Connecting rod mechanism of excavator bucket

Abstract

The utility model provides an excavator bucket connecting rod mechanism which aims to overcome the defects in the prior art and improve power transmission, motion control and working condition adaptability. The mechanism comprises a bucket, a bucket rod, a hydraulic oil cylinder assembly and a connecting rod assembly. A lower hinge point of the bucket is rotationally connected with the front end of the bucket rod. The hydraulic oil cylinder assembly comprises a driving hydraulic oil cylinder and an auxiliary hydraulic oil cylinder which are arranged in parallel, cylinder bodies are coaxially and rotationally connected above the rear portion of the bucket rod, and the end of a piston rod is rotationally connected with the connecting rod assembly. The connecting rod assembly forms a triangular force transmission structure and is provided with three hinge parts which are rotationally connected with an upper hinge point of the bucket, the ends of piston rods of the two oil cylinders and the side wall of the bucket rod respectively. The connecting rod assembly comprises a shaft sleeve, a connecting rod and the like. The connecting rod is variable in cross section and provided with a hollowed-out area in the middle. And the cylinder body of the oil cylinder is welded with the bucket rod through a mounting seat with a reinforcing rib. Power acts on the connecting rod assembly, and the power transmission efficiency is improved; the design of the connecting rod is optimized, and operation precision is improved; by adopting the double-way oil cylinder, the working condition adaptability is enhanced, and the working range is expanded.

Description

Technical Field

[0001] This utility model relates to the field of engineering machinery technology, specifically to an excavator bucket linkage mechanism. Background Technology

[0002] Excavators, as indispensable machinery in the engineering construction field, play a crucial role in excavation, loading, and unloading operations. Their working device generally consists of a boom, stick, bucket, hydraulic cylinders, and a linkage mechanism. Among these, the bucket linkage and bucket hydraulic cylinder are the core components driving the bucket's movement. The bucket hydraulic cylinder provides power through the extension and retraction of the piston rod, generating thrust or pull force, while the bucket linkage is responsible for transmitting the force from the hydraulic cylinder to the bucket to achieve excavation, unloading, and other operations.

[0003] Currently, most excavator bucket linkages use a single-link design, meaning only one link connects the bucket and the hydraulic cylinder. While this structure is simple, it has several drawbacks. First, it is relatively inefficient in terms of force transmission. During excavation, especially when encountering significant resistance, the single-link structure is prone to force loss, resulting in insufficient digging force and affecting digging efficiency and quality. Second, because there is only one link, the movement control of the bucket is not flexible enough, and the bucket's movement trajectory is relatively simple, making it difficult to accurately adapt to complex and changing digging conditions. For example, when facing soil layers of different hardness or excavation surfaces of different shapes, the single-link structure cannot flexibly adjust the bucket's posture and movement trajectory, leading to poor digging results.

[0004] Furthermore, in traditional structures, the output end of the hydraulic cylinder is usually connected to the rocker arm of a four-bar linkage. Under complex working conditions, the four-bar linkage is prone to "dead point" phenomena. When the mechanism is in the "dead point" position, no matter how much force is applied to the hydraulic cylinder, the mechanism cannot move normally. This will not only interrupt the digging operation, but may also damage the equipment, increase maintenance costs, and reduce downtime. Utility Model Content

[0005] The technical problem this utility model aims to solve is to overcome the above-mentioned technical defects and provide an excavator bucket linkage mechanism. This application optimizes and improves the bucket linkage and bucket hydraulic cylinder. By placing the power transmitted by the bucket hydraulic cylinder into the linkage assembly instead of the rocker arm, using the linkage assembly as the driving component can effectively avoid dead points and change the bucket's movement trajectory and the efficiency of digging force transmission. The use of dual-path cylinders can improve force transmission and bucket movement control to a certain extent, enabling the bucket to better adapt to different working conditions and materials during digging.

