Engine crankshaft balance block connecting structure
By designing a combination of grooves and cylindrical pin mounting holes in the engine crankshaft balance block connection structure, the problem of peristaltic wear of the balance block under accelerated centrifugal force is solved, and higher connection reliability and crankshaft safety are achieved.
Patent Information
- Application Number
- CN202421697147.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-17
- Publication Date
- 2025-05-20
- Estimated Expiration
- 2034-07-17
AI Technical Summary
The existing engine crankshaft balance block connection structure is prone to peristaltic wear under the conditions of acceleration centrifugal force, resulting in insufficient preload of the bolt and loosening failure.
A connection structure for the engine crankshaft balance block is designed. The balance block is fixed at the crank arm through connecting bolts and cylindrical pins, and a groove is opened on the mounting surface of the balance block. The cylindrical pin installation hole is located at the groove to ensure that the contact surface between the balance block and the crank arm is large and preventing creeping wear.
It effectively prevents creeping wear of the balance block, improves the reliability of the balance block connection, and improves the safety of the crankshaft.
Smart Images
Figure CN222887169U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of engine crankshafts, and particularly relates to a connecting structure of an engine crankshaft balance weight. Background Art
[0002] The power stroke of a diesel engine is completed by the rotation of each cylinder in turn. Therefore, the force acting on the crankshaft is intermittent and unbalanced. To transmit these forces smoothly, the rotation of the crankshaft itself needs to be stable. To achieve this stability, the crankshaft needs to be balanced. Usually, balance weights are used to balance the crankshaft.
[0003] In the prior art, the installation surface of the balance weight is large, and the contact surface pressure with the crank arm is small. Under the condition of accelerating centrifugal force, the joint surface between the balance weight and the crank arm shows creeping wear, resulting in a decrease in the elongation of the bolt and insufficient remaining pre-tightening force of the bolt. Therefore, major serious faults such as loosening of the bolt and the balance weight will occur.
[0004] In addition, with the continuous improvement of the intensification degree of diesel engines, the explosion pressure continues to increase, the journal diameter continues to increase, and air will be stored at the end of the inclined oil hole of the crank arm, resulting in cavitation at the end of the inclined oil hole of the crankshaft. At the same time, too much stored air will damage the lubricating oil film of the journal, resulting in a bearing seizure fault. Summary of the Utility Model
[0005] Aiming at the above-mentioned defects of the prior art, the technical problem to be solved by the utility model is to provide a connecting structure of an engine crankshaft balance weight, which can prevent the balance weight from creeping, improve the connection reliability of the balance weight, and improve the safety of the crankshaft.
[0006] To solve the above technical problems, the utility model adopts the following technical solutions:
[0007] A connecting structure of an engine crankshaft balance weight for fixing the balance weight on the crankshaft: The crankshaft includes a main journal, a connecting rod journal, and a crank arm. The main journal and the connecting rod journal are connected by the crank arm. It is characterized in that
[0008] The balance weight is fixedly installed at the crank arm through a connecting bolt and a cylindrical pin. Bolt mounting holes for installing the connecting bolt and cylindrical pin mounting holes for installing the cylindrical pin are respectively formed on the crank arm and the balance weight.
[0009] The mounting surfaces of the balance weight and the crank arm for fitting installation are a balance weight mounting surface and a crank arm mounting surface respectively. The crank arm mounting surface is a plane.
[0010] The balance weight mounting surface includes a balance weight bearing surface and a groove. The groove is formed in the middle of the balance weight bearing surface. The cylindrical pin mounting hole is formed at the groove. The balance weight bearing surface abuts against the crank arm mounting surface.
[0011] Preferably, the distance between the highest point of the main journal and the mounting surface of the crank arm is H, where 5 mm ≤ H ≤ 15 mm.
[0012] Preferably, an oil inlet hole is provided on the main journal, an oil outlet hole is provided on the connecting rod journal, the oil inlet holes on the main journal and the oil outlet holes on the connecting rod journal correspond one by one, and an inclined oil hole communicating the oil inlet hole on the main journal and the oil outlet hole on the connecting rod journal is provided on the crankshaft.
[0013] Preferably, a plug is installed at the port of the inclined oil hole, and a vent hole is provided on the plug.
[0014] Preferably, let the diameter of the vent hole be d, where 1 mm ≤ d ≤ 1.5 mm.
[0015] Preferably, let the bolt mounting hole on the crank arm be the lower bolt mounting hole, the bolt mounting hole on the balance weight be the upper bolt mounting hole, the lower bolt mounting hole be a counterbore, the large hole of the counterbore be a clearance hole, and the small hole of the counterbore be a threaded hole.
