Engine gear train and engine

Abstract

The invention provides an engine gear train and an engine, the engine gear train comprises an engine rear-end gear train, the engine rear-end gear train comprises a crankshaft rear-end gear, a camshaft gear and a plurality of rear-end intermediate gears, and the crankshaft rear-end gear is meshed with the camshaft gear through the plurality of rear-end intermediate gears; the engine comprises at least two engine rear-end accessories, the engine rear-end gear train further comprises engine rear-end accessory gears connected with transmission shafts of the engine rear-end accessories, and each engine rear-end accessory gear is correspondingly meshed with one rear-end intermediate gear. The transmission ratio of the crankshaft rear-end gear to the camshaft gear is 2: 1 by adjusting the gear tooth ratio of the engine rear-end gear train, and each engine rear-end accessory is driven by an independent rear-end intermediate gear. The adaptability of the engine accessories and the engine gear train and the universality of the engine gear train are improved, and the problem that the engine gear train and the engine accessories are difficult to arrange is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of engine parts, and in particular to an engine gear system and an engine. Background Art

[0002] The engine is a machine that converts the chemical energy of fuel into kinetic energy. It includes two major mechanisms and five systems: the valve mechanism and the crank-connecting rod mechanism. The valve mechanism is a mechanism that controls the intake and exhaust valves of the engine, and needs to meet the function of opening and closing the intake and exhaust valves on time and accurately. The working principle of the valve mechanism relies on the rotational power of the crankshaft, and through a series of transmission mechanisms, such as camshafts and rocker arms, precise control of valve movement is achieved. In a complete working cycle of a four-stroke engine, the crankshaft rotates 720 degrees, and the intake and exhaust valves are only opened and closed once each, which means that the camshaft only needs to rotate 360 ​​degrees to complete the control of the valves. Therefore, the valve mechanism needs to meet the power transmission requirements from the crankshaft through the camshaft to the valves and the requirement of a 2:1 transmission ratio from the crankshaft to the camshaft.

[0003] According to the different positions of the camshaft, the camshaft arrangement of the valve train can be divided into three types: bottom camshaft, middle camshaft and top camshaft. Among them, the middle camshaft and bottom camshaft arrangement make the camshaft and crankshaft closer, and the tappet or push rod pushes the rocker arm to control the valve; while the top camshaft arrangement allows the camshaft to directly push the rocker arm, thereby reducing the intermediate transmission link, but this arrangement also increases the distance between the camshaft and the crankshaft, and requires the use of chains or gear trains to achieve power transmission.

[0004] In order to improve engine efficiency and meet emission regulations, the engine has higher requirements for the control accuracy and function of the valve train. The valve train with the camshaft mounted overhead is conducive to reducing the reciprocating inertia force of the engine, increasing the engine speed, and facilitating more precise control of the valves. However, the current overhead camshaft scheme generally adopts a single gear transmission method to drive the accessories at the rear end of the engine, which to a certain extent limits the size and layout flexibility of the engine accessories. As the size of the engine decreases, the layout and design difficulty of the gear train and engine accessories increases significantly, especially when different derivative models are matched with different types of accessories. Due to the difference in the size of the accessories, it is often difficult to achieve universality and adaptability.

[0005] Therefore, it is necessary to provide a new technical solution to solve the above technical problems. Summary of the invention

[0006] The invention provides an engine gear system and an engine, which are used to solve the problem of difficulty in arranging the existing engine gear system and engine accessories.

[0007] The present invention provides an engine gear train, comprising an engine rear end gear train located on the engine flywheel side, the engine rear end gear train comprising a crankshaft rear end gear, a camshaft gear and a plurality of rear end intermediate gears, the crankshaft rear end gear meshing with the camshaft gear through the plurality of rear end intermediate gears; The engine includes at least two engine rear end accessories, and the engine rear end gear system also includes an engine rear end accessory gear connected to the transmission shaft of each of the engine rear end accessories, each of the engine rear end accessory gears is meshed with one of the rear end intermediate gears in a one-to-one manner, and the crankshaft rear end gear transmits the power of the engine crankshaft to the engine rear end accessories and the camshaft gear through the rear end intermediate gear, and the transmission ratio of the crankshaft rear end gear to the camshaft gear is 2 to 1 by adjusting the gear ratio of the engine rear end gear system.

