Introduction
Thesis Statement
The pressure on diesel engine manufacturers caused by the legislative body had a substantial impact on the development of the technology and can be currently considered one of the key contributors to the major success of diesel-based engines and numerous innovations and improvements that positively influenced the industry.
Rudolf Diesel’s Biography
The prototype of the hot-bulb engine appeared in 1889 and completely changed the way that oil-based engines were perceived by the inventors and the general public (Wrangham 664). This was reflected in the novel fuel injection procedure that involved compression of the air that could be located within the cylinders at that given moment. The fuel was injected into a custom hot bulb (Wrangham 664). The latter is based on the classic hot-tube engine but the core difference between the two consists in the increased level of turbulence in hot-bulb engines. If the bulb is kept at a suitable temperature and possesses a specific shape, it will secure the manifestation of automatic ignition (Wrangham 664). The engine starts when a special blow-lamp raises the temperature of the bulb, and it leads to a decreased volume of air that is necessary for the pre-ignition and subsequent ignition processes.
Brief History
The prototype of the first diesel engine was proposed by Rudolph Diesel in 1892. The key feature of this type of engine is that it utilizes compression ignition (Bennett 9). The idea behind this is that the engine ignites only under certain circumstances, whereas the vital condition is a sufficient level of compression. On a bigger scale, the development of the first diesel engine was the incorporation of Diesel’s ideas and the ideas of his colleagues and predecessors (Bennett 10). Diesel engines are way more powerful than conventional spark-ignition engines. Also, they promote fuel economy and minimize harmful environmental emissions.
Hot-bulb Engines
The prototype of the hot-bulb engine appeared in 1889 and completely changed the way that oil-based engines were perceived by the inventors and the general public (Wrangham 664). This was reflected in the novel fuel injection procedure that involved compression of the air that could be located within the cylinders at that given moment. The fuel was injected into a custom hot bulb (Wrangham 664). The latter is based on the classic hot-tube engine but the core difference between the two consists in the increased level of turbulence in hot-bulb engines. If the bulb is kept at a suitable temperature and possesses a specific shape, it will secure the manifestation of automatic ignition (Wrangham 664). The engine starts when a special blow-lamp raises the temperature of the bulb, and it leads to a decreased volume of air that is necessary for the pre-ignition and subsequent ignition processes.
Origin of the Diesel Cycle
The first ideas connected to the development of the future diesel engine revolved around the improvements that could have been made to enhance the conventional heat engines (Shrinivasa 368). Rudolf Clausius, who was a student at that time, came up with the proposition to burn the fuel right in the cylinders. His theoretical prototype was based on the idea that the engine could function on account of the very high pressure that would transfer the fuel directly to the cylinders (Shrinivasa 368). The first physical prototype proved that auto-ignition is possible. The succeeding prototypes helped to steadily get rid of the complications and various limitations of the basic diesel engine.
Development of the Diesel Cycle
The improvements that were made led to a situation where diesel engines exceeded the performance of approximately 180g/ kWh (Shrinivasa 371). The power and durability of diesel engines have predicted its use in marine vehicles (including both small boats and large cargo ships) and railway means of transportation (such as freight trains and passenger trains). The specifications of the basic diesel engine allowed the manufacturers to produce both high-speed engines (RPM > 5000) and enduring engines that could function not less than 8000 hours annually (Shrinivasa 371).
Diesel Engines and Alternative Fuels
A high level of emissions triggered the development of fuels that would not contribute to the process of global warming (Shrinivasa 372). For more than ten years, numerous cars equipped with diesel engines are functioning based on fuel that is called biodiesel. By and large, this is an oil-based fuel (manufactured from crops) that becomes more and more popular all over the world (Shrinivasa 372). The development and adoption of alternative fuels stimulate the modernizations in the areas of diesel engine performance and fuel supply and consumption.