[0016] Preferably, let the depth of the large hole of the counterbore be δ, where 4 mm ≤ δ ≤ 6 mm.
[0017] Preferably, the upper bolt mounting hole is a clearance hole.
[0018] Preferably, a cylindrical pit is provided at the top of the balance weight, and the upper bolt mounting hole is provided in the cylindrical pit.
[0019] After adopting the above technical solution, the beneficial effects of the present utility model are as follows:
[0020] For the balance weight connection structure of the engine crankshaft of the present utility model, the balance weight is fixedly installed at the crank arm through a connecting bolt and a cylindrical pin. The mounting surfaces for the mating installation of the balance weight and the crank arm are the balance weight mounting surface and the crank arm mounting surface respectively. The crank arm mounting surface is a plane. Since the balance weight mounting surface includes a balance weight bearing surface and a groove, the groove is provided in the middle of the balance weight bearing surface, and the cylindrical pin mounting hole is provided at the groove. When the balance weight is fixed on the crankshaft, the balance weight bearing surface abuts against the crank arm mounting surface, while the groove does not contact the crank arm mounting surface. The design of the groove ensures that the balance weight obtains a large contact surface pressure, preventing the balance weight mounting surface from creeping, wearing and loosening and failing. At the same time, it relieves the fillet stress at the main journal near the installation position of the balance weight. The distance H between the highest point of the main journal and the crank arm mounting surface has a relatively small value, which is convenient for the forging of the crankshaft and ensures the forging quality.
[0021] The balance weight connection structure of the engine crankshaft of the present utility model can prevent the balance weight from creeping, improve the connection reliability of the balance weight, and enhance the safety of the crankshaft. Description of the Drawings
[0022] Figure 1 is a schematic diagram of the connecting structure of the engine crankshaft balance weight of the present utility model;
[0023] Figure 2 is Figure 1 a top view schematic diagram of the engine crankshaft balance weight connecting structure in;
[0024] Figure 3 is a longitudinal sectional view of the engine crankshaft balance weight connecting structure (one balance weight is omitted);
[0025] Figure 4 is Figure 3 a view from direction A in;
[0026] Figure 5 is Figure 3 a top view schematic diagram in;
[0027] Figure 6 is Figure 3 a sectional view schematic diagram at B - B in;
[0028] Figure 7 is Figure 3 an enlarged schematic diagram at C in;
[0029] Figure 8 is a sectional view schematic diagram of the engine crankshaft balance weight;
[0030] Figure 9 is Figure 8 a top view schematic diagram of;
[0031] Figure 10 is Figure 8 a bottom view schematic diagram of;
[0032] In the figure: 1. Balance weight; 101. Balance weight bearing surface; 1010. First balance weight bearing surface; 1011. Bolt mounting hole; 1012. Second balance weight bearing surface; 102. Groove; 103. Cylindrical pit; 2. Crankshaft; 201. Main journal; 2011. Main journal oil inlet hole; 202. Crank arm; 2021. Crank arm mounting surface; 2022. Bolt lower mounting hole; 203. Connecting rod journal; 2031. Connecting rod journal oil outlet hole; 204. Inclined oil hole; 3. Connecting bolt; 4. Plug; 401. Vent hole; 5. Cylindrical pin; 501. Cylindrical pin mounting hole; R. Fillet at main journal. Specific embodiments
[0033] The technical solution of the present utility model will be described in detail below in conjunction with the accompanying drawings and specific embodiments to further understand the purpose, solution and efficacy of the present utility model, but it is not intended to limit the scope of protection of the appended claims of the present utility model.
[0034] In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. These are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present utility model.
[0035] In addition, although the terms first, second, third, etc. may be used in the text to describe multiple elements, components, regions, layers, and / or sections, these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms can only be used to distinguish one element, component, region, layer, or section from another region, layer, or section. Unless the context clearly indicates otherwise, terms such as "first", "second", and other numerical terms do not imply an order or sequence when used in the text. Therefore, the first element, component, region, layer, or section discussed below can be referred to as the second element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.
[0036] Embodiments of the present utility model disclose a connecting structure for an engine crankshaft balance weight as shown in Figures 1 to 6 for fixing the balance weight 1 on the crankshaft 2: The crankshaft 2 includes a main journal 201, a connecting rod journal 203, and a crank arm 202. The main journal 201 and the connecting rod journal 203 are connected by the crank arm 202. The balance weight 1 is fixedly installed at the crank arm 202 through a connecting bolt 3 and a cylindrical pin 5.
[0037] The crank arm 202 and the balance weight 1 are respectively provided with a bolt mounting hole for mounting the connecting bolt 3 and a cylindrical pin mounting hole 501 for mounting the cylindrical pin 5. The mounting surfaces of the balance weight 1 and the crank arm 202 for mating installation are respectively a balance weight mounting surface and a crank arm mounting surface 2021. The crank arm mounting surface 2021 is a plane.
