CN111828166A

CN111828166A - Two-stage supercharged diesel engine

Info

Publication number: CN111828166A
Application number: CN201910313901.9A
Authority: CN
Inventors: 蓝青松; 吴旭陵; 姚建明; 刘斐; 王慧; 严永华; 金天柱; 陈勇; 陈霖强; 董瑞谦; 范永奇; 徐涛; 李春玲
Original assignee: SAIC Motor Corp Ltd
Current assignee: SAIC Motor Corp Ltd
Priority date: 2019-04-18
Filing date: 2019-04-18
Publication date: 2020-10-27

Abstract

The invention discloses a two-stage supercharging diesel engine, which comprises a two-stage supercharging component, a low-pressure EGR pipeline and a high-pressure EGR pipeline, wherein an air inlet of the low-pressure EGR pipeline is connected with the downstream of an exhaust gas post-processing system, an air outlet of the low-pressure EGR pipeline is connected with the upstream of a low-pressure compressor of the two-stage supercharging component, an air inlet of the high-pressure EGR pipeline is connected with the upstream of a high-pressure turbine of the two-stage supercharging component, and an air outlet of the high. In addition, the variable vortex air intake manifold, the high-pressure common rail fuel injection system, the water-cooled intercooler, the two-stage variable oil pump, a cylinder body cooling pipeline and a cylinder cover cooling pipeline which are arranged in parallel, two balance shafts integrated in the cylinder body, a low-noise timing cover cap, a camshaft cover cap and the like are further arranged. The two-stage supercharged diesel engine can meet the emission standard of the sixth stage, has excellent power performance and NVH performance, and is low in oil consumption, reliable in operation and compact in overall structure.

Description

Two-stage supercharged diesel engine

Technical Field

The invention relates to the technical field of automobiles, in particular to a two-stage supercharged diesel engine.

Background

In the current market, the emission of diesel engines can only meet the third stage emission standard of China but can not meet the emission standard of higher stages. And at the stage that the emission standard is increased by one liter, the corresponding oil consumption limit value is reduced by 15 percent.

With the increasing strictness of emission standards, it is a technical problem to be solved by those skilled in the art to develop a diesel engine which can meet emission standards at higher stages and has better power performance and fuel economy.

Disclosure of Invention

In order to solve the technical problems, the invention provides a two-stage supercharged diesel engine which can meet the emission standard of the sixth stage (national six standard) and has better power performance and fuel economy.

The invention provides a two-stage supercharging type diesel engine which comprises two-stage supercharging components, wherein each two-stage supercharging component comprises a high-pressure turbocharger and a low-pressure turbocharger which are arranged in series, a vortex-end bypass valve and a pressure-end bypass valve, the vortex-end bypass valve is arranged between the air inlet side and the air outlet side of a turbine of the low-pressure turbocharger, and the pressure-end bypass valve is arranged on an air outlet connector of a compressor of the high-pressure turbocharger;

the exhaust gas treatment system further comprises a low-pressure EGR pipeline and a high-pressure EGR pipeline, wherein an air inlet of the low-pressure EGR pipeline is connected to the downstream of an exhaust gas after-treatment system of the two-stage supercharged diesel engine, an air outlet of the low-pressure EGR pipeline is connected to the upstream of a compressor of the low-pressure turbocharger, an air inlet of the high-pressure EGR pipeline is connected to the upstream of a turbine of the high-pressure turbocharger, and an air outlet of the high-pressure EGR pipeline is; wherein upstream and downstream of a component are based on the direction of airflow through the component.

So set up, in the operation, can switch over EGR pipeline according to the load state. The low-pressure EGR pipeline is conducted under the low-load state, and the high-pressure EGR pipeline is conducted under the medium-high load state, so that the recirculation quantity of the exhaust gas can reach the optimal condition at each working point, and the combustion process can be always in the optimal condition. Therefore, the pollution components in the emissions can be guaranteed to be minimum, so that the engine can meet the emission standard of the sixth stage.