[0006] To solve the above-mentioned technical problems, this utility model provides an excavator bucket linkage mechanism, including a bucket, a stick, a hydraulic cylinder assembly and a linkage assembly, wherein the lower hinge point of the bucket is rotatably connected to the front end of the stick, and is used to perform digging, loading and unloading actions;

[0007] The hydraulic cylinder assembly includes a main hydraulic cylinder and an auxiliary hydraulic cylinder arranged in parallel. The cylinder bodies of the main hydraulic cylinder and the auxiliary hydraulic cylinder are coaxially rotatably connected to the upper rear part of the stick, and the end of the piston rod is rotatably connected to the connecting rod assembly.

[0008] The connecting rod assembly forms a triangular force transmission structure having a first hinge, a second hinge, and a third hinge, wherein:

[0009] The first hinge is rotatably connected to the hinge point on the bucket;

[0010] The second hinge part rotatably connects the piston rod ends of the active hydraulic cylinder and the auxiliary hydraulic cylinder simultaneously;

[0011] The third hinge is symmetrically rotated with the side wall of the boom through two rockers.

[0012] Furthermore, the linkage assembly includes a first bushing disposed at the first hinge portion and a second bushing disposed at the third hinge portion;

[0013] A plurality of parallel connecting rods are connected between the first bushing and the second bushing;

[0014] The connecting rod is provided with a pin hole located at the third hinge, and the ends of the piston rods of the active hydraulic cylinder and the auxiliary hydraulic cylinder pass through several pin holes through a concentric shaft to form a rotatable connection.

[0015] The bucket has a hinge point with a pin and a bushing is fitted on the pin to form a rotatable connection.

[0016] The two rocker arms are rotatably connected to both ends of the second bushing.

[0017] Furthermore, the connecting rod has a variable cross-section structure, and its cross-sectional width gradually increases along the direction from the first hinge portion to the third hinge portion.

[0018] Furthermore, the connecting rod has a hollowed-out area in the middle.

[0019] Furthermore, the cylinder bodies of the active hydraulic cylinder and the auxiliary hydraulic cylinder are rotatably connected to the upper rear part of the stick via a mounting base with reinforcing ribs, and the mounting base is welded to the stick.

[0020] The advantages of this application compared to existing technologies are:

[0021] 1. Improved Power Transmission Efficiency: This application directly applies the power transmitted from the bucket hydraulic cylinder to the connecting rod assembly instead of the rocker arm, using the connecting rod assembly as the driving component. This design effectively reduces power transmission links and energy loss during transmission, significantly improving power transmission efficiency. Actual testing shows that power transmission efficiency is improved by more than 7% compared to traditional connecting rod structures. Under the same working conditions, the excavator can complete digging tasks faster, greatly improving work efficiency while reducing energy consumption, aligning with the current trend of energy conservation and emission reduction.

[0022] 2. Bucket Motion Control and Operational Precision Optimization: This application employs a linkage assembly to connect the bucket and hydraulic cylinder, combined with a triangular force transmission structure linkage assembly design, forming a unique structure with a first hinge, a second hinge, and a third hinge. The optimized linkage geometry, flexible bucket posture adjustment mechanism, and efficient power transmission method enable the bucket to respond to operating commands more flexibly and precisely. In complex operating environments, operators can more easily control the bucket's movements, achieving precise digging, loading, and unloading of materials, significantly improving operational accuracy, reducing material waste, minimizing environmental damage, and meeting the high-precision operation requirements of modern engineering construction.

[0023] 3. Adaptability to Working Conditions and Expanded Operating Range: The hydraulic cylinder assembly designed in this application includes parallel-arranged active and auxiliary hydraulic cylinders. This dual-cylinder design enables the excavator to better handle various complex working conditions. When operating on soft ground, the auxiliary cylinder can adjust the thrust in real time, effectively preventing the excavator from getting stuck and ensuring the safe and stable operation of the equipment. When excavating heavy materials, the dual cylinders work together to significantly improve digging capacity and ensure smooth excavation operations. Whether in mining, construction, or water conservancy projects, the excavator linkage structure designed in this application demonstrates strong adaptability due to its excellent performance, greatly expanding the excavator's operating range and adaptability to working conditions, and providing a reliable solution for different engineering scenarios. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of an excavator bucket linkage mechanism according to this application;

[0025] Figure 2 This is a schematic diagram of the hydraulic cylinder assembly structure of this application;

[0026] Figure 3 This is a cross-sectional view of the connecting rod in this application;

[0027] Figure 4 This is a simplified schematic diagram of a connecting rod assembly in which the connecting rod is subjected to force at the center.

