Ask Joe Mechanic - Diesel Engines (Part 2)

The first subject of this week’s article is how a diesel engine operates. The diesel internal combustion engine differs from the gasoline powered Otto cycle by using highly compressed hot air to ignite the fuel rather than using a spark plug (compression ignition rather than spark ignition).

In the true diesel engine, only air is initially introduced into the combustion chamber. The air is then compressed with a compression ratio typically between 15:1 and 22:1 resulting in 40-bar (4.0 MPa; 580 psi) pressure compared to 8 to 14 bars (0.80 to 1.4 MPa; 120 to 200 psi) in the petrol engine. This high compression heats the air to 550 °C (1,022 °F). At about the top of the compression stroke, fuel is injected directly into the compressed air in the combustion chamber. This may be into a (typically toroidal) void in the top of the piston or a pre-chamber depending upon the design of the engine. The fuel injector ensures that the fuel is broken down into small droplets, and that the fuel is distributed evenly. The heat of the compressed air vaporizes fuel from the surface of the droplets. The heat from the compressed air in the combustion chamber then ignites the vapor; the droplets continue to vaporize from their surfaces and burn, getting smaller, until all the fuel in the droplets has been burnt. The start of vaporization causes a delay period during ignition and the characteristic diesel knocking sound as the vapor reaches ignition temperature and causes an abrupt increase in pressure above the piston. The rapid expansion of combustion gases then drives the piston downward, supplying power to the crankshaft.

As well as the high level of compression allowing combustion to take place without a separate ignition system, a high compression ratio greatly increases the engine's efficiency. Increasing the compression ratio in a spark-ignition engine where fuel and air are mixed before entry to the cylinder is limited by the need to prevent damaging pre-ignition. Since only air is compressed in a diesel engine, and fuel is not introduced into the cylinder until shortly before top dead centre (TDC), premature detonation is not an issue and compression ratios are much higher.

Diesel's original engine injected fuel with the assistance of compressed air, which atomized the fuel and forced it into the engine through a nozzle (a similar principle to an aerosol spray). The nozzle opening was closed by a pin valve lifted by the camshaft to initiate the fuel injection before top dead centre (TDC). This is called an air-blast injection. Driving the three-stage compressor used some power but the efficiency and net power output was more than any other combustion engine at that time.

Diesel engines in service today raise the fuel to extreme pressures by mechanical pumps and deliver it to the combustion chamber by pressure-activated injectors without compressed air. With direct injected diesels, injectors spray fuel through 4 to 12 small orifices in its nozzle. The early air injection diesels always had a superior combustion without the sharp increase in pressure during combustion. Research is now being performed and patents are being taken out to again use some form of air injection to reduce the nitrogen oxides and pollution, reverting to Diesel's original implementation with its superior combustion and possibly quieter operation. In all major aspects, the modern diesel engine holds true to Rudolf Diesel's original design, that of igniting fuel by compression at an extremely high pressure within the cylinder. With much higher pressures and high technology injectors, present-day diesel engines use the so-called solid injection system applied by Herbert Akroyd Stuart for his hot bulb engine. The indirect injection engine could be considered the latest development of these low speed hot bulb ignition engines.

A vital component of all diesel engines is a mechanical or electronic governor which regulates the idling speed and maximum speed of the engine by controlling the rate of fuel delivery. Unlike Otto-cycle engines, incoming air is not throttled and a diesel engine without a governor cannot have a stable idling speed and can easily overspeed, resulting in its destruction. Mechanically governed fuel injection systems are driven by the engine's gear train. 

These systems use a combination of springs and weights to control fuel delivery relative to both load and speed. Modern electronically controlled diesel engines control fuel delivery by use of an electronic control module (ECM) or electronic control unit (ECU). The ECM/ECU receives an engine speed signal, as well as other operating parameters such as intake manifold pressure and fuel temperature, from a sensor and controls the amount of fuel and start of injection timing through actuators to maximize power and efficiency and minimize emissions. Controlling the timing of the start of injection of fuel into the cylinder is a key to minimizing emissions, and maximizing fuel economy (efficiency), of the engine. The timing is measured in degrees of crank angle of the piston before top dead centre. For example, if the ECM/ECU initiates fuel injection when the piston is 10° before TDC, the start of injection, or timing, is said to be 10° BTDC. Optimal timing will depend on the engine design as well as its speed and load.

Advancing the start of injection (injecting before the piston reaches to its SOI-TDC) results in higher in-cylinder pressure and temperature, and higher efficiency, but also results in increased engine noise due to faster cylinder pressure rise and increased oxides of nitrogen (NO_x) formation due to higher combustion temperatures. Delaying start of injection causes incomplete combustion; reduced fuel efficiency and an increase in exhaust smoke, containing a considerable amount of particulate matter and unburned hydrocarbons.

Diesel engines have several advantages over other internal combustion engines:

