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Ricardo HDD PAPER 2007(E)欧4重型柴油机设计与开发

Ricardo HDD PAPER 2007(E)欧4重型柴油机设计与开发
Ricardo HDD PAPER 2007(E)欧4重型柴油机设计与开发

HEAVY-DUTY ENGINE DESIGN AND OPERATION FOR EURO IV EMISSIONS C. H. Such, A. Skipton-Carter, Ricardo UK J. M. Vogt, Ricardo Shanghai Representative Office ABSTRACT Euro III emission regulations will be introduced in China from 2008 (in Beijing and major cities from 2006), and the next stage – Euro IV – is expected to follow in the early part of the next decade. This paper will review the engine design and technology options available to companies intending to produce heavy-duty truck engines in the Chinese market over the next 5-10 years. The importance of the supporting systems in terms of exhaust catalysts and the fuel specification for Euro IV is emphasised.
INTRODUCTION Any visitor to China is continually impressed by the extremely rapid growth of the highway system. This will stimulate the development of new trucks and truck engines. The new generation of truck engines will need to meet Euro III exhaust emissions legislation from 2008 (in Beijing and major cities from 2006), and the next stage – Euro IV – is expected to follow in the early part of the next decade. In Europe, truck operators are able to purchase Euro IV engines. In this paper a short review of the Euro IV heavy-duty engines is made in order to provide an insight into the design options available to Chinese domestic manufacturers who are considering Euro IV. Some aspects of the Euro IV legislation such as fuel quality and On Board Diagnostics are explored. This is followed by a review of the directions for development to Euro V and Euro VI, and a summary of an approach to the heavy-duty engine concept for the Chinese domestic market. CURRENT HEAVY-DUTY ENGINES IN THE EUROPEAN MARKET The number of engine manufacturers selling heavy-duty engines in the European market declined dramatically during the 1980s and 1990s due to mergers and take-overs, and the cost of developing the increasingly complex engines required to meet Euro III emissions legislation. A large investment in
the application of new fuel injection equipment with electronic control, and the change from 2 valve/cylinder to 4 valve/ cylinder was essential when moving from Euro II to Euro III, and this was not commercially feasible for many of the smaller manufacturers. The remaining manufacturers are mostly very large companies selling and manufacturing complete trucks and buses worldwide. These companies have reduced the number of engine models in the range in order to drive down costs due to increased production volume. The largest production volume in heavy-duty truck engines in Europe corresponds to engines with swept volumes between 11.6 and 13 litre, (Figure 1).
>13 litre 5%
6.0 - 8.9 litre 27%
11.6 - 13.0 litre 55%
9.0 - 11.5 litre 13%
Figure 1: Heavy-Duty Truck engine Production in Western Europe (2005) (Total production volume 430,000)

The application of these engines in trucks is shown in Figure 2, which indicates that most
450
trucks sold are between 32 and 40 tonne Gross Combined Weight.
12 kW /t
higher specific power/weight faster journey times
400
kW 10
/t
W/ 8k
t
350
MAJORITY OF HEAVY-DUTY TRUCK SALES
Power [kW]
>1 3 l
300
3l l ... 1 11.6
<11.6 l
W /t 6k
250
200
lower specific power/weight lower fuel consumption
150 15 20 25 30 35 40 45 50
Gross Combined Vehicle Weight [tonnes]
Figure 2: European Truck Power vs. Gross Vehicle Weight (Gross Combination Weight) The design of Euro III engines was reviewed in an earlier paper [1]. As outlined in that paper, one of the dominating influences on engine design has been the selection of fuel injection equipment. Since Euro IV has been introduced, the in-line fuel injection pump, which dominated heavy-duty European engines in the 1980s, has disappeared, to be replaced by a range of electronically controlled, high pressure injection systems, including Electronic Unit injector (EUI), Electronic Unit Pump (EUP), Common Rail System (CRS), and the Caterpillar Hydraulic Electronic Unit Injector (HEUI) and Cummins High Pressure Injection system (HPI).
A summary of the main features of current Euro IV engines of 11.6 – 13 litre engines is shown in Figure 3.

Configuration Aspiration Turbocharger Cylinder Head Cylinder Block Fuel injection Piston Piston bowl Inlet swirl ratio Compression ratio BMEP at rated power BMEP at max torque Max cylinder pressure NOx control Particulate control Braking
In line 6 cylinder (a) Turbocharged and air-to-air aftercooled Single stage or two stage (b) Cast iron, water cooled, crossflow ports, 4 valves/cylinder Cast iron, water cooled, integral oil cooler, wet liners Electronically controlled, pressures over 1600 bar Systems include EUI, EUP, CRS, HEUI (c), HPI (d) Aluminium with or without cooling gallery, or 2 piece with steel crown Open or slightly re-entrant From zero to 3 Ricardo swirl number From 16:1 to 19:1 15 - 19 bar 20 - 25 bar 160 - 200 bar Cooled EGR or SCR EGR: oxidation catalyst or PM-catalyst SCR: no additional measure Compression brake plus exhaust brake, electric retarder, water brake (Voith type) (a) except Mercedes OM501 and Deutz 1015 (both vee 6 cylinder) (b) Two stage turbocharged engine is DAF MX 12.9 litre (c) Caterpillar Hydraulic Electronic Unit injector (d) Cummins High Pressure Injector
Figure 3: Main Features of Euro IV 12 – 13 Litre Truck Engines STRATEGIES TO ACHIEVE EURO IV Euro IV engines were offered in trucks and buses from October 2005. At the same time, tax incentives in Germany have encouraged the purchase of vehicles compliant with Euro V. As a result, a proportion of the engines sold in Germany have been compliant with Euro V, some 3 years ahead of the Euro V introduction. To-date, all of
DaimlerChrysler SCR
these Euro V engines have been fitted with Selective Catalytic Reduction (SCR) systems, which are explained below. Figure 4 shows the current and expected development for Euro IV and V in Europe; the two main routes are Exhaust Gas Recirculation (EGR) and Selective Catalytic Reduction (SCR).
Over 2000 SCR trucks sold already; >90% EU5 10/2006: all trucks >6 tonne will use SCR technology Launch of SCR on D13 in 2006 EGR at lower rating on D12
EGR+DPF Volvo EGR+HPI+DOC SCR SCR
Scania
EGR+XPI+DOC rest of the engine range
SCR for V8s, EGR for the EUV will see introduction of V8 with EGR - without SCR
MAN
EGR+CR+PM-KAT SCR
???
Use EGR for most of Euro IV Euro V compliant SCR vehicles will be launched in 2006 Launch sale of SCR trucks in 2006 SCR for trucks >7.5 tonne Launched late 2005
DAF Iveco 2005 2006 2007
SCR SCR 2008 2009
2010
Figure 4: Strategies for Euro IV by manufacturer

