A diesel engine front end gear train structure and control method

Abstract

The present invention discloses a front-end gear train structure for a diesel engine, comprising a crankshaft pulley, a first water pump pulley, a second water pump pulley, a first generator pulley, a second generator pulley, a power turbine pulley, and an air-conditioning compressor pulley. The crankshaft pulley is connected to the crankshaft via a first electromagnetic clutch, the first water pump pulley is connected to the water pump rotating shaft via a second electromagnetic clutch, the second water pump pulley is directly connected to the water pump rotating shaft, the first generator pulley is connected to the generator rotating shaft via a third electromagnetic clutch, the second generator pulley is directly connected to the generator rotating shaft, the power turbine pulley is connected to the power turbine rotating shaft via a fourth electromagnetic clutch, and the air-conditioning compressor pulley is connected to the air-conditioning compressor rotating shaft via a fifth electromagnetic clutch. The present invention also discloses a control method for the gear train structure. By controlling the power on and off of different electromagnetic clutches under different operating conditions, the present invention achieves drag-reduced starting of the diesel engine, thereby reducing energy consumption during operation.

Description

Technical Field

[0001] The present invention belongs to the technical field of engine accessories, and in particular relates to a front-end gear train structure and a control method for a diesel engine. Background Art

[0002] The front-end gear train of a typical truck diesel engine primarily consists of the crankshaft pulley, generator pulley, water pump, and fan pulleys; for non-independent air conditioning systems, the air conditioning compressor pulley is also included. Power is transmitted via the crankshaft pulley to drive the generator, water pump, and fan. When the electromagnetic clutch of the air conditioning pulley is engaged, the crankshaft pulley also drives the air conditioning compressor through a belt drive. The generator, water pump, and fan in the front-end gear train constitute engine accessories, while the air conditioning compressor constitutes the load. The presence of these accessories creates resistance during diesel engine starting, especially during cold starts, potentially causing starting difficulties. During engine operation, these accessories consume power, hindering energy conservation. The load created by the air conditioning compressor directly consumes some engine power, resulting in energy loss.

[0003] In the prior art, Chinese Patent Publication No. CN210531036U discloses a diesel engine drag-reducing starting device using synchronizer switching. This device incorporates a synchronizer on the crankshaft free-end pulley, achieving drag-reducing starting through manual operation. However, its structure is relatively complex and inconvenient to operate, making it more suitable for starting construction machinery or stationary diesel engines. Chinese Patent Publication No. 207660681U discloses a generator operating device driven by engine waste energy. This device incorporates an electromagnetic clutch at the power turbine output and at the generator pulley, achieving energy savings through switching. However, this device only drives the generator, resulting in a single function and low overall utilization. Summary of the Invention

[0004] To address the shortcomings of the prior art, the present invention provides a diesel engine front-end gear train structure designed to eliminate the resistance generated by accessories during diesel engine startup and shorten idle warm-up time. The present invention also provides a control method for the diesel engine front-end gear train structure, addressing operational control issues that match various engine operating conditions, thereby achieving energy savings and consumption reductions.

[0005] The technical solution of the present invention is as follows: A front-end gear train structure of a diesel engine includes a crankshaft pulley, a first water pump pulley, a second water pump pulley, a first generator pulley, a second generator pulley, a power turbine pulley and an air-conditioning compressor pulley, wherein the crankshaft pulley is connected to the crankshaft through a first electromagnetic clutch, the first water pump pulley is connected to the water pump rotating shaft through a second electromagnetic clutch, the second water pump pulley rotates synchronously with the water pump rotating shaft, the water pump rotating shaft is connected to a cooling fan, the first generator pulley is connected to the generator rotating shaft through a third electromagnetic clutch, the second generator pulley rotates synchronously with the generator rotating shaft, and the power turbine pulley is connected to the fourth electromagnetic clutch. The magnetic clutch is connected to the power turbine shaft, and the power turbine is driven to rotate by the exhaust gas discharged by the exhaust turbine. The air-conditioning compressor pulley is connected to the air-conditioning compressor shaft through the fifth electromagnetic clutch. The crankshaft pulley and the air-conditioning compressor pulley and the first synchronous belt constitute a first pulley transmission mechanism. The crankshaft pulley, the first water pump pulley and the first generator pulley and the second synchronous belt constitute a second pulley transmission mechanism. The power turbine pulley, the second water pump pulley and the second generator pulley and the third synchronous belt constitute a third pulley transmission mechanism. The power turbine pulley and the air-conditioning compressor pulley and the fourth synchronous belt constitute a fourth pulley transmission mechanism.