• They burn less fuel than a petrol engine performing the same work, due to the engine's higher temperature of combustion and greater expansion ratio. Gasoline engines are typically 30 percent efficient while diesel engines can convert over 45 percent of the fuel energy into mechanical.
• They have no high voltage electrical ignition system, resulting in high reliability and easy adaptation to damp environments. The absence of coils, spark plug wires, etc., also eliminates a source of radio frequency emissions, which can interfere with navigation and communication equipment, which is especially important in marine and aircraft applications.
• The life of a diesel engine is generally about twice as long as that of a petrol engine due to the increased strength of parts used. Diesel fuel has better lubrication properties than petrol as well.
• Diesel fuel is distilled directly from petroleum. Distillation yields some gasoline, but the yield would be inadequate without catalytic reforming, which is a more costly process.
• Diesel fuel is considered safer than petrol in many applications. Although diesel fuel will burn in open air using a wick, it will not explode and does not release a large amount of flammable vapor. The low vapor pressure of diesel is especially advantageous in marine applications, where the accumulation of explosive fuel-air mixtures is a particular hazard. For the same reason, diesel engines are immune to vapor lock.
• For any given partial load the fuel efficiency (mass burned per energy produced) of a diesel engine remains nearly constant, as opposed to petrol and turbine engines, which use proportionally more fuel with partial power outputs. They generate less waste heat in cooling and exhaust.
•  Diesel engines can accept super- or turbo-charging pressure without any natural limit, constrained only by the strength of engine components. This is unlike petrol engines, which inevitably suffer detonation at higher pressure.
• The carbon monoxide content of the exhaust is minimal; therefore diesel engines are used in underground mines.
• Biodiesel is an easily synthesized, non-petroleum-based fuel (through transesterification) which can run directly in many diesel engines, while gasoline engines either need adaptation to run synthetic fuels or else use them as an additive to gasoline (e.g., ethanol added to gasohol).
  
  
  
  Many configurations of fuel injection have been used over the course of the twentieth century. Most present-day diesel engines use a mechanical single plunger high-pressure fuel pump driven by the engine crankshaft. For each engine cylinder, the corresponding plunger in the fuel pump measures out the correct amount of fuel and determines the timing of each injection. These engines use injectors that are very precise spring-loaded valves that open and close at a specific fuel pressure. Separate high-pressure fuel lines connect the fuel pump with each cylinder. Fuel volume for each single combustion is controlled by a slanted groove in the plunger, which rotates only a few degrees releasing the pressure, and is controlled by a mechanical governor, consisting of weights rotating at engine speed constrained by springs and a lever. The injectors are held open by the fuel pressure. On high-speed engines the plunger pumps are together in one unit. The length of fuel lines from the pump to each injector is normally the same for each cylinder in order to obtain the same pressure delay.
  
  
  
  
  A cheaper configuration on high-speed engines with fewer than six cylinders is to use an axial-piston distributor pump, consisting of one rotating pump plunger delivering fuel to a valve and line for each cylinder (functionally analogous to points and distributor cap on an Otto engine). 
  
  
  
  
  Many modern systems have a single fuel pump which supplies fuel constantly at high pressure with a common rail (single fuel line common) to each injector. Each injector has a solenoid operated by an electronic control unit, resulting in more accurate control of injector opening times that depend on other control conditions, such as engine speed and loading, and providing better engine performance and fuel economy.
  
  
  
  
  Both mechanical and electronic injection systems can be used in either direct or indirect injection configurations. Two-stroke diesel engines with mechanical injection pumps can be inadvertently run in reverse, albeit in a very inefficient manner, possibly damaging the engine. Large ship two-stroke d
  iesels are designed to run in either direction, obviating the need for a gearbox.
  
  
  
  
  An indirect injection diesel engine delivers fuel into a chamber off the combustion chamber, called a pre-chamber or ante-chamber, where combustion begins and then spreads into the main combustion chamber, assisted by turbulence created in the chamber. This system allows for a smoother, quieter running engine, and because combustion is assisted by turbulence, injector pressures can be lower, about 100 bar (10 MPa; 1,500 psi), using a single orifice tapered jet injector. Mechanical injection systems allowed high-speed running suitable for road vehicles (typically up to speeds of around 4000 rpm. The pre-chamber had the disadvantage of increasing heat loss to the engine's cooling system, and restricting the combustion burn, which reduced the efficiency by five to ten percent. Indirect injection engines are cheaper to build and it is easier to produce smooth, quiet-running vehicles with a simple mechanical system. In road-going vehicles most prefer the greater efficiency and better-controlled emission levels of direct injection. Indirect injection diesels can still be found in the many ATV diesel applications.
  
  
  
  
  Direct injection diesel engines have injectors mounted at the top of the combustion chamber. The injectors are activated using one of two methods - hydraulic pressure from the fuel pump, or an electronic signal from an engine controller.
  
  
  
  
  Hydraulic pressure activated injectors can produce harsh engine noise. Fuel consumption is about 15 to 20 percent lower than indirect injection diesels. The extra noise is generally not a problem for industrial uses of the engine, but for automotive usage, buyers have to decide whether or n
  ot the increased fuel efficiency would compensate for the extra noise.
  
  
  Electronic control of the fuel injection transformed the direct injection engine by allowing much greater control over the combustion.
  
  
  
  
   Unit direct injection also injects fuel directly into the cylinder of the engine. In this system the injector and the pump are combined into one unit positioned over each cylinder controlled by the camshaft. Each cylinder has its own unit eliminating the high-pressure fuel lines, achieving a more consistent injection. Volkswagen AG uses this type of injection system, also developed by Bosch, in cars (where it is called a Pumpe-Düse-System—literally pump-nozzle system) and by Mercedes Benz ("PLD") and most major diesel engine manufacturers in large commercial engines (CAT, Cummins, Detroit Diesel, Electro-Motive Diesel, Volvo). With recent advancements, the pump pressure has been raised to 2,400 bars (240 MPa; 35,000 psi), allowing injection parameters similar to common rail systems.
  
  
  
  
   In common rail systems, the separate pulsing high-pressure fuel line to each cylinder's injector is also eliminated. Instead, a high-pressure pump pressurizes fuel at up to 2,500 bar (250 MPa; 36,000 psi), in a "common rail". The common rail is a tube that supplies each computer-controlled injector containing a precision-machined nozzle and a plunger driven by a solenoid or piezoelectric actuator.
  