Exhaust Gas Recirculation (EGR) EGR is a proven NOx reduction technology [2] which is currently used by MAN and Scania for Euro IV in Europe; by Volvo, Cummins and DaimlerChrysler in the USA, and by most of the manufacturers in Japan. The system currently adopted is the “short route” method, which enables about 15–20 % of the exhaust gas to be returned to the
intake manifold via an EGR valve and EGR cooler. Two types of EGR system are shown in Figure 5.
As used by: DDC Series 60, Cummins, Mack Truck in US As used by Volvo D12 in US MBE4000 in US MAN D20 in Europe
VGT + EGR system: Pulse system: Varying turbine entry area to raise Utilising exhaust manifold exhaust manifold pressure above pressure pulses to drive EGR inlet past non-return valves Figure 5: EGR Systems - Two types of EGR systems are currently used in Heavy Duty engines
MAN in Europe, and Volvo and DaimlerChrysler in the USA use a ‘pulse system’, which has a fixed geometry turbocharger together with separate EGR pipes from each half of the exhaust manifold, separate EGR valves and coolers, and nonreturn valves (known as ‘Reed’ valves). The two separate lines enable the pressure pulses in the exhaust to be used to drive the exhaust gas into the intake, without increasing the pressure drop across the engine, which would damage fuel consumption. Cummins, Detroit Diesel and Mack Trucks in the USA use variable geometry turbochargers to control the pressure drop across the engine. Scania have developed an alternative EGR system with a Venturi and turbocompound system on the 12 litre engine. EGR tends to reduce air/fuel ratio, which increases smoke and particulates. To control the particulates, injection pressures need to increase and post injection is effective at low NOx levels [3]. This effect is shown in Figure 6.

Figure 6: Effect of Injection Pressure on NOx/soot trade-off at constant injection timing. Increased mean effective injection pressure with 2 valve EUI gives 70% reduction of soot at Euro IV NOx emissions level (graph shows mid load and speed point). Flexibility of pilot and post injection at part load improves NOx/soot trade-off For Euro IV, cooled EGR is capable of meeting the NOx limits, but currently exhaust aftertreatment in the form of oxidation catalysts or diesel particulate filters (DPF) is needed to meet the very severe particulate limits. As an example, MAN use the partial flow DPF, known as the PM-catalyst, on the D20 engine. The PM-catalyst [4] consists of an oxidation catalyst followed by a metallic mesh filter. Compared with the full flow DPF, the PM-catalyst is less efficient in reducing particulates, but has the advantage that it does not require a control system to burn off the collected particles. The application process is therefore less time-consuming than for the highly efficient full flow DPF. The PM-catalyst can be very efficient in converting gaseous HC and CO emissions, and the volatile organic components in the particulates, over relatively highly loaded test cycles such as the European Steady-State Cycle (ESC) and European Transient Cycle (ETC). However, the oxidation catalyst in the PM-catalyst is also effective in converting the sulphur in the fuel to sulphate emissions, which can temporarily deactivate the catalyst through sulphur poisoning. As a result, for this technology to be used, it is important that the fuel sulphur encountered in the field is at a low level: In Western Europe, the maximum allowable level of sulphur in diesel fuel is 50 ppm from 2005, reducing to 10 ppm from 2008. If an engine with DPF is operated at part loads on fuel with a higher sulphur content, then the sulphate produced in the oxidation catalyst tends to be stored in the filter. When the engine is then run at high loads, such as in the ESC test, the sulphate will be released from the DPF, will find its way onto the particulate filter paper, and be measured as a high particulate weight. This effect is shown in Figure 7 [5]. After running the engine at high loads for some hours, all of the sulphate stored in the DPF is released, and the particulate weights return to the level measured on low sulphur fuel (<10 ppm). For certification testing of engines fitted with catalysed DPFs (either full flow or partial flow), tests should be run on fuel with

<10 ppm sulphur. In terms of the durability of the DPF, prolonged exposure to running at
0.140
part loads on high sulphur fuel may disable the oxidation catalyst.
Catalyst Out
0.120
Engine Out
Remainder
Nitrate
0.100
Before Sulphate Conditioning
Predominantly Carbon
Water
Soluble Sulphate
Low Volatility HCs
Fuel Derived HCs
0.080
0.060
0.040
After Sulphate Conditioning
0.020
0.000 1 2 3 1 2 Test number 3 1 2 3
Figure 7: ESC emissions after durability test before and after desulphation [5]. Selective Catalytic Reduction (SCR) The alternative to EGR for Euro IV is SCR, which reduces the NOx very efficiently by means of a gaseous ammonia reaction over a catalyst. The ammonia is generated from liquid urea solution which is injected upstream of the catalyst. Over the working temperature range of the catalyst in normal operation (180 – 550°C) the NOx emissions can be reduced by 80%, provided the urea injection is matched to the NOx levels emitted from the base engine. The urea injection strategy must be carefully calibrated to control NOx on the one hand and to avoid ammonia emissions on the other hand. For Euro IV, engines are typically calibrated to give engine-out NOx emissions of about 7-8 g/kWh, which are then reduced to about 3.2 g/kWh by the SCR system. Because injection timings are more advanced, this approach gives a benefit in fuel consumption of the base engine, at the expense of the cost of the SCR system, and the additional running cost of the urea (the urea consumption is up to about 5% of the diesel fuel consumption). The other benefits of the SCR system compared with EGR are as follows: ? Fewer changes to the base engine are needed. (It should be noted that high injection pressures are also needed for SCR engines, in order to achieve the particulate limit) ? A PM-catalyst is not required to meet the particulate limit ? SCR catalyst is unlikely to be damaged if the engine is misfuelled with on high sulphur fuel ? Heat rejected to coolant is significantly lower, so modifications to the cooling system in the truck can be minimised ? Soot loading on the lubricating oil is lower, so the oil change interval can be extended ? It is possible to re-calibrate the urea dosing system to achieve Euro V, with minimal changes to the engine, unlike the EGR engine, which would need extensive changes ? In terms of the first cost of the engine and catalyst, it seems that the cost of the engine and SCR system will be similar to