[0006] Furthermore, when the first electromagnetic clutch is powered off, torque is transmitted between the crankshaft and the crankshaft pulley; when the second electromagnetic clutch is powered on, torque is transmitted between the first water pump pulley and the water pump shaft; when the third electromagnetic clutch is powered on, torque is transmitted between the first generator pulley and the generator shaft; when the fourth electromagnetic clutch is powered on, torque is transmitted between the power turbine pulley and the power turbine shaft; when the fifth electromagnetic clutch is powered on, torque is transmitted between the air-conditioning compressor pulley and the air-conditioning compressor shaft.

[0007] Furthermore, the first electromagnetic clutch includes an electromagnetic coil, a pressure plate and a force transfer plate. A coil groove is provided at the rear end of the crankshaft pulley, and the electromagnetic coil is arranged in the coil groove. The pressure plate is fixedly connected to the crankshaft and is located at the front end of the crankshaft pulley. The force transfer plate is arranged between the pressure plate and the front end of the crankshaft pulley. The force transfer plate is connected to the crankshaft pulley and transmits torque. An elastic member is provided between the force transfer plate and the crankshaft pulley. When the electromagnetic coil is energized, the force transfer plate is separated from the pressure plate. When the electromagnetic coil is de-energized, the force transfer plate is pressed tightly against the pressure plate.

[0008] Furthermore, the third synchronous belt is provided with a first eccentric tensioning wheel for tensioning the third synchronous belt, and the fourth synchronous belt is provided with a second eccentric tensioning wheel for tensioning the fourth synchronous belt.

[0009] Furthermore, in order to save shaft end space, the first electromagnetic clutch and the crankshaft pulley, the second electromagnetic clutch and the first water pump pulley, the third electromagnetic clutch and the first generator pulley, the fourth electromagnetic clutch and the power turbine pulley, and the fifth electromagnetic clutch and the air-conditioning compressor pulley are all integrated clutch pulley structures, and the integrated clutch pulley structure includes a pulley body, an electromagnetic coil and a coupling plate. The pulley body is rotatably connected to the rotating shaft through a bearing, and the coupling plate is fixedly connected to the rotating shaft and is arranged at the front end of the pulley body. A coil groove is provided at the rear end of the pulley body, and the electromagnetic coil is arranged in the coil groove. The rotating shaft is a crankshaft, a water pump shaft, a generator shaft, a power turbine shaft or an air-conditioning compressor shaft.

[0010] Furthermore, the crankshaft pulley is provided with a first belt groove and a second belt groove, the power turbine pulley is provided with a third belt groove and a fourth belt groove, the air-conditioning compressor pulley is provided with a fifth belt groove and a sixth belt groove, the first synchronous belt is wound around the first belt groove and the fifth belt groove, the second synchronous belt is wound around the second belt groove, the first water pump pulley and the first generator pulley, the third synchronous belt is wound around the fourth belt groove, the second water pump pulley and the second generator pulley, and the fourth synchronous belt is wound around the third belt groove and the sixth belt groove.