[0038] As shown in Figure 4 、 Figure 8 and Figure 10 the balance weight mounting surface includes a balance weight bearing surface 101 and a groove 102. The groove 102 is opened in the middle of the balance weight bearing surface 101. The cylindrical pin mounting hole 501 is opened at the groove 102. When the balance weight 1 is fixed on the crankshaft 2, the balance weight bearing surface 101 abuts against the crank arm mounting surface 2021, while the groove 102 does not contact the crank arm mounting surface 2021.
[0039] The design of the groove 102 ensures that the balancing weight 1 has a large contact surface pressure, preventing creep wear, loosening and failure at the mounting surface of the balancing weight. At the same time, it relieves the stress at the fillet R of the main journal near the installation position of the balancing weight 1. The distance H between the highest point of the main journal and the mounting surface 2021 of the crank arm is made to have a relatively small value, which is convenient for the forging of the crankshaft and ensures the forging quality.
[0040] As Figure 4 shown, in some embodiments, the distance H between the highest point of the main journal and the mounting surface 2021 of the crank arm is such that 5 mm ≤ H ≤ 15 mm. The value of H should not be too large to facilitate the forging of the crankshaft and ensure the forging quality. The value of H should not be too small either, otherwise the strength at the fillet of the main journal near the installation position of the balancing weight 1 will be overly weakened.
[0041] As Figure 1 shown, between the balancing weight 1 and the mounting surface 2021 of the crank arm, a combined positioning structure of a cylindrical pin 5 and a spring pin is used. Since the spring pin has a certain elasticity, the machining accuracy requirements for the spring pin mounting hole for installing the spring pin are not high, relieving the assembly stress at the cylindrical pin 5 caused by machining deviation and relieving the crankshaft stress at the weak area where the cylindrical pin 5 is installed.
[0042] An oil inlet hole 2011 is provided on the main journal 201, and an oil outlet hole 2031 is provided on the connecting rod journal 203. The oil inlet holes 2011 on the main journal correspond one by one to the oil outlet holes 2031 on the connecting rod journal, and an inclined oil hole 204 communicating the oil inlet holes 2011 on the main journal and the oil outlet holes 2031 on the connecting rod journal is provided on the crankshaft 2.
[0043] In some embodiments, with the continuous improvement of the intensification degree of the diesel engine, the explosion pressure is continuously increased and the shaft diameter is continuously enlarged. To prevent air from accumulating at the end of the inclined oil hole, resulting in cavitation at the end of the inclined oil hole, and at the same time, too much accumulated air will damage the lubricating oil film of the shaft diameter, leading to a bearing seizure failure. As Figure 3 and as Figure 7 shown, to solve this problem, a plug 4 is installed at the port of the inclined oil hole 204, and a vent hole 401 is provided on the plug 4. Installing the plug 4 with the vent hole 401 avoids cavitation at the end of the inclined oil hole and at the same time prevents bearing seizure failure.
[0044] In addition, the inclined oil hole 204 should be opened avoiding the areas with severe upper and lower stress, ensuring good stress of the crankshaft and extending the service life of the crankshaft.
[0045] As Figure 3 and as Figure 7 shown, let the diameter of the vent hole 401 be d, 1 mm ≤ d ≤ 1.5 mm. The diameter d of the vent hole 401 should not be too large to avoid discharging too much engine oil and affecting the system oil pressure.
[0046] In some embodiments, the bolt mounting hole on the crank arm 202 is the lower bolt mounting hole 2022, and the bolt mounting hole on the balance weight 1 is the upper bolt mounting hole 1011. The lower bolt mounting hole 2022 is a counterbore. The large hole of the counterbore is a clearance hole, and the small hole of the counterbore is a threaded hole. Let the hole depth of the large hole of the counterbore be δ, where 4 mm ≤ δ ≤ 6 mm. To reduce the bearing stress around the lower bolt mounting hole 2022 on the crank arm 202 and prevent excessive tensile and compressive loads at the orifice of the lower bolt mounting hole 2022 on the crank arm mounting surface 2021, resulting in excessive stress failure at the orifice, therefore, the lower bolt mounting hole 2022 is a counterbore to disperse the orifice stress.
[0047] In some embodiments, the upper bolt mounting hole 1011 is a clearance hole. A cylindrical pit 103 is provided at the top of the balance weight 1, and the upper bolt mounting hole 1011 is opened in the cylindrical pit 103.
[0048] Preferably, the balance weight 1 is fixedly mounted on the crank arm 202 by two connecting bolts 3. The two connecting bolts 3 are symmetrically arranged along the center line of the groove 102.