that of the EGR engine plus PM-catalyst plus vehicle changes for cooling system. Several of the major European truck manufacturers – DaimlerChrysler, Volvo, IVECO, DAF – have decided to adopt SCR for their Euro IV and Euro V products. The smooth introduction of SCR technology depends on the spread of urea infrastructure throughout Europe: this is currently in
progress, with several companies involved in supplying urea solution (known as ‘AdBlue’) to the filling stations. Some customers appear not to be convinced of the benefits of SCR, perhaps because of concerns over the availability of urea. As a result, some manufacturers may introduce low production volume versions of existing engines with EGR, such as Volvo on the D12F engine.
AdBlue tank, incl. heating
Control and metering unit AdBlue injection Stainless steel silencer and SCR catalyst
Figure 8: Location of SCR system on truck (source DaimlerChrysler)
Figure 9: dashboard showing AdBlue level in AdBlue tank (source IVECO)

ASPECTS OF EURO IV LEGISLATION Fuel and Lubricant As mentioned above, if EGR plus PM-catalyst or oxidation catalyst is used for Euro IV, then certification on fuel with a sulphur content <10 ppm is required, and fuel in the field should be <50 ppm, in order to avoid high particulate emissions in the field and potential damage to the PM-catalyst. Likewise, it is important to use lubricating oil which is suited to Euro IV. Especially for the EGR engines, the lubricating oil should be capable of tolerating soot and should have low levels of sulphated ash in order to avoid sulphate emissions due to the PM-catalyst. Unlike the full flow DPF, ash deposits are not stored in the PM-catalyst. On Board Diagnostics (OBD) When introducing Euro IV and V, a key concern for the European Commission was to ensure that the exhaust emission control equipment does not deteriorate significantly in service. As a result, there are requirements on the durability of the emission control, which for heavy-duty engines means that the emission control system must maintain its efficiency for 500,000 km with reasonable maintenance. The second major issue is that manufacturers must apply On Board Diagnostics (OBD). OBD is software designed into the vehicle’s on-board electronic control unit (ECU) to detect emission control system malfunctions by monitoring components and systems, which can cause increases in emissions. When an emission-related malfunction is detected, the OBD system alerts the vehicle driver by illuminating the malfunction indicator light (MIL) on the instrument panel. The driver can then arrange for the failure to be corrected quickly, and potential increases in emissions can be avoided. Additionally, the OBD system important information, such as: Specific faulty component or system stores
Nature of the fault When it first happened and its current status This allows for quick diagnosis and proper repair of the problem by technicians, helps owners to achieve less expensive repairs and enables the repairs to be carried out correctly the first time. The introduction of OBD systems should reduce the need for regular emissions checks of vehicles in service. There are two stages of OBD legislation related to Euro IV. The first stage requires OBD monitoring of the function of the fuel injection system, catalyst and particulate filter (is the filter removed or blocked?). In addition, the condition of components (boost system, EGR system and sensors) needs to be monitored in such a way that it can be estimated that the engine is still operating within certain emission thresholds (NOx 7.0 g/kWh and particulate 0.1 g/kWh). The threshold limits apply to the engine only and not the aftertreatment. In the second stage, component monitoring is again required, but the NOx threshold is reduced to 5 g/kWh. For Euro V, the NOx OBD threshold is further reduced to 3.5 g/kWh. An additional requirement is to monitor whether all powertrain related ECUs on the vehicle are communicating with each other correctly. The detection system for the particulate filter will not only have to detect any major functional failure, but it will also need to record any reduction in the efficiency of the particulate filter. As an example of what will be required on engines fitted with an SCR system, the injection of urea into the exhaust upstream of the SCR catalyst must be monitored as follows: For Euro IV 2006 ? Confirm that the urea is delivered to the injector ? Monitor the level of urea in the tank (is it empty?)

? Monitor the urea level sensor and urea dosing system electrical components (pumps, heaters etc.) For Euro V 2008/2009: ? In the case of engines with NOx sensors giving closed loop control of urea injection, it needs to be checked that the quantity of urea injection is in agreement with the desired quantity The newly introduced OBD regulations will result in a very substantial increase in development effort and engineering resources. In recent years Ricardo has developed a wide experience of the best ways to satisfy the legislative authorities in terms of introducing OBD technology (6). DEVELOPMENT TO EURO V AND EURO VI Euro V As noted above, the most likely solution for heavy-duty engines is to increase the urea flow into the SCR catalyst, with relatively small changes to the base engine. In this way, fuel consumption can be maintained at approximately Euro IV levels, with some small percentage increase in urea consumption. Alternatively, if EGR is used, then this requires a further increase in EGR rates, which will place further demands on the fuel injection equipment in terms of injection pressure requirements. New fuel injection systems are under development, which will generate 2000 bar and above, and have great flexibility in terms of multiple injection characteristics. In order to meet the
particulate limits, a particulate filter is likely to be needed, either full flow or partial flow. Fuel sulphur levels will reduce for Euro V introduction to below 10 ppm, which will assist the introduction of particulate filters with oxidation catalysts. Ricardo has successfully demonstrated the feasibility of achieving Euro V with EGR, competitive fuel consumption. Euro VI Euro VI emissions limits are under review within the European Commission. A substantial reduction of NOx is likely to be required, which is expected to need a combination of EGR and SCR. Alternative combustion regimes such as Homogeneous Charge Compression Ignition (HCCI) show promising results in terms of very low NOx and particulate emissions at part load conditions, but are not suited to the higher load conditions experienced during the heavy-duty emission test cycles. HCCI is therefore seen as more appropriate to lightduty engines at this stage. In the same time period as Euro VI, full flow particulate filters will be fitted to heavy-duty engines in the USA and Japan, and it appears very likely that they will also be required in Europe. Active regeneration strategies will be essential to avoid blockage in service: the possible layout of a future engine system is shown in Figure 10. Alternative methods of regenerating the filter include a diesel-fuelled burner to heat up the filter. Ricardo is currently developing combinations of technologies which are aimed at 0.5 g/kWh and below.