[0011] Another technical solution of the present invention is: a control method for a front-end gear train structure of a diesel engine, based on the operation of the above-mentioned front-end gear train structure of the diesel engine, comprising the following steps:

[0012] Determine the current operating condition of the diesel engine, which is divided into starting condition, idling and low load condition, and high load condition;

[0013] Under the starting condition, the first electromagnetic clutch is controlled so that the crankshaft does not transmit torque to the crankshaft pulley, and when the diesel engine rotation reaches a set value after starting is completed, the first electromagnetic clutch is controlled so that the crankshaft transmits torque to the crankshaft pulley, and the third electromagnetic clutch is controlled so that torque is transmitted between the first generator pulley and the generator shaft;

[0014] Under the idling and light load conditions, the first electromagnetic clutch is controlled to transmit torque to the crankshaft pulley, and the third electromagnetic clutch is controlled to transmit torque between the first generator pulley and the generator shaft. When the diesel engine coolant temperature is lower than a set threshold, the second electromagnetic clutch is controlled to not transmit torque between the first water pump pulley and the water pump shaft. When the diesel engine coolant temperature is not lower than the set threshold, the second electromagnetic clutch is controlled to transmit torque between the first water pump pulley and the water pump shaft.

[0015] Under the heavy load condition, the first electromagnetic clutch is controlled so that the crankshaft does not transmit torque to the crankshaft pulley, and the fourth clutch is controlled so that torque is transmitted between the power turbine pulley and the power turbine rotating shaft;

[0016] Under the idle and low-load operating condition or the high-load operating condition, when the air conditioner switch is "on", the fifth electromagnetic clutch is controlled to transmit torque between the air conditioner compressor pulley and the air conditioner compressor shaft.

[0017] Furthermore, under the idling and low-load conditions, when the diesel engine coolant temperature is lower than a set threshold and the air conditioning switch is "off", the second electromagnetic clutch is controlled so that no torque is transmitted between the first water pump pulley and the water pump rotating shaft; when the diesel engine coolant temperature is not lower than a set threshold or the air conditioning switch is "on", the second electromagnetic clutch is controlled so that torque is transmitted between the first water pump pulley and the water pump rotating shaft.

[0018] Furthermore, the current working condition of the diesel engine is determined by the engine ECU according to a start switch signal, an engine speed sensor signal and an accelerator pedal position sensor signal.

[0019] Furthermore, the set threshold value of the diesel engine coolant temperature is 80-85°C.

[0020] The advantages of the technical solution provided by the present invention are:

[0021] The engine accessories and air-conditioning compressor are driven by a pulley drive structure equipped with an electromagnetic clutch, connected to the crankshaft and power turbine. By controlling the working state of the electromagnetic clutch under different working conditions, the resistance generated by the accessories is removed when the diesel engine is started, optimizing starting performance. The operation of the water pump and cooling fan is controlled according to the coolant temperature, shortening the idle warm-up time. The drive source of the accessories and air-conditioning compressor is switched under high load to achieve energy saving and consumption reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 2. It is a front view schematic diagram of the diesel engine front end gear train structure of the embodiment.

[0023] Figure 2 yes Figure 1 AA expansion diagram.

[0024] Figure 3 2. It is a schematic diagram of a control method for a front-end gear train structure of a diesel engine according to an embodiment. DETAILED DESCRIPTION

[0025] The present invention will be further described below with reference to the following examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading this description, various equivalent modifications to this description by those skilled in the art fall within the scope defined by the claims appended to this application.

[0026] Please combine Figure 1 and Figure 2 As shown, the front-end gear train structure of the diesel engine involved in this embodiment includes a crankshaft pulley 1, a first water pump pulley 2, a second water pump pulley 3, a first generator pulley 4, a second generator pulley 5, a power turbine pulley 6 and an air-conditioning compressor pulley 7.