[0008] According to the engine gear system provided by the present invention, the multiple rear end intermediate gears include at least one pair of coaxially arranged double gears, and the double gears are composed of any two of the multiple rear end intermediate gears. The crankshaft rear end gear is meshed with one of the rear end intermediate gears in the double gears, and the camshaft gear is meshed with the other rear end intermediate gear in the double gears.

[0009] According to the engine gear train provided by the present invention, the engine rear end accessories include an air compressor and a fuel pump, the engine rear end accessory gear includes an air compressor gear and a fuel pump gear, and the rear end intermediate gear includes an air compressor intermediate gear and a fuel pump intermediate gear; The air compressor gear is connected to the transmission shaft of the air compressor, and the air compressor gear is meshed with the rear end gear of the crankshaft through the air compressor intermediate gear; the fuel pump gear is connected to the transmission shaft of the fuel pump, and the fuel pump gear is meshed with the rear end gear of the crankshaft through the fuel pump intermediate gear and the air compressor intermediate gear in turn.

[0010] According to the engine gear system provided by the present invention, the plurality of rear end intermediate gears also include a first intermediate gear, a second intermediate gear and a third intermediate gear, the first intermediate gear and the fuel pump intermediate gear are coaxially arranged to form the double gear, and the first intermediate gear is meshed with the camshaft gear through the second intermediate gear and the third intermediate gear in turn.

[0011] According to the engine gear train provided by the present invention, the gear ratio of the fuel pump intermediate gear to the first intermediate gear is 2:1, and the gear ratio of the crankshaft rear end gear to the camshaft gear is 1:1; Alternatively, the gear ratio of the first intermediate gear to the camshaft gear is 1:1, and the gear ratio of the fuel pump intermediate gear to the crankshaft rear end gear is 2:1.

[0012] According to the engine gear train provided by the present invention, the camshaft gear is connected to the camshaft of the engine, and the camshaft gear is located at one end of the engine rear end gear train close to the cylinder head of the engine.

[0013] The engine gear train provided by the present invention further comprises an engine front end gear train, the engine front end gear train is located on the fan side of the engine, and the engine comprises at least one engine front end accessory; The engine front end gear system includes a crankshaft front end gear, an engine front end accessory gear and a front end intermediate gear. The engine front end accessory gear is connected to the transmission shaft of the engine front end accessory in a one-to-one manner. Each of the engine front end accessory gears is meshed with a front end intermediate gear in a one-to-one manner. The engine front end accessory gear is meshed with the crankshaft front end gear through the front end intermediate gear.

[0014] According to the engine gear train provided by the present invention, all gears in the engine front end gear train and the engine rear end gear train are involute spur gears, and the number of teeth between the two gears meshing with each other is relatively prime.

[0015] According to the engine gear train provided by the present invention, the ratio of the diameter of the largest gear in the engine gear train to the vertical height of the engine gear train is less than 0.25.

[0016] The present invention also provides an engine, comprising an engine gear system as described in any one of the above items, and also comprising an engine body, a cylinder head, a crankshaft and a camshaft, wherein the crankshaft runs through the engine body, the cylinder head is located on the engine body, the camshaft is located on the exhaust side above the cylinder head, and the engine gear system is located on the side of the engine body and is connected to the crankshaft and the camshaft.

