Flexible constant force mechanism capable of avoiding stress stiffening

Abstract

The flexible constant force mechanism comprises a base and a guide rod, the base is of a semi-closed frame structure, a frame space is formed in the base, a negative stiffness structure and a positive stiffness structure are sequentially arranged in the base from top to bottom, a fixing rod is arranged on the inner bottom face of the base, and the guide rod is connected with the negative stiffness structure and the positive stiffness structure. The fixing rod is connected with the positive stiffness structure, one end of the guide rod is movably inserted into the base and sequentially connected with the negative stiffness structure and the positive stiffness structure, the other end of the guide rod is exposed out of the base, and the guide rod right faces the fixing rod. The integral structure is symmetrical and compact, machining and forming are simple, the integral movement stroke is large, the positive stiffness mechanism and the negative stiffness mechanism are connected through the guide rod, the stress condition is good, the output force fluctuation is small, the positive stiffness mechanism avoids the stress stiffening effect, and stable and high-precision constant force can be provided.

Description

Technical Field

[0001] The utility model relates to the field of power machinery, in particular to a flexible constant force mechanism capable of avoiding stress rigidification. Background Art

[0002] The force mechanism can provide an almost constant output force within a certain displacement range. The constant force mechanism is particularly important for situations where the displacement input is uncertain and the reaction force must be constant. The constant force mechanism has been widely used in many fields and occasions. For example, the constant force mechanism can be used in the manual operating system of a car, such as manual shifter, handbrake, etc. It can provide a constant force, making manual operation easier and more precise. It can be widely used in aerospace, electronics, medical equipment, precision machining, etc.

[0003] Currently, the way to obtain constant force is to introduce a force sensor and then adjust the output of constant force through a control system. However, the production cost of the entire system is high and the design is relatively complex; or the energy storage characteristics of the spring are used instead of the rigid mechanism to achieve constant force output. However, the constant force output by this method fluctuates greatly and is difficult to meet the needs of actual applications. Utility Model Content

[0004] In order to solve the above technical problems, the utility model provides a flexible constant force mechanism that can avoid stress rigidification.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A flexible constant force mechanism that can avoid stress stiffening includes a base and a guide rod. The base is a semi-closed frame structure. A frame space is formed in the base. A negative stiffness structure and a positive stiffness structure are arranged in the base from top to bottom. A fixed rod is provided on the bottom surface of the base. The fixed rod is connected to the positive stiffness structure. One end of the guide rod is movably inserted into the base and is connected to the negative stiffness structure and the positive stiffness structure in sequence. The other end of the guide rod is exposed outside the base, and the guide rod is opposite to the fixed rod.

[0007] As a further improvement, the negative stiffness structure includes at least two groups of flexible oblique beams, an even number of which are inclined in each group, and the flexible oblique beams are inclined in the same direction.

[0008] As a further improvement, the negative stiffness structure includes two groups of flexible oblique beams, one group of flexible oblique beams is arranged on one side of the guide rod, and the other group of flexible oblique beams is arranged on the other side of the guide rod. The two groups of flexible oblique beams are symmetrically arranged with the guide rod as the center, and an angle greater than 0 is formed between the flexible oblique beams and the horizontal line, and the two groups of flexible oblique beams are respectively connected to the side walls of the base.

[0009] As a further improvement, a group of flexible inclined beams includes at least two flexible inclined plates spaced apart from each other, and the at least two flexible plates are inclined upward.

[0010] As a further improvement, the side wall of the base is provided with a horizontal protrusion, and the flexible inclined sheet is connected to the horizontal protrusion.

[0011] As a further improvement, the connection positions of the two groups of flexible inclined beams and the guide rods are located on the same horizontal line.

[0012] As a further improvement, the positive stiffness structure includes at least four groups of flexible straight beams in an even number, and the angle between the flexible straight beams and the horizontal line is 0.

[0013] As a further improvement, the positive stiffness structure includes four groups of flexible straight beams, two of which are arranged on one side of the guide rod, and the other two groups are arranged on the other side of the guide rod, and are symmetrically distributed on the left and right sides with the guide rod as the center;

[0014] As a further improvement, the two groups of flexible straight beams located on the same side of the guide rod are connected in series through a connecting piece, and one group of flexible straight beams is connected to the guide rod, and the other group of flexible straight beams is connected to the fixed rod.

[0015] As a further improvement, a group of flexible straight beams includes a connecting block and two flexible straight pieces spaced apart from each other. One side of the connecting block is connected to one of the flexible straight pieces, and the other side of the connecting block is connected to the other flexible straight piece.

