame to lift or fall relative to the base.

[0006] Further, the lead screw is provided with an external thread structure, and a thread angle of the external thread structure is greater than an equivalent friction angle of a threaded pair composed of the lead screw and the nut.

[0007] Further, the lead screw is a steel piece, a copper piece or a copper alloy piece; and the nut is a steel piece, a copper piece or a copper alloy piece.

[0008] Further, a pitch diameter of the external thread structure is 3mm to 6mm, and a lead of the external thread structure is 2.5mm to 5.5mm.

[0009] Further, the lifting assembly further comprises: a motor bracket, the motor bracket being hingedly connected to the connecting frame, the driving part being mounted on the motor bracket, and the lead screw being arranged through the motor bracket and connected to the driving part.

[0010] Further, the lifting assembly further comprises: a rotating piece, the rotating piece being sleeved on an outer side of the lead screw, the lead screw being provided with a stepped structure, and the rotating piece being located between the stepped structure and the motor bracket to enable the lead screw and the motor bracket to be rotationally connected.

[0011] Further, opposite sides of the nut outer wall are provided with first cylindrical bosses, the base is provided with a first accommodating groove, and the first cylindrical bosses are accommodated in and rotatable in the first accommodating groove.

[0012] Further, opposite sides of the motor support are provided with second cylindrical bosses, the connecting frame is provided with a second accommodating groove, and the second cylindrical bosses are accommodated in and rotatable in the second accommodating groove.

[0013] Further, the mechanical joint further comprises a connecting shaft, an axis of the connecting shaft is parallel to an axis of the first cylindrical boss and connected to the base, and an end of the connecting frame close to the base is sleeved outside the connecting shaft and rotatably connected to the connecting shaft.

[0014] Further, the end of the connecting frame close to the base is provided with a connecting ring, the connecting ring is sleeved outside the connecting shaft, and the mechanical joint further comprises a connecting bearing connected between the connecting ring and the connecting shaft.

[0015] In a second aspect, the present application provides a mechanical arm, comprising the mechanical joint of any one of the first aspect.

[0016] In a third aspect, the present application provides a cleaning device, comprising the mechanical arm of any one of the second aspect.

[0017] The mechanical joint, the mechanical arm and the cleaning device provided by the embodiments of the present application, the mechanical joint comprises a connecting frame and a lifting assembly, the connecting frame is hinged to a base, so that the connecting frame can rotate relative to the base; the lifting assembly comprises a nut, a lead screw and a driving part, the nut and the lead screw are connected through a threaded structure, the lead screw is driven to rotate by the driving part, so that the nut and the lead screw can move relative to each other, since the nut is hinged to the base and the driving part is arranged on the connecting frame, the lead screw can move relative to the nut in a direction close to or away from the base, thereby the connecting frame can be lifted or lowered relative to the base to meet the requirements of different functions such as working or storage of the mechanical arm. Since the nut and the lead screw are connected through non-self-locking threads, when the mechanical joint is powered off accidentally in the lifted state, the connecting frame can be lowered relative to the base by external force acting on the mechanical joint to meet the requirement of folding and storing the mechanical arm, thereby avoiding the problem that the lifting assembly cannot be lowered and remains in the lifted state when the mechanical joint is powered off accidentally in the lifted state in the related art, which makes the mechanical arm occupy a larger space, affects the moving range of the cleaning device and is inconvenient to store, the operability of the mechanical joint is greatly improved, and the user experience is improved.

[0018] The above description is only a summary of the technical solutions of the present application, in order to more clearly understand the technical means of the present application, the specific embodiments of the present application can be implemented according to the content of the description, and in order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the following specific embodiments of the present application are described. Attached Figure Description

[0019] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. Wherein:

[0020] Figure 1 shows a three-dimensional structural schematic diagram of the robotic arm of the present invention from one perspective;

[0021] Figure 2 shows a schematic diagram of the mechanical joint of the robotic arm of the present invention in a raised state from one perspective.

[0022] Figure 3 shows a partial structural schematic diagram of the mechanical joint of the mechanical part of the present invention in a raised state;

[0023] Figure 4 shows another structural schematic diagram of the mechanical joint of the mechanical part of the present invention in a raised state;

[0024] Figure 5 shows a partially enlarged schematic diagram of point A in the embodiment shown in Figure 4;

[0025] Figure 6 shows a schematic diagram of the forces acting on the mechanical joints when the robotic arm retracts into its magazine;

[0026] Figure 7 shows a schematic diagram of the forces acting on the mechanical joints when the robotic arm is held in the working position;

[0027] Figure 8 shows a structural schematic diagram of the mechanical joint of the robotic arm of the present invention in a landing state from one perspective.

[0028] Figure 9 shows a partial structural schematic diagram of the mechanical joint of the robotic arm of the present invention in the landing state.

[0029] Figure 10 shows a partially enlarged schematic diagram of section B in the embodiment shown in Figure 9;

[0030] Figure 11 shows a schematic diagram of the forces acting on the mechanical joints when the robotic arm exits the bin;

[0031] Figure 12 shows a structural schematic diagram of the base of the robotic arm of the present invention from one perspective;

[0032] Figure 13 shows a partial structural schematic diagram of the lifting assembly of the present invention;

[0033] Figure 14 shows a structural schematic diagram of the cleaning device of the present invention from one perspective.