  
  
  
  In cold weather, high-speed diesel engines can be difficult to start because the mass of the cylinder block and cylinder head absorb the heat of compression, preventing ignition due to the higher surface-to-volume ratio. Pre-chambered engines make use of small electric heaters inside the pre-chambers called glowplugs, while the direct-injected engines have these glowplugs in the combustion chamber.
  
  
  
  
  Many engines use resistive heaters in the intake manifold to warm the inlet air for starting, or until the engine reaches operating temperature. Engine block heaters (electric resistive heaters in the engine block) connected to the utility grid are used in cold climates when an engine is turned off for extended periods (more than an hour), to reduce startup time and engine wear. Block heaters are also used for emergency power standby Diesel-powered generators, which must rapidly pick up load on a power failure. In the past, a wider variety of cold-start methods were used. Some engines, such as Detroit Diesel engines used a system to introduce small amounts of ether into the inlet manifold to start combustion. Others used a mixed system, with a resistive heater-burning methanol. An impromptu method, particularly on out-of-tune engines, is to manually spray an aerosol can of ether-based engine starter fluid into the intake air stream (usually through the intake air filter assembly).
  
  
  
  
  Diesel fuel is also prone to waxing or gelling in cold weather; both are terms for the solidification of diesel oil into a partially crystalline state. The crystals build up in the fuel line (especially in fuel filters), eventually starving the engine of fuel and causing it to stop running. Low-output electric heaters in fuel tanks and around fuel lines are used to solve this problem. Also, most engines have a spill return system, by which any excess fuel from the injector pump and injectors is returned to the fuel tank. Once the engine has warmed, returning warm fuel prevents waxing in the tank.
  
  
  
  
  Due to improvements in fuel technology with additives, waxing rarely occurs in all but the coldest weather when a mix of diesel and kerosene may be used to run a vehicle. Gas stations in regions with a cold climate are required to offer winterized diesel in the cold seasons that allow operation below a specific Cold Filter Plugging Point. In Europe these diesel characteristics are described in the EN 590 standard.
  
  
  
  
  Most diesels are now turbocharged and some are both turbocharged and supercharged. Because diesels do not have fuel in the cylinder before combustion is initiated, more than one bar (100 kPa) of air can be loaded in the cylinder without pre-ignition. A turbocharged engine can produce significantly more power than a naturally aspirated engine of the same configuration, as having more air in the cylinders allows more fuel to be burned and thus more power to be produced. A supercharger is powered mechanically by the engine's crankshaft, while the engine exhaust, not requiring any mechanical power, powers a turbocharger. Turbocharging can improve the fuel economy of diesel engines by recovering waste heat from the exhaust, increasing the excess air factor, and increasing the ratio of engine output to friction losses.
  
  
  
  
  A two-stroke engine does not have a discrete exhaust and intake stroke and thus is incapable of self-aspiration. Therefore all two-stroke engines must be fitted with a blower to charge the cylinders with air and assist in dispersing exhaust gases, a process referred to as scavenging. In some cases, the engine may also be fitted with a turbocharger, whose output is directed into the blower inlet. A few designs employ a hybrid turbocharger for scavenging and charging the cylinders, which device is mechanically driven at cranking and low speeds to act as a blower.
  
  
  
  
  As turbocharged or supercharged engines produce more power for a given engine size as compared to naturally aspirated engines, attention must be paid to the mechanical design of components, lubrication, and cooling to handle the power. Pistons are usually cooled with lubrication oil sprayed on the bottom of the piston. Large engines may use water, seawater, or oil supplied through telescoping pipes attached to the crosshead.
  
  
  
  
  As with petrol engines, there are two classes of diesel engines in current use: two-stroke and four-stroke. The four-stroke type is the "classic" version, tracing its lineage back to Rudolf Diesel's prototype. It is also the most commonly used form, being the preferred power source for many motor vehicles, especially buses and trucks. Much larger engines, such as used for railroad locomotion and marine propulsion, are often two-stroke units, offering a more favorable power-to-weight ratio, as well as better fuel economy
  
  
  
  
  Two-stroke diesel engine operation is similar to that of petrol counterparts, except that fuel is not mixed with air before induction, and the crankcase does not take an active role in the cycle. The traditional two-stroke design relies upon a mechanically driven positive displacement blower to charge the cylinders with air before compression and ignition. The charging process also assists in expelling (scavenging) combustion gases remaining from the previous power stroke.
  
  
  
  
  The archetype of the modern form of the two-stroke diesel is the (high-speed) Detroit Diesel Series 71 engine, designed by Charles F. "Boss" Kettering and his colleagues at General Motors Corporation in 1938, in which the blower pressurizes a chamber in the engine block that is often referred to as the "air box". The (very much larger medium-speed) Electro-Motive Diesel engine is used as the prime mover in EMD diesel-electric locomotive, marine and stationary applications, and was designed by the same team, and is built to the same principle. However, a significant improvement built into later EMD engines is the mechanically assisted turbo-compressor, which provides charge air using mechanical assistance during starting (thereby obviating the necessity for Roots-blown scavenging), and provides charge air using an exhaust gas-driven turbine during normal operations—thereby providing true turbocharging and additionally increasing the engine's power output by at least fifty percent. 
  
  
  
  
  In a two-stroke diesel engine, as the cylinder's piston approaches the bottom dead centre exhaust ports or valves are opened relieving most of the excess pressure after which a passage between the air box and the cylinder is opened, permitting air flow into the cylinder. The airflow blows the remaining combustion gases from the cylinder—this is the scavenging process. As the piston passes through bottom center and starts upward, the passage is closed and compression commences, culminating in fuel injection and ignition. Refer to two-stroke diesel engines for more detailed coverage of aspiration types and supercharging of two-stroke diesel engines.
  