[0049] As Figure 8 and Figure 10 shown, the balance weight bearing surface 101 includes a first balance weight bearing surface 1010 and a second balance weight bearing surface 1012. The first balance weight bearing surface 1010 and the second balance weight bearing surface 1012 are symmetrically arranged along the center line of the groove 102. The two connecting bolts 3 are respectively located at the central positions of the first balance weight bearing surface 1010 and the second balance weight bearing surface 1012.
[0050] Since the first balance weight bearing surface 1010 and the second balance weight bearing surface 1012 are symmetrically arranged along the center line of the groove 102, after the balance weight 1 is installed, the first balance weight bearing surface 1010 and the second balance weight bearing surface 1012 are symmetrically and evenly stressed, without slight inclination, preventing the connecting bolts 3 from generating additional couples due to asymmetric support surfaces and reducing the bolt additional stress. The areas of the first balance weight bearing surface 1010 and the second balance weight bearing surface 1012 should not be too large, otherwise the contact surface pressure is too small, and there will be a risk of creep during operation. At the same time, the areas of the first balance weight bearing surface 1010 and the second balance weight bearing surface 1012 should not be too small, and need to be controlled below the allowable contact surface pressure of the material to prevent the contact surface between the balance weight bearing surface 101 and the crank arm mounting surface 2021 from being crushed or deformed excessively and failing. The surface pressure of the first balance weight bearing surface 1010 is obtained by dividing the pre-tightening force of the connecting bolt 3 by the area of the first balance weight bearing surface 1010.
[0051] In summary, the engine crankshaft balance weight connection structure of the present invention can prevent the balance weight from creeping, improve the connection reliability of the balance weight, and enhance the safety of the crankshaft.
[0052] The present utility model is not limited to the above embodiments. All improvements made based on the concept, principle, structure and method of the present utility model fall within the protection scope of the present utility model.
Claims
1. An engine crankshaft balance block connection structure, used for fixing the balance block on the crankshaft: the crankshaft comprises a main journal, a connecting rod journal and a crank arm, the main journal and the connecting rod journal are connected through the crank arm, characterized in that: The balancing block is fixedly mounted on the crank arm by connecting bolts and cylindrical pins, and the crank arm and the balancing block are respectively provided with bolt mounting holes for mounting the connecting bolts and cylindrical pin mounting holes for mounting the cylindrical pins. The mounting surfaces for the balancing block and the crank arm to be mounted in cooperation are the balancing block mounting surface and the crank arm mounting surface respectively, and the crank arm mounting surface is a plane. The balancing block mounting surface includes a balancing block pressure-bearing surface and a groove, wherein the groove is arranged in the middle of the balancing block pressure-bearing surface, the cylindrical pin mounting hole is arranged in the groove, and the balancing block pressure-bearing surface is in contact with the crank arm mounting surface.
2. The engine crankshaft balance block connection structure according to claim 1, characterized in that: The distance between the highest point of the main journal and the crank arm mounting surface is H, 5mm≤H≤15mm.
3. The engine crankshaft balance block connection structure according to claim 1, characterized in that: The main journal is provided with a main journal oil inlet hole, the connecting rod journal is provided with a connecting rod journal oil outlet hole, the main journal oil inlet hole and the connecting rod journal oil outlet hole correspond to each other one by one, and the crankshaft is provided with an oblique oil hole connecting the main journal oil inlet hole and the connecting rod journal oil outlet hole.
4. The engine crankshaft balance block connection structure according to claim 3, characterized in that: A screw plug is installed at the port of the inclined oil hole, and a vent hole is opened on the screw plug.
5. The engine crankshaft balance block connection structure according to claim 4, characterized in that: Assume that the diameter of the air vent is d, 1mm≤d≤1.5mm.
6. The engine crankshaft balance block connection structure according to claim 1, characterized in that: Assume that the bolt mounting hole on the crank arm is a lower bolt mounting hole, the bolt mounting hole on the balance block is an upper bolt mounting hole, the lower bolt mounting hole is a countersunk hole, the large hole of the countersunk hole is a smooth hole, and the small hole of the countersunk hole is a threaded hole.
7. The engine crankshaft balance block connection structure according to claim 6, characterized in that: Assume that the hole depth of the large hole of the countersunk hole is δ, 4mm≤δ≤6mm.
8. The engine crankshaft balance block connection structure according to claim 6, characterized in that: The mounting hole on the bolt is a smooth hole.
9. The engine crankshaft balance block connection structure according to claim 8, characterized in that: A cylindrical pit is arranged on the top of the balancing block, and the mounting hole on the bolt is opened in the cylindrical pit.