Multi-attitude adjustment mechanism for a seat

Abstract

This invention relates to the field of seat structure technology, specifically to a multi-posture adjustment mechanism for a seat, comprising: a base, a support arm, a main arm, and a load-bearing part. The base has first and second hinge points at its upper and lower ends. The support arm is divided into a main arm and a secondary arm: the lower end of the main arm is hinged to the first hinge point, and the upper end is hinged to the middle of the main arm; the lower end of the secondary arm is hinged to the second hinge point, and the upper end is hinged to the lower end of the main arm. A first lead screw is parallel to the main arm and rotates; one end of a first connecting rod is hinged to the middle of the main arm, and the other end has a lead screw nut, reciprocating with the rotation of the lead screw. An arc-shaped limiter is located in the middle of the main arm and has an arc-shaped limiting groove. A second lead screw is parallel to the load-bearing part and rotates; one end of a second connecting rod is rotatably connected within the limiting groove, and the other end has a lead screw nut, reciprocating with the rotation of the lead screw. The advantages of this invention are: it achieves stable adjustment of the seat to multiple postures such as sitting, lying, and standing within a limited space, while simultaneously improving load-bearing capacity and operational stability.

Description

Technical Field

[0001] This invention relates to the field of seat structure technology, specifically to a multi-posture adjustment mechanism for seats. Background Technology

[0002] Multi-posture adjustment mechanisms for seats are widely used in medical rehabilitation equipment such as wheelchairs and nursing beds. With the increasing aging population and the growing demand for self-care abilities among people with lower limb dysfunction, wheelchairs with multiple posture adjustment functions, including sitting, lying, and standing, are attracting increasing market attention. To achieve multi-posture adjustment, the common approach is to use an electric push rod as a driving element to move the mechanical structure. For example, the Chinese invention patent "Electric Wheelchair Seat Height and Angle Adjustment System" (application number 201811304614.3) discloses a height adjustment component and an angle adjustment component driven by an electric push rod, which adjusts the seat height and angle through the extension and retraction of the electric push rod.

[0003] However, existing multi-posture adjustment solutions for seats using electric actuators have significant shortcomings in practical applications. First, the electric actuators themselves require considerable installation space, and their cylinders and actuators occupy a large range of motion during extension and retraction. This is particularly disadvantageous for space-constrained devices such as wheelchairs, resulting in a bulky and cumbersome overall structure. Second, the electric actuators have limited load capacity, and are prone to bending and jamming under heavy loads, affecting the stability and reliability of the system. Third, electric actuators typically require the use of complex linkage mechanisms; multiple electric actuators working together not only increase system complexity but also raise manufacturing costs. Furthermore, existing solutions are insufficient in terms of precise control and posture recognition during posture adjustment, failing to meet users' needs for smooth transitions between different postures.

[0004] Therefore, there is an urgent need for a multi-posture adjustment mechanism for seats that is compact, occupies little space, has a strong load-bearing capacity, operates stably, and can achieve precise adjustment of various postures, in order to solve the above-mentioned problems caused by space constraints and insufficient load in the existing technology. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a multi-posture adjustment mechanism for seats, so as to achieve smooth adjustment of the seat to various postures such as sitting, lying down and standing within a limited space, while improving load-bearing capacity and operational stability.

[0006] To achieve the above objectives, a multi-posture adjustment mechanism for a seat is designed, comprising: a base, a support arm hinged at one end to the base, a main arm hinged at the other end of the support arm, and a load-bearing part rotatably connected to the main arm; the upper and lower ends of the base are respectively provided with a first hinge point and a second hinge point; the support arm includes a main support arm and a secondary support arm, the lower end of the main support arm is hinged to the first hinge point and the upper end is hinged to the middle of the main arm, the lower end of the secondary support arm is hinged to the second hinge point and the upper end is hinged to the lower end of the main arm; a first lead screw is parallel to the main arm and rotates axially about the extension direction of the main arm; a first connecting rod is hinged at one end to the middle of the main support arm and the other end is provided with a first lead screw nut, the first lead screw nut being threaded onto the first lead screw and reciprocating with the rotation of the lead screw. The system includes: a traveling motion; an arc-shaped limiter located in the middle of the boom with an arc-shaped limiting groove; a second lead screw parallel to the bearing section, rotating axially around the extension direction of the bearing section; a second connecting rod, one end of which is fitted into the arc-shaped limiting groove and rotatably connected to the arc-shaped limiter, and the other end of which is provided with a second lead screw nut, threaded onto the second lead screw, and reciprocating with the rotation of the lead screw; a first reduction motor and a second reduction motor are respectively provided on the side walls of the boom and the bearing section; worm gears are provided inside the boom and the bearing section and are connected to the first and second reduction motors; the worm gears are also connected to the first and second lead screws to drive the first and second lead screws to rotate axially in both forward and reverse directions.