  
  
  
  Normally, the number of cylinders is used in multiples of two, although any number of cylinders can be used as long as the load on the crankshaft is counterbalanced to prevent excessive vibration. The inline-six-cylinder design is the most prolific in light- to medium-duty engines, though small V8 and larger inline-four displacement engines are also common. Small-capacity engines (generally considered to be those below five liters in capacity) are generally four- or six-cylinder types, with the four-cylinder being the most common type found in automotive uses. Five-cylinder diesel engines have also been produced, being a compromise between the smooth running of the six-cylinder and the space-efficient dimensions of the four-cylinder. Diesel engines for smaller plant machinery; boats, tractors, generators and pumps may be four-, three- or two-cylinder types, with the single-cylinder diesel engine remaining for light stationary work. Direct reversible two-stroke marine diesels need at least three cylinders for reliable restarting forwards and reverse, while four-stroke diesels need at least six cylinders.
  
  
  
  
  The desire to improve the diesel engine's power-to-weight ratio produced several novel cylinder arrangements to extract more power from a given capacity. The uniflow opposed-piston engine uses two pistons in one cylinder with the combustion cavity in the middle and gas in- and outlets at the ends. This makes a comparatively light, powerful, swiftly running and economic engine suitable for use in aviation. An example is the Junkers Jumo 204/205. The Napier Deltic engine, with three cylinders arranged in a triangular formation, each containing two opposed pistons, the whole engine having three crankshafts, is one of the better known.
  
  
  
  
  Some information for this article obtained from Wikipedia.org.
  
  
  
  
  Recent Recalls:
  
  
  27,933 Ford 2012-2013 Edge vehicles equipped with 2.0L engines.
  The fuel line pulse damper metal housing may crack as a result of an improper manufacturing process. A cracked fuel line pulse damper housing may result in a combination of fuel odor, weepage, or a continuous leak while the fuel system is pressurized. A fuel leak in the presence of an ignition source may result in a fire.
  
  
  
  
  300 Ford 2011-2012 Explorers certain replacement steering gears installed as service parts.
  The affected gears may lock, preventing the driver from being able to steer the vehicle. The inability to steer the vehicle increases the risk of a crash.
  
  
  
  Contact your local dealership for more information and how to proceed.
  
  
  
  
  
  
  
  
  
  
  
  

Ask Joe Mechanic - Diesel Engine Historical Timeline

A Historic Timeline of significant developments pertaining to diesel engines:





1890s

• 1891: Herbert Akroyd Stuart invents the first internal combustion engine to use a pressurized fuel injection system.
• 1892: February 23, Rudolf Diesel obtained a patent (RP 67207) titled "Arbeitsverfahren und Ausführungsart für Verbrennungsmaschinen".
• 1892: Akroyd Stuart builds his first working Diesel engine.
• 1893: Diesel's essay titled Theory and Construction of a Rational Heat-engine to Replace the Steam Engine and Combustion Engines Known Today appeared.
• 1893: August 10, Diesel built his first working prototype in Augsburg.
• 1897: Adolphus Busch licenses rights to the Diesel Engine for the USA and Canada.
• 1899: Diesel licensed his engine to builders Krupp and Sulzer, who quickly became major manufacturers.

1900s

• 1902: Until 1910 MAN produced 82 copies of the stationary diesel engine.
• 1903: Two first diesel-powered ships were launched, both for river and canal operations: Petite-Pierre in France, powered by Dyckhoff-built diesels, and Vandal tanker in Russia, powered by Swedish-built diesels with an electrical transmission.
• 1904: The French built the first diesel submarine, the Z.
• 1905: Four diesel engine turbochargers and intercoolers were manufactured by Büchl (CH), as well as a scroll-type supercharger from Creux (F) company.
• 1908: Prosper L'Orange and Deutz developed a precisely controlled injection pump with a needle injection nozzle.
• 1909: The prechamber with a hemispherical combustion chamber was developed by Prosper L'Orange with Benz.

1910s

• 1910: The Norwegian research ship Fram was a sailing ship fitted with an auxiliary diesel engine, and was thus the first ocean-going ship with a diesel engine.
•  1912: The Danish built the first ocean-going ship exclusively powered by a diesel engine, MS Selandia. The first locomotive with a diesel engine also appeared.
• 1913: U.S. Navy submarines used NELSECO units. Rudolf Diesel died mysteriously when he crossed the English Channel on the SS Dresden.
• 1914: German U-boats were powered by MAN diesels.
• 1919: Prosper L'Orange obtained a patent on a prechamber insert and made a needle injection nozzle. First diesel engine from Cummins.

1920s

• 1922: The first vehicle with a (pre-chamber) diesel engine was Agricultural Tractor Type 6 of the Benz Söhne agricultural tractor OE Benz Sendling.
• 1923: The first truck with pre-chamber diesel engine made by MAN and Benz. Daimler-Motoren-Gesellschaft testing the first air-injection diesel-engined truck.
• 1924: The introduction on the truck market of the diesel engine by commercial truck manufacturers in the IAA. Fairbanks-Morse starts building diesel engines.
• 1927: First truck injection pump and injection nozzles of Bosch. First passenger car prototype of Stoewer.

1930s

• 1930s: Caterpillar started building diesels for their tractors.
• 1930: First US diesel-power passenger car (Cummins powered Packard) built in Columbus, Indiana (USA)
• 1933: First European passenger cars with diesel engines (Citroën Rosalie); Citroën used an engine of the English diesel pioneer Sir Harry Ricardo. The car did not go into production due to legal restrictions on the use of diesel engines.
• 1936: Mercedes-Benz built the 260D diesel car. AT&SF inaugurated the diesel train Super Chief. The airship Hindenburg was powered by diesel engines. First series of passenger cars manufactured with diesel engine (Mercedes-Benz 260 D, Hanomag and Saurer). Daimler Benz airship diesel engine 602LOF6 for the LZ129 Hindenburg airship

1940s

• 1942: Tatra started production of Tatra 111 with air-cooled V12 diesel engine.
• 1943-'46: The Common-rail (CRD) system was invented (and patented by) Clessie Cummins
• 1944: Development of air cooling for diesel engines by Klöckner Humboldt Deutz AG (KHD) for the production stage, and later also for Magirus Deutz.