In addition, during operation, the supercharger can be switched according to the rotating speed and the supercharging pressure. At low rotation speed, the vortex end bypass valve and the pressure end bypass valve are closed, and at the moment, the high-pressure turbocharger plays a main role, so that the problem of insufficient low-speed power can be solved; when the boost pressure is increased to the set pressure of the high-pressure turbocharger along with the increase of the rotating speed, the vortex end bypass valve is opened, the pressure end bypass valve is kept closed, and the high-pressure turbocharger and the low-pressure turbocharger play the same role at the moment, so that the stable increase of the power and the high torque output in a large rotating speed range can be ensured. At high rotation speed, the pressure end bypass valve and the vortex end bypass valve are opened, and the low-pressure turbocharger plays a main role at the moment, so that sufficient air inflow and high power output can be ensured. Therefore, the engine can obtain better power performance and fuel economy under different rotating speeds.

The variable vortex air intake manifold comprises a first air passage and a second air passage which correspond to the same cylinder, and a variable vortex control valve is arranged in each first air passage; the variable vortex control valve is connected with the control shaft so as to rotate along with the rotation of the control shaft to open and close the first air passage.

The high-pressure common rail fuel injection system has the advantages that the maximum injection pressure is 2000bar, the minimum injection interval is 0.2ms, the maximum injection frequency of each cycle is 8 times, and the high-pressure common rail fuel injection system has the functions of pre-injection, main injection and post-injection.

Furthermore, the air compressor further comprises a water-cooled intercooler and a low-temperature radiator, wherein the water-cooled intercooler is communicated with an outlet of the air compressor, the low-temperature radiator is specially used for radiating the water-cooled intercooler, and an electronic water pump is arranged on a communication pipeline between the low-temperature radiator and the water-cooled intercooler.

Further, the engine further comprises a two-stage variable oil pump, and is configured to: when the rotating speed v is less than 1800rpm, the engine oil pressure is 1.8bar, and when the rotating speed v is less than or equal to 1800rpm and less than or equal to 4000rpm, the engine oil pressure is 3.6 bar.

Further, still including parallelly connected cylinder body cooling pipeline and the cylinder cap cooling pipeline who sets up, be equipped with the cylinder cap thermostat on the cylinder cap cooling pipeline, be equipped with the cylinder body thermostat on the cylinder body cooling pipeline to realize the separation cooling of cylinder cap and cylinder body.

Further, valve chamber shroud and cylinder cap of two-stage booster-type diesel engine pass through the bolt and link to each other, the pole portion periphery cover of bolt is equipped with the bolt bush, the upper end periphery of bolt bush is equipped with first cyclic annular flange, the periphery cover of bolt bush is equipped with the rubber packing ring, the rubber packing ring supports to press between first cyclic annular flange and the valve chamber shroud.

Further, a crankshaft of the two-stage supercharged diesel engine is arranged below the cylinder and is in a left position, and two balance shafts of the two-stage supercharged diesel engine are arranged in the cylinder body; the first balance shaft is positioned at the upper left of the crankshaft, and a driving gear of the first balance shaft is directly meshed with a crankshaft gear arranged at the rear end of the crankshaft; the second balance shaft is positioned at the upper right part of the crankshaft, and a driving gear of the second balance shaft is indirectly meshed with the crankshaft gear through an idle gear coated with a sound insulation coating.

Furthermore, the crankshaft of the two-stage supercharged diesel engine drives the camshaft and the fuel pump to operate through the timing toothed belt and also drives the oil pump to operate through the oil pump toothed belt.

Further, the timing cover of the two-stage supercharged diesel engine is connected to the front sides of the cylinder body and the cylinder cover through bolts, and vibration isolating cushions are arranged between the timing cover and the cylinder body and between the timing cover and the cylinder cover.

Drawings

FIG. 1 is a front view of one embodiment of a diesel engine provided in accordance with the present invention;

FIG. 2 is a rear view of the embodiment of FIG. 1;

FIG. 3 is a top view of the embodiment shown in FIG. 1;

FIG. 4 is a schematic illustration of a variable swirl intake manifold according to the exemplary embodiment of FIG. 1;

FIG. 5 is a schematic illustration of the accessory drive assembly of the exemplary embodiment of FIG. 1;

FIG. 6 is a schematic view of the valve chamber cover of the embodiment of FIG. 1;

FIG. 7 is a schematic illustration of the valve chamber cover and cylinder head attachment location of FIG. 6;

FIG. 8 is a schematic view of the arrangement of two balance shafts of the embodiment of FIG. 1;

FIG. 9 is a schematic diagram of the transmission structure of the balance shaft and the crankshaft and the transmission structure of the oil pump and the crankshaft of the embodiment shown in FIG. 1;

FIG. 10 is a schematic diagram of the camshaft and crankshaft drive configuration of the embodiment shown in FIG. 1.

