Engine gear transmission system

Abstract

This invention discloses an engine gear transmission system, relating to the field of engine technology. It includes a crankshaft gear mounted on a crankshaft, a camshaft gear mounted on a camshaft, and an idler gear transmission mechanism mounted on the engine block. The idler gear transmission mechanism includes a first idler gear connected to the crankshaft gear and a second idler gear meshing between the first idler gear and the camshaft gear. The second idler gear is mounted on the engine block via an eccentric gear shaft. The eccentric gear shaft includes a housing journal that is interference-fitted onto the engine block, a backlash adjustment head coaxially disposed with the housing journal, and a gear journal eccentrically disposed with respect to the housing journal. The second idler gear is rotatably mounted on the gear journal. The eccentric gear shaft supports the second idler gear and adjusts the backlash between the second idler gear and the first idler gear and the camshaft gear. This invention achieves precise backlash setting and compensation, effectively resolving the contradiction between machining errors and assembly requirements.

Description

Technical Field

[0001] This invention relates to the field of engine technology, and more specifically to an engine gear transmission system. Background Technology

[0002] In engine design and manufacturing, the reliability of the gear transmission system directly affects the overall performance, efficiency, and lifespan of the engine. For gear systems composed of camshaft gears, idler gears, etc., one of the core evaluation indicators of meshing quality is backlash. Insufficient backlash can easily lead to gear meshing interference, abnormal wear, excessive temperature rise, and even seizing; excessive backlash can cause impact, increased noise, decreased transmission accuracy, and unbalanced load. Long-term operation may induce serious malfunctions such as tooth breakage, threatening the safe and stable operation of the engine.

[0003] Currently, to achieve a compact layout and modular design, many V-type engines adopt a split-body structure, separating the camshaft housing from the crankshaft housing. While this design facilitates manufacturing and assembly, it also introduces complex dimensional chains and significant cumulative tolerances. The machining and assembly errors of multiple components accumulate, ultimately manifesting in the center distance deviation of the gear train, making it difficult to guarantee the designed ideal backlash during actual assembly. This is especially pronounced in multi-stage idler gear transmission systems, where error propagation and amplification effects are more significant. Traditional fixed-center-distance gear shaft structures lack effective on-site adjustment and compensation methods to address this backlash control challenge caused by complex structures and large cumulative tolerances. They often resort to improving the machining accuracy of individual components or selective assembly, which not only significantly increases manufacturing costs and time but also offers limited adjustment flexibility, often resulting in unsatisfactory outcomes. Summary of the Invention

[0004] In view of the above-mentioned defects in the existing technology, the present invention provides an engine gear transmission system that realizes precise setting and compensation of backlash, and can control backlash within the optimal range of the design, effectively solving the contradiction between machining error and assembly requirements.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] An engine gear transmission system includes a crankshaft gear mounted on a crankshaft, a camshaft gear mounted on a camshaft, and an idler gear transmission mechanism mounted on the engine block. The idler gear transmission mechanism includes a first idler gear connected to the crankshaft gear and a second idler gear meshing between the first idler gear and the camshaft gear. The second idler gear is mounted on the engine block via an eccentric gear shaft. The eccentric gear shaft includes a housing journal that is interference-fitted onto the engine block, a backlash adjustment head coaxially disposed with the housing journal, and a gear journal eccentrically disposed with respect to the housing journal. The second idler gear is rotatably mounted on the gear journal. The eccentric gear shaft supports the second idler gear and adjusts the backlash between the second idler gear and the first idler gear and the camshaft gear.

[0007] The seat hole journal includes a first seat hole journal that is interference-fitted with a first seat hole of the machine body and a second seat hole journal that is interference-fitted with a second seat hole of the machine body. The diameter of the first seat hole journal is larger than the diameter of the second seat hole journal. The gear journal is located between the first seat hole journal and the second seat hole journal. The backlash adjustment head is connected to the end of the first seat hole journal.

[0008] The eccentric gear shaft is equipped with a lubrication and cooling system, which is connected to the oil passage of the machine body.

[0009] The lubrication and cooling system includes a first oil hole that is radially arranged and penetrates the first seat hole journal, a second oil hole that is radially arranged and penetrates the gear journal, and a third oil hole that is axially arranged. The third oil hole penetrates the backlash adjusting head and the first oil hole and extends into the gear journal to communicate with the second oil hole. The opening end of the third oil hole is threaded with a plug.