1950s

• 1953: Turbo-diesel truck for Mercedes in small series.
• 1954: Turbo-diesel truck in mass production by Volvo. First diesel engine with an overhead cam shaft of Daimler Benz.

1960s

• 1960: The diesel drive displaced steam turbines and coal fired steam engines.
• 1962-'65: A diesel compression braking system, eventually to be manufactured by Jacobs (of drill chuck fame) and nicknamed the "Jake Brake", was invented and patented by Clessie Cummins.
•  1968: Peugeot introduced the first 204 small cars with a transversally mounted diesel engine and front-wheel drive.

1970s

• 1973: DAF produced an air-cooled diesel engine.
• 1976 February: Tested a diesel engine for the Volkswagen Golf passenger car. The Cummins Common Rail injection system was further developed by the ETH Zurich from 1976 to 1992.
• 1978: Mercedes produced the first passenger car turbo-diesels (Mercedes 300 SD).
• 1978: Oldsmobile introduced the first passenger car diesel engine produced by an American car company.

1980s

• 1985: ATI Intercooler diesel engine from DAF. European Truck Common Rail system with the IFA truck type W50 introduced.
• 1986: Electronic Diesel Control (EDC) of Bosch with the BMW 524td.
• 1986: The Fiat Croma was the first passenger car in the world to have a direct injection turbodiesel engine in (1986).

1990s

• 1991: European emission standards Euro 1 met with the truck diesel engine of Scania.
• 1994: Unit injector system by Bosch for diesel engines.
• 1995: First successful use of common rail in a production vehicle, by Denso in Japan, Hino "Rising Ranger" truck.
• 1997: First common rail in passenger car, Alfa Romeo 156.
•  1998: BMW made history by winning the 24 Hour Nürburgring race with the 320d, powered by a two-litre, four-cylinder diesel engine. The combination of high-performance with better fuel efficiency allowed the team to make fewer pit stops during the long endurance race.

2000s

• 2002: A street-driven Dodge Dakota pickup with a 735 horsepower (548 kW) diesel engine built at Gale banks engineering hauls its own service trailer to the Bonneville Salt Flats and set an FIA land speed record as the world's fastest pickup truck with a one-way run of 222 mph (357 km/h) and a two-way average of 217 mph (349 km/h).
• 2004: In Western Europe, the proportion of passenger cars with diesel engine exceeded 50%. Selective catalytic reduction (SCR) system in Mercedes, Euro 4 with EGR system and particle filters of MAN. Piezoelectric injector technology by Bosch.
• 2006: Audi R10 TDI won 12 hours running in Sebring and defeated all other engine concepts. The same car won the 2006 24 Hours of Le Mans.
• 2006: JCB Dieselmax broke the FIA Diesel Land speed record from 1973, eventually setting the new record at over 350 mph (563 km/h).
• 2008: Subaru introduced the first horizontally opposed diesel engine to be fitted to a passenger car. This is a Euro 5 compliant engine with an EGR system.
• 2009: Volkswagen won the 2009 Dakar Rally held in Argentina and Chile. The first diesel to do so. Race Touareg 2 finished 1st and 2nd.

2010s

• 2010: Mitsubishi developed and started mass production of its 4N13 1.8 L DOHC I4, the world's first passenger car diesel engine that features a variable valve timing system.

Next week; How diesel engines work, types of diesel engines and if space permits, advantages and disadvantages of diesel engines.

Some information obtained from Wikipedia.org.

Ask Joe Mechanic - Diesel Engine Vehicles (Part 1)

After covering hybrid and electric powered vehicles for the previous several weeks, I am now going to spend several weeks discussing diesel-powered vehicles. I will demonstrate their history, how they work, types, inherent advantages and disadvantages, why they are so efficient, safety, recent and future innovations.  Also we will discuss the comparisons of diesel use throughout the world as compared to the USA, and why the disparity exists.

A diesel engine (also known as a compression-ignition engine) is an internal combustion engine that uses the heat of compression to initiate ignition and burn the fuel that has been injected into the combustion chamber. This contrasts with spark-ignition engines such as a gasoline engine or gas engine (using a gaseous fuel as opposed to gasoline), which use a spark plug to ignite an air-fuel mixture. The diesel engine has the highest thermal efficiency of any standard internal or external combustion engine due to its very high compression ratio.

Diesel engines are manufactured in two-stroke and four-stroke versions. They were originally used as a more efficient replacement for stationary steam engines. Since the 1910s they have been used in submarines and ships. Use in locomotives, trucks, heavy equipment and electric generating plants followed later. In the 1930s, they slowly began to be used in a few automobiles. 

According to the British Society of Motor Manufacturing and Traders, the EU average for diesel cars account for 50 percent of the total diesel powered vehicles sold, including 70 percent in France and 38 percent in the UK. 

In 1885, the English inventor Herbert Akroyd Stuart began investigating the possibility of using paraffin oil (very similar to modern-day diesel) for an engine, which unlike petrol would be difficult to be vaporized in a carburetor as its volatility is not sufficient to allow this. 