[0027] The crankshaft pulley 1 is connected to the crankshaft 8 via a first electromagnetic clutch. Whether the first electromagnetic clutch is engaged or not determines whether torque is transmitted between the crankshaft pulley 1 and the crankshaft 8. The first electromagnetic clutch is a reverse-acting electromagnetic clutch. That is, when the first electromagnetic clutch is energized, the crankshaft 8 does not transmit torque to the crankshaft pulley 1. When the first electromagnetic clutch is de-energized, the crankshaft 8 transmits torque to the crankshaft pulley 1. Specifically, the first electromagnetic clutch and crankshaft pulley 1 are integrally designed. The crankshaft pulley 1 is rotatably connected to the free end of the crankshaft 8 via a bearing. A drive plate 9 is bolted to the free end of the crankshaft 8. A front pressure plate 10 is riveted to the drive plate 9. A force transmission plate 11, shaped like a centrally-holed circular disc and made of magnetically conductive material, is positioned within a shallow, concave cylindrical cavity at the front end of the crankshaft pulley 1. The force transmission plate 11 is axially movable along circumferentially arranged sliding guide pins 12. A circumferentially arranged pre-compressed compression spring 13 extends through a blind hole at the front end of the crankshaft pulley 1. A drive pin is positioned along the axis of the compression spring 13. A coil slot is located at the rear end of the crankshaft pulley 1. The electromagnetic coil 14 of the first electromagnetic clutch is located within the slot. The grounding wire of the electromagnetic coil 14 is bolted to the engine gear cover. The lead wire of the electromagnetic coil 14 is connected to the engine ECU. The housing of the electromagnetic coil 14 is secured to the engine gear cover with multiple screws. The outer cylindrical surface of the crankshaft pulley 1 is machined with a first belt slot for winding the first timing belt 32 and a second belt slot for winding the second timing belt 33.

[0028] The first water pump pulley 2 is connected to the water pump shaft 15 via a second electromagnetic clutch, and the second water pump pulley 3 rotates synchronously with the water pump shaft 15. In a forced circulation closed water cooling system, the centrifugal water pump 16 is coaxial with the cooling fan 17, that is, the cooling fan 17 is also connected to the water pump shaft 15. The water pump adopts a centrifugal water pump 16 and maintains the original assembly position, that is, it is fastened to the engine cylinder block; the extended end of the water pump shaft 15 is machined with a shaft shoulder, and the second water pump pulley 3 is slidably fitted on the water pump shaft 15, with the rear end of the second water pump pulley 3 close to the shaft shoulder, and the front end of the second water pump pulley 3 is axially limited by a shaft elastic ring. The second water pump pulley 3 is machined with a belt groove for winding the third synchronous belt 34, and a flat key placed between the water pump shaft 15 and the second water pump pulley 3 is used to transmit torque.

[0029] A second electromagnetic clutch is located at the front end of the water pump shaft 15. The first water pump pulley 2 and the second electromagnetic clutch form an integrated clutch pulley structure. The pulley body of the first water pump pulley 2 is rotationally connected to the water pump shaft 15 via a bearing. A coupling plate 18 is fixedly connected to the water pump shaft 15 and disposed at the front end of the pulley body. A coil slot is provided at the rear end of the pulley body, within which an electromagnetic coil 19 is disposed. The grounding wire of the electromagnetic coil 19 is bolted to the front end cover of the water pump body. The lead wire of the electromagnetic coil 19 is connected to the engine ECU, and the housing of the electromagnetic coil 19 is secured to the front end cover of the water pump body with multiple screws. The outer cylindrical surface of the pulley body is machined with a belt slot for winding the second timing belt 33.

[0030] The first generator pulley 4 is connected to the generator shaft 20 via a third electromagnetic clutch, and the second generator pulley 5 rotates synchronously with the generator shaft 20. The silicon rectifier generator 23 maintains its original assembly position. A shoulder is machined on the extended end of the generator shaft 20. The second generator pulley 5 is slip-fitted (clearance-fitted) onto the generator shaft 20, with the rear end of the second generator pulley 5 abutting the shoulder and the front end axially limited by a shaft circlip. The second generator pulley 5 is machined with a belt groove for winding a third synchronous belt 34. A flat key is placed between the generator shaft 20 and the second generator pulley 5 to transmit torque.

[0031] The silicon rectifier generator 23 has a third electromagnetic clutch located at the front end of the generator shaft 20. The first generator pulley 4 and the third electromagnetic clutch form an integrated clutch pulley structure. The pulley body of the first generator pulley 4 is rotationally connected to the generator shaft 20 via a bearing. The engaging plate 21 is fixedly connected to the generator shaft 20 and disposed at the front end of the pulley body. The rear end of the pulley body is provided with a coil slot, within which the electromagnetic coil 22 is disposed. The grounding wire of the electromagnetic coil 22 is bolted to the generator front cover. The lead wire of the electromagnetic coil 22 is connected to the engine ECU. The housing of the electromagnetic coil 22 is secured to the generator front cover with multiple screws. The outer cylindrical surface of the pulley body is machined with a belt slot for winding the second timing belt 33.