[0007] Preferably, the present invention further includes: a deformable quadrilateral closed-loop linkage transmission relationship between the main support arm, the auxiliary support arm, the base, and the upper arm; a deformable triangular closed-loop linkage transmission relationship between the first lead screw of the upper arm, the main support arm, and the first connecting rod; a deformable triangular closed-loop linkage transmission relationship between the load-bearing part, the upper arm, and the second connecting rod; and each connecting rod having its hinge point rotate to change its interior angle, and each hinge point sharing the external load.

[0008] Preferably, the present invention further includes: the arc-shaped limiter includes: an arc-shaped stop bar and an arc-shaped stop block, the outer surfaces of the arc-shaped stop bar and the arc-shaped stop block are arc surfaces with the same curvature, and the two are arranged concentrically, with a gap between the arc-shaped stop bar and the arc-shaped stop block, the gap forming an arc-shaped limiting groove with the same curvature; the lower end of the second connecting rod is provided with an arc-shaped protrusion, the upper and lower surfaces of the arc-shaped protrusion are arc surfaces, and the arc surfaces have the same curvature as the arc-shaped stop bar and the arc-shaped stop block, the width of the arc-shaped protrusion matches the groove width of the arc-shaped limiting groove, and is engaged in the arc-shaped limiting groove, the lower end of the second connecting rod makes an arc-shaped sliding movement with a limited angle in the arc-shaped limiting groove through the arc-shaped protrusion.

[0009] Preferably, the present invention further includes: bearings are respectively fitted at both ends of the first lead screw and the second lead screw, and the outer ring of the bearing is connected to the housing of the upper arm and the bearing part to form a rotational limiting connection between the upper arm and the first lead screw, the bearing part and the second lead screw.

[0010] Preferably, the present invention further includes: a potentiometer electrically connected to the first and second geared motors for identifying and outputting the motion of the first and second geared motors; and a controller for converting the motion of the geared motors into the relative angle between the load-bearing part, the boom, and the support arm.

[0011] Preferably, the present invention further includes: the potentiometer for outputting the motion of the motor; the controller for calculating the relative angle between the support part, the upper arm, and the support arm based on the motion, so as to identify the current posture of the seat; the controller for controlling the forward and reverse rotation of the first reduction motor and the second reduction motor, thereby adjusting the rotation of the first lead screw and the second lead screw respectively, thereby changing the angle β between the support part and the upper arm and the angle α between the upper arm and the base, so as to achieve multiple posture adjustments: when α=β, the support part and the base remain parallel, realizing the seat rising or falling in the normal sitting posture; when α remains constant at its minimum and β increases, the seat tilts back to achieve a reclining posture; when β remains constant at its minimum and α increases to 90°, the seat tilts forward to form a standing posture; when α and β increase simultaneously, and the increase in β is greater than the increase in α, the support part tilts forward and rises simultaneously to form an assisted standing posture to assist users with lower limb weakness in standing up.

[0012] Preferably, the present invention further includes: an upper cover plate provided on the supporting part for connecting with the seat surface.