His engines, built from 1891 by Richard Hornsby and Sons, were the first internal combustion engines, to use a pressurized fuel injection system. The Hornsby-Akroyd engine used a comparatively low compression ratio, so that the temperature of the air compressed in the combustion chamber at the end of the compression stroke was not high enough to initiate combustion. Combustion instead took place in a separated combustion chamber, the "vaporizer" (also called the "hot bulb") mounted on the cylinder head, into which fuel was sprayed. Self-ignition occurred from contact between the fuel-air mixture and the hot walls of the vaporizer. As the engine's load increased, so did the temperature of the bulb, causing the ignition period to advance; to counteract pre-ignition, water was dripped into the air intake. 

The modern diesel engine incorporates the features of direct (airless) injection and compression-ignition. Akroyd Stuart and Charles Richard Binney patented both of these ideas in May 1890. Another patent was taken out on 8 October 1890, detailing the working of a complete engine - essentially that of a diesel engine - where air and fuel are introduced separately. The difference between the Akroyd engine and the modern diesel engine was the requirement to supply extra heat to the cylinder to start the engine from cold. By 1892, Akroyd Stuart had produced an updated version of the engine that no longer required the additional heat source, a year before diesel's engine.

            In 1892, Akroyd Stuart patented a water-jacketed vaporizer to allow compression ratios to be increased. In the same year, Thomas Henry Barton at Hornsbys built a working high-compression version for experimental purposes, whereby the vaporizer was replaced with a cylinder head, therefore not relying on air being preheated, but by combustion through higher compression ratios. It ran for six hours - the first time automatic ignition was produced by compression alone. This was five years before Rudolf Diesel built his well-known high-compression prototype engine in 1897.

Rudolf Diesel was, however, subsequently credited with the innovation, and he was able to improve the engine further, whereas Akroyd Stuart stopped development on his engine in 1893.

In 1892, he received patents in Germany, Switzerland, the United Kingdom and the United States for "Method of and Apparatus for Converting Heat into Work". In 1893, he described a "slow-combustion engine" that first compressed air thereby raising its temperature above the igniting-point of the fuel, then gradually introducing fuel while letting the mixture expand "against resistance sufficiently to prevent an essential increase of temperature and pressure", then cutting off fuel and "expanding without transfer of heat”. In 1894 and 1895 he filed patents and addenda in various countries for his Diesel engine; the first patents were issued in Spain (No. 16,654), France (No. 243,531) and Belgium (No. 113,139) in December 1894, and in Germany (No. 86,633) in 1895 and the United States (No. 608,845) in 1898. He operated his first successful engine in 1897.

At Augsburg, on August 10, 1893, Rudolf Diesel's prime model, a single 10-foot (3.0 m) iron cylinder with a flywheel at its base, ran on its own power for the first time. Diesel spent two more years making improvements and in 1896 demonstrated another model with a theoretical efficiency of 75 percent, in contrast to the 10 percent efficiency of the steam engine. By 1898, Diesel had become a millionaire. His engines were used to power pipelines, electric and water plants, automobiles and trucks, and marine craft. They were soon to be used in mines, oil fields, factories, and transoceanic shipping.

Ask Joe Mechanic - Electric Vehicles (Part 2)

In the United States, General Motors (GM) ran in several cities a training program for firefighters and first responders to demonstrate the sequence of tasks required to safely disable the Chevrolet Volt’s powertrain and its 12 volt electrical system, which controls its high-voltage components, and then proceed to extricate injured occupants. The Volt's high-voltage system is designed to shut down automatically in the event of an airbag deployment, and to detect a loss of communication from an airbag control module. GM also made available an Emergency Response Guide for the 2011 Volt for use by emergency responders. The guide also describes methods of disabling the high voltage system and identifies cut zone information. Nissan also published a guide for first responders that details procedures for handling a damaged 2011 Leaf at the scene of an accident, including a manual high-voltage system shutdown, rather than the automatic process built-in the car's safety systems.

 Great effort is taken to keep the mass of an electric vehicle as low as possible to improve its range and endurance. However, the weight and bulk of the batteries themselves usually makes an EV heavier than a comparable gasoline vehicle, reducing range and leading to longer braking distances; it also has less interior space. However, in a collision, the occupants of a heavy vehicle will, on average, suffer fewer and less serious injuries than the occupants of a lighter vehicle; therefore, the additional weight brings safety benefits despite having a negative effect on the car's performance. An accident in a 2,000 lb (900 kg) vehicle will on average cause about 50% more injuries to its occupants than a 3,000 lb (1,400 kg) vehicle. In a single car accident and for the other car in a two-car accident, the increased mass causes an increase in accelerations and hence an increase in the severity of the accident. Some electric cars use low rolling resistance tires, which typically offer less grip than normal tires. Many electric cars have a small, light and fragile body, though, and therefore offer inadequate safety protection. The Insurance Institute for Highway Safety in America had condemned the use of low speed vehicles and "mini trucks," referred to as neighborhood electric vehicles (NEVs) when powered by electric motors, on public roads.

At low speeds, electric cars produced less roadway noise as compared to vehicles propelled by internal combustion engines. Blind people or the visually impaired consider the noise of combustion engines a helpful aid while crossing streets, hence electric cars and hybrids could pose an unexpected hazard. Tests have shown that this is a valid concern, as vehicles operating in electric mode can be particularly hard to hear below 20 mph (30 km/h) for all types of road users and not only the visually impaired. At higher speeds, the sound created by tire friction and the air displaced by the vehicle start to make sufficient audible noise.

The Government of Japan, the U.S. Congress, and the European Parliament passed legislation to regulate the minimum level of sound for hybrids and plug-in electric vehicles when operating in electric mode, so that blind people and other pedestrians and cyclists can hear them coming and detect from which direction they are approaching. The Nissan Leaf was the first electric car to use Nissan's Vehicle Sound for Pedestrians system, which includes one sound for forward motion and another for reverse. As of March 2013, most of the hybrids and plug-in electric cars available in the United States make warning noises using a speaker system. The Tesla Model S is one of the few electric-drive cars without warning sounds, because Tesla Motors is awaiting the National Highway Traffic Safety Administration final rule.

