Scissor fork joint type lifting mechanism

Abstract

The invention discloses a scissor-fork joint type lifting mechanism, belongs to the field of mechanical transmission, and mainly aims at overcoming the defects that an existing lifting table is poor in stability, large in weight, low in lifting height and the like. The lifting body is characterized in that all the rhombic latticed bearing surfaces are connected together through the bent connecting pin shafts, the freedom degree of all the surfaces is limited, the seesaw effect is avoided, the lifting body of a triangular truss structure, a quadrilateral truss structure and the like is formed, and the stability is greatly improved. Especially, the triangular structure also has the characteristic of good stability of the triangle, the structure is simpler, the weight is lighter, and due to the super-good stability, the consumption of raw materials and the dependence on high-quality materials can be further reduced, and the gravity center and the cost of the product are also reduced. Due to the fact that the proportional relation n and the assembly relation n-1 of the long bearing rod and the short bearing rod are found, the lifting device can be achieved, otherwise, only the equilateral shape can ascend and descend. And different length * width size requirements of the lifting platform can be met by different n. Three kinds of lifting assemblies which are unconventional and unorthodox are also bright spots, especially the first kind of umbrella-shaped structure.

Description

Technical Field

[0001] The present invention is a hydraulic-mechanical lifting mechanism, belonging to the field of mechanical transmission, and is widely applied to lifting platforms and devices with requirements for linear transmission. Background Art

[0002] Currently, the widely used lifting platforms generally have defects such as poor stability, large weight, poor safety performance, insufficient lifting height, etc. The reasons for this situation are analyzed as follows: See Figure 1 , a rhombic grid-shaped load-bearing surface assembly is formed by stacking multiple layers of long load-bearing rods 1 and direct pin shafts 2. The two assemblies are placed in parallel, playing the roles of lifting and load-bearing of the lifting platform. The lifting of the platform is achieved by an oil cylinder acting on a connecting rod 3. This forms a seesaw with the oil cylinder as the fulcrum, the connecting rod 3 as the pressing plate, and the two rhombic grid-shaped load-bearing surfaces as the force application points. When the forces at the two force application points change (when people or objects move on the platform), due to the seesaw principle, this causes the lifting platform to shake. This is one of the reasons. Another reason is that the two load-bearing surfaces are placed in parallel and are not joined together with a bent connecting pin shaft 4, so a truly closed connection is not formed. Although there are several connecting rods 3 horizontally connecting the two load-bearing surfaces, in the theory of structural mechanics, from the perspective of being beneficial to increasing stiffness, no matter how many connecting rods 3 horizontally connect the two surfaces, it is ineffective. It can also be said that the connecting rod 3 does not restrict the degrees of freedom of the two load-bearing surfaces. This is a design defect. In order to improve the deficiencies of the existing structure, two oil cylinders are arranged side by side on a connecting rod 3 to form two fulcrums, which improves the situation at this layer, reduces the seesaw effect, but increases the cost and reduces the reliability. This only improves at this layer. For the layers without oil cylinders, since they are not joined with a bent connecting pin shaft 4 and do not form a truly closed structure and are free, the overall stability has not been fundamentally improved. Poor stability, in addition to being unsafe, affects work efficiency and quality in some application scenarios, such as installation, decoration, electric welding, etc. at high altitudes, where a stable and low-vibration working environment is required. Especially for lifting platforms with self-propelling functions, when moving work positions, the swing amplitude above is very large. Currently, in order to obtain sufficient stiffness for the lifting platform, rather than just meeting the requirements, the outer dimensions and wall thickness of the load-bearing rods have to be made very large, greatly increasing the weight and also raising the center of gravity. The height of the center of gravity has a great impact on stability and safety. Summary of the Invention

[0003] (Elaborated from three aspects) First, the technical problems to be solved: The present invention is designed to overcome the shaking of the existing hydraulic lifting platform during operation, which affects safety, efficiency, operation quality and even makes it unable to perform its work properly. Therefore, to a certain extent, it also limits its height and other defects. A scissor-joint type lifting mechanism with good stability, light weight, high lifting height, beautiful appearance and low cost is designed to meet the market's need for high-performance and low-cost lifting platforms.