[0013] Compared with the prior art, the advantages of this invention are: The multi-posture adjustment mechanism of this invention uses a geared motor in conjunction with a worm gear and lead screw drive as the drive system, and deeply integrates this drive system with a multi-link mechanical mechanism. By setting the first lead screw parallel to the inside of the upper arm and rotating along the extension direction of the upper arm, and setting the second lead screw parallel to the inside of the support part and rotating along the extension direction of the support part, the lead screws and their drive components make full use of the internal space of the upper arm and the support part, avoiding the large stroke required by an external electric push rod, and significantly reducing the overall space occupation of the mechanism, making it particularly suitable for devices with limited installation space, such as wheelchairs. Meanwhile, the main support arm, auxiliary support arm, base, and upper arm form a quadrilateral closed-loop linkage transmission relationship, while the first lead screw, main support arm, and first connecting rod form a triangular closed-loop linkage transmission relationship. The load-bearing part, upper arm, and second connecting rod also form a triangular closed-loop linkage transmission relationship. Each connecting rod rotates at the hinge point to change the interior angle, and each hinge point shares the external load. This allows the mechanism to distribute the load through multiple hinge points when bearing large loads such as the user's weight, avoiding overload at a single point of force and effectively improving the overall load-bearing capacity and structural stability of the mechanism. Furthermore, by outputting the motion of the first and second geared motors via potentiometers and converting it into the relative angles between the support unit, the upper arm, and the support arm by the controller, the current posture of the seat can be accurately identified. The controller controls the forward and reverse rotation of the two geared motors, adjusting the rotation of the first and second lead screws respectively, thereby changing the angle β between the support unit and the upper arm and the angle α between the upper arm and the base, enabling precise adjustment of various postures: when α equals β, the support unit and the base remain parallel, allowing the seat to rise or fall smoothly in a normal sitting posture; when α remains constant at its minimum and β increases, the seat reclines to a lying posture; when β remains constant at its minimum and α increases to 90°, the seat tilts forward to a standing posture; when α and β increase simultaneously and the increase in β is greater than the increase in α, the support unit rises while tilting forward, effectively assisting users with lower limb weakness in standing up. The arc-shaped limiter guides the arc-shaped protrusion at the lower end of the second connecting rod in a curved sliding manner through its arc-shaped limiting groove, ensuring that the swing angle of the load-bearing part relative to the main arm is limited within a safe range, further improving the safety and reliability of the mechanism's operation. The drive system of this invention is deeply integrated with the mechanical structure. Compared to the traditional solution using two electric push rods, it not only improves load capacity but also enhances system stability and enables automatic recognition and precise adjustment of the seat in multiple postures. Attached Figure Description

[0014] Figure 1 This is a front view of the present invention; Figure 2 This is a rear view of the present invention; Figure 3This is a schematic diagram of the multi-posture of the present invention, wherein Figure (a) is a schematic diagram of the descending state of the conventional sitting posture, Figure (b) is a schematic diagram of the lying posture, Figure (c) is a schematic diagram of the ascending state of the conventional sitting posture, Figure (d) is a schematic diagram of the user being in a standing posture by tilting the seat forward, and Figure (e) is a schematic diagram of the assisted standing posture. Figure 4 This is a schematic diagram of several closed-loop linkage transmission relationships and included angles α and β of the present invention; In the diagram: 1. Base, 1.1 First hinge point, 1.2 Second hinge point, 2. Main support arm, 3. Secondary support arm, 4. First connecting rod, 5. First lead screw nut, 6. First lead screw, 7. Main arm, 8. Second connecting rod, 9. Second lead screw nut, 10. Top cover plate, 11. Second lead screw, 12. Support arm, 13. Arc-shaped limiter, 13.1. Arc-shaped limit groove, 14. Arc-shaped stop bar, 15. Arc-shaped stop block, 16. Arc-shaped protrusion, 17. First reduction motor, 18. Second reduction motor, 19. Worm gear, 20. Seat surface, 21. Included angle α, 22. Included angle β. Detailed Implementation

[0015] To make the purpose, principle and structure of the present invention clearer, the following description is provided in conjunction with the accompanying drawings and specific embodiments.

[0016] like Figure 1 and Figure 2 As shown, the multi-posture adjustment mechanism for a seat provided by the present invention mainly includes a base 1, a main support arm 2, a secondary support arm 3, a first connecting rod 4, a first lead screw nut 5, a first lead screw 6, a large arm 7, a second connecting rod 8, a second lead screw nut 9, an upper cover plate 10, a second lead screw 11, a support arm 12, an arc-shaped limiter 13, an arc-shaped stop bar 14, an arc-shaped stop block 15, an arc-shaped protrusion 16, a first reduction motor 17, a second reduction motor 18, a worm gear 19, and a seat surface 20.

[0017] The base 1 serves as the fundamental support component of the entire mechanism, used to mount and fix the mechanism to the wheelchair frame or other seating carrier. The upper end of the base 1 has a first hinge point 1.1, and the lower end has a second hinge point 1.2. These two hinge points are spaced apart along the height of the base 1 and are used to hinge with the lower ends of the main support arm 2 and the auxiliary support arm 3, respectively. The upper arm 7 is a long, rectangular shell structure, hollow inside to accommodate the first lead screw 6 and related transmission components. The middle and lower ends of the upper arm 7 are respectively equipped with hinge structures for hinge with the upper ends of the main support arm 2 and the auxiliary support arm 3.

[0018] The support unit is located above the upper arm 7 and is used to install the seat surface 20. The support unit is also a hollow shell structure, which houses the second lead screw 11 and related transmission components. A top cover plate 10 is fixedly installed on the support unit. The top cover plate 10 is located on the top of the support unit and is used to directly connect with the seat surface 20. The seat surface 20 is fixedly installed on the upper surface of the top cover plate 10. When the user sits on the seat, the load is transmitted through the seat surface 20 to the top cover plate 10 and then to the entire mechanism.