[0017] The above technical solution of the present invention has the following beneficial effects: The engine gear system and the engine of the present invention connect the crankshaft rear end gear and the camshaft gear in the engine rear end gear system through a plurality of rear end intermediate gears, and can achieve a transmission ratio of 2 to 1 from the crankshaft rear end gear to the camshaft gear by adjusting the gear tooth number ratio of the engine rear end gear system, thereby meeting the power transmission requirement from the crankshaft through the camshaft to the valve; and, the present invention meshes each engine rear end accessory gear with a rear end intermediate gear one by one, so that in the process that the crankshaft rear end gear transmits the power of the engine crankshaft to the camshaft gear through the rear end intermediate gear, the power of the crankshaft can also be transmitted to the engine rear end accessory through the rear end intermediate gear. Since each engine rear end accessory is driven by a separate rear end intermediate gear, the rear end intermediate gear can be adjusted to adapt to engine accessories of different sizes and models, thereby improving the adaptability of the engine accessories to the engine gear system and the versatility of the engine gear system, and solving the problem of the difficulty of arranging the engine gear system and the engine accessories. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A schematic diagram of the assembly of an engine provided by an embodiment of the present invention; Figure 2 A simplified structural diagram of an engine gear train provided in an embodiment of the present invention.

[0020] Reference numerals: 1. Oil pump intermediate gear; 2. Oil pump gear; 3. Crankshaft front end gear; 4. Engine body; 5. Fuel pump; 6. Air compressor; 7. Air compressor gear; 8. Crankshaft rear end gear; 9. Air compressor intermediate gear; 10. Fuel pump intermediate gear; 11. Fuel pump gear; 12. First intermediate gear; 13. Second intermediate gear; 14. Third intermediate gear; 15. Camshaft gear; 16. Camshaft; 17. Crankshaft; 100. Engine front end gear train; 200. Engine rear end gear train. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] See also Figure 1 The present invention provides an engine, including a body 4, a cylinder head, a crankshaft, a camshaft 16 and an engine gear train, wherein the crankshaft passes through the body 4, the cylinder head is located on the body 4, the camshaft 16 is located on the exhaust side above the cylinder head, and the engine gear train is located on the side of the body 4 and connected to the crankshaft and the camshaft 16. The engine of this embodiment can adopt an overhead camshaft valve train arrangement, and transmit the power of the crankshaft to the camshaft through the engine gear train to realize the overhead camshaft, so as to reduce the reciprocating inertia force of the engine.

[0023] See also Figure 1 and Figure 2 The engine gear train can play a role in camshaft timing and drive engine accessories. Specifically, the engine gear train includes an engine front end gear train 100 and an engine rear end gear train 200, the engine front end gear train 100 is located on the engine fan side, and the engine rear end gear train 200 is located on the engine flywheel side.

[0024] The engine rear end gear train 200 includes a crankshaft rear end gear 8, a camshaft gear 15 and a plurality of rear end intermediate gears (9, 10, 12, 13, 14). The crankshaft 17 runs through the entire engine body 4. The crankshaft rear end gear 8 is fixedly connected to the rear end of the crankshaft 17. The camshaft gear 15 is fixedly connected to the rear end of the camshaft 16. The crankshaft rear end gear 8 is meshed with the camshaft gear 15 through a plurality of rear end intermediate gears. The camshaft gear 15 is located at one end of the engine rear end gear train 200 close to the cylinder head of the engine. The crankshaft rear end gear 8 is the driving gear of the engine rear end gear train 200, and its rotation speed is the same as that of the crankshaft 17.

[0025] A plurality of engine accessories may be provided on the engine, including but not limited to fuel pumps, air compressors, water pumps, oil pumps, and rear power take-off devices. In the present embodiment, the plurality of engine accessories include at least two engine rear end accessories located at the rear end of the engine. The engine rear end gear system 200 also includes an engine rear end accessory gear connected to the transmission shaft of each engine rear end accessory, each engine rear end accessory gear meshes with a rear end intermediate gear in a one-to-one correspondence, the crankshaft rear end gear 8 transmits the power of the engine crankshaft 17 to the engine rear end accessories and the camshaft gear 15 through the rear end intermediate gear, and the transmission ratio of the crankshaft rear end gear 8 to the camshaft gear 15 is 2 to 1 by adjusting the gear ratio of the engine rear end gear system, so as to meet the power transmission requirements from the crankshaft 17 through the camshaft 16 to the valve.