[0034] Correspondence between reference signs and component names in FIGS. 1-14 is as follows: 100 mechanical joint, 110 connecting frame, 111 connecting ring, 120 lifting assembly, 121 nut, 1211 first cylindrical boss, 122 screw rod, 1221 external thread structure, 123 driving part, 124 motor support, 1241 second cylindrical boss, 125 rotating part, 130 connecting shaft, 140 connecting bearing, 200 mechanical arm, 210 rotary joint, 211 base, 2111 first accommodating groove, 2112 mounting hole, 220 fixing seat, 230 first overturning joint, 240 second overturning joint, 250 mechanical hand, 300 cleaning device, 310 main body. DETAILED DESCRIPTION

[0035] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the technical solutions provided by the present application. However, it will be apparent to one of ordinary skill in the art that the technical solutions provided by the present application can be practiced without one or more of these specific details.

[0036] It should be noted that the terms used herein are only intended to describe specific embodiments and are not intended to limit exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. In addition, it should be understood that the terms "comprise" and / or "include" as used in the specification indicate the presence of the stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0037] Exemplary embodiments according to the present application will now be described in more detail with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in various different forms, and should not be interpreted as being limited to the embodiments set forth herein. It should be understood that the embodiments are provided so that the present disclosure is complete and complete, and the concepts of the exemplary embodiments are sufficiently conveyed to those of ordinary skill in the art.

[0038] As shown in FIGS. 1-14, the embodiment of the first aspect of the present application provides a mechanical joint 100, the embodiment of the second aspect of the present application provides a mechanical arm 200, and the embodiment of the third aspect of the present application provides a cleaning device 300. Among them, the mechanical joint 100 is applied to the mechanical arm 200, the mechanical arm 200 is applied to the cleaning device 300, and the cleaning device 300 can be a sweeping robot, a sweeping and mopping integrated machine, or other cleaning robots that meet the requirements.

[0039] As shown in FIG. 14, the cleaning device 300 includes, but is not limited to, a main body 310, a driving system, a cleaning system, etc. The above-mentioned various systems are coordinated with each other, so that the cleaning device 300 can move autonomously to realize the cleaning function. The functional elements and the like constituting the above-mentioned various systems in the cleaning device 300 are integrally arranged in the main body 310. It can be understood that the cleaning device 300 can be a self-moving cleaning device. The self-moving cleaning device is a device that automatically performs cleaning operation in a certain to-be-cleaned area without user operation.

[0040] Further, as shown in FIG. 14, the mechanical arm 200 is applied to the cleaning device 300, such as the mechanical arm 200 being connected with the main body 310 of the cleaning device 300, so as to realize the grabbing or moving of the obstacles, objects and garbage near the cleaning device 300 by the mechanical hand 250 at the end of the mechanical arm 200, so as to better realize the autonomous cleaning function.

[0041] As shown in FIG. 1, FIG. 2, FIG. 3, FIG. 8 and FIG. 9, when the mechanical arm 200 is in the working state, part of the mechanical joints 100 needs to be kept in the lifted state to make the mechanical hand 250 at the end of the mechanical arm 200 reach the appropriate position for grabbing or placing operation, and when the mechanical arm 200 is in the non-working state, the mechanical joints 100 in the lifted state need to be lowered to make the mechanical arm 200 in the folded and stored state for storage.

[0042] As shown in FIG. 2, FIG. 3, FIG. 8 and FIG. 9, the embodiment of the first aspect of the present application provides a mechanical joint 100 for a mechanical arm 200, which includes a connecting frame 110 and a lifting assembly 120. The connecting frame 110 is hinged to a base 211 of the mechanical arm 200, and the lifting assembly 120 includes a nut 121, a lead screw 122 and a driving part 123. The nut 121 is hingedly connected with the lead screw 122 and arranged on the base 211 by using a non-self-locking thread. The driving part 123 is arranged on the connecting frame 110. A first end of the lead screw 122 is connected with the driving part 123, and a second end of the lead screw 122 passes through the nut 121 and is arranged towards the base 211. The driving part 123 is used to drive the lead screw 122 to rotate, so as to make the lead screw 122 and the nut 121 move relatively to drive the connecting frame 110 to lift or lower relative to the base 211.

[0043] The base 211 of the mechanical arm 200 can be a structure for connecting the mechanical arm 200 with the main body 310 of the cleaning device 300, or can be part of the structure in other joints of the mechanical arm 200.

[0044] The mechanical joint 100 provided by the embodiment of the present application comprises a connecting frame 110 and a lifting assembly 120. The connecting frame 110 is hinged to a base 211, so that the connecting frame 110 can rotate relative to the base 211. The lifting assembly 120 comprises a nut 121, a screw rod 122 and a driving part 123. The nut 121 and the screw rod 122 are connected through a threaded structure. The driving part 123 is used to drive the screw rod 122 to rotate, so that the nut 121 and the screw rod 122 can move relative to each other. Since the nut 121 is hinged to the base 211 and the driving part 123 is arranged on the connecting frame 110, the screw rod 122 can move relative to the nut 121 towards or away from the base 211, so as to lift or lower the connecting frame 110 relative to the base 211. Thus, the lifting and lowering of the mechanical joint 100 can be realized, so as to meet the needs of lifting the mechanical arm 200 to different heights and different positions for object clamping operation, and meet the needs of lowering the mechanical arm 200 to a folded state for storage when the mechanical arm 200 is not working. Since the nut 121 and the screw rod 122 are connected through a non-self-locking threaded structure, when the mechanical joint 100 is accidentally powered off in the lifting state, an external force is applied to the mechanical joint 100, such as an external force applied to the connecting frame 110, so that the screw rod 122 and the nut 121 move relative to each other to drive the connecting frame 110 to lower relative to the base 211. Thus, the needs of folding and storing the mechanical arm 200 can be met, and the problem that the mechanical joint in the related art cannot be lowered and remains in the lifting state when accidentally powered off in the lifting state, so as to occupy a large space, affect the moving range of the cleaning equipment and be inconvenient to store, can be avoided. The operability of the mechanical joint 100 is greatly improved, the operability of the mechanical arm 200 is improved, and the user experience is improved.