Far and away, the largest concern for electric vehicles is their batteries. The limitations of range, availability of charging, safety, lifespan, cost of replacement are just some of the things considered regarding batteries.  Finding the economic balance of range against performance, energy density, and accumulator type versus cost challenges every EV manufacturer. While most current highway-speed electric vehicle designs focus on lithium-ion and other lithium-based variants a variety of alternative batteries can also be used. Lithium-based batteries are often chosen for their high power and energy density but have a limited shelf-life and cycle lifetime which can significantly increase the running costs of the vehicle. Variants such as Lithium iron phosphate and Lithium-titanate attempt to solve the durability issues with traditional lithium-ion batteries.

Other battery technologies include:

• Lead acid batteries are still the most used form of power for most of the electric vehicles used today. The initial construction costs are significantly lower than for other battery types, and while power output to weight is poorer than other designs, range and power can be easily added by increasing the number of batteries. NiCd - Largely superseded by NiMH
• Nickel metal hydride (NiMH)
• Nickel iron battery - Known for its comparatively long lifetime and low power density

Several battery technologies are also in development such as:

• Zinc-air battery
• Molten salt battery
• Zinc-bromine flow batteries or Vanadium redox batteries can be refilled, instead of recharged, saving time. The depleted electrolyte can be recharged at the point of exchange, or taken away to a remote station.

Unlike vehicles powered by fossil fuels, BEVs are most commonly and conveniently charged from the power grid overnight at home, without the inconvenience of having to go to a filling station. Charging can also be done using a street or shop charging station.  The electricity on the grid is in turn generated from a variety of sources; such as coal, hydroelectricity, nuclear and others. Power sources such as roof top photovoltaic solar cell panels, micro hydro or wind may also be used and are promoted because of concerns regarding global warming.

                  
 Most electric cars have used conductive coupling to supply electricity for recharging after the California Air Resources Board settled on the SAE J1772-2001 standard as the charging interface for electric vehicles in California in June 2001. In Europe the ACEA has decided to use the Type 2 connector from the range of IEC_62196 plug types for conductive charging of electric vehicles in the European Union as the Type 1 connector (SAE J1772-2009) does not provide for three-phase charging.  Another approach is inductive charging using a non-conducting "paddle" inserted into a slot in the car. Delco Electronics developed the Magne Charge inductive charging system around 1998 for the General Motors EV1 and it was also used for the Chevrolet S-10 EV and Toyota RAV4 EV vehicles.

Reports emerged in late July 2013 of a significant conflict between the companies responsible for the two types of charging machines. The Japanese-developed CHAdeMO standard is favored by Nissan, Mitsubishi, and Toyota, while the Society of Automotive Engineers’ (SAE) International J1772 Combo standard is backed by GM, Ford, Volkswagen, and BMW. Both are direct-current quick-charging systems designed to charge the battery of an electric vehicle to 80 percent in approximately 20 minutes, but the two systems are completely incompatible. In light of an ongoing feud between the two companies, experts in the field warned that the momentum of the electric vehicle market would be severely affected. Richard Martin, editorial director for clean technology marketing and consultant firm Navigant Research, stated:

“Fast charging, however and whenever it gets built out, is going to be key for the development of a mainstream market for plug-in electric vehicles. The broader conflict between the CHAdeMO and SAE Combo connectors, we see that as a hindrance to the market over the next several years that needs to be worked out. Newer cars and prototypes are looking at ways of dramatically reducing the charging times for electric cars. The BMW i3 for example, can charge 0-80% of the battery in under 30 minutes in rapid charging mode.”

                  
 More electrical power to the car reduces charging time. Power is limited by the capacity of the grid connection, and, for level 1 and 2 charging, by the power rating of the car's on-board charger. A normal household outlet is between 1.5 kW (in the US, Canada, Japan, and other countries with 110 volt supply) to 3 kW (in countries with 230V supply). The main connection to a house may sustain 10, 15 or even 20 kW in addition to "normal" domestic loads—although, it would be unwise to use all the apparent capability—and special wiring can be installed to use this.  As examples of on-board chargers, the Nissan Leaf at launch has a 3.3 kW charger and the Tesla Roadster can accept up to 16.8 kW (240V at 70A) from the High Power Wall Connector. These power numbers are small compared to the effective power delivery rate of an average petrol pump, about 5,000 kW.

Even if the electrical supply power can be increased, most batteries do not accept charge at greater than their charge rate ("1C"), because high charge rates have an adverse effect on the discharge capacities of batteries. Despite these power limitations, plugging in to even the least-powerful conventional home outlet provides more than 15 kilowatt-hours of energy overnight, sufficient to propel most electric cars more than 70 kilometres (43 mi).  Using regenerative braking, a feature, which is present on many hybrid electric vehicles, approximately 20 percent of the energy usually lost in the brakes, is recovered to recharge the batteries.

An alternative to quick recharging is to exchange a discharged battery or battery pack for a fully charged one, saving the delay of waiting for the vehicle's battery to charge. Battery swapping is common in warehouses using electric forklift trucks.  The concept of exchangeable battery service was first proposed as early as 1896 in order to overcome the limited operating range of electric cars and trucks. The concept was first put into practice by Hartford Electric Light Company through the GeVeCo battery service and was initially available for electric trucks. Both vehicles and batteries were modified to facilitate a fast battery exchange. The service was provided between 1910 and 1924 and during that period covered more than 6 million miles. A rapid battery replacement system was implemented to keep running 50 electric buses at the 2008 Summer Olympics.