[0019] The support arm 12 comprises two rods: a main support arm 2 and a secondary support arm 3. The main support arm 2 and the secondary support arm 3 together form a composite support arm 12. The main support arm 2 and the secondary support arm 3 are arranged parallel or approximately parallel to each other between the base 1 and the main arm 7. The lower end of the main support arm 2 is hinged to the upper end of the base 1 at a first hinge point 1.1 via a hinge or pin. The upper end of the main support arm 2 is hinged to the middle of the main arm 7 via a hinge or pin. The lower end of the secondary support arm 3 is hinged to the lower end of the base 1 at a second hinge point 1.2 via a hinge or pin. The upper end of the secondary support arm 3 is hinged to the lower end of the main arm 7 via a hinge or pin. Thus, the base 1, main support arm 2, secondary support arm 3, and upper arm 7 form a deformable quadrilateral closed-loop linkage structure. The four vertices of this quadrilateral closed-loop linkage structure are the hinge points between the base 1 and the main support arm 2, between the main support arm 2 and the upper arm 7, between the secondary support arm 3 and the upper arm 7, and between the secondary support arm 3 and the base 1. Each of the four hinge points can rotate around its respective hinge axis, thereby changing the angles of the quadrilateral's interior angles and achieving the quadrilateral's unfolding and folding deformation. In this quadrilateral closed-loop linkage structure, the main support arm 2 and secondary support arm 3 serve as the side arms, the base 1 as the lower bottom edge, and the upper arm 7 as the upper bottom edge. When the upper arm 7 moves up and down relative to the base 1, the main support arm 2 and secondary support arm 3 swing synchronously, causing the quadrilateral's shape to change. The included angle α21 between the main arm 7 and the support arm 12 is determined by the degree of deformation of the quadrilateral closed-loop linkage structure. Specifically, the included angle α21 is the angle between the extension direction of the main arm 7 and the extension direction of the support arm 12. When the quadrilateral is unfolded, the included angle α21 increases, and when the quadrilateral is folded, the included angle α21 decreases.

[0020] The first lead screw 6 is arranged parallel to the inside of the main arm 7, extending along the length of the main arm 7. Both ends of the first lead screw 6 are connected to the housing of the main arm 7 via bearings. The inner ring of the bearing is fitted onto the end of the first lead screw 6, and the outer ring of the bearing is fixedly connected to the housing of the main arm 7, thus forming a rotational limiting connection between the main arm 7 and the first lead screw 6. This allows the first lead screw 6 to rotate axially around its own axis inside the main arm 7, while simultaneously restricting the first lead screw 6 from displacing relative to the main arm 7 along its own axial direction. One end of the first connecting rod 4 is hinged to the middle of the main support arm 2 via a hinge or pin. The other end of the first connecting rod 4 is provided with a first lead screw nut 5, which is fitted onto the first lead screw 6 and threadedly engaged with it. When the first lead screw 6 rotates around its own axis, the threaded engagement causes the first lead screw nut 5 to reciprocate linearly along the axial direction of the first lead screw 6, thereby moving that end of the first connecting rod 4 along the length of the main arm 7. Since one end of the first connecting rod 4 is hinged to the middle of the main support arm 2, and the other end moves with the first lead screw nut 5, the first lead screw 6, the main support arm 2, and the first connecting rod 4 form a deformable triangular closed-loop connecting rod structure. The three vertices of this triangular closed-loop connecting rod structure are the hinge point between the main support arm 2 and the upper arm 7, the hinge point between the main support arm 2 and the first connecting rod 4, and the position point of the first lead screw nut 5 on the first lead screw 6. The movement of the first lead screw nut 5 along the first lead screw 6 changes the included angle between the first connecting rod 4 and the upper arm 7, thereby pushing the main support arm 2 to swing relative to the upper arm 7. Since the main support arm 2 and the auxiliary support arm 3 are hinged to the upper arm 7 and the base 1 respectively to form a quadrilateral closed-loop connecting rod structure, the swing of the main support arm 2 causes the entire quadrilateral closed-loop connecting rod structure to deform, thereby increasing or decreasing the included angle α21 between the upper arm 7 and the support arm 12. The first reduction motor 17 is mounted on the side wall of the boom 7. Specifically, the first reduction motor 17 is fixedly installed at a suitable position on the outer side wall of the boom 7. The output shaft of the first reduction motor 17 extends into the boom 7 and is connected to the worm gear 19 for transmission. Several worm gears 19 are arranged inside the boom 7, and these worm gears 19 are respectively connected to the output shaft of the first reduction motor 17 and the first lead screw 6 for transmission. Specifically, the output shaft end of the first reduction motor 17 has a worm structure, which meshes with the worm gear 19. The worm gear 19 is fixedly sleeved on the end of the first lead screw 6 or connected to the first lead screw 6 through a coupling. When the first reduction motor 17 is energized, its output shaft drives the worm to rotate, the worm drives the worm gear 19 to rotate, and the worm gear 19 drives the first lead screw 6 to rotate axially in either forward or reverse direction, thereby realizing the drive of the first lead screw 6 by the first reduction motor 17.