Wherein the reference numerals in fig. 1 to 10 are explained as follows:

1 two-stage supercharging component, 2 water-cooled intercooler, 3 timing cover, 4 oil pan, 5 flywheel, 6 valve chamber cover, 6a bolt, 7 high-pressure common rail fuel injection system, 8 variable vortex intake manifold, 8a first air passage, 8b second air passage, 9 variable vortex control valve, 10 control shaft, 11 driving motor, 12 crankshaft pulley, 13 water pump pulley, 14 power-assisted steering pulley, 15 generator pulley, 16 accessory belt, 17 double damping tensioner, 18 bolt bush, 18a first annular flange, 18b second annular flange, 19 rubber gasket, 20 cylinder, 21 balance shaft, 22 crankshaft, 23 idler gear, 24 crankshaft gear, 25 crankshaft driving pulley, 26 oil pump toothed belt, 27 fuel pump pulley, 28 crankshaft timing pulley, 29 camshaft timing pulley, 30 timing toothed belt, 31 double-edge automatic tensioner.

Detailed Description

In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution of the present invention is further described in detail below with reference to the accompanying drawings and the detailed description.

Referring to fig. 1 to 10, fig. 1 is a front view of an embodiment of a diesel engine according to the present invention; FIG. 2 is a rear view of the embodiment of FIG. 1; FIG. 3 is a top view of the embodiment shown in FIG. 1; FIG. 4 is a schematic illustration of a variable swirl intake manifold according to the exemplary embodiment of FIG. 1; FIG. 5 is a schematic illustration of the accessory drive assembly of the exemplary embodiment of FIG. 1; FIG. 6 is a schematic view of the valve chamber cover of the embodiment of FIG. 1; FIG. 7 is a schematic illustration of the valve chamber cover and cylinder head attachment location of FIG. 6; FIG. 8 is a schematic view of the arrangement of two balance shafts of the embodiment of FIG. 1; FIG. 9 is a schematic diagram of the transmission structure of the balance shaft and the crankshaft and the transmission structure of the oil pump and the crankshaft of the embodiment shown in FIG. 1; FIG. 10 is a schematic diagram of the camshaft and crankshaft drive configuration of the embodiment shown in FIG. 1.

As shown in fig. 1, the two-stage supercharging diesel engine (hereinafter referred to as engine) includes a two-stage supercharging component 1, and the two-stage supercharging component 1 specifically includes a high-pressure turbocharger, a low-pressure turbocharger, a turbine-side bypass valve, and a pressure-side bypass valve.

Wherein the high-pressure turbocharger and the low-pressure turbocharger are connected in series with each other. Specifically, a turbine of the high-pressure turbocharger (hereinafter, referred to as a high-pressure turbine) communicates with an exhaust manifold of the cylinder, and a compressor of the high-pressure turbocharger (hereinafter, referred to as a high-pressure compressor) communicates with an intake manifold of the cylinder. A turbine of a low-pressure turbocharger (hereinafter, simply referred to as a low-pressure turbine) is connected in series on the exhaust side of the high-pressure turbine. A compressor of the low-pressure turbocharger (hereinafter referred to as a low-pressure compressor) is connected in series to an air inlet side of the high-pressure compressor. Specifically, the high-pressure turbocharger may be a Variable Nozzle Turbocharger (VNT), and the low-pressure turbocharger may be a Waste Gate Turbocharger (WGT).

Wherein the scroll-end bypass valve is arranged between an intake side and an exhaust side of the low pressure turbine. When the turbine-end bypass valve is open, exhaust gas discharged from the cylinder flows through the bypass in which the turbine-end bypass valve is located, and thus does not substantially flow through the high pressure turbine.

The pressure end bypass valve is arranged on an air inlet joint and an air outlet joint of the high-pressure compressor. When the pressure side bypass valve is open, air discharged from the low pressure compressor flows through the bypass where the pressure side bypass valve is located, and thus does not substantially flow through the high pressure compressor.