[0028] Figure 5This is a simplified schematic diagram of a connecting rod assembly in which the connecting rod is subjected to hinge forces.

[0029] As shown in the figure: 1. Bucket, 2. Stick, 3. Hydraulic cylinder assembly, 31. Active hydraulic cylinder, 32. Auxiliary hydraulic cylinder, 4. Connecting rod assembly, 41. First hinge, 411. First bushing, 42. Second hinge, 43. Third hinge, 431. Second bushing, 44. Connecting rod, 441. Pin hole, 442. Hollowed-out area, 5. Rocker arm, 6. Mounting base. Detailed Implementation

[0030] The present invention will now be described in further detail with reference to the accompanying drawings.

[0031] The specific embodiments of this utility model will be further described below with reference to the accompanying drawings. Identical components are indicated by the same reference numerals.

[0032] It should be noted that the terms “front,” “back,” “left,” “right,” “up,” and “down” used in the following description refer to the directions shown in the attached diagram, while the terms “inside” and “outside” refer to the directions toward or away from the geometric center of a specific component, respectively.

[0033] To make the content of this utility model easier to understand, the technical solutions in the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings.

[0034] Reference Appendix Figure 1 This utility model provides an excavator bucket linkage mechanism, including a bucket 1, a stick 2, a hydraulic cylinder assembly 3 and a linkage assembly 4. The lower hinge point of the bucket 1 is rotatably connected to the front end of the stick 2, and is used to perform digging, loading and unloading actions.

[0035] Reference Appendix Figure 2 The hydraulic cylinder assembly 3 includes a parallel-arranged active hydraulic cylinder 31 and an auxiliary hydraulic cylinder 32. The cylinder bodies of the active hydraulic cylinder 31 and the auxiliary hydraulic cylinder 32 are coaxially rotatably connected to the upper rear part of the boom 2, and the piston rod end is rotatably connected to the connecting rod assembly 4. The dual-cylinder system is connected to the excavator's hydraulic control system through independent hydraulic lines. The hydraulic control system can precisely control the oil intake and pressure of the dual-cylinder system according to different working conditions and operating commands. At the start of the digging operation, the active hydraulic cylinder 31 first pushes the connecting rod with a large thrust, causing the bucket 1 to cut into the material. As the digging depth increases or when encountering conditions with greater resistance, the auxiliary hydraulic cylinder 32 operates synchronously under the command of the hydraulic control system, supplementing the additional thrust and working in tandem with the active hydraulic cylinder 31 to enhance the digging force and effectively prevent the bucket from jamming.

[0036] The connecting rod assembly 4, as the core of this design, forms a triangular force transmission structure with a first hinge 41, a second hinge 42, and a third hinge 43. The first hinge 41 is rotatably connected to the upper hinge point of the bucket 1 through precision-machined pins and bushings, ensuring smooth bucket movement. The second hinge 42 is rotatably connected to the piston rod ends of both the active hydraulic cylinder 31 and the auxiliary hydraulic cylinder 32, forming a dual-path power input, effectively improving digging force and the ability to cope with complex working conditions. The third hinge 43 is symmetrically rotatably connected to the side wall of the stick 2 through two rocker arms 5. This design not only enhances the stability of the structure but also makes the bucket's movement trajectory more flexible and varied.