[0021] The second lead screw 11 is arranged parallel to the inside of the bearing part, along the length extension direction of the bearing part. Both ends of the second lead screw 11 are connected to the housing of the bearing part via bearings. The inner ring of the bearing is fitted onto the end of the second lead screw 11, and the outer ring of the bearing is fixedly connected to the housing of the bearing part, thus forming a rotational limiting connection between the bearing part and the second lead screw 11. This allows the second lead screw 11 to rotate axially around its own axis inside the bearing part, while simultaneously limiting the displacement of the second lead screw 11 relative to the bearing part along its own axial direction. The arc-shaped limiter 13 is located in the middle of the upper arm 7, specifically on the side wall at the symmetrical center point of the upper arm 7. The arc-shaped limiter 13 includes an arc-shaped stop bar 14 and an arc-shaped stop block 15. Both the arc-shaped stop bar 14 and the arc-shaped stop block 15 are arc-shaped block structures with a certain thickness. The outer surfaces of the arc-shaped stop bar 14 and the arc-shaped stop block 15 are arc surfaces with the same curvature, and the arc-shaped stop bar 14 and the arc-shaped stop block 15 are concentric, meaning their arc curvature centers are located at the same point. A gap is left between the arc-shaped stop bar 14 and the arc-shaped stop block 15, which forms an arc-shaped limiting groove 13.1. The arc-shaped limiting groove 13.1 also has the same curvature as the outer arc surface of the arc-shaped stop bar 14 and the arc-shaped stop block 15, that is, the arc-shaped limiting groove 13.1 has an arc-shaped curved groove structure. One end of the second connecting rod 8 is provided with an arc-shaped protrusion 16. The upper and lower sides of the arc-shaped protrusion 16 are both arc surfaces, and the curvature of the arc surface is the same as that of the arc-shaped stop bar 14 and the arc-shaped stop block 15. The width of the arc-shaped protrusion 16 matches the groove width of the arc-shaped limiting groove 13.1. The arc-shaped protrusion 16 is engaged in the arc-shaped limiting groove 13.1 and can slide freely in the arc-shaped limiting groove 13.1. Since the curvature of the arc-shaped protrusion 16 matches the curvature of the arc-shaped limiting groove 13.1, the movement trajectory of the arc-shaped protrusion 16 in the arc-shaped limiting groove 13.1 is limited to an arc-shaped trajectory centered on the center of the arc-shaped stop bar 14 and the arc-shaped stop block 15. That is, the arc-shaped protrusion 16 can only make arc-shaped sliding movements along the arc-shaped limiting groove 13.1 with a limited angle, and cannot leave the arc-shaped limiting groove 13.1. One end of the second connecting rod 8 is engaged in the arc-shaped limiting groove 13.1 through the arc-shaped protrusion 16 to achieve a sliding connection with the arc-shaped limiter 13. At the same time, the arc-shaped limiter 13 is fixedly set in the middle of the upper arm 7, so this end of the second connecting rod 8 can swing in an arc relative to the upper arm 7. The other end of the second connecting rod 8 is provided with a second lead screw nut 9, which is sleeved on the second lead screw 11 and threadedly engaged with the second lead screw 11. When the second lead screw 11 rotates around its own axis, the second lead screw nut 9 reciprocates linearly along the axial direction of the second lead screw 11 through the threaded engagement, thereby driving the end of the second connecting rod 8 to move along the length direction of the bearing part.Since one end of the second connecting rod 8 is connected to the arc-shaped limiter 13 via the arc-shaped protrusion 16 and can slide around the arc-shaped limit groove 13.1, and the other end moves with the second lead screw nut 9, a deformable triangular closed-loop connecting rod structure is formed between the bearing part, the upper arm 7, and the second connecting rod 8. The three vertices of this triangular closed-loop connecting rod structure are the sliding position of the arc-shaped protrusion 16 on the arc-shaped limiter 13, the position of the second lead screw nut 9 on the second lead screw 11, and the hinge point or connection point between the bearing part and the upper arm 7. The movement of the second lead screw nut 9 along the second lead screw 11 changes the included angle β22 between the bearing part and the upper arm 7, thereby changing the tilt angle of the bearing part relative to the upper arm 7. The second reduction motor 18 is set on the side wall of the bearing part. Specifically, the second reduction motor 18 is fixedly installed at a suitable position on the outer side wall of the bearing part, and the output shaft of the second reduction motor 18 extends into the interior of the bearing part and is connected to the worm gear 19 for transmission. A worm gear 19 is also provided inside the bearing section. This worm gear 19 is connected to the output shaft of the second reduction motor 18 and the second lead screw 11. Specifically, the output shaft of the second reduction motor 18 is provided with a worm structure, which meshes with the worm gear 19. The worm gear 19 is fixedly sleeved on the end of the second lead screw 11 or connected to the second lead screw 11 through a coupling. When the second reduction motor 18 is powered on, its output shaft drives the worm to rotate, the worm drives the worm gear 19 to rotate, and the worm gear 19 drives the second lead screw 11 to rotate axially in either forward or reverse direction, thereby realizing the drive of the second lead screw 11 by the second reduction motor 18.