[0010] The third oil hole is eccentrically disposed on the backlash adjustment head. The axis of the third oil hole and the axis of the gear journal are located on opposite sides of the axis of the seat hole journal. The axes of the first oil hole, the second oil hole, the third oil hole, the seat hole journal, and the gear journal are in the same plane.

[0011] The lubrication and cooling system further includes an annular oil inlet groove disposed on the outer wall of the first bearing journal, wherein both openings of the first oil hole are located within the annular oil inlet groove.

[0012] The gear journal is fitted with an annular bushing, and the second idler gear is rotatably fitted onto the bushing.

[0013] The backlash adjustment head is an external hexagonal head, and the backlash adjustment head, the seat hole journal, and the gear journal are integrally formed.

[0014] The engine gear transmission system includes two sets of idler gear transmission mechanisms and two camshaft gears. A double gear is rotatably mounted on the engine body. The large gear of the double gear meshes between the crankshaft gear and the first idler gear of one of the idler gear transmission mechanisms, and the small gear of the double gear meshes with the first idler gear of the other idler gear transmission mechanism.

[0015] The machine body includes a crankshaft housing and a camshaft housing that are fastened together. The crankshaft is rotatably mounted on the crankshaft housing, and the camshaft is rotatably mounted on the camshaft housing. The camshaft housing and the crankshaft housing together form the first seat hole and the second seat hole.

[0016] By adopting the above technical solution, the beneficial effects of the present invention are:

[0017] The engine gear transmission system provided by this invention, because the second idler gear is mounted on the engine block via an eccentric gear shaft, allows for direct and continuous fine-tuning of the center distance of the gear pair during assembly and maintenance. This enables precise setting and compensation of backlash, essentially adding a "fine-tuning knob" to the gear transmission system. This keeps the backlash within the optimal design range, effectively resolving the conflict between machining errors and assembly requirements. It significantly reduces reliance on precision measurement and selective assembly (grinding, pad selection), effectively lowering manufacturing costs and shortening production cycles. Furthermore, engineers can provide more lenient tolerance zones for various structural dimensions, simplifying complex tolerance chain calculations and improving design robustness and process feasibility. In after-sales service and maintenance, adjusting backlash becomes simple and quick, significantly reducing maintenance difficulty and spare parts costs. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the engine gear transmission system of the present invention;

[0019] Figure 2 yes Figure 1 A partial structural diagram of AA;

[0020] Figure 3 yes Figure 2 Schematic diagram of the structure of the eccentric gear shaft;

[0021] Figure 4 yes Figure 3 A schematic diagram of direction B;

[0022] Figure 5 yes Figure 3 A schematic diagram of direction C;

[0023] In the diagram: 1. Engine body; 11. Crankshaft housing; 111. Oil passage; 12. Camshaft housing; 2. Crankshaft; 3. Camshaft; 4. Crankshaft gear; 5. Camshaft gear; 6. First idler gear; 7. Second idler gear; 8. Eccentric gear shaft; 81. Seat hole journal; 811. First seat hole journal; 812. Second seat hole journal; 82. Gear journal; 83. Backlash adjusting head; 84. First oil hole; 85. Second oil hole; 86. Third oil hole; 87. Annular oil inlet groove; 9. Bushing; 10. Double gear. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the drawings are all schematic diagrams used to assist in understanding the invention; the specific embodiments described are only for explaining the invention and are not intended to limit the invention.

[0025] like Figures 1 to 5 As shown, an engine gear transmission system is disclosed, including a crankshaft gear 4 mounted on a crankshaft 2, a camshaft gear 5 mounted on a camshaft 3, and an idler gear transmission mechanism mounted on a machine body 1. The idler gear transmission mechanism includes a first idler gear 6 that is connected to the crankshaft gear 4 and a second idler gear 7 meshing between the first idler gear 6 and the camshaft gear 5. The second idler gear 7 is mounted on the machine body 1 via an eccentric gear shaft 8. The eccentric gear shaft 8 includes a seat journal 81 that is interference-fitted onto the machine body 1, a backlash adjustment head 83 that is coaxially mounted with the seat journal 81, and a gear journal 82 that is eccentrically mounted with the seat journal 81. The second idler gear 7 is rotatably mounted on the gear journal 82. The eccentric gear shaft 8 is used to support the second idler gear 7 and to adjust the backlash between the second idler gear 7 and the first idler gear 6 and the camshaft gear 5.