[0032] The power turbine pulley 6 is connected to the power turbine shaft 24 via a fourth electromagnetic clutch. The power turbine 25 is connected in series with the exhaust turbocharger 26. The exhaust inlet of the exhaust turbocharger 26 is bolted to the exhaust manifold flange after the engine's integration. When the engine is operating, the exhaust gas energy drives the radial turbine to rotate, driving the coaxial centrifugal compressor, thereby achieving intake air pressure boosting. The exhaust gas undergoes energy conversion in the radial turbine, reducing its flow rate, temperature, and pressure, and is discharged through the exhaust duct, entering the power turbine 25 inlet. The exhaust gas, still containing kinetic and pressure energy, continues to expand within the power turbine, partially converting it into mechanical energy, driving the power turbine 25 to rotate. After further energy conversion, the exhaust gas enters the engine exhaust manifold through the power turbine 25 exhaust port. The power turbine 25 is fastened to the engine block bracket.

[0033] A fourth electromagnetic clutch is located at the front end of the power turbine shaft 24. The power turbine pulley 6 and the fourth electromagnetic clutch form an integrated clutch pulley structure. The pulley body of the power turbine pulley 6 is rotationally connected to the power turbine shaft 24 via a bearing. A coupling plate 27 is fixedly connected to the power turbine shaft 24 and disposed at the front end of the pulley body. A coil slot is provided at the rear end of the pulley body, housing an electromagnetic coil 28. The grounding wire of the electromagnetic coil 28 is bolted to the housing of the power turbine 25. The lead wire of the electromagnetic coil 28 is connected to the engine ECU, and the housing of the electromagnetic coil 28 is secured to the housing of the power turbine 25 with multiple screws. The outer cylindrical surface of the pulley body is machined with a third belt slot for winding the fourth timing belt 35 and a fourth belt slot for winding the third timing belt 34.

[0034] The air conditioner compressor pulley 7 is connected to the air conditioner compressor shaft 29 via a fifth electromagnetic clutch. The air conditioner compressor pulley 7 and the fifth electromagnetic clutch form an integrated clutch pulley structure. The pulley body of the air conditioner compressor pulley 7 is rotationally connected to the air conditioner compressor shaft 29 via a bearing. A coupling plate 30 is fixedly connected to the air conditioner compressor shaft 29 and disposed at the front end of the pulley body. A coil slot is provided at the rear end of the pulley body, within which an electromagnetic coil 31 is disposed. The grounding wire of the electromagnetic coil 31 is bolted to the front cover of the air conditioner compressor 38. The lead wire of the electromagnetic coil 30 is connected to the engine ECU, and the housing of the electromagnetic coil 31 is secured to the front cover of the air conditioner compressor 38 with multiple screws. The outer cylindrical surface of the pulley body is machined with a fifth belt slot for winding the first timing belt 32 and a sixth belt slot for winding the fourth timing belt 35.

[0035] The first belt groove of the crankshaft pulley 1 is aligned with the fifth belt groove of the air-conditioning compressor pulley 7, around which a first synchronous belt 32 is wound, forming the first pulley transmission mechanism. The tension of the first synchronous belt 32 is adjusted by a kidney-shaped groove located at the bottom of the air-conditioning compressor 38. The second belt groove of the crankshaft pulley 1 is aligned with the belt grooves of the first water pump pulley 2 and the first generator pulley 4, around which a second synchronous belt 33 is wound, forming the second pulley transmission mechanism. The tension of the second synchronous belt 33 is adjusted by the tensioning mechanism originally located on the first generator pulley 4. The fourth belt grooves of the second water pump pulley 3 and the second generator pulley 5 are aligned with the power turbine pulley 6, around which a third synchronous belt 34 is wound, forming the third pulley transmission mechanism. The tension of the third synchronous belt 34 is adjusted by a first eccentric tensioner 36 located above and to the left of the second generator pulley 5 and the second water pump pulley 3. The first eccentric tensioner 36 can be mounted on a bracket fixed to the engine block. The third belt groove of the power turbine pulley 6 and the sixth belt groove of the air-conditioning compressor pulley 7 are in the same plane, and the fourth synchronous belt 35 is wound around to form a fourth pulley transmission mechanism. The fourth synchronous belt 35 is adjusted by a second eccentric tensioner 37 arranged above its middle part, and the second eccentric tensioner 37 is installed on a bracket fixed to the engine cylinder block.