[0022] In the multi-posture adjustment mechanism of the seat of the present invention, each hinge point is connected by a pin or hinge, allowing the links to rotate relative to each other. Specifically, the hinge points between the main support arm 2 and the base 1, the main support arm 2 and the upper arm 7, the auxiliary support arm 3 and the base 1, the auxiliary support arm 3 and the upper arm 7, the first link 4 and the main support arm 2, the connection point between the first lead screw nut 5 and the first link 4, the sliding engagement point between the arc-shaped protrusion 16 and the arc-shaped limiter 13, and the connection point between the second lead screw nut 9 and the second link 8, all allow the connected components to rotate relative to each other around the hinge axis, thereby changing the internal angle of each link structure by rotating each hinge point. Meanwhile, the aforementioned hinge points share the external load in actual use. That is, when the user sits on the seat 20, the user's weight and the load in various postures are transmitted through the seat 20 to the upper cover 10 and the load-bearing part, and then distributed through the hinge points to the upper arm 7, the first link 4, the second link 8, the main support arm 2, the auxiliary support arm 3 and the base 1, and finally to the wheelchair frame. The hinge points share the load, avoiding the concentration of the load on a single hinge point.

[0023] like Figure 3 and Figure 4As shown, the multi-posture adjustment mechanism of the seat of the present invention is further provided with a potentiometer and a controller (not shown in the figure). The potentiometer is electrically connected to the first reduction motor 17 and the second reduction motor 18 respectively. The potentiometer is used to identify and output the motion of the first reduction motor 17 and the second reduction motor 18. Specifically, the potentiometer can be configured as an angular displacement sensor that rotates synchronously with the output shaft of the reduction motor, and outputs an electrical signal representing the motion of the motor by detecting the rotation angle of the output shaft of the reduction motor. The controller is electrically connected to the potentiometer, the first reduction motor 17 and the second reduction motor 18 respectively. The controller receives the motion signal output by the potentiometer and calculates the relative angle between the bearing part, the upper arm 7 and the support arm 12 based on the motion. Since the motion of the first reduction motor 17 is proportional to the number of rotations of the first lead screw 6, and the number of rotations of the first lead screw 6 is proportional to the displacement of the first lead screw nut 5 along the first lead screw 6, this displacement determines the angle between the first connecting rod 4 and the upper arm 7, and thus determines the degree of deformation of the quadrilateral closed-loop connecting rod structure and the angle α21 between the upper arm 7 and the support arm 12, the controller can calculate the current value of the angle α21 based on the motion of the first reduction motor 17. Similarly, the motion of the second reduction motor 18 is proportional to the number of rotations of the second lead screw 11, and the number of rotations of the second lead screw 11 is proportional to the displacement of the second lead screw nut 9 along the second lead screw 11, this displacement determines the angle between the second connecting rod 8 and the bearing part, and thus determines the angle β22 between the bearing part and the upper arm 7, the controller can calculate the current value of the angle β22 based on the motion of the second reduction motor 18. The controller can identify the current posture of the seat by calculating the included angles α21 and β22.