[0045] It can be understood that, as shown in FIGS. 2 and 3, when the connecting frame 110 is lifted relative to the base 211 to be in the unfolded state, i.e., the mechanical joint 100 is lifted relative to the base 211 to be in the unfolded state, such as when the connecting frame 110 is lifted and unfolded relative to the base 211 to be in the vertical position, the mechanical arm 200 can be in the working state. As shown in FIGS. 8 and 9, when the connecting frame 110 is lowered relative to the base 211 to be in the folded state, i.e., the mechanical joint 100 is lowered relative to the base 211 to be in the folded state, such as when the connecting frame 110 of the mechanical joint 100 is in the horizontal position, the mechanical arm 200 can be in the folded storage position and not work, so as to reduce the space occupied by the mechanical arm 200. The lifting or lowering operation of the mechanical joint 100 relative to the base 211 can be realized through cooperation of the driving part 123, the screw rod 122 and the nut 121, which is simple in structure and convenient to operate, and can meet the design needs of compact structure and small size of the mechanical arm 200.

[0046] Further, when the mechanical joint 100 is lifted to the unfolded state, i.e., the mechanical arm 200 is in the working state, the driving part 123 is powered on, so that the mechanical joint 100 can resist the working load and remain in the lifted state. It can be understood that the torque provided by the driving part 123 in this posture can be associated with the working load, so that the mechanical joint 100 can resist the working load and reliably and stably remain in the lifted state, avoiding the phenomenon that the mechanical arm is compressed to fall back when the working load increases. It can be understood that, since the nut 121 and the screw rod 122 are connected by non-self-locking threads, the driving part 123 provides a smaller torque, which is converted into a supporting force by the nut 121 and the screw rod 122, so as to support a larger working load, which is conducive to reducing the energy consumption of the driving part 123.

[0047] When the mechanical joint 100 is accidentally powered off when lifted to the unfolded state, since the nut 121 and the screw rod 122 are connected by non-self-locking threads, the mechanical joint 100 can be returned to the folded state by external force (such as working load or user hand pressing), so that the mechanical arm 200 returns to the folded storage position, reduces the space occupied by the mechanical arm 200, and improves the user's satisfaction.

[0048] The driving part 123 can be a motor, and the output shaft of the motor is connected with the first end of the screw rod 122. For example, the output shaft of the driving part 123 can be connected with the screw rod 122 by an adhesive, a key, or other means. It can be understood that the output shaft of the driving part 123 can also be connected with the screw rod 122 through a transmission mechanism, such as a gear mechanism, a belt mechanism, a chain transmission mechanism, etc.

[0049] Further, the driving part 123 is connected with the screw rod 122 to drive the screw rod 122 and the nut 121 to move relatively, which is smaller than the driving force in the related art in which the driving part is connected with the nut to drive the screw rod and the nut to move relatively. In this way, in the case of accidental power failure of the driving part 123, the connecting frame 110 in the lifted and unfolded state can be lowered to the folded state by a small external force, i.e., the user can press the mechanical joint 100 to the lowered and folded state by overcoming a small pressure, which facilitates the folding and storage of the mechanical arm 200, facilitates the operation of the user, and improves the user's satisfaction.

[0050] Further, the connecting frame 110 is hinged with the base 211, and the nut 121 is hinged with the base 211, so that during the process that the driving part 123 drives the screw rod 122 and the nut 121 to move relatively to drive the connecting frame 110 to lift or lower relative to the base 211, the nut 121 will not interfere with the base 211, i.e., the nut 121 can rotate relative to the base 211, so as to ensure that the screw rod 122 and the nut 121 move within a certain range and adapt to the rotation range of the connecting frame 110 relative to the base 211.

[0051] As shown in FIG. 13, in some possible implementation embodiments provided by the present application, the lead screw 122 is provided with an external thread structure 1221, and the second end of the lead screw 122 is arranged in the nut 121, so that the external thread structure 1221 of the lead screw 122 cooperates with the nut 121 to realize the connection of the lead screw 122 and the nut 121. By the thread angle of the external thread structure 1221 on the lead screw 122 being greater than the equivalent friction angle of the thread pair composed of the lead screw 122 and the nut 121, the lead screw 122 and the nut 121 can realize non-self-locking threaded connection, so that after the driving part 123 is powered off, the lead screw 122 and the nut 121 can move relative to each other by external force, so that the mechanical joint 100 in the lifting and unfolding state returns to the landing and folding state, and the mechanical arm 200 in the working position returns to the storage position, thereby reducing the space occupied by the mechanical arm 200 and improving the user's satisfaction.

[0052] In some possible implementation embodiments provided by the present application, the lead screw 122 is a steel piece, a copper piece, or a copper alloy piece, and the nut 121 is a steel piece, a copper piece, or a copper alloy piece.