[0026] Since each engine rear end accessory is driven by a separate rear end intermediate gear, the rear end intermediate gear can be adjusted to adapt to engine accessories of different sizes and models, thereby improving the adaptability of the engine accessories to the engine gear system and the versatility of the engine gear system, and solving the difficulty of arranging the engine gear system and engine accessories.

[0027] In one embodiment, the rear end accessories of the engine include an air compressor 6 and a fuel pump 5 as an example for explanation. The air compressor 6 and the fuel pump 5 are arranged at the rear end of the engine body 4, the rear end accessory gears of the engine include an air compressor gear 7 and a fuel pump gear 11, and the rear end intermediate gears include an air compressor intermediate gear 9 and a fuel pump intermediate gear 10.

[0028] Among them, the air compressor gear 7 is fixedly connected to the transmission shaft of the air compressor 6, and the air compressor gear 7 is meshed with the crankshaft rear end gear 8 through the air compressor intermediate gear 9. The crankshaft rear end gear 8 drives the air compressor gear 7 to rotate through the air compressor intermediate gear 9, thereby driving the air compressor 6 to work. At the same time, the crankshaft rear end gear 8 also transmits the power of the crankshaft 17 to the camshaft 16 side through the air compressor intermediate gear 9.

[0029] The fuel pump gear 11 is fixedly connected to the transmission shaft of the fuel pump 5, and the fuel pump gear 11 is meshed with the crankshaft rear end gear 8 through the fuel pump intermediate gear 10 and the air compressor intermediate gear 9 in turn. The crankshaft rear end gear 8 drives the fuel pump gear 11 to rotate through the air compressor intermediate gear 9 and the fuel pump intermediate gear 10, thereby driving the fuel pump 5 to work. At the same time, the crankshaft rear end gear 8 also transmits the power of the crankshaft 17 to the camshaft 16 side through the air compressor intermediate gear 9 and the fuel pump intermediate gear 10.

[0030] Among them, the air compressor intermediate gear 9 and the fuel pump intermediate gear 10 are the intermediate gears of the entire engine rear end gear system 200, and are also the driving gears of the air compressor 6 and the fuel pump 5 respectively. With such a design, the function of the rear end intermediate gear is increased, that is, the rear end intermediate gear is also used to drive the engine rear end accessories in the process of realizing the adjustment of the crankshaft rear end gear to the camshaft gear transmission ratio, thereby reducing the number of gears in the entire gear system. In addition, the size or number of teeth of the air compressor intermediate gear 9 and the fuel pump intermediate gear 10 can be adjusted to adapt to engine accessories of different sizes.

[0031] Further, the plurality of rear-end intermediate gears include at least one pair of coaxially arranged double gears, and the double gears are composed of any two of the plurality of rear-end intermediate gears. Here, the plurality of rear-end intermediate gears including a pair of double gears are used as an example for explanation, the crankshaft rear-end gear 8 is meshed with one of the rear-end intermediate gears in the double gears, and the camshaft gear 15 is meshed with the other rear-end intermediate gear in the double gears.

[0032] Specifically, the plurality of rear-end intermediate gears also include a first intermediate gear 12, a second intermediate gear 13 and a third intermediate gear 14. The first intermediate gear 12 and the fuel pump intermediate gear 10 are coaxially arranged to form a double gear. The first intermediate gear 12 is meshed with the camshaft gear 15 through the second intermediate gear 13 and the third intermediate gear 14 in sequence to transmit the power output by the crankshaft 17 to the camshaft 16. The crankshaft rear end gear 8, the air compressor intermediate gear 9, the air compressor gear 7, the fuel pump intermediate gear 10 and the fuel pump gear 11 are meshed to transmit the power output by the crankshaft rear end gear 8.