During operation, the ECU may switch the supercharger based on the rotational speed and boost pressure. At low rotation speed, the vortex end bypass valve and the pressure end bypass valve are closed, and at the moment, the high-pressure turbocharger plays a main role, so that the problem of insufficient low-speed power can be solved; when the boost pressure is increased to the set pressure of the high-pressure turbocharger along with the increase of the rotating speed, the vortex end bypass valve is opened, the pressure end bypass valve is kept closed, and the high-pressure turbocharger and the low-pressure turbocharger play the same role at the moment, so that the stable increase of the power and the high torque output in a large rotating speed range can be ensured. At high rotation speed, the pressure end bypass valve and the vortex end bypass valve are opened, and the low-pressure turbocharger plays a main role at the moment, so that sufficient air inflow and high power output can be ensured. Therefore, the engine can obtain better power performance and fuel economy under different rotating speeds. In a specific implementation, the rotation speed interval of the low rotation speed is set to 700rpm-1500rpm, the rotation speed interval of the high rotation speed is set to 3000rpm-4000rpm, and the set pressure of the high-pressure turbocharger is set to 2 bar.

Also, the engine includes a low pressure EGR line and a high pressure EGR line.

Wherein the air inlet of the low-pressure EGR pipeline is connected with the downstream of an exhaust gas post-treatment system of the two-stage supercharged diesel engine, and the exhaust gas post-treatment system is connected with the downstream of the low-pressure turbine and is used for purifying and treating the exhaust gas discharged from the low-pressure turbine. The exhaust port of the low pressure EGR line is connected upstream of the low pressure compressor, and more particularly between the low pressure compressor and the air cleaner. And the low-pressure EGR pipeline is provided with a low-pressure EGR valve and a low-pressure EGR cooler.

Wherein the inlet of the high-pressure EGR line is connected upstream of the high-pressure turbine, more specifically to the intake manifold of the cylinder. The exhaust port of the high-pressure EGR pipeline is connected with the downstream of the high-pressure compressor, and more specifically is connected with the air inlet manifold of the cylinder. And the high-pressure EGR pipeline is provided with a high-pressure EGR valve and a high-pressure EGR cooler.

It should be noted that, both upstream and downstream of a certain component are based on the direction of the airflow passing through the component, and the position where the airflow passes first is upstream and the position where the airflow passes later is downstream. For example, the so-called compressor upstream is based on the flow of air through the compressor, and the so-called turbine upstream is based on the flow of exhaust gas through the turbine.

By the arrangement, in the operation process, the ECU can switch the EGR pipeline according to the load state, the low-pressure EGR pipeline is conducted under the low-load state, and the high-pressure EGR pipeline is conducted under the medium-high load state, so that the recirculation quantity of the exhaust gas can reach the optimal condition at each working point, and the combustion process can be always in the optimal condition. Therefore, the pollution components in the emissions can be guaranteed to be minimum, so that the engine can meet the emission standard of the sixth stage.

Preferably, the high-pressure EGR valve and the low-pressure EGR valve are both high-precision electric control valves so as to realize precise control. The high-pressure EGR cooler and the low-pressure EGR cooler are both plate-fin heat exchangers so as to obtain higher heat exchange efficiency.

Preferably, the high-pressure EGR valve and the high-pressure EGR cooler are integrated into an integral structure, and the low-pressure EGR valve and the low-pressure EGR cooler are integrated into an integral structure, so as to make the engine compact as a whole.

Further, an intake manifold of the engine is provided as a variable swirl intake manifold 8.

Specifically, as shown in fig. 4, the variable swirl intake manifold 8 includes a first air passage 8a and a second air passage 8b corresponding to the same cylinder, that is, one first air passage 8a and one second air passage 8b are provided for each cylinder, and in the figure, the engine is configured as a four-cylinder engine, and four first air passages 8a and four second air passages 8b are provided.

Moreover, the first air passages 8a and the second air passages 8b are alternately arranged one by one along the front-rear direction (i.e., the extension direction of the crankshaft), that is, the first air passages 8a, the second air passages 8b, the first air passages 8a, and the second air passages 8b …, which is convenient to implement.

Further, one variable swirl control valve 9 is provided in each first gas passage 8a (not provided in the second gas passage 8 b). Each variable swirl control valve 9 is connected to the same control shaft 10 to be driven by the same control shaft 10. As shown in fig. 4, the control shaft 10 passes through each of the first air passages 8a and each of the second air passages 8b, and one end of the control shaft 10 is connected to the drive motor 11 through a transfer arm.