T-MAF
COMPRESSOR
INTERCOOLER Temp INTAKE THROTTLE T-MAP
AFTER COOLER BYPASS VALVE
EGR VALVE Temp
Rail Press. Sensor
Oil Press. HP PUMP Fuel Temp INJECTORS Glow plugs Metering Unit
Crank Cam
ECT
EGR COOLER BYPASS VALVE
λ
Temp VGT Temp
DPS EGT1 CATALYST
DPF
EGT2
Figure 10: Typical Layout of Sensors in Future Heavy-Duty Diesel Engine TMAF TMAP λ VGT EGT DPS Temperature and Mass Air Flow sensors Temperature sensor downstream of aftercooler Lambda sensor for measuring air/fuel ratio Feedback sensor on position of variable geometry turbocharger Exhaust gas temperature sensors Differential pressure sensor across Diesel Particulate Filter (DPF) SCR Widespread availability of urea solution SCR systems (urea tank, hardware and software for urea injection system, catalyst and canning) Fuel Injection Equipment High pressure, electronically controlled fuel injection systems will be required for both EGR and SCR Software for On Board Diagnostics will be needed to meet Euro IV legislation Ricardo is committed to assisting the Chinese engine manufacturers to achieve the Euro IV emission legislation with the best performance and with acceptable cost.
CONCLUDING REMARKS: CONSIDERATIONS FOR CHINESE HEAVYDUTY ENGINES For the manufacturers of heavy-duty diesel engines in China, both EGR and SCR systems are feasible solutions for Euro IV. However certain pre-conditions are required. EGR Widespread availability of low sulphur diesel fuel (< 50 ppm if catalysed particulate filters are to be used) Availability of suitable lubricating oil (low ash to avoid blockage of particulate filter) Turbochargers capable of providing sufficient boost pressure EGR systems (EGR valves, coolers)

REFERENCES 1. Such C H, Hellman A, Weller G B, “Heavy-Duty Engine Options for the Chinese Market” Chinese Combustion Engines Institution Conference Shanghai December 2004 Havenith C, Such C H, Porter BC, Nicol AJ, “Demonstration of a Euro 3 HeavyDuty Diesel Engine using Exhaust Gas Recirculation” Vienna Motorsymposium 1997 Such C H, Best C, Rogers B J, “Investigation of a Two valve Electronically Controlled Unit Injector on a Euro IV Heavy-Duty Diesel Engine using Design of Experiment Methods” Institution of Mechanical Engineers, December 2002 Jacob E, Lammermann R, Pappenheimer A, Rothe D, “Exhaust Gas Aftertreatment for Euro 4 HeavyDuty Engines” MTZ magazine June 2005 Searles R A, Bosteels D, Such C H, Nicol A J, Andersson J D, Jemma C A, “Investigation of the Feasibility of Achieving Euro V Heavy-Duty Emissions Limits with Advanced Emission Control Systems” Paper F02E310 FISITA conference Helsinki June 2002 Noble A D, Such C H, Hellman A, “On Board Diagnostics for Heavy-Duty Diesel Engines” SIA Congress, The Diesel Engine Today and Tomorrow, Lyon 2004
TERMINOLOGY AdBlue Commercial name for urea solution supplied in Europe for SCR vehicles BMEP Brake Mean Effective Pressure CRS Common Rail System DOC Diesel Oxidation Catalyst DPF Diesel Particulate Filter DPS Differential pressure sensor across Diesel Particulate Filter (DPF) ECU Electronic Control Unit EGT Exhaust gas temperature sensors EGR Exhaust Gas Recirculation EUI Electronic Unit Injector EUP Electronic Unit Pump HCCI Homogeneous Charge Compression Ignition HEUI Hydraulic Electronic Unit Injector (Caterpillar) HPI High Pressure Injection system (Cummins) MIL Malfunction Indicator Light NCV Needle Control Valve NOP Nozzle Opening Pressure OBD On Board Diagnostics PM catalyst Particulate Matter Catalyst (open DPF) SCR Selective Catalytic Reduction TMAF Temperature and Mass Air Flow sensors TMAP Temperature sensor downstream of aftercooler VGT Variable Geometry Turbocharger XPI Extra high Pressure Injection system (Cummins/Scania) λ Lambda sensor for measuring air/fuel ratio
2.
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5.
6.

发动机曲轴结构设计

2.1 曲轴的结构 曲轴的作用是把活塞往复运动通过连杆转变为旋转运动,传给底盘的传动机构。同时,驱动配气机构和其它辅助装置,如风扇、水泵、发电机等【18】。 曲轴一般由主轴颈,连杆轴颈、曲柄、平衡块、前端和后端等组成,如图1.1所示。一个主轴颈、一个连杆轴颈和一个曲柄组成了一个曲拐,直列式发动机曲轴的曲拐数目等于气缸数,而V型发动机曲轴的曲拐数等于气缸数的一半。 图1.1 主轴颈是曲轴的支承部分,通过主轴承支承在曲轴箱的主轴承座中。主轴承的数目不仅与发动机气缸数目有关,还取决于曲轴的支承方式。 曲柄是主轴颈和连杆轴颈的连接部分,断面为椭圆形,为了平衡惯性力,曲柄处常设置平衡重。平衡重用来平衡发动机不平衡的离心力矩及一部分往复惯性力,从而保证了曲轴旋转的平稳性【19】。 曲轴的连杆轴颈是曲轴与连杆的连接部分,曲柄与主轴颈的相连处用圆弧过渡,以减少应力集中。直列发动机的连杆轴颈数目与气缸数相等而V型发动机的连杆轴颈数等