The Current State of Affairs
Throughout the latest decade, diesel-based technologies were exposed to serious challenges which led to critical changes. This trivial evolution ultimately ended up in the development of unit injectors, electronic engine controls, and a fuel injection system that is based on the common rail (Bennett 13). The only category that did not fall under the common legislation was marine engines. This happened because this market was insignificant if one compared it to the automotive industry and the production of heavy trucks. The fact is diesel engines that were installed on-road vehicles and trucks were often installed on marine means of transport as well. This led to a situation where all the standards enforced by the new legislation on automotive and trucks were also transferred to marine vehicles. For more than ten years (since 2004), diesel engines that are installed on marine transportation have to comply with the regulations itemized by the US Environmental Protection Agency (Pallas 113). Moreover, it is important to mention that these regulations become more and more rigorous in terms of emissions requirements.
The Evolution of Diesel Engines
Electronic Engine Controls
Description of the Technology
This innovational technology initially replaced the previous mechanical governor. It fulfilled all the functions of the existing technology and was connected to an electronic control unit (ECU) via an engine speed sensor. The ECU functions based on signals that are sent out to the actuator. This helps the engine to fluctuate the level of fuel injection by moving the fuel rack in the injection pump. Therefore, the anticipated engine speed is reached using adjusting the rate of fuel injection (Schobert 372). The ECU input signals also developed over time and allowed to govern the functionality of the fuel rack more efficiently. The absence of this system on the old cars always led to the emission of black smoke during the intervals of sudden acceleration. Currently, even the least complex electronically-controlled diesel engines can evade this confusion and, at the same time, a perilous aspect of diesel engines (Schobert 173).
The Benefits of Using ECUs in Diesel Engines
The employment of ECU and common rail injection brought several critical improvements and positively influenced the performance of diesel engines. The conventional engines were based on a fuel rack that affected all the cylinders when undergoing the process of fuel injection (Schobert 369). On the contrary, the new system allowed to control the injection process separately for each of the cylinders. This visible independence was supported by complex decisions that were made by the ECU. The most up-to-date generation of ECUs features electronically connected transmission and throttle. All of the devices controlled by the ECU are not connected mechanically (Schobert 369). Instead, there is a data cable intended to transfer all the necessary data to the cockpit displays.
Networking
Controller Area Network
Another important part of the evolution of diesel engines is the advent of a controller area network (CAN). This feature is synonymous with a specific protocol and is currently used in all the ECUs. For instance, if the computer is plugged into the CAN system, it is possible to diagnose various problems and scrutinize the operating history of the vehicle (Grescoe). Further development of this technology led to the advent of NMEA 2000 – the latest generation of electronically-transferred data. On a bigger scale, this innovation allows the manufacturers to connect diesel engine electronics to navigational electronics. Over time, NMEA 2000 allowed to ensure a functional interaction between a diesel engine and navigational electronics which worked both ways (Gumus et al. 484). What is even more important, this functionality is being constantly updated.
Innovational Aspects of the Controller Area Network
The implementation of electronic engine control systems allowed the manufacturers to minimize the number of wires connected to diesel engines. As an alternative, the ECU unit is interconnected with all the necessary engine sensors using point-to-point wiring. By doing this, the manufacturers ensure that the data is successfully transferred from the engine to the engine controls and displays (Grescoe). This allows the ECU to display the necessary information incoming from all the sensors instead of pinging individual sensors and outputting the signal to the gauges. The latter is gradually coming out of circulation and are being replaced with their electronic alternative (most often, an on-screen display).
Implications of Networking in Diesel Engines
The interconnection between the elements of the diesel engine and electronic output signals opened several prospects for both manufacturers and mechanics. From now on, the ECU can transfer the data regarding necessary diagnostics, possible failures, and operational history (Gumus et al. 490). Regardless, this data cannot be troubleshot and, consequently, repaired by an incompetent or inexperienced mechanic. Despite the improvements, there is a need to explore the vulnerabilities of the existing networking such as weak circuits and disruptive network buses. Some manufacturers currently offer the possibility to override the system in case of dysfunction manually (Gumus et al. 493). Therefore, buying a car with a fully electronic diesel engine imposes several complications on the purchaser. Even though the improvements also took into account the electromagnetic interference and radio frequency interference, the capability of being fully functional at all times is hard to achieve and requires a power supply of a certain level (Gumus et al. 494). Unpredictable responses during low voltage are characteristic of electronic networks in diesel engines and can be followed by a complete stoppage of the network. This is why critical elements (transmission, steering, engine) of the vehicles running on diesel engines are contingent on the presence of uninterruptible power supplies (Gumus et al. 494).