[0053] The steel piece has high strength and hardness, is not prone to rust, has a long service life, and has low cost, and is suitable for popularization and application.

[0054] The copper piece has good corrosion resistance, can meet the low cleanliness and humid working environment of the cleaning device 300, and has low failure rate.

[0055] The copper alloy piece has high strength, high corrosion resistance, excellent wear resistance, a long service life, and is suitable for popularization and application.

[0056] In some possible implementation embodiments provided by the present application, the pitch diameter of the external thread structure 1221 is 3 mm to 6 mm, and the lead of the external thread structure 1221 is 2.5 mm to 5.5 mm.

[0057] The thread angle formula of the external thread structure 1221 of the lead screw 122 is ψ=arctan(nP / πd2), n is the number of threads of the external thread structure 1221, P is the pitch, and d2 is the pitch diameter of the external thread structure.

[0058] The equivalent friction angle formula of the thread pair composed of the lead screw 122 and the nut 121 is ρ=arctan(1.15μ), and μ is the friction coefficient of the thread pair.

[0059] Therefore, by setting the pitch diameter of the external thread structure 1221 to 3mm to 6mm, and the lead of the external thread structure 1221 to 2.5mm to 5.5mm, the thread angle of the external thread structure 1221 can be ensured to be greater than the equivalent friction angle of the thread pair composed of the screw rod 122 and the nut 121, so as to ensure that the nut 121 and the screw rod 122 are connected by non-self-locking thread.

[0060] Specifically, the pitch diameter of the external thread structure 1221 can be 3mm, 4mm, 5mm, 6mm, or other sizes; the lead of the external thread structure 1221 can be 2.5mm, 3.5mm, 4.5mm, 5.5mm, or other sizes.

[0061] Specifically, taking the friction coefficient μ of the thread pair composed of the screw rod nut 121 as 0.25, the external thread structure 1221 of the screw rod 122 as TR4, the thread pitch diameter d of the thread as about 3.5mm, and the thread lead as 4mm as an example, according to the thread angle formula and the equivalent friction angle formula of the thread pair, it is calculated that the thread angle ψ of the external thread structure 1221 of the screw rod 122 is 0.35 rad, and the equivalent friction angle ρ of the thread pair composed of the screw rod 122 and the nut 121 is 0.28 rad, so it can be seen that the thread angle of the external thread structure 1221 of the screw rod 122 is greater than the equivalent friction angle of the thread pair composed of the screw rod 122 and the nut 121.

[0062] As shown in FIGS. 4, 5, 9 and 10, in some possible implemented embodiments provided by the present application, the lifting assembly 120 further comprises a motor bracket 124, the motor bracket 124 is hinged with the connecting frame 110, the driving part 123 is installed on the motor bracket 124, and the screw rod 122 is arranged through the motor bracket 124 and connected with the driving part 123.

[0063] In the embodiment, the motor bracket 124 is hinged with the connecting frame 110, i.e., the motor bracket 124 is rotatable relative to the connecting frame 110, the driving part 123 is installed on the motor bracket, and the screw rod 122 is arranged through the motor bracket 124 and connected with the driving part 123. Such arrangement can ensure that the driving part 123 connected with the screw rod 122 does not interfere with the connecting frame 110 during the lifting or lowering of the connecting frame 110 relative to the base 211, and further can ensure that the screw rod 122 moves smoothly relative to the nut 121 without being stuck, and further can improve the reliability and smoothness of the lifting and lowering of the mechanical joint 100.

[0064] That is, the mechanical joint 100 provided by the embodiment of the present application is hinged by the connecting frame 110 and the base 211, hinged by the nut 121 and the base 211, and hinged by the motor support 124 and the connecting frame 110, thereby forming a movable triangular structure. The screw rod 122 is connected with the driving part 123 and passes through the nut 121, so that the driving part 123 drives the screw rod 122 to rotate to enable the screw rod 122 to move relative to the nut 121, thereby realizing the lifting or lowering of the connecting frame 110 relative to the base 211, and the structure is simple.

[0065] Specifically, as shown in FIG. 5 and FIG. 10, the rotation center of the connecting frame 110 relative to the base 211 is arranged on the base 211, and the hinge point of the connecting frame 110 and the base 211 is point O. The rotation center of the nut 121 relative to the base 211 is arranged on the base 211, and the hinge point of the nut 121 and the base 211 is point N, thereby the distance ON between O and N is constant. Similarly, the rotation center of the motor support 124 relative to the connecting frame 110 is arranged on the connecting frame 110, and the hinge point of the motor support 124 and the connecting frame 110 is point M, thereby the distance OM between O and M is constant. When the position of the base 211 is fixed, the lifting and lowering of the connecting frame 110 can be realized by adjusting the distance MN between the rotation center N of the nut 121 relative to the base 211 and the rotation center M of the motor support 124 relative to the connecting frame 110. Since the screw rod 122 is connected with the nut 121 through the thread structure, when the driving part 123 drives the screw rod 122 to rotate, the nut 121 will move away from or approach the driving part 123, that is, the distance MN between the rotation center N of the nut 121 relative to the base 211 and the rotation center M of the motor support 124 relative to the connecting frame 110 is changed. Therefore, the lifting and lowering of the mechanical joint 100 can be realized by driving the relative movement of the screw rod 122 and the nut 121 through the driving part 123, and the structure is simple and the operation is convenient.