[0004] Second, Technical Solution To solve the above technical problems, the present invention is realized through the following technical solutions: The present invention includes: rollers, guide rails, a chassis, and also includes a lifting body and a lifting assembly. The following describes the lifting body and the lifting assembly respectively: Lifting body (with various forms) It is a load-bearing surface in the shape of a wide diamond grid composed of several long load-bearing rods 1 and straight pins 2; a load-bearing surface in the shape of a narrow diamond grid composed of several short load-bearing rods 5 and straight pins 2; according to the permutation and combination of different or the same number of wide and narrow load-bearing surfaces, after being joined using bent joint pins 4, a truss structure with lifting function and various shapes is formed, which is called the lifting body. According to the differences in the horizontal cross-sectional projection graphics of different styles of lifting bodies, the present invention can be divided into "human" shape (formed by joining two wide load-bearing surfaces with bent joint pins, figure omitted); "triangle" (formed by joining two wide load-bearing surfaces and one narrow load-bearing surface with bent joint pins), see Figure 2 , 3 , 4, 7; "quadrilateral" (formed by alternately arranging two wide and two narrow load-bearing surfaces each and joining them with bent joint pins), see Figure 5 , 6 ; "polygon" (formed by alternately arranging the same number of wide and narrow load-bearing surfaces and joining them with bent joint pins, figure omitted). It should be noted that the present invention has requirements for the geometric dimensions and assembly relationships of the long load-bearing rods 1 in the wide load-bearing surface and the short load-bearing rods 5 in the narrow load-bearing surface. The ratio of the center distance between the two holes on both sides of the long load-bearing rod to the center distance between the two holes on both sides of the short load-bearing rod should be an integer n. When the wide and narrow load-bearing surfaces are joined using bent joint pins, the narrow load-bearing surface is not joined at every point. It has intervals and is joined every n - 1 points, see Figure 7 . As long as the above two conditions are met, the movement trajectory of the rollers during the lifting process of the present invention is linear and the internal angles of the horizontal cross-sectional projection geometric graphics remain unchanged; being linear enables the use of linear guide rails, and the unchanged internal angles enable the use of bent joint pins with fixed angles. However, there are exceptions. When it is a "quadrilateral", n may not be an integer and it may not meet the requirement of joining every n - 1 points. At this time, its internal angles also remain unchanged, but during the entire lifting process, the movement trajectory of its rollers is parabolic. Fortunately, for the section we use, the movement trajectory of the rollers is close to an arc shape and a circular arc guide rail can be used to replace it, which is easy to process and manufacture.

[0005] Lifting assembly (in three forms) 1. This assembly is an umbrella structure composed of an oil cylinder 6, a steel wire rope 7 and some connecting fasteners, as shown in Figure 2 、 5 。The steel wire rope here can also be replaced by a pull rod 8. The processing and assembly relationships of the steel wire rope, pull rod and related parts are shown in Figure 8 、 9 respectively. The acting force should pass through the connection line of the two force-bearing points so that the bending joint pin does not generate a moment. In addition to the pull rod with a ball head, a rod-end spherical plain bearing SI can also be used. The figure is omitted.

[0006] 2. This assembly is composed of an oil cylinder 6, a steel wire rope 7 (or a pull rod 8) and a sliding lifting support rod, as shown in Figure 3 、 6 respectively. The two ends of the sliding lifting support rod 9 are in sliding fit with the spherical plain bearings inserted in the long load-bearing rod 1. The figure is omitted.

[0007] 3. This assembly is composed of an SWL screw jack 10 and a sliding lifting support rod 9, as shown in Figure 4 。

[0008] Third, beneficial effects The most remarkable feature of the present invention is that each diamond grid-shaped load-bearing surface is joined together through a bending joint pin, restricting their respective degrees of freedom and eliminating the seesaw effect. At the same time, "triangle", "quadrilateral" and other closed truss structures are formed (unlike the current lifting platform where the two parallel load-bearing surfaces have no substantial connection). Due to the joining and closing, the stability is greatly improved. The load-bearing surfaces of "triangle" and "quadrilateral" have three and four sides respectively, both more than those of the current lifting platform (seemingly four sides, but two of them do not bear load). I emphasize here that the "triangle" of the present invention has more remarkable advantages. In addition to the reasons for good stability described above, the triangular structure itself has stability, and the superimposed effect is even more stable. The "triangle" of the present invention has only three sides, and the narrow load-bearing surface is generally made very narrow, so the total weight is relatively light. Utilizing the characteristic of large stiffness in the direction parallel to the load-bearing surface, the position where the narrow load-bearing surface is located plays a more important role in preventing shaking, such as Figure 2 、 7As shown, it (the narrow load-bearing surface) exists like a backbone, which is exactly what the widely used lift lacks nowadays. Now, I will introduce what the practical significance of the ratio n of the center distances of the holes on both sides of the long and short load-bearing rods is. Take an application example to illustrate: For the lifts commonly seen on the market nowadays, the size of the workbench surface is mostly 3×1 in length×width. In this case, we can take n = 3; there are also those with a length×width of 2×1, and at this time we take n = 2 to meet the size requirements of different lifts. It is precisely because the proportional relationship n and the assembly relationship n - 1 were discovered that this invention was achieved. It can also be considered that this application has both an invention and a discovery, and it is very likely to be written into textbooks as a new mechanical mechanism in the future.