[0026] In this embodiment of the engine gear transmission system, since the second idler gear 7 is mounted on the engine body 1 via the eccentric gear shaft 8, the backlash M between the camshaft gear 5 and the second idler gear 7, and the backlash N between the second idler gear 7 and the first idler gear 6 can be directly and continuously fine-tuned at the assembly site and during maintenance by rotating the backlash adjustment head 83 of the eccentric gear shaft 8. This achieves precise setting and compensation of the backlash M and backlash N. The adjustment method is as follows: slightly rotating the eccentric gear shaft 8 counterclockwise decreases the backlash M and backlash N; slightly rotating the eccentric gear shaft 8 clockwise increases the backlash M and backlash N. This is equivalent to adding a "fine-tuning knob" to the gear transmission system, ensuring that the backlash M and backlash N are always controlled within the optimal design range, effectively resolving the contradiction between machining errors and assembly requirements.

[0027] In this embodiment, the seat hole journal 81 includes a first seat hole journal 811 that is interference-fitted with the first seat hole of the machine body 1 and a second seat hole journal 812 that is interference-fitted with the second seat hole of the machine body 1. The diameter of the first seat hole journal 811 is larger than the diameter of the second seat hole journal 812. The gear journal 82 is located between the first seat hole journal 811 and the second seat hole journal 812. The backlash adjustment head 83 is connected to the end of the first seat hole journal 811.

[0028] In this embodiment, the interference fit between the first seat hole journal 811 and the first seat hole, and the interference fit between the second seat hole journal 812 and the second seat hole are preferably controlled between 0.03mm and 0.1mm. The eccentricity between the eccentric gear shaft 8, the gear journal 82 and the seat hole journal 81 is T1. The eccentricity T1 should not be too large and should be controlled between 5mm and 8mm. Otherwise, the torque generated by the gear transmission force on the eccentricity T1 will be too large. In order to overcome the torque, a larger interference fit must be used to prevent the eccentric gear shaft 8 from rotating, which will result in time-consuming and laborious adjustment.

[0029] In order to improve the service life of the second idler gear 7 and the eccentric gear shaft 8, an annular bushing 9 is fitted on the gear journal 82 in this embodiment, and the second idler gear 7 is rotatably fitted on the bushing 9.

[0030] Preferably, the gear journal 82 and the bushing 9 adopt an oil-free groove structure, which can reduce the working pressure ratio of the gear journal 82 and the bushing 9, reduce the wear of the bushing 9, and thus further improve the service life of the second idler gear 7 and the bushing 9.

[0031] In order to further alleviate the wear of bushing 9 and extend its service life, this embodiment provides a lubrication and cooling system in the eccentric gear shaft 8, which is connected to the oil passage 111 of the machine body 1.

[0032] Specifically, the lubrication and cooling system includes a first oil hole 84 radially arranged and penetrating the first seat bore journal 811, a second oil hole 85 radially arranged and penetrating the gear journal 82, and a third oil hole 86 axially arranged. The third oil hole 86 penetrates the backlash adjusting head 83 and the first oil hole 84 and extends into the gear journal 82, communicating with the second oil hole 85. A screw plug (not shown in the figure) is threaded to the open end of the third oil hole 86. The lubricating oil in the oil passage 111 enters between the bushing 9 and the second idler gear 7 through the first oil hole 84, the third oil hole 86, and the second oil hole 85 in sequence to cool and lubricate the bushing 9 and the second idler gear 7.

[0033] In this embodiment, the third oil hole 86 is eccentrically positioned on the backlash adjustment head 83. The axis of the third oil hole 86 and the axis of the gear journal 82 are located on opposite sides of the axis of the seat journal 81. Furthermore, the axes of the first oil hole 84, the second oil hole 85, the third oil hole 86, the seat journal 81, and the gear journal 82 are all in the same plane. By eccentrically positioning the third oil hole 86, it serves as a reference for assembly, facilitating correct assembly and reducing subsequent adjustment work. Specifically, the eccentric distance T2 between the third oil hole 86 and the seat journal 81 is controlled between 8mm and 12mm.