In the operation process, the ECU can control the start and stop of the driving motor 11 according to the operation condition, after the driving motor 11 is started, the control shaft 10 is driven to rotate, and correspondingly, each variable vortex control valve 9 rotates along with the variable vortex control valve, so that the vortex ratio of the combustion chamber is changed, and the vortex ratio is continuously variable between 1.6 and 2.5, so that the engine can obtain the optimal vortex ratio under various operation conditions, and the optimal oil-gas mixing state and the optimal combustion state are achieved, therefore, the amount of particles and CO in the discharged waste gas can be greatly reduced, the environmental protection performance of the engine is further improved, the oil consumption is also reduced, and the fuel economy of the engine is further improved.

Further, the fuel injection system of the engine is provided as a high pressure common rail fuel injection system 7. The high-pressure common rail fuel injection system 7 has the maximum injection pressure of 2000bar, the minimum injection interval of 0.2ms, the maximum injection frequency of 8 times per cycle, and has the functions of pre-injection, main injection and post-injection. By the arrangement, the power performance, the fuel economy and the NVH performance of the engine can be further improved.

Specifically, the high-pressure common rail fuel injection system 7 can adopt a CRS2-20 (hereinafter referred to as CRS2-20) high-pressure common rail fuel injection system of BOSCH company, and CRS2-20 can meet the configuration requirements, and has the advantages of accurate rail pressure, high system efficiency, stable supply, light weight, compact structure, long service life, high oil storage pressure, small pressure fluctuation and the like.

Further, an intercooler of the engine is provided as a water-cooled intercooler 2, i.e., high-temperature air discharged from the compressor is cooled by cooling water. The water-cooled intercooler 2 is higher in heat exchange efficiency than an air-cooled intercooler, so that the engine can obtain higher inflation efficiency and higher output power, and the fuel economy and the power performance of the engine can be further improved. In addition, the water-cooling intercooler 2 also has the characteristics of small structural size, short matching pipeline and the like, so that the arrangement is more convenient and the pressure loss is more favorably reduced.

Preferably, the engine is further provided with a low-temperature radiator special for radiating heat of the water-cooled intercooler 2, and an electronic water pump is arranged on a connecting pipeline between the low-temperature radiator and the water-cooled intercooler 2. So, can accurate control flow through the cooling water temperature of water-cooling intercooler.

Further, the oil pump of the engine is provided as a two-stage variable oil pump, and is configured to: when the rotating speed v is less than 1800rpm, the engine oil pressure is 1.8bar, and when v is more than or equal to 1800rpm and less than or equal to 4000rpm, the engine oil pressure is 3.6 bar. By the arrangement, the oil consumption of the engine can be further reduced by 2-3%.

Further, a cylinder cooling pipeline (i.e., a cooling pipeline communicated with the cylinder) and a cylinder head cooling pipeline (i.e., a cooling pipeline communicated with the cylinder head water jacket) of the engine are arranged in parallel, a cylinder head thermostat is arranged on the cylinder head cooling pipeline, and a cylinder body thermostat is arranged on the cylinder body cooling pipeline.

Specifically, one end of each of the cylinder body cooling pipeline and the cylinder cover cooling pipeline is connected with the water pump, the other end of each of the cylinder body cooling pipeline and the cylinder cover cooling pipeline is connected with the radiator, cooling water is distributed after flowing out of the water pump, one part of the cooling water flows through the cylinder body thermostat and the cylinder body thermostat in sequence, the other part of the cooling water flows through the cylinder cover water jacket and the cylinder cover thermostat in sequence, and then the cooling water is converged and.

Because a part of cooling water directly enters the cylinder cover water jacket without passing through the cylinder body, under the working condition of large load, the wall temperature of the cylinder cover combustion chamber is favorably reduced, and the heat load level of the cylinder cover is improved. The cylinder body thermostat is arranged independently, so that the cooling water flowing through the cylinder body can be independently controlled, and the cooling water flowing through the cylinder body is basically close to a stagnation state in the engine warming-up process, so that the warming-up process can be accelerated, and the fuel economy of the engine is further improved.

Here, the radiator and the low-temperature radiator are two independent components, and the water pump and the electronic water pump are also two independent components. The water pump as referred to herein is driven by the crankshaft through the accessory drive assembly.

Specifically, as shown in fig. 5, the accessory drive assembly includes a crankshaft pulley 12 provided at a front end of the crankshaft, a water pump pulley 13 driving a water pump, a power steering pulley 14 driving a power steering gear, a generator pulley 15 driving a generator, and an accessory belt 16 wound around the four pulleys, and further includes a double damping tensioner 17 and a plurality of idler pulleys (two in the drawing). One end of the flywheel 5 is a rear end of the crankshaft 22, and the other end is a front end of the crankshaft 22.