[0016] As a further improvement, a guide hole is provided on the base, an edge of the guide hole is provided with a groove, and the guide rod is movably inserted into the base through the guide hole.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects:

[0018] The overall structure is symmetrical and compact, the processing and molding are simple, and the overall motion range is large;

[0019] The positive and negative stiffness mechanisms are connected by a guide rod, and the negative stiffness structure is located close to the output end, while the positive stiffness structure is located at the innermost part of the base. The force is well-bearing and the output force fluctuation is small. The positive stiffness mechanism avoids the stress stiffening effect and can provide stable and high-precision constant force. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the three-dimensional structure of the utility model;

[0021] Figure 2 This is a schematic diagram of the main structure of the utility model.

[0022] Reference numerals:

[0023] Output end 1 of the guide rod, guide rod 2, flexible inclined beam 3, flexible inclined piece 31, connecting block 4, base 5, groove 6, fixing rod 7, flexible straight beam 8, flexible straight piece 81. DETAILED DESCRIPTION

[0024] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention.

[0025] In the description of the present invention, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like are used to indicate the orientation or position relationship based on the orientation or position relationship shown in the accompanying drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0026] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed connections, removable connections, or integral connections. They may refer to mechanical connections or electrical connections. They may refer to direct connections or indirect connections through an intermediary, and they may refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of these terms in this utility model based on the specific circumstances.

[0027] Example 1

[0028] like Figure 1 and 2As shown, a flexible constant force mechanism that can avoid stress stiffening includes a base 5 and a guide rod 2. The base 5 is a semi-enclosed frame structure. A frame space is formed within the base 5. The base 5 is provided with a negative stiffness structure and a positive stiffness structure from top to bottom. A fixed rod 7 is provided on the bottom surface of the base 5, and the fixed rod 7 is connected to the positive stiffness structure. One end of the guide rod 2 is movably inserted into the base and connected to the negative stiffness structure and the positive stiffness structure in sequence. The other end of the guide rod is exposed outside the base, and the guide rod is directly opposite the fixed rod. The semi-enclosed frame structure of the base is formed into a rectangular shape by bending the external profile. To facilitate the insertion of the guide rod, a guide hole is provided on one side of the base. The size of the guide hole is larger than the guide rod, ensuring that the guide rod can move freely after being inserted through the guide hole and output the applied force outward. There is only one frame space within the base, and the negative stiffness structure and the positive stiffness structure are both in the same space, which helps to achieve better control and buffering. The end of the guide rod exposed outside the base is the output end.

[0029] For the overall structure, the negative stiffness structure is located near the output port and is connected to both the guide rod and the side wall of the base. The positive stiffness structure is connected to the guide rod at one end and the fixed rod at the other. The positive stiffness mechanism can avoid the stress stiffening effect and provide a more stable and higher-precision constant force for the overall compliant constant force mechanism.

[0030] In addition, a plurality of grooves are provided at the edge of the guide hole to facilitate the installation of the guide plate. The guide rod can be preferably selected as a quadrangular prism.

[0031] Example 2

[0032] refer to Figure 1 and 2 As shown, the negative stiffness structure includes two sets of flexible inclined beams 3, one set of which is located on one side of the guide rod 2, and the other set of which is located on the other side of the guide rod 2. The two sets of flexible inclined beams are symmetrically arranged around the guide rod, forming an angle greater than 0 with the horizontal line, preferably 8 degrees with the horizontal line. The two sets of flexible inclined beams are respectively connected to the side walls of the base. The connection points of the two sets of flexible inclined beams and the guide rod are on the same horizontal line.

[0033] Each set of flexible oblique beams 3 includes two spaced-apart flexible slats 31, each inclined upward at the same angle, forming two flexible slats on the same side of the guide rod. One end of each flexible slat is connected to the guide rod, and a horizontal bump can be provided on the inner sidewall of the base. The other end of each flexible slat is also connected to the horizontal bump. Because the two flexible slats in the same set of flexible oblique beams are spaced apart, a gap exists between them, facilitating force buffering. The number and shape of the flexible slats on both sides of the guide rod remain the same.

[0034] The flexible inclined piece is elastic and inclined toward the output end, which can achieve better flexible force transmission.

[0035] Example 3

[0036] refer to Figure 1 and 2 As shown, the positive stiffness structure comprises four sets of flexible beams 8, two of which are located on one side of the guide rod 2, and the other two on the other side. These beams are symmetrically arranged left and right around the guide rod, with the angle between the flexible beams and the horizontal being 0 degrees. Each set of flexible beams 8 comprises a connecting block 4 and two flexible straight pieces 81 spaced vertically apart. One side of the connecting block is connected to one of the flexible straight pieces, and the other side of the connecting block is connected to the other flexible straight piece.