[0033] Among them, the air compressor intermediate gear 9, the fuel pump intermediate gear 10, the first intermediate gear 12, the second intermediate gear 13 and the third intermediate gear 14 are used as the intermediate gears of the engine rear end gear system 200, and the crankshaft rear end gear 8 can sequentially transmit the power of the crankshaft 17 to the camshaft 16 through the air compressor intermediate gear 9, the fuel pump intermediate gear 10, the first intermediate gear 12, the second intermediate gear 13, the third intermediate gear 14 and the camshaft gear 15. Among them, the design of the double gear can reduce the size of the gear system in vertical height on the one hand, and on the other hand, it is conducive to realizing that each engine rear end accessory is driven by a separate gear.

[0034] The transmission ratio of the crankshaft rear end gear 8 to the camshaft gear 15 of the present invention is 2:1, which is achieved by adjusting the gear ratio of the engine rear end gear system 200. For example, the gear ratio of the fuel pump intermediate gear 10 to the first intermediate gear 12 is adjusted to 2:1, the gear ratio of the crankshaft rear end gear 8 to the camshaft gear 15 is adjusted to 1:1, and the gear ratios of the remaining rear end intermediate gears to the crankshaft rear end gear 8 or the camshaft gear 15 are all 1:1, so as to achieve a transmission ratio of 2:1 from the crankshaft rear end gear 8 to the camshaft gear 15. Alternatively, the gear ratio of the first intermediate gear 12 to the camshaft gear 15 is 1:1, the gear ratio of the fuel pump intermediate gear 10 to the crankshaft rear end gear 8 is 2:1, and the gear ratios of the remaining rear end intermediate gears to the camshaft gear 15 are all 1:1, so as to achieve a transmission ratio of 2:1 from the crankshaft rear end gear 8 to the camshaft gear 15. In this way, the size of the crankshaft rear end gear 8 and the camshaft gear 15 can be reduced without having the size ratio of the two gears being 1:2, which is beneficial to the small-size design of the entire gear system.

[0035] Of course, the gear ratio adjustment scheme is not limited to the above two. The transmission ratio can also be adjusted step by step in a multi-level gradient manner. As long as the gear ratio of the rear end gear system 200 of the engine is adjusted to ultimately achieve a transmission ratio of 2 to 1 from the rear end gear 8 of the crankshaft to the camshaft gear 15, any scheme is acceptable.

[0036] It can be understood that the double gear can be arranged at any one of the air compressor intermediate gear 9, the fuel pump intermediate gear 10, the first intermediate gear 12, the second intermediate gear 13 or the third intermediate gear 14, and the double gear can be composed of any two gears of the air compressor intermediate gear 9, the fuel pump intermediate gear 10, the first intermediate gear 12, the second intermediate gear 13 and the third intermediate gear 14. The number of double gears can be one pair, two pairs or more pairs, which is not limited here.

[0037] Please continue reading Figure 1 and Figure 2 The engine front end gear train 100 is located at the engine fan side. The engine includes at least one engine front end accessory located at the front end of the engine. The engine front end accessories include but are not limited to any one or more of the above engine accessories. The engine front end gear train 100 includes a crankshaft front end gear 3, an engine front end accessory gear and a front end intermediate gear. The engine front end accessory gear is connected to the transmission shaft of the engine front end accessory in a one-to-one correspondence. Each engine front end accessory gear is meshed with a front end intermediate gear in a one-to-one correspondence. The engine front end accessory gear is meshed with the crankshaft front end gear 3 through the front end intermediate gear.