[0036] Please combine Figure 3 As shown, the control method based on the above diesel engine front-end gear train structure is as follows:

[0037] The engine ECU determines the diesel engine operating conditions, which are starting condition, idling and low load condition, and high load condition.

[0038] During starting, the starter key is turned to the on position, and the starter switch signal STA is transmitted to the engine ECU. The engine ECU issues a command, energizing the electromagnetic coil of the first electromagnetic clutch, generating electromagnetic force. The force transfer plate is attracted and moves along the guide pin toward the front end of the crankshaft pulley, overcoming the force of the compression spring. A gap is created between the force transfer plate and the pressure plate, preventing crankshaft power transmission and disabling accessories such as the generator, water pump, and fan. At this time, the other electromagnetic clutches are de-energized.

[0039] At the moment the engine starts, accessories such as the generator, water pump and fan do not work, which reduces the starting resistance and ensures the starting performance to a certain extent.

[0040] After the diesel engine is successfully started, the engine ECU determines that the start is successful based on the speed signal from the engine speed sensor (shared with the engine electronic control system). If the speed reaches 500r / min, the ECU issues a command to cut off the power supply to the electromagnetic coil of the first electromagnetic clutch. At the same time, the third electromagnetic clutch is energized, the electromagnetic force of the first electromagnetic clutch disappears, and the compression spring force pushes the transmission plate along the sliding guide pin to close the pressure plate. The crankshaft pulley rotates with the crankshaft, and the accessories enter normal operation. The power transmission line is: crankshaft → flat key → drive plate → pressure plate → transmission plate → transmission pin → crankshaft pulley → accessory operation.

[0041] After successful starting, it ensures that the generator (one of the car's power sources, connected in parallel with the battery) can supply power to the vehicle's electrical system in a timely manner.

[0042] During idle and light-load conditions, the coolant temperature sensor detects the coolant temperature, with a threshold set at 80°C (selectable between 80 and 85°C). When the coolant temperature is below 80°C, the engine enters the idle warm-up phase, the second electromagnetic clutch is de-energized, the engine enters the small-cycle phase, and the water pump and fan do not operate. When the engine coolant temperature rises to approximately 80°C, the engine cooling system enters the large-cycle phase, the second electromagnetic clutch is energized, and the second pulley drive mechanism drives the cooling water pump and fan to operate normally, shortening the warm-up time. Since the water pump and fan accessories are not operating during the idle warm-up phase, energy conservation is achieved to a certain extent.

[0043] Under high-load conditions, the engine ECU determines the diesel engine speed and accelerator pedal opening based on the accelerator pedal position sensor and engine speed sensor signals. By setting pedal position and speed thresholds, the ECU determines that the engine is operating under high load when the accelerator pedal position sensor signal exceeds the threshold or the diesel engine speed exceeds the threshold. Under these conditions, more fuel is injected into the engine cylinders, generating greater heat during the combustion cycle, causing the coolant to heat up quickly and resulting in more exhaust gas energy.

[0044] When the first electromagnetic clutch is energized, the crankshaft pulley is inoperative. When the fourth electromagnetic clutch is energized, the power turbine pulley operates, and accessories such as the generator, water pump, and fan are directly driven by the power turbine via the second generator pulley and the second water pump and fan pulley. The second and third electromagnetic clutches can be energized or de-energized.