[0037] At the first hinge portion 41 of the connecting rod assembly 4, a precision-machined first bushing 411 is provided. This bushing is tightly fitted with the pin at the hinge point on the bucket 1 to ensure the smoothness and accuracy of the bucket's movement. At the third hinge portion 43, a second bushing 431 is provided. This bushing is symmetrically rotatably connected to the side wall of the stick 2 via two rocker arms 5. One end of each rocker arm 5 is rotatably connected to the second bushing 431, while the other end is rotatably connected to both sides of the stick 2. This design not only enhances the stability of the structure but also makes the movement trajectory of the bucket 1 more flexible.

[0038] Regarding the installation of the hydraulic cylinder assembly 3, the cylinder bodies of the active hydraulic cylinder 31 and the auxiliary hydraulic cylinder 32 are securely and coaxially rotatably connected to the upper rear part of the boom 2 via a mounting base 6 with reinforcing ribs. The mounting base 6 and the boom 2 are welded together to ensure structural stability and durability. Simultaneously, the piston rod end of the hydraulic cylinder passes through a pin hole 441 on the connecting rod 44 via a concentric shaft, forming a rotatable connection to ensure smooth power transmission.

[0039] Reference Appendix Figure 3 In one embodiment, the connecting rod 44 has a variable cross-section structure, with its cross-sectional width gradually increasing from the first hinge portion 41 to the third hinge portion 43. This design, based on advanced computer-aided engineering (CAE) analysis software, simulates the stress conditions of the connecting rod under various working conditions, thereby determining the optimal shape and dimensional parameters. In areas subjected to larger loads, such as the connection between the connecting rod 44 and the hydraulic cylinder piston rod, the cross-sectional area is appropriately increased to improve the strength and stiffness of the structure; while in areas subjected to smaller loads, the cross-sectional area is reduced, effectively reducing the weight of the connecting rod. Furthermore, the connecting rod 44 also has a hollowed-out area 442 in the middle, a design that not only further reduces weight but also improves material utilization and lowers production costs.

[0040] The variable cross-section connecting rod design in this embodiment significantly improves the strength and stiffness of the connecting rod assembly while reducing weight and material costs. In practical applications, this design enables excavators to maintain high digging performance while being more energy-efficient and environmentally friendly, thus improving overall economic efficiency.

[0041] Reference Appendix Figure 4 - Appendix Figure 5 To analyze the impact of the bucket linkage structure on digging efficiency more specifically, the operating parameters for the excavator's working device are set as follows:

[0042] Hydraulic cylinder thrust (P): 50kN

[0043] Leverage ratio (L1 / L2): 1.34

[0044] Connecting rod 44 length (L): 1.2m

[0045] Material yield strength (σy): 355 MPa (Q355 steel)

[0046] Elastic modulus (E): 210 GPa

[0047] Safety factor (n): 1.5

[0048] The following is an analysis of the excavation efficiency of the same linkage assembly 4 under different stress points:

[0049] (1) When the thrust is applied to the center of the connecting rod 44, the connecting rod 44 is mainly subjected to axial pressure and the bending moment is relatively small.

[0050] Axial stress: σ ax =P / A

[0051] Euler critical load: K - Length coefficient is set to 1

[0052] (2) When the thrust is applied at the hinge position, the connecting rod 44 is subjected to a significant bending moment load and needs to be calculated as a cantilever beam or simply supported beam.

[0053] Maximum bending moment: M = P * L eff (L eff (for the effective lever arm)

[0054] Bending stress: σ bending =M / Z

[0055] Deformation amount:

[0056] Moment of inertia of cross section:

[0057] Section modulus of bending:

[0058] When the thrust P = 50KN, the connecting rod 44 is 1.2m long, made of Q355 material, and has the following cross-sectional dimensions: b = 25mm, h = 80mm, A = 2000mm2, i = 1.07×106mm4, Z = 26.7×103mm3.

[0059] Force analysis at the center:

[0060] Axial stress

[0061] stability:

[0062] Force analysis at the hinge position (Leff = 0.3m):

[0063] M = 50 × 0.3 = 15

[0064] Bending stress:

[0065] Deformation amount: Excessive deformation leads to energy loss in the hydraulic cylinder, reducing transmission efficiency.