[0066] As shown in FIG. 3, FIG. 5, FIG. 10 and FIG. 13, in some possible implemented embodiments provided by the present application, the lifting assembly 120 further comprises a rotating piece 125, the rotating piece 125 is sleeved on the outside of the screw rod 122, the screw rod 122 is provided with a stepped structure, and the rotating piece 125 is located between the stepped structure and the motor support 124 to enable the screw rod 122 and the motor support 124 to be rotationally connected. Such arrangement enables the axial thrust of the screw rod 122 to be supported by the motor support 124, thereby reducing the friction of the screw rod 122 in movement, and further facilitating the improvement of the service life of the screw rod 122 and the reliability of the mechanical joint 100.

[0067] The rotating piece 125 comprises a bearing or a sleeve to reduce the friction of the screw rod 122 in movement.

[0068] In specific embodiments, since the mechanical joint adopts a threaded pair composed of a lead screw and a nut to perform the lifting or lowering movement of the mechanical joint, the required torque of the driving motor can be calculated according to the following formula:

[0069] ψ = arctan(nP / πd2); p = arctan(1.15μ);

[0070] wherein F is the circumferential load on the threaded pair; d2 is the pitch diameter of the external thread junction; ψ is the thread angle; n is the number of threads in the external thread structure; P is the pitch; p is the equivalent friction angle; and μ is the friction coefficient of the threaded pair. The "+" and "-" in the formula depend on the direction of the friction force in different motion conditions.

[0071] In specific embodiments, the external thread structure specification of the lead screw is TR4, the thread diameter d is about 3.5 mm, the friction coefficient μ of the lead screw and the nut is about 0.25, and the thread lead is 4 mm. Then the thread angle ψ is calculated to be 0.35 rad, and the equivalent friction angle p of the threaded pair composed of the lead screw 122 and the nut 121 is 0.28 rad. The thrust force F2 generated by the driving of the lead screw 122 by the driving part 123 is in the NM direction, and the force arm R2 of the mechanical joint 100 relative to the center of rotation of the base 211 is about 7 mm.

[0072] Suppose that the mechanical arm 200 is in the warehouse, and the load of the aforementioned mechanical joint 100 is T1_1 = 0.5 Nm, and the maximum load in the lifting working state is T1_2 = 3 Nm. Then the stress conditions of the three working conditions are discussed respectively.

[0073] I. Leaving the warehouse

[0074] When the mechanical arm 200 leaves the warehouse, the mechanical joint 100 needs to perform the lifting movement. At this time, the lead screw 122 is driven to rotate by the driving part 123, and the nut 121 moves along the lifting direction of the lead screw 122. As shown in FIG. 10, the nut moves in the Y+ direction.

[0075] For the lead screw 122, it moves in the opposite direction of the lifting direction relative to the nut 121, i.e., the lead screw 122 moves in the Y- direction relative to the nut 121, and the stress diagram is shown in FIG. 11.

[0076] Wherein, Fa is the axial support force of the screw rod 122 received by the rotating part 125; Fm is the circumferential driving force of the driving part 123; Fn is the reverse support force of the nut 121 to the screw rod 122, Ff is the friction force of the nut 121 to the screw rod 122, the resultant force of Fn and Ff is the total reverse force Fr of the nut 121, the included angle between Fr and Fn is the equivalent friction angle p of the screw pair, and y is the thread angle of the external thread structure of the screw rod 122, wherein the direction of Fa is parallel or coincides with the axial direction of the screw rod 122 in the landing folded state of the mechanical arm 200.

[0077] Therefore, according to the force balance triangle, Fm = Fa x arctan (y + p); the torque (motor forward rotation) required to be provided by the motor is: Nm = Fm x d / 2 = Fa x arctan (y + p) x d / 2;

[0078] Based on the foregoing parameters, it is obtained that Fa = 71.4 N, Fm = 51.95 N, and Nm = 0.09 Nm.

[0079] II. Warehouse

[0080] When the mechanical arm 200 is returned to the warehouse, the mechanical joint 100 needs to be lowered and retracted, at this time, the screw rod 122 is driven to rotate by the driving part 123, and the nut 121 moves in the reverse lifting direction of the screw rod 122, as shown in FIG. 5, the nut 121 moves along the screw rod in the Y direction.

[0081] For the screw rod 122, it moves in the lifting direction relative to the nut 121, as shown in FIG. 5, the screw rod 122 moves relative to the nut 121 in the Y+ direction, and the force diagram is as shown in FIG. 6.

[0082] Wherein, Fa is the axial support force of the screw rod 122 received by the rotating part 125; Fm is the circumferential driving force of the driving part 123; Fn is the reverse support force of the nut 121 to the screw rod 122, Ff is the friction force of the nut 121 to the screw rod 122, the resultant force of Fn and Ff is the total reverse force Fr of the nut 121, the included angle between Fr and Fn is the equivalent friction angle p of the screw pair, and y is the thread angle of the external thread structure of the screw rod 122, wherein the direction of Fa is parallel or coincides with the axial direction of the screw rod 122 in the landing folded state of the mechanical arm 200.

[0083] Therefore, according to the force balance triangle, Fm = -Fa x arctan (y - p),

[0084] The torque (motor reverse rotation) required to be provided by the driving part 123 is: Nm = Fm x d / 2 = -Fa x arctan (y - p) x d / 2;

[0085] Since the scheme adopts non-self-locking screw nut 122, i.e. ψ-ρ>0, Fm should be negative. That is, without considering factors such as mechanism bias, friction, motor gear box rotation resistance, etc., the motor driving mechanical joint 100 back to the warehouse basically does not need to provide driving torque. Wherein the direction indicated by the Fm arrow in Figure 6 is the motor rotation direction.