[0045] In the above-mentioned idle and low-load conditions, or high-load conditions, as long as the air conditioning switch signal is turned on, the fifth electromagnetic clutch is energized, so that the crankshaft or power turbine provides power to the air conditioning compressor to achieve cooling. In the idle and low-load conditions, the second electromagnetic clutch is also energized, and the fan is always working to ensure the normal operation of the air conditioning system condenser.

[0046] During diesel engine operation, the engine idles for approximately 25% of the time. If the temperature is low and the wind speed is high, the coolant temperature at idle may drop below 80°C, rendering the water pump and fan inoperative and improving engine efficiency. The present invention eliminates the thermostat in conventional diesel engine water cooling systems, simplifying the structure and reducing costs. During normal operation, exhaust gas removes 25% to 45% of the heat, and the exhaust temperature is 700 to 900K. Under high-load conditions, an exhaust-driven power turbine is used to drive accessories such as the generator, water pump, and fan. When air conditioning is required, the power turbine also drives the system, achieving energy savings and reducing consumption.

Claims

1. A diesel engine front end gear train structure, characterized in that: It includes a crankshaft pulley, a first water pump pulley, a second water pump pulley, a first generator pulley, a second generator pulley, a power turbine pulley and an air-conditioning compressor pulley, the crankshaft pulley is connected to the crankshaft through a first electromagnetic clutch, the first water pump pulley is connected to the water pump rotating shaft through a second electromagnetic clutch, the second water pump pulley rotates synchronously with the water pump rotating shaft, the water pump rotating shaft is connected to a cooling fan, the first generator pulley is connected to the generator rotating shaft through a third electromagnetic clutch, the second generator pulley rotates synchronously with the generator rotating shaft, and the power turbine pulley is connected to the power turbine rotating shaft through a fourth electromagnetic clutch. Then, the power turbine is driven to rotate by the exhaust gas discharged by the exhaust turbine, the air-conditioning compressor pulley is connected to the air-conditioning compressor shaft through the fifth electromagnetic clutch, the crankshaft pulley and the air-conditioning compressor pulley and the first synchronous belt constitute a first pulley transmission mechanism, the crankshaft pulley, the first water pump pulley and the first generator pulley and the second synchronous belt constitute a second pulley transmission mechanism, the power turbine pulley, the second water pump pulley and the second generator pulley and the third synchronous belt constitute a third pulley transmission mechanism, the power turbine pulley and the air-conditioning compressor pulley and the fourth synchronous belt constitute a fourth pulley transmission mechanism.

2. The diesel engine front end gear train structure according to claim 1, characterized in that: When the first electromagnetic clutch is powered off, torque is transmitted between the crankshaft and the crankshaft pulley; when the second electromagnetic clutch is powered on, torque is transmitted between the first water pump pulley and the water pump shaft; when the third electromagnetic clutch is powered on, torque is transmitted between the first generator pulley and the generator shaft; when the fourth electromagnetic clutch is powered on, torque is transmitted between the power turbine pulley and the power turbine shaft; when the fifth electromagnetic clutch is powered on, torque is transmitted between the air-conditioning compressor pulley and the air-conditioning compressor shaft.

3. The diesel engine front end gear train structure according to claim 2, characterized in that: The first electromagnetic clutch includes an electromagnetic coil, a pressure plate and a force transfer plate. A coil groove is provided at the rear end of the crankshaft pulley, and the electromagnetic coil is arranged in the coil groove. The pressure plate is fixedly connected to the crankshaft and is located at the front end of the crankshaft pulley. The force transfer plate is arranged between the pressure plate and the front end of the crankshaft pulley. The force transfer plate is connected to the crankshaft pulley and transmits torque. An elastic member is provided between the force transfer plate and the crankshaft pulley. When the electromagnetic coil is energized, the force transfer plate is separated from the pressure plate. When the electromagnetic coil is de-energized, the force transfer plate is pressed tightly against the pressure plate.

4. The diesel engine front end gear train structure according to claim 1, characterized in that: The third synchronous belt is provided with a first eccentric tensioning wheel for tensioning the third synchronous belt, and the fourth synchronous belt is provided with a second eccentric tensioning wheel for tensioning the fourth synchronous belt.