[0038] In one embodiment, the front-end accessories of the engine include an oil pump, and the front-end gear system 100 of the engine includes an oil pump gear 2 and an oil pump intermediate gear 1. The oil pump gear 2 is fixedly connected to the transmission shaft of the oil pump, and the oil pump gear 2 is meshed with the front-end gear 3 of the crankshaft through the oil pump intermediate gear 1. The front-end gear 3 of the crankshaft is the driving gear in the front-end gear system 100 of the engine, and its rotation speed is the same as that of the crankshaft 17. The front-end gear 3 of the crankshaft transmits the power of the crankshaft 17 to the oil pump gear 2 through the oil pump intermediate gear 1. The oil pump gear 2 drives the oil pump to transport the oil in the oil pan to the entire engine.

[0039] Of course, in other embodiments, the oil pump intermediate gear 1 may not be provided, that is, the crankshaft front end gear 3 directly meshes with the oil pump gear 2 .

[0040] In one embodiment, all gears in the engine front end gear train 100 and / or the engine rear end gear train 200 are involute spur gears, and the number of teeth between the two gears meshing with each other is relatively prime. Involute spur gears have the characteristic of a fixed transmission ratio, and gears with relatively prime numbers of teeth can maintain higher precision and stability during the meshing process, thereby reducing transmission errors, further enhancing the fixed transmission ratio characteristics, and enabling the gear train to transmit torque and speed more accurately. In addition, when the number of teeth of two meshing gears is relatively prime, each tooth of one of the gears will mesh with each tooth of the mating gear, thereby avoiding the appearance of fixed wear points. Since the wear is evenly distributed to each tooth, the degree of wear of a single tooth will be significantly reduced, thereby extending the life of the entire gear train.

[0041] In one embodiment, the gear ratio between the two meshing gears is between 0.60 and 1.62.

[0042] In one embodiment, all gears in the engine front end gear train 100 and / or the engine rear end gear train 200 are helical gears or V-type gears, and variable gears may be used in the gear arrangement.

[0043] In one embodiment, the gear modules, pressure angles, and helix angles of the engine front end gear train 100 and the engine rear end gear train 200 are the same.

[0044] Among them, the engine of the present invention, while satisfying the requirements of overhead camshaft of the engine valve mechanism and a transmission ratio of 2:1 from the engine crankshaft to the camshaft, can also achieve a small-size design of the engine gear system because there is no need to make the size ratio of the crankshaft rear end gear and the camshaft gear 1:2.

[0045] In one embodiment, a ratio of a diameter of a largest gear in the engine gear train to a vertical height of the engine gear train is less than 0.25.

[0046] Furthermore, the ratio of the diameter of the largest gear in the front end gear train of the engine to the vertical height of the front end gear train of the engine is less than 0.25, and / or the ratio of the diameter of the largest gear in the rear end gear train of the engine to the vertical height of the rear end gear train of the engine is less than 0.25.

[0047] In addition, each engine accessory of the engine of the present invention is driven by a separate intermediate gear, and can be adapted to engine accessories of different sizes and models by adjusting the size and position of the intermediate gear, thereby improving the adaptability of the engine accessories to the engine gear system and the versatility of the engine gear system, meeting the adjustment and upgrade space of the overall layout of the engine, and solving the difficulty of arranging the engine gear system and the engine accessories. The engine of the present invention has a higher speed, a smaller reciprocating inertia force and a higher transmission efficiency.

[0048] like Figure 2 As shown, the present invention also provides an engine gear system, which is applied to an engine, and can be specifically applied to an engine with a single overhead camshaft or an engine with a double overhead camshaft. The engine gear system of the present invention is specifically described in the above text, and will not be repeated here.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention. Various changes or deformations based on the principles and ideas of the present invention, such as changing the gear displacement coefficient to reduce the number of teeth to achieve the purpose of optimizing the size of the gear set, or changing the number of intermediate gears to achieve the purpose of transmission effect, are all within the scope of protection of the present invention.