[0024] The controller adjusts the rotation direction of the first lead screw 6 and the second lead screw 11 by controlling the forward and reverse rotation of the first reduction motor 17 and the second reduction motor 18, thereby changing the size of the included angles α21 and β22 and achieving precise adjustment of various postures.

[0025] Specifically, when the seat needs to be raised in a normal sitting posture, the controller controls the first reduction motor 17 and the second reduction motor 18 to operate in the same direction and at the same speed, so that the included angles α21 and β22 increase synchronously and keep the value of angle α equal to the value of angle β. At this time, the support part is parallel to the base 1, the entire mechanism unfolds in the vertical direction, the seat surface 20 rises, and the seat surface 20 remains horizontal.

[0026] When the seat needs to be lowered in a normal sitting posture, the controller controls the first reduction motor 17 and the second reduction motor 18 to run in opposite directions or in the same direction and at the same speed, so that the included angles α21 and β22 decrease synchronously and the value of angle α is equal to the value of angle β. At this time, the support part is parallel to the base 1, the entire mechanism folds in the vertical direction, the seat surface 20 is lowered, and the seat surface 20 remains horizontal.

[0027] When the seat needs to be reclined to a lying position, the controller controls the first reduction motor 17 to maintain the current state so that the included angle α21 remains at its minimum, while controlling the second reduction motor 18 to rotate forward so that the included angle β22 increases. At this time, the support part swings backward relative to the upper arm 7, the rear end of the upper cover 10 and the front end of the seat 20 descend and rises, and the user reclines with the seat 20 to achieve a lying position.

[0028] When it is necessary to tilt the seat forward to a standing position, the controller controls the second reduction motor 18 to maintain the current state so that the included angle β22 remains at its minimum, while controlling the first reduction motor 17 to rotate forward so that the included angle α21 increases to 90°. At this time, the upper arm 7 swings forward relative to the base 1 to a near-vertical state, and the support part and the seat 20 tilt forward with the upper arm 7. The seat 20 changes from horizontal to near vertical, and the user tilts forward with the seat 20 to form a standing position.

[0029] When a user with lower limb weakness needs assistance to stand up, the controller controls the first reduction motor 17 and the second reduction motor 18 to rotate forward simultaneously, increasing the included angles α21 and β22 at the same time. The controller also controls the rotation speed of the second reduction motor 18 to be greater than that of the first reduction motor 17, so that the increase in included angle β22 is greater than the increase in included angle α21. At this time, the support part tilts forward and rises to a certain height, and the seat 20 gradually tilts forward and moves diagonally upward, forming an assisted standing posture to help the user transition from a sitting to a standing posture.

[0030] The arc-shaped limiter 13 guides the arc-shaped protrusion 16 at the lower end of the second connecting rod 8 through the arc-shaped limiting groove 13.1 in a curved sliding manner, limiting the swing angle of the bearing part relative to the upper arm 7 within the range of the central angle corresponding to the arc-shaped limiting groove 13.1. This prevents excessive swing of the bearing part from causing safety hazards and ensures the operational safety of the mechanism during various posture adjustments. The arc surface cooperation between the arc-shaped protrusion 16 and the arc-shaped limiting groove 13.1 significantly increases the contact area between the end of the second connecting rod 8 and the arc-shaped limiter 13 compared to the traditional hinge connection of a cylindrical pin and a round hole. This avoids stress concentration caused by the load being concentrated at a single contact point, effectively reducing the pressure at the connection end of the second connecting rod 8 and improving the fatigue resistance and service life of this connection part.

[0031] In one specific embodiment of the present invention, the base 1 is fixedly mounted on the chassis of the wheelchair, and the seat 20 is fixedly mounted on the upper cover 10 for the user to sit on. When the user needs to adjust the seat posture, he / she issues a command through the operation controller. The controller controls the rotation direction and speed of the first reduction motor 17 and the second reduction motor 18 according to the command, thereby realizing the switching of the various postures mentioned above. During the posture switching process, the potentiometer outputs the motor motion signal to the controller in real time. The controller calculates the current values ​​of the included angles α21 and β22 in real time and feeds back the current posture information for closed-loop control to ensure the accuracy and stability of posture adjustment.

[0032] The above description is merely a specific embodiment of the invention, but the scope of protection of the invention is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the invention, based on the technical solution and concept of the invention, should be covered within the scope of protection of the invention.