[0037] For ease of description, four groups of flexible beams are defined. Those located on the left side of the guide rod are defined as the upper left flexible beam and the lower left flexible beam, respectively. Those located on the right side of the guide rod are defined as the upper right flexible beam and the lower right flexible beam, respectively. The two flexible straight pieces in the upper left flexible beam are connected via a connecting block. One flexible straight piece in the upper left flexible beam is connected to one flexible straight piece in the lower left flexible beam. The two flexible straight pieces in the lower left flexible beam are connected to each other, and the other flexible straight piece in the lower left flexible beam is connected to the fixed rod. The upper right and lower right flexible beams are connected in the same manner as the upper left and lower left flexible beams.

[0038] In the positive stiffness structure, a total of 8 flexible straight pieces and 6 connecting blocks are provided, and two adjacent flexible straight pieces on the same side of the guide rod are connected by the connecting block.

[0039] The base, guide rods, positive stiffness structure, negative stiffness structure, and fixed rod are all 3D-printed from PLA, reducing manufacturing complexity. The guide rods connect the positive and negative stiffness mechanisms, ensuring good force distribution and minimal output force fluctuation. The positive stiffness mechanism avoids stress stiffening effects, providing stable, highly precise constant force.

[0040] It should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent replacements for some of the technical features therein. However, any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A flexible constant force mechanism capable of avoiding stress rigidification, comprising a base and a guide rod, characterized in that: The base is a semi-closed frame structure, and a frame space is formed inside the base. A negative stiffness structure and a positive stiffness structure are arranged in sequence from top to bottom in the base. A fixed rod is provided on the bottom surface of the base, and the fixed rod is connected to the positive stiffness structure. One end of the guide rod is movably inserted into the base and is connected to the negative stiffness structure and the positive stiffness structure in sequence. The other end of the guide rod is exposed outside the base, and the guide rod is facing the fixed rod.

2. The flexible constant force mechanism capable of avoiding stress rigidification according to claim 1, characterized in that: The negative stiffness structure includes at least two groups of flexible inclined beams, which are an even number, and each group of flexible inclined beams is inclined in the same direction.

3. The flexible constant force mechanism capable of avoiding stress rigidification according to claim 2, characterized in that: The negative stiffness structure includes two groups of flexible oblique beams, one group of flexible oblique beams is arranged on one side of the guide rod, and the other group of flexible oblique beams is arranged on the other side of the guide rod. The two groups of flexible oblique beams are symmetrically arranged with the guide rod as the center, and an angle greater than 0 is formed between the flexible oblique beams and the horizontal line, and the two groups of flexible oblique beams are respectively connected to the side walls of the base.

4. The flexible constant force mechanism capable of avoiding stress rigidification according to claim 3, characterized in that: A group of flexible inclined beams includes at least two flexible inclined sheets spaced apart from each other, and the at least two flexible sheets are inclined upward.

5. The flexible constant force mechanism capable of avoiding stress rigidification according to claim 4, characterized in that: The side wall of the base is provided with a horizontal protrusion, and the flexible inclined sheet is connected to the horizontal protrusion.

6. The flexible constant force mechanism capable of avoiding stress rigidification according to claim 3, characterized in that: The connection positions of the two groups of flexible oblique beams and the guide rods are located on the same horizontal line.

7. The flexible constant force mechanism capable of avoiding stress rigidification according to claim 1, characterized in that: The positive stiffness structure includes at least four groups of flexible straight beams in an even number, and the angle between the flexible straight beams and the horizontal line is 0.

8. The flexible constant force mechanism capable of avoiding stress rigidification according to claim 7, characterized in that: The positive stiffness structure includes four groups of flexible straight beams, two of which are arranged on one side of the guide rod, and the other two groups are arranged on the other side of the guide rod, and are symmetrically distributed on the left and right sides with the guide rod as the center; The two groups of flexible straight beams located on the same side of the guide rod are connected in series through a connecting piece, and one group of flexible straight beams is connected to the guide rod, and the other group of flexible straight beams is connected to the fixed rod.

9. The flexible constant force mechanism capable of avoiding stress rigidification according to claim 8, characterized in that: A group of flexible straight beams includes a connecting block and two flexible straight pieces spaced apart from each other. One side of the connecting block is connected to one of the flexible straight pieces, and the other side of the connecting block is connected to the other flexible straight piece.

10. The flexible constant force mechanism capable of avoiding stress rigidification according to claim 1, characterized in that: The base is provided with a guide hole, the edge of the guide hole is provided with a groove, and the guide rod is movably inserted into the base through the guide hole.

Images