于气缸数的一半。 曲轴前端装有正时齿轮,以驱动风扇和水泵的皮带轮以及起动爪等。为了防止机油沿曲轴轴颈外漏,在曲轴前端装有一个甩油盘,在齿轮室盖上装有油封。曲轴的后端用来安装飞轮,在后轴颈与飞轮凸缘之间制成档油凸缘与回油螺纹,以阻止机油向后窜漏。 曲轴的形状和曲拐相对位置取决于气缸数、气缸排列和发动机的发火顺序。多缸发动机的发火顺序应使连续作功的两缸保持尽量远的距离,这样既可以减轻主轴承的载荷,又能避免可能发生的进气重叠现象。此外作功间隔应力求均匀,也就是说发动机在完成一个工作循环的曲轴转角,每个气缸都应发火作功一次,以保证发动机运转平稳。 曲轴的作用:它与连杆配合将作用在活塞上的气体压力变为旋转的动力,传给底盘的传动机构。同时,驱动配气机构和其它辅助装置,如风扇、水泵、发电机等。工作时,曲轴承受气体压力,惯性力及惯性力矩的作用,受力大而且受力复杂,并且承受交变负荷的冲击作用。同时,曲轴又是高速旋转件,因此,要求曲轴具有足够的刚度和强度,具有良好的承受冲击载荷的能力,耐磨损且润滑良好【20】。 2.2 曲轴的疲劳损坏形式 曲轴的工作情况十分复杂,它是在周期性变化的燃气作用力、往复运动和旋转运动惯性力及其他力矩作用下工作的,因而承受着扭转和弯曲的复杂应力。曲轴箱主轴承的不同心度会影响到曲轴的受力状况,其次,由于曲轴弯曲与扭转振动而产生的附加应力,再加上曲轴形状复杂,结构变化急剧,产生了严重的应力集中。最后曲轴主轴颈与曲柄销是在比压下进行高速转动,因而产生强烈的磨损。因此柴油机在运转中发生曲轴裂纹和断裂事故不为鲜见,尤其是发电柴油机曲轴疲劳破坏较多。依曲轴产生裂纹的交变应力的性质不同,主要有以下三种疲劳裂纹:弯曲疲劳裂纹、扭转疲劳裂纹和弯曲一扭转疲劳裂纹【21】,如图2.1所示。

发动机课程设计汇总

课程设计说明书 设计题目 院(系)专业班学生姓名 完成日期 指导教师(签字) 华中科技大学

目录 一目的与要求 (1) 二设计任务 (2) 三工作过程模拟计算 (3) 四动力学计算 (7) 五设计感想 (10) 参考文献 (11) 附录A 发动机外特性曲线 (12) 附录 B F g-?、F j-?、F-?曲线图 (13) 附录 C F N-?、F L-?、F t-?、F k-?、R B-?曲线图 (14) 附录 D 发动机合成扭矩∑M k-?曲线图 (15)

一目的与要求 1.目的 发动机课程设计是《发动机现代设计》课程的后续教学环节,旨在对刚学习过的发动机设计课程以及发动机原理课程的知识进行综合运用,加深对专业知识的理解。在课程设计环节,通过总体性能计算(工作过程模拟计算与动力学计算)将发动机的结构参数与性能参数结合起来,弄清结构与性能之间的内在联系;通过发动机总体布置图设计,对发动机的总体结构有一个全面而具体的了解,并深化对发动机各主要零件的作用和设计要求的理解。 2.要求 对提供的教学参考资料要认真分析,在理解的基础上借鉴,不要盲目照搬照抄。独立完成,可以讨论,不许抄袭;按时完成,不得延期。交课程设计材料(计算说明书与图纸)时必须通过指导教师的考核,不得代交。计算说明书应包括:计算目的、已知条件、变量说明、计算结果及说明(分析)等,其中动力学计算应有受力分析图,曲线图应标明坐标及单位。所绘图纸应符合工程图纸规范要求。

二设计任务 4110柴油机总体方案设计 1. 技术参数 机型:立式,直列,水冷,四冲程,废气涡轮增压、中冷燃烧室型式:直喷式 气缸直径:110mm 活塞行程:125mm(曲柄半径:62.5mm) 缸数:4 发火顺序:1-3-4-2 压缩比:17 标定功率(kW)/转速(r/min):140/2300 最大扭矩(N.m)/转速(r/min): 640/1450~1550 外特性最低燃油耗率(g/kW.h):200 标定工况燃油耗率(g/kW.h):210 机油耗率(g/kW.h):≤1.0 调速率:≤8% 怠速(r/min): 750 曲轴旋转方向(从前端看):顺时针 气门间隙(冷态):进气门0.3~0.4,排气门0.4~0.5 冷却方式:强制水冷 润滑方式:压力、飞溅复合式 启动方式:电启动 配气定时:进气门开,上止点前20oCA;进气门关,下止点后43oCA排气门开,下止点前60oCA;排气门关,上止点后20oCA 供油提前角:上止点前18±2oCA 2. 其他有关数据 活塞质量:1.32kg 活塞销质量:0.58kg 活塞环总质量:0.088kg 连杆大头质量(直开口/斜开口, kg): 1.89/1.98 连杆小头质量(kg):0.704 连杆长度L(mm):210 曲柄销直径:70mm 曲柄销长度:40mm 主轴颈直径:85mm 主轴颈长度(非止推挡):36mm 曲柄臂厚度:28mm 曲柄臂宽度:126mm

