Sandquist believes that engine capacities will stabilize at today’s level, and might even see a
the tax on combustion engine vehicles.
The price for the Volkswagen Passat R-Line in Malaysia has been announced. It starts at RM203k.
introduction of plug-in hybrid engine are not new.
Volkswagen CEO Ralf Brandstaetter has said that the Volkswagen brand has no plans to develop a new Internal Combustion
Toyota will be entering a Corolla Sport (Corolla hatchback) race car powered by a hydrogen-burning combustion
Cycle & Carriage Bintang Berhad (C&C) and Mercedes-Benz Malaysia’s (MBM) has opened its
we go on, it is important that you know the following engine cycles: Otto Cycle Atkinson Cycle Miller
First launched in Malaysia in March 2014, the current generation Honda City is nearing the final legs
as seen in the Jazz e:HEV.Power output is rated at 109 PS/253 Nm from the motor and 98 PS/127 Nm from
The plan will phase out both internal combustion engine (ICE) cars and hybrid cars.Announced together
The average person who is used to combustion engine cars might find this hard to believe, but the first
engine-powered models by half, reports Reuters.In a Reuters exclusive, the news agency says the decision
applied throughout the cars lifespan) at neutral levels.However, the limited driving range could deter
Håkan Sandquist holds a Ph.D. in internal combustion engines from Sweden’s Chalmers University
Headlining the all-new City are features such as the new 1.5-litre i-MMD engine (new 1.5-litre DOHC engine
Hyundai Motor Co. has started construction works on their new electric vehicle (EV) hub in Singapore
Malaysian driving conditions yet but actually the Honda City engine itself is not new to us.Back in
undergo regular up- skilling training at the Mercedes-Benz Malaysia Training Academy.
In these countries and regions, electric vehicles cannot always reduce CO2 over the life cycle of vehicles.However
Cycle & Carriage, together with Mercedes-Benz Malaysia, officially unveiled the newly upgraded Johor
makes one of the most focused driver’s cars—says that they will be moving on from internal combustion
When Cycle & Carriage opened its Mercedes-Benz Autohaus facility in Mutiara Damansara back in 2006
In what can only be called an ambitious move, Thailand has set out to phase out the internal combustion
the internal combustion engine.
Cycle & Carriage Bintang, one of the authorized Mercedes-Benz dealers in Malaysia, has announced
MINI is intensifying its efforts to phase out internal combustion engines and focusing on electric mobility
the Covid-19 situation, it may arrive later than initially anticipated.In the facelift, a new plug-in
litre turbocharged 3-cylinder engine.The 1.5-litre turbocharged 3-cylinder engine is the smallest in
What you see here, is a photo of Mazda’s upcoming rotary engine, mentioned alongside Mazda&rsquo
The Otto Cycle is the basis for all spark ignition internal combustion engines and engines which use spark ignition are called Otto engines, in honor of German engineer Nikolaus Otto. It represents an idealized thermodynamic cycle whereby we neglect all the losses due to friction, viscous effects etc. [CC Image courtesy of UtzOnBike on Wikimedia] The Otto cycle is called constant volume cycle because the combustion occurs at constant volume. We may call it isochoric combustion. This is in contrast to the ideal Diesel cycle in which the combustion occurs at constant pressure. We may call that as isobaric combustion. The cycle consists of the following processes which correspond to the 4 strokes of an IC engine. [CC Image courtesy of Luc1992 on Wikimedia] Process 0-1 - Intake Stroke Air is sucked in at constant pressure through the open intake valve as the piston moves from TDC to BDC. Process 1-2 - Isentropic Compression The air is compressed by the piston while moving from the BDC to TDC under reversible adiabatic conditions. In this both intake and exhaust valves are closed. Process 2-3 – Constant Volume Heat Addition (Isochoric Combustion) The actual combustion occurs in this process. A spark ignition causes the system (fuel-air mixture) to undergo combustion thereby adding heat to the fuel-air mixture under a constant volume condition. Constant volume because 2-3 occurs when the piston is at TDC and volume change is negligible as combustion occurs very rapidly. Process 3-4 – Isentropic Expansion Now that the system (fuel-air mixture) is fully energized, it’s time to use that energy to do some useful work. That’s exactly what happens in this step. The hot fuel-air mixture does work on the piston by pushing it from TDC to BDC. Process 4-1 – Constant Volume Heat Rejection In this process, the residual energy of the system is released at a constant volume. Constant volume because 4-1 occurs when the piston is at the BDC. Process 1-0 – Exhaust Air is finally released into the environment at constant pressure. Looking at the diesel cycle below, the difference is clearly seen in the process 2–3 (marked in red) in which heat is added under a constant pressure condition. [CC Image courtesy of Tokino MaxDZ8 on Wikimedia] TDC = Top Dead Center - the position that the piston can travel farthest from the crankshaft. BDC = Bottom Dead Center - the position that the piston can travel nearest to the crankshaft.