[0034] To ensure sufficient oil supply, the lubrication and cooling system in this embodiment also includes an annular oil inlet groove 87 provided on the outer wall of the first bearing journal 811, and both openings of the first oil hole 84 are located in the annular oil inlet groove 87.

[0035] In this embodiment, the diameter ΦX of the first bearing journal 811 is controlled between 75mm and 85mm, the length L1 of the first bearing journal 811 is controlled between 45mm and 55mm, the diameter ΦY of the second bearing journal 812 is controlled between 40mm and 50mm, the length L2 of the second bearing journal 812 is controlled between 20mm and 25mm, and the width L3 of the annular oil inlet groove 87 is controlled between 8mm and 12mm, so as to obtain a better interference fit and anti-rotation capability with the first and second bearing journals on the machine body 1, and prevent the eccentric gear shaft 8 from rotating under eccentric torque; the distance L4 between the end of the annular oil inlet groove of the first bearing journal 811 and the annular oil inlet groove 87 is controlled between 8mm and 12mm, so as to obtain a better sealing effect and prevent oil leakage.

[0036] In this embodiment, the radial distance L6 between the first seat hole journal 811 and the gear journal 82 is controlled between 1mm and 2mm to prevent interference between the gear journal 82 and the first seat hole when adjusting the backlash of the eccentric gear shaft 8; the radial distance L7 between the second seat hole journal 812 and the gear journal 82 is controlled between 1mm and 2mm to facilitate the installation of the second idler gear 7 into the eccentric gear shaft 8.

[0037] In this embodiment, the backlash adjusting head 83 is an external hexagonal head, and the backlash adjusting head 83, the seat hole journal 81, and the gear journal 82 are integrally formed. This configuration improves the strength of the eccentric gear shaft.

[0038] Preferably, the width S of the backlash adjustment head 83 is controlled between 36mm and 46mm, and the thickness L5 is controlled between 12mm and 20mm, so as to be able to bear a strong rotational torque when adjusting the backlash.

[0039] The engine in this embodiment is a V-type engine. Therefore, the engine gear transmission system in this embodiment includes two sets of idler gear transmission mechanisms and two camshaft gears 5. A double gear 10 is rotatably mounted on the engine body 1. The large gear of the double gear 10 meshes between the crankshaft gear 4 and the first idler gear 6 of one of the idler gear transmission mechanisms. The small gear of the double gear 10 meshes with the first idler gear 6 of the other idler gear transmission mechanism for transmission.

[0040] To achieve a compact layout and modular design, and to facilitate manufacturing and assembly, the body 1 in this embodiment adopts a split structure, including a crankshaft housing 11 and a camshaft housing 12 that are fastened together. The crankshaft 2 is rotatably mounted on the crankshaft housing 11, and the camshaft 3 is rotatably mounted on the camshaft housing 12. The camshaft housing 12 and the crankshaft housing 11 together form the first seat hole and the second seat hole.

[0041] When the eccentric gear shaft 8 is assembled with the machine body 1, the second oil hole 85 is arranged at an angle downwards to lubricate and cool the heavily loaded area first, and the third oil hole 86 is located between the first idler gear 84 and the second idler gear 7 (e.g., Figure 1 (As shown); when fine-tuning the backlash, slightly rotating the eccentric gear shaft 8 counterclockwise reduces backlash M and backlash N, and slightly rotating the eccentric gear shaft 8 clockwise increases backlash M and backlash N.

[0042] The above describes in detail one embodiment of the engine gear transmission system of the present invention; many other embodiments are not detailed here. In summary, the present invention effectively resolves the contradiction between machining errors and assembly requirements, significantly reduces reliance on precision measurement and selective assembly, effectively lowers manufacturing costs, shortens production cycle time, and allows engineers to provide more relaxed tolerance zones for various related structural dimensions, simplifying complex tolerance chain calculations, improving design robustness and process feasibility. Furthermore, in after-sales service and maintenance, adjusting backlash becomes simple and quick, significantly reducing maintenance difficulty and spare parts costs.