Further, as shown in fig. 6, a valve chamber cover 6 of the engine is connected to the cylinder head by bolts 6 a. As shown in fig. 7, a bolt bushing 18 is fitted around the outer periphery of the shaft portion of the bolt 6a, and a rubber washer 19 is fitted around the outer periphery of the bolt bushing 18. The bolt bush 18 is provided at the upper end outer periphery thereof with a first annular flange 18a, and a rubber gasket 19 is pressed between the first annular flange 18a and the valve chamber cover 6.

In the attached state, as shown in fig. 7, the first annular flange 18a of the bolt bush 18 and the rubber washer 19 are blocked between the head portion of the bolt 6a and the valve chamber cover 6, so that vibration of the valve chamber cover 6 in the axial direction can be absorbed, and at the same time, the bolt bush 18 is also blocked between the stem portion of the bolt 6a and the valve chamber cover 6, so that vibration of the valve chamber cover 6 in the radial direction can be absorbed, whereby NVH performance of the engine can be effectively improved.

Preferably, the bolt bush 18 is further provided at a lower end outer periphery thereof with a second annular flange 18b, and the valve chamber cover 6 is provided at a lower end inner periphery thereof with a step surface against which the second annular flange 18b abuts upward. By providing the second annular flange 18b, vibrations of the valve chamber cover 6 in the axial direction can be better absorbed. In the figure, a wear-resistant bush is further arranged in the connecting hole of the valve chamber cover 6, and the step surface is formed on the inner hole wall of the wear-resistant bush.

Further, as shown in fig. 8 and 9, the crankshaft 22 of the engine is disposed at a position to the left below the cylinder, and two balance shafts 21 of the engine are disposed inside the cylinder block, wherein the first balance shaft 21 is located at the upper left of the crankshaft 22, and the second balance shaft 21 is located at the upper right of the crankshaft 22. Therefore, a better balance effect can be achieved, and the size of the engine is greatly reduced.

As shown in fig. 9, the drive gear of the first balance shaft 21 directly meshes with a crank gear 24 provided at the rear end of the crankshaft. The driving gear of the second balance shaft 21 is indirectly engaged with the crank gear 24 through the idle gear 23 coated with the soundproof coating, so that the gear clearance can be optimized, the gear engagement noise can be improved, and the NVH performance of the engine can be further improved.

Further, the crankshaft 22 of the engine drives the oil pump through an oil belt drive system, and drives the camshaft and the fuel pump through a timing belt drive system.

Specifically, as shown in fig. 9, the oil belt drive system includes an oil pump pulley (not visible) that drives the oil pump, a crankshaft drive pulley 25 provided at the rear end of the crankshaft, and an oil pump toothed belt 26 wound around both.

Specifically, as shown in fig. 10, the timing belt drive system includes a fuel pump pulley 27 that drives a fuel pump, a crankshaft timing pulley 28 provided at a front end of the crankshaft, a camshaft timing pulley 29 provided at a front end of the camshaft, and a timing toothed belt 30 wound around the three. A double-ribbed automatic tensioner 31 and a plurality of idler pulleys (three in the drawing) are also provided. The double-rib automatic tensioner 31 can effectively prevent the belt from deviating.

Further, the timing cover 3 of the engine is bolted to the front sides of the cylinder block 20 and the cylinder head, and vibration insulators are arranged between the timing cover 3 and the cylinder block 20 and the cylinder head, so that the NVH performance of the engine is further improved.

Preferably, can also set up seal ring between timing shroud 3 and cylinder body 20 and the cylinder cap to form inclosed timing chamber, so, can prevent effectively that flying stone, dust, water etc. from getting into timing chamber, avoid causing the problem that the belt take-up pulley jumps the tooth and leads to the unable normal start-up of engine because of the foreign matter invasion, can promote the operational reliability of engine from this.

In addition, in order to further improve the NVH performance of the engine, a silencer can be mounted on the intake manifold, and the oil pan 4 made of a sandwich material (namely, a material with damping rubber arranged between two layers of thin steel plates) can be selected.