In the ideal Otto cycle (spark ignition) combustion occurs at constant volume, thus represented by a vertical line at the pV diagram. In ideal Diesel cycle (compression ignition) combustion occurs at constant pressure, represented by a flat line on the pV diagram. Picture: Qin, is heat addition to the system (combustion)
There is only one major difference. The p-V (pressure vs. volume) diagram. Posted below are both p-V and T-s (temperature vs. entropy) diagrams I managed to find with illustrations of piston positions for the stages of the cycle for both types of engines. Otto (“petrol”): The Otto cycle engines has two isochoric (constant volume) events where heat is brought into the system (spark ignition) and taken out of the system (exhaust valve opening). It also has two isentropic (constant entropy) events where work is put into the system (compression cycle) and work is received from the system. Diesel: The Diesel cycle has an isobaric (constant pressure) event where heat is brought into the system (injection of fuel, burning process, the beginning of the cylinder moving down) and an isochoric (constant volume) event, where heat is taken out of the system (exhaust valve opening). There are, just like with the Otto cycle, two isentropic (constant entropy) events where work is put into the system (compression cycle) and work is received from the system. As you can see, going from point 3 to point 2 around the diagram is largely the same as far as constant entropy and volume are concerned. ,The main difference, is in the process going from point 2 to point 3 in the pressure-volume diagram, so in the process of ,energy being brought into the system,. Otto cycle:, Energy is brought into the system at a ,constant volume,. The spark ignites the mixture, which explodes, the volume doesn’t change, while the temperature and pressure rise dramatically. After the process is concluded, the piston starts moving down in stage 3–4. Diesel engine:, Energy is brought into the system at a ,constant pressure,. Fuel in an Otto cycle engine explodes, while fuel in a diesel cycle engine burns (combusts). This is a slower process. This explains why the energy is brought into the system at a constant pressure with changing volume. The piston starts moving down with the mixture still burning, this causes the temperature to be rising, but the volume is increasing quickly enough to keep pressure constant. This is true for the first part of the piston travel. When the burning process is completed the pressure and temperature start falling with volume increasing. This is where the burnt mixture of hot gasses is expanding and producing work through expansion. This part of the process is similar to the Otto cycle, as shown by the diagrams. Both types of engines throw excess heat away in the exhaust cycle (stage 4–1) by opening the exhaust valve, which causes an almost instantaneous lowering of the pressure and temperature. Due to the speed of the process this occurs at a constant volume. Comments on other answers: Spark plugs:, currently Otto cycle engines do indeed have spark plugs, but these are not required in theory. You could just as easily ignite the mixture by injecting the fuel at a similar point in the cycle as with the Diesel cycle engine, which would ignite given a high enough temperature. There is also a lot of work being done on HCCI engines, which ignite the pre-made mixture just by heating it up with compression. There are also some other technologies being developed that use the spark plugs ‘passively’ - search for Turbulent Jet Ignition (used to ignite mixtures that are to lean to be ignited by spark plugs). Compression ratio:, the compression ratio is again something that doesn’t need to be higher for diesel engines. A higher compression ratio increases efficiency by increasing the temperature of the high-temperature part of the cycle. It also makes the emissions worse, an Otto cycle engine with a compression ratio of ~16:1 or more would have NOx and particle emission just like diesels have (high temperatures cause the nitrogen to disintegrate, oxygen bonds with it instead of carbon, which then produces soot). Mazda for example is using 14:1 compression ratio engine designs for both Diesel and Otto cycle - for efficiency reasons in the case of Otto cycle engines (high compression in regards to competition) and for emissions reasons in the case of Diesel cycle engines (low compression in regards to competition). Fuel injection pressure:, This is connected to the compression ratio and the pressures inside the cylinder at TDC. A higher air pressure here will require a higher fuel rail pressure to squeeze the fuel into the cylinder. Higher pressures also tend to help with the atomization of the fuel, where it forms a mist instead of bigger droplets (this of course helps the homogeneity of the mixture, increasing the efficiency and improving emissions). Audi has conducted research on efficiency in regards to injection pressures when developing the Le Mans diesel engines and has seen an increase in efficiency with higher pressures. But this is harder on the equipment and can cause issues with reliability (we are talking about ~2500 bar, which is huge!) As Arnis Tarassu mentions, many parts can be common between both types of engines and this is exactly what BMW and Jaguar are very actively trying to do with common cylinder sizes (same bore and stroke) with the intention of using the same block, same crankshaft and maybe even pistons for both types of engines at equal capacity points.