Tesla Motors designed its Model S to allow fast battery swapping. In June 2013, Tesla announced their goal to deploy a battery swapping station in each of its supercharging stations.  At a demonstration event, Tesla showed that a battery swap operation with the Model S takes just over 90-seconds, about half the time it takes to refill a gasoline-powered car.  The first stations will be deployed along Interstate 5 in California where, according to Tesla, a large number of Model S sedans make the San Francisco-Los Angeles trip regularly.  The Washington, DC to Boston corridor, will follow these stations. Each swapping station will cost $500,000 USD and will have about 50 batteries available without requiring reservations. The service would be offered for the price of about 15 US gallons (57 l; 12 imp gal) of gasoline at the current local rate, around $60 to $80 USD at June 2013 prices.

 Battery life should be considered when calculating the extended cost of ownership, as all batteries eventually wear out and must be replaced. The rate at which they expire depends on the type of battery technology and how they are used — many types of batteries are damaged by depleting them beyond a certain, optimal level.  Lithium-ion batteries degrade faster when stored at higher temperatures.

The future of battery electric vehicles depends primarily upon the cost and availability of batteries with high specific energy, power density, and long life, as all other aspects such as motors, motor controllers, and chargers are fairly mature and cost-competitive with internal combustion engine components. Diarmuid O'Connell, VP of Business Development at Tesla Motors, estimates that by the year 2020 30 percent of the cars driving on the road will be battery electric or plug-in hybrid.

Nissan CEO Carlos Ghosn has predicted that one in 10 cars globally will run on battery power alone by 2020. Additionally, a recent report claims that by 2020 electric cars and other green cars will take a third of the total of global car sales. It is estimated that there are sufficient lithium reserves to power four billion electric cars.

As of November 2013, the number of mass production highway-capable all-electric passenger cars and utility vans available in the market is limited to about 25 models. Most electric vehicles in the world roads are low-speed, low-range neighborhood electric vehicles (NEVs) or electric quadricycles. Pike Research estimated there were almost 479,000 NEVs on the world roads in 2011. The two largest NEV markets in 2011 were the United States, with 14,737 units sold, and France, with 2,231 units. The Renault Twizy all-electric heavy quadricycle, launched in Europe in March 2012 and with global sales of 9,020 units through December 2012, became the best selling plug-in electric vehicle in Europe for 2012. The top selling markets were Germany with 2,413 units, France with 2,232 units, and Italy with 1,545 units sold in 2012. As of November 2013, global Twizy sales totaled 11,879 units.

The world's top selling highway-capable electric car ever is the Nissan Leaf, released in December 2010, with global sales of over 92,000 units delivered by early December 2013. All-electric models scheduled for market launch in 2014 include the Volkswagen e-Golf, Mercedes-Benz B-Class Electric Drive, Mercedes-Benz SLS AMG Electric Drive, Tesla Model X, and the limited production Detroit Electric SP.01.

As of September 2013, over 60,000 all-electric cars have been sold in the U.S. since 2008, led by the Nissan Leaf, with 35,588 units, followed by the Tesla Model S with 16,251 units, and the Ford Focus Electric with 2,028 units sold through September 2013. Accounting for plug-in hybrid electric cars sold since 2010 (about 80,000), the United States has the largest fleet of plug-in electric vehicles (PEVs) in the world, with over 140,000 highway-capable plug-in electric cars sold through September 2013. A total of 17,800 plug-in electric cars were delivered during 2011, more than 53,000 during 2012, and over 67,700 units during the first nine months of 2013. PEV sales during the first nine months of 2013 represented a 0.58 percent market share of total new car sales, up from of 0.37 percent in 2012, and 0.14 percent in 2011.

                  
 The Chevrolet Volt is the top selling plug-in hybrid, with 48,218 units, followed by the Toyota Prius Plug-in Hybrid with 20,724 units, and the Ford C-Max Energi with 6,668 units sold through September 2013. During the first nine months of 2013 sales were led by the Chevrolet Volt with 16,760 units, followed by the Nissan Leaf with 16,076 cars, and the Tesla Model S with about 13,500 units. August 2013 is the best month on record for U.S. plug-in vehicle sales, with more than 11,000 units delivered, representing a market share of 0.76 percent of new car sales.

California, the largest United States car market, is also the leading plug-in electric-drive market in the country. About 40 percent of the segment's nationwide sales during 2011 and 2012 were made in California, while the state represents about 10 percent of all new car sales in the country.  From January to May 2013, 52 percent of American plug-in electric car registrations were concentrated in five metropolitan areas: San Francisco, Los Angeles, Seattle, New York and Atlanta.

 During 2011, all-electric cars (10,064 sold) oversold plug-in hybrids (7,671 sold), but increased Volt sales, together with the introduction of the Prius PHV and the Ford C-Max Energi, allowed plug-in hybrids to take the lead over pure electric cars during 2012, with 38,584 PHEVs sold versus 14,251 BEVs. During the first nine monts of 2013, sales of pure electric cars (35,261) outsold plug-in hybrids (32,718), due to large sales of the Tesla Model S and Nissan Leaf during 2013. During the first half of 2013, all-electric vehicle sales also outsold plug-in hybrids in California. During this period a total of 15,444 new plug-in electric vehicles were sold in the state, with plug-in hybrids representing a market share of 0.7 percent of new vehicle sales, while battery electric vehicle market share was 1.1 percent.

Hopefully, this wealth of information on hybrid and full electric vehicles will help you make your decision if one of these vehicles is in your future. We will also look at diesel engine vehicles, as there have been a lot of advancements in diesel technology and new model introductions in recent years.