Unit Injectors
Description of the Technology
This technology majorly contributed to the evolution of the diesel engine after the development of intricate ECUs (Neslen). The core function of unit injectors is to control the functioning of the fuel pump and the way it draws fuel from the tank. After the primary and secondary filters, the fuel is discharged into a gallery at moderately low pressure. In other words, the unit injectors are supplied by the gallery (Neslen). The excess of the fuel returns to the tank while the pressure in the gallery is regulated by a distinct valve designed to regulate the pressure. The injectors should be cool and loosened to function properly. This is why the system allows a continuous flow of fuel. Each injector contains a designated pump that is similar to the conservative jerk pump (Qate et al. 335). The pump is activated and controlled by a camshaft that can be located in each diesel engine with the help of unit injectors. When it is required, the fuel is injected directly into the engine using the pump (Qate et al. 337). The speed of the engine is controlled by the adjustments made to the injection pulse and the pumping element.
Application of Unit Injectors in Diesel Engines
In the current diesel engines, the functions responsible for the injection timing and fuel pressure are successfully separated (in out-of-date systems, these two functions were combined). The pumping pulse triggers the decision-making process in the ECU regarding the fuel injection (Rakopoulos et al. 218). The technology of unit injection commonly involves extremely high pressures and is applied on diesel engines that are larger than usual. This can be explained by bigger combustion chambers and the increased distance that fuel will have to travel. Consequently, unit injectors are hardly ever installed on smaller diesel engines because of inefficiency and cost/ performance compatibility (Rakopoulos et al. 222).
Common Rail System
Major Aspects of the Technology
Unit injection systems are almost identical to common rail systems in terms of the way that they function. The fuel that is drawn from the tank incessantly circulates through the gallery and gets back in the tank (Rakopoulos et al. 221). The difference between the two lies in the fact that a common rail system requires the system to function at full injection pressure. The latter ultimately eradicate the use of unit injectors as they become impractical. This fuel injection system requires that the fuel is transferred at the right moment and in the right quantity using a special valve (Rakopoulos et al. 222).
Core Functions of the Common Rail System
The evolution of the diesel engines led to a situation where the engine’s computer efficiently manages an electromagnetic valve. The core function of the common rail system is to separate the processes of injection timing and the generation of fuel pressure (Rakopoulos et al. 223). This pressure is used to store the fuel in a state of readiness in the vehicle’s accumulator rail. The ECU is used to control the time intervals during which the electronic valve is either opened or closed to let fuel into the cylinders.
Advantages of Common Rail and Unit Injection
The diesel engines that are currently outdated featured a basic injection pump, and this created an ultimate lag between the initiation of the pumping activity and the moment when the fuel was injected. This lag was contingent on several factors which included the weariness of the pump, fuel temperature, and even springiness of the injection lines (Knothe et al. 28). The modern systems (common rail system and unit injection) evade the gap because they function in real-time. Consequently, this enables accurate regulation of the fuel injection mechanisms. Moreover, outdated injection systems could not deliver a large quantity of fuel to the injection line. This happened because of the pressure drops which adversely affected the efficacy of injections (Knothe et al. 406). The peculiarities of the common rail system allowed it to disregard pressure drops and equalize the volumes of both the pressurized and the injected fuel. The evolution of diesel engines led to a situation in which the ECU is responsible for the regulation of the injection process. This significantly improves the performance and gives more control over the system if compared to the old injection systems (Knothe et al. 147). Additionally, the evolution positively impacted the majority of the operating conditions of diesel engines. The current vehicles based on diesel engines are proved to minimize the emission of air pollutants and generate less noise (Knothe et al. 254). More importantly, the improvements that were made during the process of evolution allowed the manufacturers to extend the life of diesel engines.