[0009] Next, I will introduce the characteristics and applications of each type of the present invention composed of different forms of lifting bodies: The "triangle" type of the present invention has significant advantages such as good stability, light weight, simple structure, high lifting height, and good appearance, and should be the first choice. See Figure 2 、 3 、4. The "quadrilateral" type of the present invention also has advantages such as good stability and high lifting height. It is slightly inferior to the former in terms of simple structure and light weight, but is superior to the former in terms of load-bearing. See Figure 5 、 6 . The "herringbone" structure is simpler and lighter in weight, but its stability is not very good. It is suitable for lifts with a high-to-low lifting height. The figure is omitted. The three types of lifting components for lifting also have their own characteristics and application scenarios: First, the umbrella-shaped structure has a relatively low cost, and there is a certain difficulty in assembly (it is better with the pull rod), and the comprehensive performance index is the best. Second, the lifting support rod structure has a relatively higher cost, and the comprehensive performance index is better. Third, the screw lift structure has the lowest cost. It saves the relatively large expenses of the oil cylinder, pump valve, oil pipe, etc., and replaces them with a screw lift with a very low cost. In this way, not only the cost is greatly reduced, but also the reliability is improved. However, due to its relatively small output force, it is only suitable for lifting platforms with a relatively low lifting height and a relatively small load-bearing. To sum up, due to the many advantages brought by the extremely high stability, the present invention can greatly reduce the material usage and the dependence on high-quality materials, achieving the highest cost performance. At the same time, it also makes it possible for us to make the lift higher as we hope. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is the existing hydraulic lift; Figure 2 is the "triangle" type of the present invention with an umbrella-shaped lifting component made of wire rope; Figure 3 is the "triangle" type of the present invention with a sliding lifting support rod as the lifting component; Figure 4 is the "triangle" type of the present invention with an SWL screw lift as the lifting component; Figure 5 is the "quadrilateral" type of the present invention with a wire rope as the lifting component; Figure 6The present invention is a "quadrilateral" in which the lifting component is a sliding lifting support rod; Figure 7 It is a "triangle" lifting body with n = 3; Figure 8 It is the processing and assembly relationship between the steel wire rope and the bent connecting pin shaft; Figure 9 It is the processing and assembly relationship between the tie rod and the bent connecting pin shaft.

[0011] In the figure: 1 long load-bearing rod, 2 straight pin shaft, 3 connecting rod, 4 bent connecting pin shaft, 5 short load-bearing rod, 6 oil cylinder, 7 steel wire rope, 8 tie rod, 9 sliding lifting support rod, 10 SWL screw jack.

Claims

1. A scissor cross-joint lifting mechanism, comprising rollers, guide rails, a chassis, a lifting body and a lifting assembly, characterized in that, Refer to the respective descriptions of the lifting body and the lifting assembly as described below: Lifting body (there are various forms) a. A wide diamond-shaped grid load-bearing surface, which is composed of several long load-bearing rods, straight pins, and bent connecting pins; b. A narrow diamond-shaped grid load-bearing surface, which is composed of several short load-bearing rods, straight pins, and bent connecting pins; c. By the wide and narrow diamond-shaped grid load-bearing surfaces, through different or the same number of permutations and combinations, after being connected by bent connecting pins, lifting bodies of different geometric shapes are formed. The projection of the horizontal cross-section of the lifting body can be divided into "V" shape (formed by the connection of two wide load-bearing surfaces), "triangle" (formed by the connection of two wide load-bearing surfaces and one narrow load-bearing surface), "quadrilateral" (formed by the alternating connection of two wide and narrow load-bearing surfaces each), and "polygon" (formed by the alternating connection of the same number of wide and narrow load-bearing surfaces); Lifting assembly (there are three types) I. This assembly is an umbrella-shaped structure composed of an oil cylinder, a steel wire rope (or a pull rod), and a fastener; II. This assembly is composed of an oil cylinder, a steel wire rope (or a pull rod), and a sliding lifting support rod; III. This assembly is composed of an SWL screw lift and a sliding lifting support rod.

2. The scissor-joint type lifting mechanism according to claim 1, wherein For the wide diamond-shaped grid load-bearing surface that makes up the lifting body, the ratio n of the center distance between the two holes on both sides of the long load-bearing rod to the center distance between the two holes on both sides of the short load-bearing rod in the narrow diamond-shaped grid load-bearing surface should be an integer; when the wide and narrow diamond-shaped grid load-bearing surfaces are connected by bent connecting pins to form different lifting bodies, the narrow load-bearing surface does not connect with the wide load-bearing surface at every point. It connects with the wide load-bearing surface once every n - 1 points.

3. The scissor-joint type lifting mechanism according to claim 2, characterized in that, Regarding the ratio n of the center distance between the two holes on both sides, when the lifting body is a "quadrilateral", it is not limited to an integer. At this time, during the entire lifting process, the traveling track of the lift roller is not linear but parabolic. Fortunately, within the lifting range we use, the traveling track of the roller is close to an arc shape, and an arc-shaped track can be used instead.

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