[0043] This invention is not limited to the specific embodiments described above. Any modifications made by those skilled in the art based on the above concept without creative effort are within the scope of protection of this invention.

Claims

1. An engine gear transmission system, comprising a crankshaft gear (4) mounted on a crankshaft (2), a camshaft gear (5) mounted on a camshaft (3), and an idler gear transmission mechanism mounted on an engine block (1), wherein the idler gear transmission mechanism comprises a first idler gear (6) pulverically connected to the crankshaft gear (4) and a second idler gear (7) meshing between the first idler gear (6) and the camshaft gear (5), characterized in that, The second idler gear (7) is mounted on the machine body (1) via an eccentric gear shaft (8). The eccentric gear shaft (8) includes a seat journal (81) that is interference-fitted onto the machine body (1), a backlash adjustment head (83) that is coaxially mounted with the seat journal (81), and a gear journal (82) that is eccentrically mounted with the seat journal (81). The second idler gear (7) is rotatably mounted on the gear journal (82). The eccentric gear shaft (8) is used to support the second idler gear (7) and to adjust the backlash between the second idler gear (7), the first idler gear (6), and the camshaft gear (5).

2. The engine gear transmission system according to claim 1, characterized in that, The seat hole journal (81) includes a first seat hole journal (811) that is interference-fitted with the first seat hole of the machine body (1) and a second seat hole journal (812) that is interference-fitted with the second seat hole of the machine body (1). The diameter of the first seat hole journal (811) is larger than the diameter of the second seat hole journal (812). The gear journal (82) is located between the first seat hole journal (811) and the second seat hole journal (812). The backlash adjustment head (83) is connected to the end of the first seat hole journal (811).

3. The engine gear transmission system according to claim 2, characterized in that, The eccentric gear shaft (8) is equipped with a lubrication and cooling system, which is connected to the oil passage (111) of the machine body (1).

4. The engine gear transmission system according to claim 3, characterized in that, The lubrication and cooling system includes a first oil hole (84) that is radially arranged and penetrates the first seat hole journal (811), a second oil hole (85) that is radially arranged and penetrates the gear journal (82), and a third oil hole (86) that is axially arranged. The third oil hole (86) penetrates the backlash adjusting head (83) and the first oil hole (84) and extends into the gear journal (82) to communicate with the second oil hole (85). The open end of the third oil hole (86) is threaded with a plug.

5. The engine gear transmission system according to claim 4, characterized in that, The third oil hole (86) is eccentrically disposed on the backlash adjusting head (83). The axis of the third oil hole (86) and the axis of the gear journal (82) are located on opposite sides of the axis of the seat hole journal (81). The axes of the first oil hole (84), the second oil hole (85), the third oil hole (86), the seat hole journal (81), and the gear journal (82) are in the same plane.

6. The engine gear transmission system according to claim 4, characterized in that, The lubrication and cooling system also includes an annular oil inlet groove (87) provided on the outer wall of the first bearing journal (811), and the two openings of the first oil hole (84) are both located in the annular oil inlet groove (87).

7. The engine gear transmission system according to claim 1, characterized in that, An annular bushing (9) is fitted on the gear journal (82), and the second idler gear (7) is rotatably fitted on the bushing (9).

8. The engine gear transmission system according to claim 1, characterized in that, The backlash adjustment head (83) is an external hexagonal head, and the backlash adjustment head (83), the seat hole journal (81), and the gear journal (82) are integrally formed.

9. The engine gear transmission system according to claim 1, characterized in that, The engine gear transmission system includes two sets of idler gear transmission mechanisms and two camshaft gears (5). A double gear (10) is rotatably mounted on the engine body (1). The large gear of the double gear (10) meshes between the crankshaft gear (4) and the first idler gear (6) of one of the idler gear transmission mechanisms. The small gear of the double gear (10) meshes with the first idler gear (6) of the other idler gear transmission mechanism.

10. The engine gear transmission system according to claim 2, characterized in that, The body (1) includes a crankshaft housing (11) and a camshaft housing (12) that are fastened together. The crankshaft (2) is rotatably mounted on the crankshaft housing (11), and the camshaft (3) is rotatably mounted on the camshaft housing (12). The camshaft housing (12) and the crankshaft housing (11) together form the first seat hole and the second seat hole.

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