发动机冷却系统设计规范

编号: 冷却系统设计规范 编制:万涛 校对: 审核: 批准: 厦门金龙联合汽车工业有限公司技术中心 年月曰

第2页 一、概述 要使发动机正常工作,必须使其得到适度的冷却,冷却不足或冷却过度均会带来严 重的影响。 发动机过热,会破坏各运动机件原来正常的配合间隙,导致摩擦阻力增 特别是活塞 环和气缸壁之间的运动,严重时会发生烧蚀、卡滞,使发动 “拉缸”现象,刮伤活塞或气缸,更严重时还会发生连杆打烂气缸体现 油变稀,运动机件间的油膜破坏,造成干摩擦或半干摩擦,加速磨损。 同时会降低发动 机充气量,使发动机功率下降。 发动机过度冷却时,由于冷却水带走太多热量,使发动机功率下降、动力性能变差。 发动机过冷,气缸磨损加剧。同时,由于过冷,混合气形成的液体,容易进入曲轴箱使 润 滑油变稀,影响润滑作用。 由此可见,使发 动机工作温度保持在最适宜范围内的冷却系,是何其重要。一般地, 发动机最适宜的工作温度是其气缸盖处冷却水温度保持在 80C ~90C ,此时发动机的动力 性、经济性最好。 、冷却系统设计的总体要求 a )具有足够的冷却能力,保证在所有工况下发动机出水温度低于所要求的许用值( 般为55°); 冷却系统的设计应保证散热器上水室的温度不超过99 Co 采用105 kPa 压力盖,在不连续工况运行下,最高水温允许到 110 C,但一年中 水温达到和 超过99 C 的时间不应超 过50 ho 冷却液的膨胀容积应等于整个系统冷却液容量的 6 %o 冷却系统必须用 不低于19 L/min 的速度加注冷却液,直至达到应有的冷却液平面, 以保证 所有工作条件下气缸体水套内冷却液能保持正常的压力。 三、冷却系统的构成 液体冷却系主要由以下部件组成:散热器、风扇、风扇护风罩、皮带轮、风扇离合器、 水泵、节温器、副水箱、发动机进水管、发动机出水管、散热器除气管、发动机除气管冷却不足, 加,磨损加剧, 机停转或者发生 象。也会使润滑 a) C ) d) e)

柴油机各系统 设计

第三章各系统的设计及主要零部件的结构特点 3.1活塞组 活塞组包括活塞,活塞销和活塞环。它们在气缸里做往复惯性运动,活塞主要作用是承受气缸的气体压力,并将此力通过活塞销传给连杆,以次推动曲轴旋转。它还和气缸壁面一起活动构成密封装置,保证燃烧室的良好密封,这个功能是通过装在活塞头部环槽的一系列带开口的弹性活塞实现的。在高温,高负荷,高速和少量的机油消耗的情况下,它一方面要保证漏气量少,另一方面又要使摩擦损失不大,同时还要保证足够的耐久性。因此设计时要选用热强度好,耐磨,比重小,热膨胀系数小,导热性好,具有良好减磨性,工艺性的材料。目前制造活塞常用的材料有共晶铝硅合金,过晶铝硅合金和铝铜合金。设计选用共晶铝硅合金材料。 1、活塞设计的主要尺寸 [4] (1)活塞高度H: 根据《柴油机设计手册》,对于中小型柴油机而言,H/D范围在 1.0-1.1,而D=110mm,取H=113.5mm。在选择活塞高度时要注意在合理布置的情况下尽量选择小的活塞高度,如果转速越高,要使H越小,尽量减轻活塞重量,从而控制由于转速高而应引的惯性力的增大。(2)压缩高度H1: 根据《柴油机设计手册》,H1/D范围在0.6-0.8,取H1=67mm。HI=H5(换带高度)+H4(上裙高度)+h(顶岸高度)。在保证气环良好良好工作情况下,宜缩短H1高度,以便降低整机的高度尺寸。 (3)顶岸高度h(第一活塞环至活塞顶部距离): 根据《柴油机设计手册》,对铝活塞h/D范围在0.07-0.20,取h=13.4mm。在保证第一道环可靠工作下,也要使h尽量小,降低活塞重量和高度,但h越小,会使第一道环的热负荷越高,。 一般第一道环的温度不应该超过240度,否则润滑油可能粘结甚至结碳,易使活塞环在活塞中失去活动性,散失了密封和传热的功能 (4)活塞环数目及排列: 根据《柴油机设计手册》,中速机气环3-4道,油环1-2道,取气环2道,油环一道。2道气环在上面,1道油环在气环下面。为了降低活塞和整台发动机的高度,减少惯性力和摩擦功率损耗,应该减少环数。 (5)环岸高度:

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柴油机曲轴加工工艺及夹具设计

目录 摘要 1 Abstract 2 0 引言 1 1 R180柴油机曲轴工艺设计 3 1.1 分析零件图 3 1.2 确定生产类型 3 1.3 确定毛坯 3 1.4 机械加工工艺过程设计 3 1.5 选择加工设备与工艺装备 6 1.6 确定工序尺寸 7 1.7 确定切削用量及时间定额 9 1.8 填写工艺规程卡 15 2 R180柴油机曲轴第一套夹具设计 16 2.1 明确设计任务、收集分析原始资料 16 2.2 确定夹具的结构方案 17 2.3 绘制夹具结构草图 19 3 R180柴油机曲轴第二套夹具设计 21 3.1 明确设计任务、收集分析原始资料 21 3.2 确定夹具的结构方案 22 3.3 夹具定位误差分析 22 3.4 拟订夹具总装图的尺寸、公差与配合及技术要求 22 3.5 绘制夹具总装图 23

4 结论 24 致谢 25 26 附件清单 27 摘要 本文主要介绍了R180柴油机曲轴工艺设计及其中两道工序的夹具设计。本文作者是在保证产品质量、提高生产率、降低成本、充分利用现有生产条件、保证工人具有良好而安全劳动条件的前提下进行设计的。在工艺设计中,作者结合实际进行理论设计,对曲轴传统生产工艺进行了改进,优化了工艺过程和工艺装备,使曲轴的生产加工更经济、合理。在夹具设计部分,作者在收集加工所用机床、刀具及辅助工具等有关资料后,对工件材料、结构特点、技术要求及工艺分析的基础上,按照夹具设计步骤设计出符合曲轴生产工艺及夹具制造要求的夹具。 关键词:柴油机曲轴工艺夹具 Abstract This text introduce R180 diesel engine crankshaft technological design and two of them jig of process design mainly. The author of this text is guaranteeing product quality, boost productivity, lower costs, utilize existing working condition, guaranteeing worker to have good work prerequisite of terms to design . In technological design, the author bine carrying on theory design, improve the traditional production technology of the crankshaft actually, optimize craft course and craft equip, enable economy rational even more of production and processing of the crankshaft. Designing in the jig , the author collect the relevant materials, such as lathe, cutter and handling tool,etc. At the foundation of the analyse of work piece material, specification requirement and craft, and make jig of request according to jig measure design and cankshaft production technology and jig.