Claims

1. A multi-posture adjustment mechanism for a seat, characterized in that, include: A base, a support arm hinged to the base at one end, a main arm hinged to the other end of the support arm, and a load-bearing part rotatably connected to the main arm. The base has a first hinge point and a second hinge point at its upper and lower ends, respectively. The outrigger includes a main outrigger and a secondary outrigger. The lower end of the main outrigger is hinged to the first hinge point and the upper end is hinged to the middle of the main arm. The lower end of the secondary outrigger is hinged to the second hinge point and the upper end is hinged to the lower end of the main arm. The first lead screw is set parallel to the boom and rotates axially around the extension direction of the boom. The first connecting rod is hinged at one end to the middle of the main support arm, and the other end is provided with a first lead screw nut. The first lead screw nut is threaded onto the first lead screw and reciprocates with the rotation of the lead screw. An arc-shaped limiter is installed in the middle of the boom, and an arc-shaped limit groove is provided on it; The second lead screw is arranged parallel to the bearing part and rotates axially around the extension direction of the bearing part. The second connecting rod has one end fitted in the arc-shaped limiting groove and rotatably connected to the arc-shaped limiter, and the other end is provided with a second lead screw nut. The second lead screw nut is threaded on the second lead screw and reciprocates with the rotation of the lead screw. The upper arm and the load-bearing part are respectively provided with a first reduction motor and a second reduction motor on their side walls. The upper arm and the load-bearing part are provided with a worm gear that is connected to the first reduction motor and the second reduction motor. The worm gear is also connected to the first lead screw and the second lead screw respectively, and is used to drive the first lead screw and the second lead screw to rotate axially in both forward and reverse directions.

2. The seat multi-posture adjustment mechanism as described in claim 1, characterized in that, The main arm, auxiliary arm, base, and boom form a deformable quadrilateral closed-loop linkage transmission relationship. A deformable triangular closed-loop linkage transmission relationship is formed between the first lead screw of the boom, the main support arm, and the first connecting rod; A deformable triangular closed-loop linkage transmission relationship is formed between the load-bearing part, the boom, and the second link; Each link rotates at its hinge point to change the interior angle, and each hinge point shares the external load.

3. The seat multi-posture adjustment mechanism as described in claim 1, characterized in that, The arc-shaped limiter includes: The arc-shaped baffle and the arc-shaped block have outer surfaces with the same curvature and are arranged at the same center. A gap is left between the arc-shaped baffle and the arc-shaped block, and the gap forms an arc-shaped limiting groove with the same curvature. The lower end of the second connecting rod is provided with an arc-shaped protrusion. The upper and lower sides of the arc-shaped protrusion are both arc surfaces, and the curvature of the arc surface is the same as that of the arc-shaped stop bar and the arc-shaped stop block. The width of the arc-shaped protrusion matches the width of the arc-shaped limiting groove and is locked in the arc-shaped limiting groove. The lower end of the second connecting rod makes a limited-angle arc-shaped sliding movement in the arc-shaped limiting groove through the arc-shaped protrusion.

4. The seat multi-posture adjustment mechanism as described in claim 1, characterized in that, Bearings are respectively fitted at both ends of the first lead screw and the second lead screw. The outer ring of the bearing is connected to the housing of the upper arm and the load-bearing part, forming a rotational limiting connection between the upper arm and the first lead screw, the load-bearing part and the second lead screw.

5. A seat multi-posture adjustment mechanism as described in claim 1, characterized in that, It also includes a potentiometer, which is electrically connected to the first and second geared motors, and is used to identify and output the motion of the first and second geared motors. It also includes a controller for calculating the motion of the geared motor and the relative angles between the load-bearing part, the boom, and the outrigger.

6. A seat multi-posture adjustment mechanism as described in claim 5, characterized in that, The potentiometer is used to output the amount of motion of the motor, and the controller calculates the relative angle between the load-bearing part, the upper arm and the support arm based on the amount of motion to identify the current posture of the seat. The controller adjusts the rotation of the first and second lead screws by controlling the forward and reverse rotation of the first and second reduction motors, thereby changing the angle β between the support part and the upper arm and the angle α between the upper arm and the base to achieve various posture adjustments. When α=β, the supporting part remains parallel to the base, enabling the seat to rise or fall in a normal sitting posture; When α remains at its minimum and β increases, the seat reclines to a lying position. When β remains at its minimum and α increases to 90°, the seat tilts forward, forming a standing posture. When α and β increase simultaneously, and the increase in β is greater than the increase in α, the supporting part rises while tilting forward, forming an auxiliary standing posture to assist users with weak lower limbs to stand up.

7. A multi-posture adjustment mechanism for a seat as described in claim 1, characterized in that, The supporting part is provided with an upper cover plate for connecting with the seat surface.

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