Claims

1. An engine gear train, characterized in that: The engine rear end gear system includes a crankshaft rear end gear, a camshaft gear and a plurality of rear end intermediate gears, wherein the crankshaft rear end gear is meshed with the camshaft gear through the plurality of rear end intermediate gears; The engine includes at least two engine rear end accessories, and the engine rear end gear system also includes an engine rear end accessory gear connected to the transmission shaft of each of the engine rear end accessories, each of the engine rear end accessory gears is meshed with one of the rear end intermediate gears in a one-to-one manner, and the crankshaft rear end gear transmits the power of the engine crankshaft to the engine rear end accessories and the camshaft gear through the rear end intermediate gear, and the transmission ratio of the crankshaft rear end gear to the camshaft gear is 2 to 1 by adjusting the gear ratio of the engine rear end gear system.

2. The engine gear train according to claim 1, characterized in that: The multiple rear end intermediate gears include at least one pair of coaxially arranged double gears, and the double gears are composed of any two of the multiple rear end intermediate gears. The crankshaft rear end gear is meshed with one of the rear end intermediate gears in the double gears, and the camshaft gear is meshed with the other rear end intermediate gear in the double gears.

3. The engine gear train according to claim 2, characterized in that: The rear-end accessories of the engine include an air compressor and a fuel pump, the rear-end accessory gears of the engine include an air compressor gear and a fuel pump gear, and the rear-end intermediate gears include an air compressor intermediate gear and a fuel pump intermediate gear; The air compressor gear is connected to the transmission shaft of the air compressor, and the air compressor gear is meshed with the rear end gear of the crankshaft through the air compressor intermediate gear; the fuel pump gear is connected to the transmission shaft of the fuel pump, and the fuel pump gear is meshed with the rear end gear of the crankshaft through the fuel pump intermediate gear and the air compressor intermediate gear in turn.

4. The engine gear train according to claim 3, characterized in that: The plurality of rear end intermediate gears also include a first intermediate gear, a second intermediate gear and a third intermediate gear. The first intermediate gear and the fuel pump intermediate gear are coaxially arranged to form the double gear. The first intermediate gear is meshed with the camshaft gear through the second intermediate gear and the third intermediate gear in turn.

5. The engine gear train according to claim 4, characterized in that: The gear ratio of the fuel pump intermediate gear to the first intermediate gear is 2:1, and the gear ratio of the crankshaft rear end gear to the camshaft gear is 1:1; Alternatively, the gear ratio of the first intermediate gear to the camshaft gear is 1:1, and the gear ratio of the fuel pump intermediate gear to the crankshaft rear end gear is 2:

1.

6. The engine gear train according to claim 1, characterized in that: The camshaft gear is connected to the camshaft of the engine, and the camshaft gear is located at one end of the rear end gear train of the engine close to the cylinder head of the engine.

7. The engine gear train according to claim 1, characterized in that: Also included is an engine front end gear train, the engine front end gear train being located on the fan side of the engine, the engine including at least one engine front end accessory; The engine front end gear system includes a crankshaft front end gear, an engine front end accessory gear and a front end intermediate gear. The engine front end accessory gear is connected to the transmission shaft of the engine front end accessory in a one-to-one manner. Each of the engine front end accessory gears is meshed with a front end intermediate gear in a one-to-one manner. The engine front end accessory gear is meshed with the crankshaft front end gear through the front end intermediate gear.

8. The engine gear train according to claim 7, characterized in that: All the gears in the engine front end gear train and the engine rear end gear train are involute spur gears, and the numbers of teeth between the two gears meshing with each other are mutually prime.

9. The engine gear train according to claim 1 or 7, characterized in that: The ratio of the diameter of the largest gear in the engine gear train to the vertical height of the engine gear train is less than 0.

25.

10. An engine, characterized in that: It comprises the engine gear train as described in any one of claims 1 to 9, and also comprises an engine body, a cylinder head, a crankshaft and a camshaft, wherein the crankshaft runs through the engine body, the cylinder head is located on the engine body, the camshaft is located on the exhaust side above the cylinder head, and the engine gear train is located on the side of the engine body and connected to the crankshaft and the camshaft.

Images