[0086] Based on the foregoing parameters, it is obtained that Fa=71.4N; Fm=-4.9335N; Nm=-0.0086Nm.

[0087] III. In the working position

[0088] When the mechanical arm 200 is kept in the working state, in order to resist the working load to keep the position of the mechanical joint 100, the driving part 123 needs to make the screw nut 121 have a tendency to move along the lifting direction of the screw 122, as shown in Figure 5, that is, the screw nut 121 has a tendency to move along the screw 122 in the Y+ direction. For the screw 122, the force diagram is as shown in Figure 7.

[0089] Wherein, Fa is the axial support force of the screw 122 received by the rotating part 125; Fm is the circumferential driving force of the driving part 123; Fn is the counter support force of the screw nut 121 to the screw 122, Ff is the friction force of the screw nut 121 to the screw 122, the resultant force of Fn and Ff is the total counter force of the screw nut 121, the included angle between Fr and Fn is the equivalent friction angle ρ of the threaded pair, and ψ is the thread angle of the external thread structure of the screw 122. Wherein, the direction of Fa is parallel or coincides with the axial direction of the screw 122 in the lifting state of the mechanical arm 200.

[0090] Then according to the force balance triangle, Fm=Fa×arctan(ψ-ρ), the torque (motor positive rotation) required by the motor is: Nm=Fm×d / 2=Fa×arctan(ψ-ρ)×d / 2

[0091] Based on the foregoing parameters, it is obtained that Fa=428.57N; Fm=29.6N; Nm=0.0518Nm.

[0092] From the above data, it can be seen that at this time, only a small holding torque needs to be provided to the motor, so that the motor can be kept in the working position. When the mechanical joint 100 needs to be pushed down by external force to make the mechanical arm 200 back to the warehouse, the motor is powered off, so that the mechanical joint 100 is unlocked. At this time, a small external force can be used to push the mechanical joint 100 to make the mechanical joint 100 fall, which is convenient for the user to operate. In this way, after the mechanical joint 100 is in the lifting and unfolding state and the driving part 123 is accidentally powered off, the user can use a small force to push the mechanical joint 100 to fall to make the mechanical arm 200 back to the warehouse, which is simple to operate and convenient to use.

[0093] As shown in FIG. 5, FIG. 10, FIG. 12, in some possible implementation embodiments provided by the present application, opposite sides of the outer wall of the nut 121 are provided with first cylindrical bosses 1211, and the base 211 is provided with first accommodating grooves 2111, and the first cylindrical bosses 1211 are accommodated in and rotatable in the first accommodating grooves 2111, so that the nut 121 is hinged to the base 211 through the two sides from the first cylindrical bosses 1211, which is simple in structure, easy to process, low in cost, and suitable for popularization and application. Moreover, such an arrangement enables the rotation range of the nut 121 relative to the base 211 to reach 360°, thereby being able to meet the requirement of a large lifting range of the connecting frame 110 relative to the base 211, and expanding the use range of the product.

[0094] Specifically, the first cylindrical bosses 1211 and the nut 121 can be an integral molding structure or a split structure. When the first cylindrical bosses 1211 and the nut 121 are an integral structure, it is convenient to process and simplifies the operation of connecting the first cylindrical bosses 1211 and the nut 121, and is suitable for mass production. When the first cylindrical bosses 1211 and the nut 121 are a split structure, the first cylindrical bosses 1211 and the nut 121 can be disassembled and separated for maintenance or replacement, thereby saving the cost of maintenance and replacement parts. It can be understood that the first cylindrical bosses 1211 and the nut 121 can be connected by means of a bolt structure, a clamping structure, a mortise and tenon structure, an adhesive, welding, etc.

[0095] As shown in FIG. 5, FIG. 10, in some possible implementation embodiments provided by the present application, opposite sides of the motor support 124 are provided with second cylindrical bosses 1241, and the connecting frame 110 is provided with second accommodating grooves, and the second cylindrical bosses 1241 are accommodated in and rotatable in the second accommodating grooves.

[0096] Therefore, the motor support 124 is hinged to the connecting frame 110 through the second cylindrical bosses 1241 and the second accommodating grooves, which is simple in structure, easy to process, low in cost, and suitable for popularization and application. Such an arrangement enables the rotation range of the motor support 124 relative to the connecting frame 110 to reach 360°, thereby being able to meet the requirement of a large lifting angle of the connecting frame 110 relative to the base 211.

[0097] Specifically, the second cylindrical bosses 1241 and the first cylindrical bosses 1211 are parallel in axis, which can ensure that the nut 121 and the base 211 will not be stuck and the motor support 124 and the connecting frame 110 will not be stuck during the relative movement of the screw rod 122 and the nut 121, so as to ensure the smoothness of the lifting and landing of the connecting frame 110 and improve the smoothness of the lifting and landing of the mechanical joint 100.

[0098] Specifically, the second cylindrical boss 1241 and the motor support 124 can be an integral structure or a split structure. When the second cylindrical boss 1241 and the motor support 124 are an integral structure, it is convenient to process and simplifies the operation of connecting the second cylindrical boss 1241 and the motor support 124, which is suitable for mass production. When the second cylindrical boss 1241 and the motor support 124 are a split structure, the second cylindrical boss 1241 and the motor support 124 can be disassembled and separated for maintenance or replacement, which saves maintenance and replacement costs. It can be understood that the second cylindrical boss 1241 and the motor support 124 can be connected by bolt structure, clamping structure, mortise and tenon structure, adhesive, welding and the like.