That's the difference between the diesel cycle and the otto cycle. For otto cycle engines (which all spark ignition engines are), the combustible mixture is compressed, then ignited when the piston is close to top dead centre. The entire combustion process takes place while the volume of the combustion chamber is fairly constant (within a few degrees of TDC). The pressure rapidly increases due to the increase in temperature, and as the crank moves away from TDC, the pressure drives the piston down as the pressure falls due to expansion. For diesel cycle engines, only air is compressed. At some point close to TDC, fuel is injected and spontaneously starts to burn due to the heat of compression. This raises the temperature and hence the pressure - as for the otto cycle. At this point, the 2 cycles differ. In otto cycle, the entire fuel charge is present when ignition occurs. In the diesel, fuel continues to be injected as the piston moves down, keeping the temperature and pressure fairly constant, until enough fuel has been injected to use up all the oxygen (this is a known quantity as it's measured going in). This is why diesels have so much more torque - the ‘push’ on the piston is sustained for much longer during each power stroke. The combustion chamber pressure is constant for most of the power stroke.
Well this is a nice question, let us first of all take a look at what otto and diesel cycle actually are. Otto Cycle It is the ideal cycle for ,spark ignition, engines which has following processes considering air standard assumptions. The ,air standard assumption, allow us to treat air as working fluid, and the combustion of fuel is replaced by constant volume heat addition process, exhaust is replaced by constant volume heat rejection. 1–2 : ,isentropic compression, of air in cylinder. 2–3 : ,constant volume heat addition,. 3–4 : ,isentropic expansion ,of air. 4–1 : ,constant volume heat rejection,. Now let us take a look at diesel cycle. Diesel cycle It is the ideal cycle for ,compression ignition, engines and the process in accordance with air standard assumptions are. 1–2 : ,isentropic compression, of air in cylinder. 2–3 : ,constant pressure heat addition, to air. 3–4 : ,isentropic expansion, of air. 4–1 : ,constant volume heat rejection,. Here also we have replaced combustion process with constant pressure heat addition and exhaust with constant volume heat rejection in accordance with air standard assumptions. Now we can discuss differences between them. Differences between otto and diesel cycle: 1,: For a ,given compression ratio,, i.e V1 / V2 , the ,efficiency of otto cycle is higher ,than diesel cycle. 2,: The ,combustion, process occurs at ,constant volume in case of otto cycle ,and occurs at ,constant pressure in diesel cycle. 3,: ,Combustion in otto cycle, occurs due to ,generation of spark in the cylinder, when the piston reaches tdc and is ,instantaneous,. Whereas in case of ,diesel cycle, combustion is ,time consuming, and occurs due to ,injection of fuel in cylinder ,which is filled with ,hot compressed air, (at point 2 in figure) due to which ,auto ignition, of fuel takes place. 4:, Due to the fact that ,we compress air in diesel cycle ,rather than fuel(in otto cycle) , the ,air can be compressed to very high pressures, and then the fuel can be injected accordingly , thus ,incresing compression ratio and higher efficiency of diesel cycle. 5,: So ,for same max pressure of cycle, diesel cycle is more efficient ,that otto cycle. 6,: The ,compression ratio, in case of ,otto cycle ,is however ,limited, because in otto cycle , ,air fuel mixture is being compressed which can lead to very high temperature of air fuel mixture and can cause auto ignition, of fuel before the power stroke. 7: The ,compression ratio in diesel cycle, is also ,limited, due to the ,metallurgical reasons, , air is compressed to such temperatures which will ,not harm the engine parts,.
The Otto Cycle and Diesel cycle are power cycles. The processes involved in these cycles cause for the motion of the crankshaft. The crankshaft transfers the motion to the gear drive. The Otto and Diesel cycle have mainly four process : Compression, Combustion, Expansion, Exhaustion. When the combustion occurs inside the cylinder the pressure causes the moment of the piston, the piston transfers it to the crankshaft (linear motion is converted to rotatory motion). The excess energy produced during combustion is tapped by the flywheel which is connected to crankshaft. This energy causes the moment of the piston during the remaining cycle (Expansion, Exhaustion, Combustion). Thus the mechanical cycle is correlated to power cycles(Otto cycle and Diesel) to produce motion.