船舶冷却水系统设计指导

编制大纲: 需要补充的内容:1,水泵(定速离心泵,变频泵);2,温控阀;3,节流孔板;4,热平衡计算的理论公式,温升热量水量公式;5,特殊案例的区分(温控阀,板冷,变频泵对整个冷却系统形式选定的影响;分离封闭式,高低温混流式,配置变频海水泵没有温控阀的中央式。)6,利用目前的实船进行计算公式的验证,还有一些经验系数的反推导(特别是一些厂家自己的经验系数)7,膨胀水箱;8,补充开发设计需要的部分,参考《船舶管舾装设计工艺实用手册》 前言(目的) 以《船舶设计实用手册---轮机分册》---国防工业出版社为蓝本,将其中的冷却水系统做了进一步内容扩展和深化描述,提供给详细设计人员参考。 参考《船舶管舾装设计工艺实用手册》,补充一部分工程计算公式; 系统发展核心: 1,稳定调节; 2,节省能源,余热循环利用; 3,节省成本,替代方案的方式; 关键词: 将冷却水稳定可靠的输送到需要冷却的设备中:这个可靠和稳定来源于几个参数:稳定的压力,稳定的流量,稳定的温度,稳定的水质(这个水质包含化学成分稳定不结垢,物理成分稳定,极少气泡,气泡会影响热交换器的效率)

冷却水系统 目录 1,范围 2,冷却水系统的基本形式 3,系统形式的选择 4,冷却水系统实例 5,中央冷却系统热平衡计算 6,冷却水系统的主要设备配置要点 7,制淡装置(造水机) 8,具有冰区航行船级符号船舶的冷却水系统特殊要求9,海水进水阀操纵位置的要求 10,冷却水系统的温控阀 11,冷却水系统的节流孔板 12,冷却水系统的泵 13,冷却水系统的膨胀水箱

冷却水系统 1,冷却水系统的基本形式 冷却水系统的基本形式见表1, 注解: (1),所谓开式和闭式冷却水系统是指柴油机本身冷却水系统而言。开式系统是指柴油机本身直接用舷外海水或者江水冷却。如今除江河小船之外,基本不采用开式系统。海拖(海洋港口拖轮)还在使用海水直接冷却柴油机。(潜在问题:船内海水泄露,在与柴油机连接的弹性管配置不正确时容易出现,已有其他公司的海拖因为这个弹性管破裂造成沉船)

柴油机设计说明书.doc11

镇江高专 ZHENJIANG COLLEGE 毕业设计(论文) 基于柴油机拆装的零件设计与数控编程 Based on disassembly of parts engine design and NC programming 系名:机械工程系 专业班级: 学生姓名: 学号: 指导教师姓名: 指导教师职称: 二○一一年九月

目录 第一章R175A柴油机的工作原理 (1) 1.1 柴油机的概述 (1) 1.2 柴油机的工作原理 (1) 1.2.1 进气冲程 (2) 1.2.2 压缩冲程 (2) 1.2.3 燃烧膨胀冲程 (3) 1.2.4 排气冲程 (3) 第二章曲轴概述 (4) 2.1 曲轴的作用 (4) 2.2 曲轴的组成 (5) 2.2.1主轴颈 (5) 2.2.2连杆轴颈 (6) 2.2.3曲柄 (6) 2.2.4自由端(前端) (6) 2.2.5功率输出自由端(后端) (6) 第三章曲轴的加工工艺 (7) 3.1 一般曲轴的加工工艺 (7) 3.2 零件设计与工艺分析 (8) 3.2.1零件材料选择 (8) 3.2.2零件几何尺公差及技术要求的确定 (9) 3.3 确定生产类型 (10) 3.3.1确定毛坯种类 (10) 3.3.2确定铸件余量及形状 (10) 3.4 曲轴加工工艺过程设计 (10) 3.4.1选择表面加工方法 (10) 3.4.2确定工艺过程方案 (11)

3.5选择加工设备与工艺装备 (13) 3.5.1选择机床 (13) 3.5.2选择夹具 (13) 3.5.3选择刀具 (13) 3.5.4选择量具 (14) 3.6 确定工序尺寸 (14) 致谢 (18) 参考文献 (19)

柴油机曲轴设计

1前言 1.1柴油机与曲轴 1.1.1柴油机的工作原理 柴油机的每个工作循环都要经历进气、压缩、做功和排气四个过程。 四行程柴油机的工作过程:柴油机在进气冲程吸入纯空气,在压缩冲程接近终了时,柴油经喷油泵将油压提高到10MPa以上,通过喷油器以雾状喷入气缸,在很短时间内与压缩后的高温空气混合,形成可燃混合气。压缩终了时气缸内空气压力可达3.5~4.5MPa,温度高达476.85℃~726.85℃,极大地超过柴油的自燃温度,因此柴油喷人气缸后,在很短的时间内即着火燃烧,燃气压力急剧达到6~9MPa,温度升高到1726.85℃~2226.85℃。在高压气体推动下,活塞向下运动并带动曲轴旋转做功。废气同样经排气门、排气管等处排出。 四行程柴油机的每个工作循环均经过如下四个行程: (1)进气行程在这个行程中,进气门开启,排气门关闭,气缸与化油器相通,活塞由上止点向下止点移动,活塞上方容积增大,气缸内产生一定的真空度。可燃混合气被吸人气缸内。活塞行至下止点时,曲轴转过半周,进气门关闭,进气行程结束。 由于进气道的阻力,进气终了时气缸内的气体压力稍低于大气压,约为0.07~0.09MPa。混合气进入气缸后,与气缸壁、活塞等高温机件接触,并与上一循环的高温残余废气相混合,所以温度上升到96.85℃~126.85℃。 (2)压缩行程进气行程结束后,进气门、排气门同时关闭。曲轴继续旋转,活塞由下止点向上止点移动,活塞上方的容积缩小,进入到气缸中的混合气逐渐被压缩,使其温度、压力升高。活塞到上止点时,压缩行程结束。 压缩终了时鼓,混合气温度约为326.85℃~426.85℃,压力一般为0.6~ 1.2MPa。 (3)做功行程活塞带动曲轴转动,曲轴通过转动把扭矩输出。 (4)排气行程进气口关闭,排气口打开,排除废气。 由上可知,四行程汽油机或柴油机,在一个工作循环中,只有一个行程作功,其余三个行程作为辅助行程都是为作功行程创造条件的。因此,单缸发动机工作不平稳。现代汽车都采用多缸发动机,在多缸发动机中,所有气缸的作功行程并不同时进行,而尽可能有一个均匀的作功间隔,因而多缸发动机曲轴运转均匀,工作平稳,并可获得足够大的功率。例如六缸发动机,在一个工作循环中,曲轴要旋转720°,曲轴转角每隔120°就有一个气缸作功。

发动机冷却系统设计规范..