[0099] As shown in FIGS. 3, 5 and 10, in some possible implemented embodiments provided by the application, the mechanical joint 100 further comprises a connecting shaft 130, an axis of the connecting shaft 130 is arranged in parallel with the axis of the first cylindrical boss 1211 and is connected to the base 211; the end of the connecting frame 110 close to the base 211 is sleeved outside the connecting shaft 130 and is rotationally connected with the connecting shaft 130, so that the connecting frame 110 and the base 211 are hinged by the rotational connection of the end of the connecting frame 110 close to the base 211 relative to the connecting shaft 130, which is simple in structure and easy to implement.

[0100] The axis of the connecting shaft 130 is arranged in parallel with the axis of the first cylindrical boss 1211, which can ensure that the nut 121 and the base 211 are not stuck during the relative movement of the screw rod 122 and the nut 121, and the connecting frame 110 and the base 211 are not stuck, so as to ensure the smoothness of the lifting and landing of the connecting frame 110 and improve the smoothness of the lifting and landing of the mechanical joint 100.

[0101] The connecting shaft 130 can be relatively fixedly connected to the base 211, i.e., the connecting shaft 130 does not rotate relative to the base 211. Specifically, the connecting shaft 130 can be connected to the base 211 by clamping structure, plug-in structure, mortise and tenon structure, key and the like.

[0102] Further, as shown in FIG. 12, the base 211 is provided with a mounting hole 2112 for mounting the connecting shaft 130, and the mounting hole 2112 and the first accommodating groove 2111 are located on the same side wall of the base 211. For example, the first accommodating groove 2111 and the mounting hole 2112 are arranged on the opposite two side walls of the base 211, and the axis of the first accommodating groove 2111 and the axis of the mounting hole 2112 are arranged in parallel.

[0103] As shown in FIG. 5 and FIG. 10, in some possible implementation embodiments provided by the present application, the connecting frame 110 is provided with a connecting ring 111 near the end of the base 211, the connecting ring 111 is sleeved outside the connecting shaft 130, and the mechanical joint 100 further comprises a connecting bearing 140 connected between the connecting ring 111 and the connecting shaft 130. Thus, the rotating connection of the connecting shaft 130 and the connecting ring 111 can be realized through the connecting bearing 140, and then the rotating connection of the connecting frame 110 and the connecting shaft 130 is realized, so as to realize the hinging of the connecting frame 110 and the base 211, and the structure is simple.

[0104] In the embodiment, the number of the connecting rings 111 is two, and the rotating connection of the two connecting rings 111 and the connecting shaft 130 can improve the reliability and stability of the rotating of the connecting frame 110 relative to the base 211, and then improve the reliability and stability of the lifting and landing of the mechanical joint 100.

[0105] As shown in FIG. 1, FIG. 2, FIG. 8 and FIG. 9, the embodiment of the second aspect of the present application provides a mechanical arm 200, comprising the mechanical joint 100 of any one of the embodiments of the first aspect. Since the mechanical arm 200 comprises the mechanical joint 100 of any one of the preceding embodiments, the mechanical arm 200 has all the beneficial technical effects of the mechanical joint 100, which will not be repeated here.

[0106] Specifically, the mechanical arm 200 further comprises a fixing seat 220, and the mechanical arm 200 is connected with a machine body 310 through the fixing seat 220, so that the installation of the mechanical arm 200 and the machine body 310 can be realized. The end of the mechanical arm 200 further comprises a mechanical hand 250, and the mechanical hand 250 can realize the operations of grabbing and placing objects, so as to realize the grabbing or moving of obstacles, objects and garbage near the cleaning equipment 300.

[0107] Further, in order to improve the flexibility of the movement of the mechanical arm 200, the mechanical arm 200 can further comprise other joints. As shown in FIG. 1 and FIG. 2, the mechanical arm 200 can further comprise a rotating joint 210, a first overturning joint 230 and a second overturning joint 240. The rotating joint 210 is connected with the fixing seat 220, and the rotating joint 210 is rotatable relative to the fixing seat 220. The mechanical joint 100 is connected with the rotating joint 210. Specifically, the base 211 can be a part of the rotating joint 210, and the mechanical joint 100 is lifted or lowered relative to the rotating joint 210. The first overturning joint 230 is connected with the mechanical joint 100, and the first overturning joint 230 and the rotating joint 210 are located at two ends of the mechanical joint 100. The first overturning joint 230 can be lifted or lowered relative to the mechanical joint 100. The second overturning joint 240 and the mechanical joint 100 are located at two ends of the first overturning joint 230, and the second overturning joint 240 can be lifted or lowered relative to the first overturning joint 230. The mechanical hand 250 and the first overturning joint 230 are connected at two ends of the second overturning joint 240.

[0108] That is, the mechanical arm 200 provided by the embodiment of the present application has a fixed seat 220 and a mechanical hand 250 at two ends, and a rotation joint 210, a mechanical joint 100, a first turnover joint 230 and a second turnover joint 240 are sequentially connected from the fixed seat 220 to the mechanical hand 250, so that the movement range of the mechanical arm 200 can be increased, and the cleaning range of the cleaning equipment 300 can be improved, and the use range of the product can be expanded.