[0066] Quantitative efficiency comparison:

[0067] Theoretical exploration power F theory = P × leverage ratio, actual digging force F actual =F theory - Deformation loss

[0068] Location of force Theoretical exploration power Deformation loss Actual excavation force Efficiency loss Central force 125 Negligible 125 <1％ Force at hinge position 125 2mm 117.5 7％

[0069] The excavation efficiency of the center-loaded scheme of connecting rod 44 is about 6% to 8% higher than that of the articulated scheme, and the structure is more reliable.

[0070] The geometry and dimensions of connecting rod 44 were meticulously optimized. Advanced computer-aided engineering (CAE) analysis software was used to simulate the stress conditions of the connecting rod under various working conditions. Based on this, the optimal shape and dimensional parameters of connecting rod 44 were determined. Connecting rod 44 was designed as a variable cross-section structure, with the cross-sectional area appropriately increased in areas bearing larger loads to improve structural strength and stiffness; while the cross-sectional area was reduced in areas with smaller loads to reduce the weight of the connecting rod, thus achieving lightweight design while ensuring structural performance. This optimized connecting rod geometry and dimensions not only better adapt to complex excavation conditions and improve the bucket's operating performance, but also reduce material costs and improve the overall economy of the excavator.

[0071] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the inventive spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A bucket linkage mechanism for an excavator, comprising a bucket (1), a boom (2), a hydraulic cylinder assembly (3), and a linkage assembly (4), characterized in that: The lower hinge point of the bucket (1) is rotatably connected to the front end of the stick (2) for performing digging, loading and unloading actions; The hydraulic cylinder assembly (3) includes a parallel active hydraulic cylinder (31) and an auxiliary hydraulic cylinder (32). The cylinder bodies of the active hydraulic cylinder (31) and the auxiliary hydraulic cylinder (32) are coaxially rotatably connected to the upper rear part of the boom (2), and the piston rod end is rotatably connected to the connecting rod assembly (4). The connecting rod assembly (4) forms a triangular force transmission structure having a first hinge (41), a second hinge (42), and a third hinge (43), wherein: The first hinge part (41) is rotatably connected to the hinge point on the bucket (1); The second hinge (42) simultaneously rotatably connects the piston rod end of the active hydraulic cylinder (31) and the auxiliary hydraulic cylinder (32); The third hinge (43) is symmetrically rotated with the side wall of the stick (2) through two rocker arms (5).

2. A dragline bucket linkage according to claim 1, characterised in that: The connecting rod assembly (4) includes a first bushing (411) disposed at the first hinge portion (41) and a second bushing (431) disposed at the third hinge portion (43); A plurality of parallel connecting rods (44) are connected between the first bushing (411) and the second bushing (431); The connecting rod (44) is provided with a pin hole (441) located at the third hinge part (43), and the ends of the piston rods of the active hydraulic cylinder (31) and the auxiliary hydraulic cylinder (32) pass through several pin holes (441) through a concentric shaft to form a rotatable connection; The bucket (1) has a hinge point with a pin and a bushing (11) is fitted on the pin to form a rotatable connection; The two rocker arms (5) are rotatably connected to both ends of the second bushing (431).

3. A dragline bucket linkage according to claim 2, characterised in that: The connecting rod (44) has a variable cross-section structure, and its cross-sectional width gradually increases from the first hinge part (41) to the third hinge part (43).

4. A dragline bucket linkage according to claim 2, characterised in that: The connecting rod (44) has a hollow area (442) in the middle.

5. The excavator bucket linkage of claim 1, wherein: The cylinder bodies of the active hydraulic cylinder (31) and the auxiliary hydraulic cylinder (32) are rotatably connected to the upper rear part of the boom (2) via a mounting base (6) with reinforcing ribs, and the mounting base (6) is welded to the boom (2).

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