In summary, the two-stage supercharged diesel engine provided by the invention has the following technical effects:

1. the emission standard of the sixth stage can be met;

2. the two-stage supercharged diesel engine in the specific embodiment can keep 480Nm high torque output in a rotating speed range of 1500rpm-2400rpm and can achieve 160kW high power output at the rotating speed of 4000 rpm.

3. The two-stage supercharged diesel engine has excellent fuel economy, and the specific fuel consumption of the two-stage supercharged diesel engine in the specific embodiment is less than 314g/kw.h under the load of 2000rpm and 2 bar.

4. The whole structure is compact, and the size of the two-stage supercharged diesel engine in the specific embodiment is 565mm multiplied by 695mm multiplied by 681 mm.

5. The NVH performance is excellent, namely the operation noise is low.

The two-stage supercharged diesel engine provided by the invention is described in detail above. The principles and embodiments of the present invention are explained herein using specific examples, which are presented only to assist in understanding the method and its core concepts. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

Claims

1. A two-stage supercharged diesel engine characterized by comprising a two-stage supercharging component including a high-pressure turbocharger and a low-pressure turbocharger arranged in series, a scroll-end bypass valve arranged between an intake side and an exhaust side of a turbine of the low-pressure turbocharger, and a pressure-end bypass valve arranged on an outlet joint of a compressor of the high-pressure turbocharger;

2. The two-stage supercharged diesel engine according to claim 1, further comprising a variable swirl intake manifold including first and second gas passages corresponding to the same cylinder, a variable swirl control valve being provided in each of the first gas passages; the variable vortex control valve is connected with the control shaft so as to rotate along with the rotation of the control shaft to open and close the first air passage.

3. A two-stage supercharged diesel engine according to claim 2, characterized in that it further comprises a high-pressure common rail fuel injection system having a maximum injection pressure of 2000bar, a minimum injection interval of 0.2ms, a maximum number of injections per cycle of 8, and having the functions of pre-injection, main injection and post-injection.

4. The two-stage supercharged diesel engine according to claim 3, further comprising a water-cooled intercooler communicated with an outlet of the compressor, and a low-temperature radiator dedicated for radiating heat of the water-cooled intercooler, wherein an electronic water pump is arranged on a communication pipeline between the low-temperature radiator and the water-cooled intercooler.

5. The two-stage supercharged diesel engine of claim 4, further comprising a two-stage variable oil pump and configured to: when the rotating speed v is less than 1800rpm, the engine oil pressure is 1.8bar, and when the rotating speed v is less than or equal to 1800rpm and less than or equal to 4000rpm, the engine oil pressure is 3.6 bar.

6. The two-stage supercharged diesel engine according to claim 5, further comprising a cylinder cooling pipeline and a cylinder head cooling pipeline which are arranged in parallel, wherein a cylinder head thermostat is arranged on the cylinder head cooling pipeline, and a cylinder body thermostat is arranged on the cylinder cooling pipeline, so that the cylinder head and the cylinder body are cooled separately.

7. The two-stage supercharged diesel engine according to any of claims 1 to 6, characterized in that the valve chamber cover and the cylinder head of the two-stage supercharged diesel engine are connected by a bolt, a bolt bushing is sleeved on the outer periphery of the rod portion of the bolt, a first annular flange is arranged on the outer periphery of the upper end of the bolt bushing, a rubber gasket is sleeved on the outer periphery of the bolt bushing, and the rubber gasket is pressed between the first annular flange and the valve chamber cover.

8. The two-stage supercharged diesel engine according to claim 7, characterized in that the crankshaft of the two-stage supercharged diesel engine is disposed to the left below the cylinder, and the two balance shafts of the two-stage supercharged diesel engine are disposed inside the cylinder block; the first balance shaft is positioned at the upper left of the crankshaft, and a driving gear of the first balance shaft is directly meshed with a crankshaft gear arranged at the rear end of the crankshaft; the second balance shaft is positioned at the upper right part of the crankshaft, and a driving gear of the second balance shaft is indirectly meshed with the crankshaft gear through an idle gear coated with a sound insulation coating.

9. A two-stage supercharged diesel engine according to claim 8, characterized in that the crankshaft of the two-stage supercharged diesel engine drives the camshaft and the fuel pump to run via a timing toothed belt and also drives the oil pump to run via an oil pump toothed belt.

10. The two-stage supercharged diesel engine according to claim 9, characterized in that the timing cover of the two-stage supercharged diesel engine is bolted to the front sides of the cylinder block and the cylinder head with vibration insulators interposed therebetween.