Essentially all are same in terms of cycle compression ignition expansion exhaust intake The difference is at the combustion part and mechanism which occurs in split second. OTTO CYCLE: Ignition is done by a spark plug. A spark ignites the rich mixture, and combustion occurs during the -almost- entire expansion stroke. Thus it is treated “constant pressure heat addition” proccess. Stroke of the piston (compression ratio) is low. DIESEL CYCLE: Ignition is done by only the compressing air fuel mixture -which is preheated- to a very high pressure that ignites itsef. Combustion procces occurs more like an “explosion” manner. Much faster than Otto Cycle. Thus, it is treated as “constat volume heat addition” proccess. Stroke (compression ratio) is high. DUAL CYCLE: This cycle is just in between Otto and Diesel cycle. Some part of the combustion occurs at constant volume, and the rest of it at constant pressure. Efficiency Aspect: Otto cycle is the most efficinet cycle ,IF THE COMPRESSION RATIOS ARE THE SAME,. But due to chemical behavior of benzin, it is not possible to go up to high compression ratios. This yields Diesel Engine is more efficient currently.
In a single sentence, in constant pressure cycle, heat is added in a constant pressure process, and that is at const volume in a constant volume process. The otto cycle (or gasoline cycle) is a constant volume process (combustion occurs when the volume remains constant ideally). You have to provide a spark to initiate the combustion. This is called Spark Ignition engine. The diesel cycle is a constant pressure cycle where combustion occurs at constant pressure. You compress and compress the gas until it reaches it self ignition point and ignites. This is is called Self ignition engine. However, in real life it is possible to control the combustion in both constant volume and constant pressure rigidly. So definitely there is a deviation, just give a google search on ideal vs real otto and diesel cycle. Anyway, there is also a blend of these two cycles, where heat addition (combustion) process takes place in a partial constant volume and partial constant pressure process!
The fastest speed will be after 90°ATDC on the power stroke of a single cylinder 4 stroke engine. 90°ATDC is where the combustion gas has the most leverage, but not the most instantaneous angular velocity. An engine will always have a deceleration rate when there is no fuel. That deceleration rate is still present for the 3 phases of a full combustion cycle which are not adding power. The combustion phase has to accelerate the engine during that 1/4 of the cycle at least as much as the deceleration rate of the rest of the cycle to maintain constant speed. Since the deceleration rate is always dependent on load, the acceleration rate of the cylinder during the combustion phase will vary based on that load. I'll put this thought in a formula: ΔS(rpm) = A_combustion(rpm/s) - D_friction(rpm/s) - D_pumping(rpm/s) - D_load(rpm/s) Where ΔS is the change in engine speed over one OTTO cycle, A_combustion is the acceleration which occurs during the power stroke, D_friction is the deceleration due to friction, D_pumping is the deceleration due to pumping work which is needed to evacuate and recharge the cylinder (this is semi variable with load), and D_load is the deceleration due to load on the engine. In order to leave out inertia we must assume that ΔS is zero, but this still works for our purposes today. Now, lets look at two cases to see what happens with changes in D_load. One is a full load situation. In order for the piston to accelerate during the combustion phase, the cylinder pressure in the chamber must be higher than the pressure in the crank case. During high loads there pressure in the combustion chamber at 90°ATDC will be much higher than the pressure in the crankcase which means that the crankshaft will still be accelerating past 90°ATDC until 180°ATDC. The rate of acceleration will be slower as the pressure lowers with expansion and heat loss, but the crankshaft will still be accelerating. During low loads the fastest point of the crankshaft may be a bit before 180°ATDC because the rate of acceleration during the first portion of the combustion phase may be high enough to overcome the deceleration forces against the engine, which means that the deceleration forces of load and friction overcome the acceleration forces towards the bottom of the combustion stroke. In summary, the crankshaft angle with the highest angular velocity is dependent on engine load. Under lower loads the highest angular velocity will be earlier due to lower acceleration needs while under high loads the highest angular velocity will approach 180°ATDC.
The fuel air mixture will swirl around the combustion chamber as the piston rises to compress it. Just before the piston is at the top of the cylinder the spark plug will ignite the mixture and a very fast burn and expansion of the mixtures occurs. This expansion pushes the piston down on the power stroke. How cleanly and completely the fuel burns is a function of the combustion chamber and inlet manifold design. Please note there is no explosion just an extremely fast controlled expansion.