5. The diesel engine front end gear train structure according to claim 1, characterized in that: The first electromagnetic clutch and the crankshaft pulley, the second electromagnetic clutch and the first water pump pulley, the third electromagnetic clutch and the first generator pulley, the fourth electromagnetic clutch and the power turbine pulley, and the fifth electromagnetic clutch and the air-conditioning compressor pulley are all integrated clutch pulley structures, and the integrated clutch pulley structure includes a pulley body, an electromagnetic coil and a coupling plate. The pulley body is rotatably connected to the rotating shaft through a bearing, the coupling plate is fixedly connected to the rotating shaft and is arranged at the front end of the pulley body, and a coil groove is provided at the rear end of the pulley body. The electromagnetic coil is arranged in the coil groove, and the rotating shaft is a crankshaft, a water pump shaft, a generator shaft, a power turbine shaft or an air-conditioning compressor shaft.

6. The diesel engine front end gear train structure according to claim 1, characterized in that: The crankshaft pulley is provided with a first belt groove and a second belt groove, the power turbine pulley is provided with a third belt groove and a fourth belt groove, the air-conditioning compressor pulley is provided with a fifth belt groove and a sixth belt groove, the first synchronous belt is wound around the first belt groove and the fifth belt groove, the second synchronous belt is wound around the second belt groove, the first water pump pulley and the first generator pulley, the third synchronous belt is wound around the fourth belt groove, the second water pump pulley and the second generator pulley, and the fourth synchronous belt is wound around the third belt groove and the sixth belt groove.

7. A method for controlling a front-end gear train structure of a diesel engine, characterized in that: The operation of the diesel engine front-end gear train structure according to any one of claims 1 to 6 includes the following steps: Determine the current operating condition of the diesel engine, which is divided into starting condition, idling and low load condition, and high load condition; Under the starting condition, the first electromagnetic clutch is controlled so that the crankshaft does not transmit torque to the crankshaft pulley, and when the diesel engine rotation reaches a set value after starting is completed, the first electromagnetic clutch is controlled so that the crankshaft transmits torque to the crankshaft pulley, and the third electromagnetic clutch is controlled so that torque is transmitted between the first generator pulley and the generator shaft; Under the idling and light load conditions, the first electromagnetic clutch is controlled to transmit torque to the crankshaft pulley, and the third electromagnetic clutch is controlled to transmit torque between the first generator pulley and the generator shaft. When the diesel engine coolant temperature is lower than a set threshold, the second electromagnetic clutch is controlled to not transmit torque between the first water pump pulley and the water pump shaft. When the diesel engine coolant temperature is not lower than the set threshold, the second electromagnetic clutch is controlled to transmit torque between the first water pump pulley and the water pump shaft. Under the heavy load condition, the first electromagnetic clutch is controlled so that the crankshaft does not transmit torque to the crankshaft pulley, and the fourth electromagnetic clutch is controlled so that torque is transmitted between the power turbine pulley and the power turbine rotating shaft; Under the idle and low-load operating condition or the high-load operating condition, when the air conditioner switch is "on", the fifth electromagnetic clutch is controlled to transmit torque between the air conditioner compressor pulley and the air conditioner compressor rotating shaft.

8. The control method of the diesel engine front end gear train structure according to claim 7, characterized in that: Under the idling and low-load conditions, when the diesel engine coolant temperature is lower than a set threshold and the air conditioning switch is "off", the second electromagnetic clutch is controlled so that no torque is transmitted between the first water pump pulley and the water pump rotating shaft; when the diesel engine coolant temperature is not lower than the set threshold or the air conditioning switch is "on", the second electromagnetic clutch is controlled so that torque is transmitted between the first water pump pulley and the water pump rotating shaft.

9. The control method of the diesel engine front end gear train structure according to claim 7, characterized in that: The current working condition of the diesel engine is determined by the engine ECU based on the start switch signal, the engine speed sensor signal and the accelerator pedal position sensor signal.

10. The control method of the diesel engine front end gear train structure according to claim 7, characterized in that: The set threshold value of the diesel engine coolant temperature is 80-85°C.

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