发动机冷却系统设计规范..

号: 冷却系统设计规范 编制:万涛 校对: 审核: 批准: 第1页

第1页

水泵、节温器、副水箱、发动机进水管、发动机出水管、散热器除气管、发动机除气管等。 四、主要部件的设计选型 1、散热器 散热器的散热量(Q)和散热器散热系数(K)、散热器散热面积(A)及气液温差(⊿T)有关: Q=K·A·⊿T 其中:Q---散热器的散热量(kcal/h) K---散热器散热系数(kcal/m2?h?oC) A---散热器散热面积(m2) ⊿T---气液温差:散热器进水温度和散热器进风温度之差(oC)散热器的散热系数是代表散热效率的重要指标,主要影响因素如下: ①冷却管内冷却液的流速---据试验结果,冷却液流速由0.2m/s提高到0.8m/s,散热效 率有较大提高,但超过0.8m/s后,效果不大; ②通过散热器芯部的空气流量---空气的导热系数很小,因此散热器的散热能力主要取决 于空气的流动,通过散热器芯部的风量起了决定性作用; ③散热器的材料和管带的厚度---国内散热器的材料目前基本上已标准化; ④制造质量---主要是冷却管和散热带之间的贴合性和焊接质量; 第1页

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目录 摘要 (2) 1引言 (3) 1.1国内外内燃机研究现状 (3) 1.2任务与分析 (5) 2柴油机工作过程计算 (6) 2.1 已知条件 (6) 2.2 参数选择 (7) 2.3 195柴油机额定工况工作过程计算 (7) 3 连杆设计 (11) 3.1 连杆结构设计 (11) 3.2 连杆材料选择 (13) 4 连杆螺钉强度校核 (14) 4.1 连杆螺钉的结构设计 (14) 4.2 连杆螺钉的强度校核 (14) 5 结论 (18) 致谢 (19) 参考文献 (19) 附录:195柴油机额定工况工作过程计算程序 (20)

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目录 中文摘要…………………………………………………………………………………………I 1.引言 (1) 2.曲轴的生产纲领 (2) 3.零件的分析 (2) 3.1曲轴的用途及工作条件 (2) 3.2分析零件上的技术要求,确定要加工的表面 (3) 3.3加工表面的尺寸和形状精度 (4) 3.4尺寸和位置精度 (4) 3.5加工表面的粗糙度及其它方面的质量要求 (4) 3.6热处理要求 (4) 4.曲轴材料和毛坯的定 (4) 4.1确定毛坯的类型 (4) 4.2确定毛坯的生产方法 (4) 4.3确定毛坯的加工余量 (4) 5.曲轴的工艺过程设计 (5) 5.1粗、精加工的定位基准 (5) 5.1.1粗加工 (5) 5.1.2粗加工 (5) 5.2工件表面加工方法的选择 (5) 5.3曲轴机械加工的基本路线 (5) 5.4加工余量及毛坯尺寸 (6) 5.5工序设计 (6) 5.5.1加工设备与工艺装备的选择 (8) 5.5.2机械加工余量、工序尺寸及公差的确定 (9) 5.6确定工时定额 (11) 5.7机械加工工艺规程卡片和机械加工工序卡片 (12) 5.7.1机械加工工艺过程卡片 (12) 5.7.2机械加工工序卡片 (12) 6.柴油机曲轴加工键槽夹具设计 (13) 6.1.1夹具类型的分析 (13) 6.1.2工装夹具定位方案的确定 (13) 6.1.3工件夹紧形式的确定 (13) 6.1.4对刀装置 (13) 6.1.5分度装置的确定以及补补助装置 (14) 6.1.6夹具定位夹紧方案的分析论证 (14) 6.1.7夹具结构类型的设计 (15) 6.2夹具总图设计 (16) 6.4绘制夹具零件图 (16)

柴油机齿轮设计

目录 1. 设计题目及参数 (1) 2. 数学模型地建立 (1) 3. 程序框图 (5) 4. 程序清单及结果 (6) 5. 设计总结 (12) 6. 参考文献 (13) 7.中期检查报告 (14) 1.设计题目及参数 已知:齿轮齿数Z 1=22,Z 2=44,m=5mm ,分度圆压力角а=20°; 齿轮为正常齿轮,在闭式的润滑油池中工作。 要求:1)用C 语言编写程序,选择两轮变位系数,计算齿轮各部分尺寸。 2)绘制柴油机机构运动简图 3)编写说明书一份。 2.数学模型的建立 1) 实际中心距a '的确定:2 )(21z z m a +? = ; a '=(a/5+1)?5; 2) 啮合角α': ;)cos(2)()cos(21ααα?'?+= 'z z m

αααinv z z x x inv +++=')/()(tan 22121; 3) 分配变位系数21x x 、; min 1min min 1/)(z z z h x a -=* ;min 2min min 2/)(z z z h x a -=* ; 4)中心距变动系数 y=(a a -')/m ; 5) 齿轮基本参数: 注:下面单位为mm 模数: m=5 压力角: ο20=α 齿数: 1z =22 2z =44 齿顶高系数: 0.1=* a h 齿根高系数: 25.0=*c 传动比: 12/z z i = 齿顶高变动系数: y x x -+=21σ 分度圆直径; 11mz d = 22mz d = 基圆直径; αcos 11mz d b = 齿顶高: )(11σ-+=* x h m h a a

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