The Advent of Hybrids and Additional Improvements
Developmental Issues of Diesel Engines
During the last ten years, the manufacturers of diesel engines made several important steps forward. They were able to improve the efficiency of marine vehicles featuring a diesel engine and fuel-related productivity (Knothe et al. 191). All the improvements were useful not only for commercial manufacturers but the general public as well. Even though the evolution of diesel engines was rather extensive and included numerous effective improvements, there is a secondary effect which can be described as the increased use of the systems that are based on electric propulsion (Knothe et al. 34). It was found that this approach is almost as profitable as other innovative methods intended to improve fuel efficiency and it can be used together with the conventional fuel injection systems (turning the vehicle into a hybrid) (Knothe et al. 37).
Problems Associated with Hybrid Diesel Engines
The problem is that the potential benefits of the current technologies weaken at the same time with the increasing public interest regarding hybrid means of transportation (Shehata 514). It is also safe to say that the existing diesel-engined cars are way more performant than their hybrid competitors. On a bigger scale, this involves the use of alternative energy sources and exposes the manufacturers to several new challenges that significantly impact the market for vehicles with diesel engines (Shehata 516). The manufacturers of hybrid vehicles are forced to conduct research and seek the optimal decisions when it comes to fuel efficiency and the consolidation of conventional and innovative technologies (Shehata 517). The problem is, currently, there are no manufacturers that can support this level of productional complexity. The investigations and research connected to this problem should be supported by grants and additional funding to turn into a successful project and popularization of diesel engines (Shehata 520). Nowadays, the evolution of diesel engines can be described as an event that had almost no effect on the public perceptions regarding diesel engines. Even considering all the technological advances and a rapid shift to electronic systems, the owner-vehicle interactions are still limited as the owners have little control over their vehicles in terms of maintaining and operating them.
Conclusion
Diesel engines have come a long way from the simplest injection systems to computerized interfaces, ECUs, and intelligent fuel supplies. At this time, the manufacturers expect to make the best use of sophisticated electronics and all the accompanying functionalities. Owing to the evolution of diesel engines, the latter became smarter but still require specific knowledge in terms of maintaining the engine. Most probably, this will change when the ECUs control the whole process of fuel supply and consumption, but for now, the vehicles with diesel engines are still controlled by mechanics and feature conventional injection systems. Nonetheless, the evolution bears a positive connotation because there is hope that someday the owners of diesel engines will not have to address qualified professionals who operate complex hi-tech tools.
Works Cited
Bennett, Sean. Modern Diesel Technology: Diesel Engines. Cengage Learning, 2015.
Grescoe, Taras. “The Dirty Truth about ‘Clean Diesel’.” The New York Times, The New York Times, 2016. Web.
Gumus, Metin, et al. “The Impact of Fuel Injection Pressure on the Exhaust Emissions of a Direct Injection Diesel Engine Fueled with Biodiesel–Diesel Fuel Blends.” Fuel, vol. 95, 2012, pp. 486–494. Web.
Knothe, Gerhard, et al. The Biodiesel Handbook. Elsevier Science, 2015.
Neslen, Arthur. “Diesel Cars May Be Worse Than Petrol for Carbon Emissions, Report Claims.” The Guardian, Guardian News and Media, 2016. Web.
Pallas, Jean. AC Maintenance & Repair Manual for Diesel Engines. A&C Black, 2013.
Qate, Mehran, et al. “A Review of Ignition Delay and Combustion Characteristics of Biodiesel Fueled Diesel Engine.” Applied Mechanics and Materials, vol. 390, no. 2, 2013, pp. 333–337. Web.
Rakopoulos, Dimitrios, et al. “Characteristics of Performance and Emissions in High-Speed Direct Injection Diesel Engine Fueled with Diethyl Ether/Diesel Fuel Blends.” Energy, vol. 43, no. 1, 2012, pp. 214–224. Web.
Schobert, Harold. Energy and Society: An Introduction. Taylor & Francis, 2012.
Shehata, Mohamed. “Emissions, Performance and Cylinder Pressure of Diesel Engine Fuelled by Biodiesel Fuel.” Fuel, vol. 112, 2013, pp. 513–522. Web.
Shrinivasa, U. (2012). The Evolution of Diesel Engines. Resonance, 17(4), 365-377. Web.
Stonecypher, Lamar. “Biography of Rudolf Diesel, Inventor of Diesel Engine.” Bright Hub, 2009. Web.
Wrangham, Digby. The Theory & Practice of Heat Engines. Cambridge University Press, 2013.