[0109] As shown in FIG. 14, the embodiment of the third aspect of the present application provides a cleaning equipment 300, which comprises the mechanical arm 200 provided by any of the foregoing embodiments. Since the cleaning equipment 300 comprises the mechanical arm 200 provided by any of the foregoing embodiments, the cleaning equipment 300 has all the technical effects of the mechanical arm 200, which will not be repeated here.

[0110] The cleaning equipment 300 comprises a main body 310, and the mechanical arm 200 is connected with the main body 310, so that the mechanical arm can move with the main body 310, and can move to a work position with the main body 310 to realize the movement of grabbing the object.

[0111] Further, the main body 310 is provided with a containing cavity, and the fixed seat 220 of the mechanical arm 200 is connected in the containing cavity. The mechanical arm 200 can be accommodated in the containing cavity or extended to the outside of the containing cavity, so that the mechanical arm 200 can be extended to the outside of the containing cavity or accommodated in the containing cavity according to the demand of grabbing the object. Since the containing cavity is arranged on the main body 310, the structure of the main body 310 can be fully utilized, that is, the mechanical arm 200 can be accommodated, the structure is simple, and the design demand of compact structure and small volume of the cleaning equipment 300 can be met. Meanwhile, when the object does not need to be grabbed, the mechanical arm 200 is accommodated in the containing cavity, so that the damage of the mechanical arm 200 caused by the collision of foreign objects can be reduced, and the service life of the mechanical arm 200 can be improved.

[0112] The present disclosure has been described by the above-mentioned embodiments, but it should be understood that the above-mentioned embodiments are only for the purpose of example and illustration, and are not intended to limit the present disclosure to the scope of the described embodiments. In addition, those skilled in the art can understand that the present disclosure is not limited to the above-mentioned embodiments, and more kinds of variations and modifications can be made according to the teaching of the present disclosure, which all fall within the scope of the present disclosure. The protection scope of the present disclosure is defined by the attached claims and their equivalent scope.

Claims

1. A mechanical joint (100) for a mechanical arm (200), wherein the mechanical joint (100) comprises: a connecting frame (110) and a lifting assembly (120), the connecting frame (110) is hinged to a base (211) of the mechanical arm (200), the lifting assembly (120) comprises a nut (121), a screw rod (122) and a driving part (123), the nut (121) is connected with the screw rod (122) by non-self-locking thread and is hinged to the base (211), the driving part (123) is arranged on the connecting frame (110), a first end of the screw rod (122) is connected with the driving part (123), and a second end of the screw rod (122) is arranged in the nut (121). The driving part (123) is configured to drive the screw rod (122) to rotate, so that the screw rod (122) and the nut (121) move relatively to drive the connecting frame (110) to lift or fall relative to the base (211). 2.The mechanical joint (100) of claim 1, wherein the screw rod (122) is provided with an external thread structure (1221), and a thread angle of the external thread structure (1221) is greater than an equivalent friction angle of a thread pair composed of the screw rod (122) and the nut (121). 3.The mechanical joint (100) of claim 2, wherein the screw rod (122) is made of steel, copper or copper alloy; the nut (121) is made of steel, copper or copper alloy. 4.The mechanical joint (100) of claim 3, wherein a pitch diameter of the external thread structure (1221) is 3mm to 6mm, and a lead of the external thread structure (1221) is 2.5mm to 5.5mm. 5.The mechanical joint (100) of any one of claims 1 to 4, wherein the lifting assembly (120) further comprises: a motor support (124), the motor support (124) is hinged to the connecting frame (110), the driving part (123) is mounted on the motor support (124), and the screw rod (122) is arranged in the motor support (124) and connected with the driving part (123). 6.The mechanical joint (100) of claim 5, wherein the lifting assembly (120) further comprises: a rotating member (125), the rotating member (125) is arranged outside the screw rod (122), the screw rod (122) is provided with a stepped structure, and the rotating member (125) is located between the stepped structure and the motor support (124) to connect the screw rod (122) and the motor support (124) rotatably. 7.The mechanical joint (100) of claim 5, wherein Opposite sides of the nut (121) outer wall are provided with first cylindrical bosses (1211), the base (211) is provided with a first containing groove (2111), the first cylindrical boss (1211) is contained in the first containing groove (2111) and can rotate in the first containing groove (2111).

8. The mechanical joint (100) according to claim 7, wherein Opposite sides of the motor support (124) are provided with second cylindrical bosses (1241), the connecting frame (110) is provided with a second containing groove, the second cylindrical boss (1241) is contained in the second containing groove and can rotate in the second containing groove.

9. The mechanical joint (100) according to claim 7, further comprising: A connecting shaft (130), an axis of the connecting shaft (130) is parallel to an axis of the first cylindrical boss (1211) and is connected to the base (211); The end of the connecting frame (110) close to the base (211) is sleeved outside the connecting shaft (130) and is rotationally connected to the connecting shaft (130).

10. The mechanical joint (100) according to claim 9, wherein The end of the connecting frame (110) close to the base (211) is provided with a connecting ring (111), the connecting ring (111) is sleeved outside the connecting shaft (130); The mechanical joint (100) further comprises a connecting bearing (140) connected between the connecting ring (111) and the connecting shaft (130).

11. A robot arm (200) comprising: The mechanical joint (100) according to any one of claims 1 to 10.

12. A cleaning apparatus (300) comprising: The mechanical arm (200) according to claim 11.

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