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smart fortwo to go electric?
"In the new generation we will install lithium ion batteries already next year, and if testing is successful, we could quickly offer it in series production." -- smart brand chief Anders Jensen. Testing may take place in LA, the city where the smart sells best.
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Daimler delivers smart fortwo electric drive to RWE
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smart tour at Computer History Museum
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smart fortwo mhd (micro hybrid drive)
With the backdrop of the Live Earth concerts a particularly economical
52 kW/71 hp variant of the smart fortwo with a stop-start function is
announced which will roll off the production line in Hambach:
the smart fortwo micro hybrid drive. From the end of the year it will be
available as a coupé and a cabrio in all three lines – pure, pulse and
passion. The smart fortwo micro hybrid drive uses the idle phases to
switch off the engine and thus avoids fuel consumption, exhaust gas
and noise emissions when stopped. The system works in combination with
the automated manual transmission already fitted in the production vehicle.
Powerful belt-driven starter generator
At the heart of the system is a special belt-driven starter generator that supplies the vehicle's electrical system and has a secondary function as a starter. It is able to smoothly start up the combustion engine in a fraction of a second as soon as the driver releases the brake pedal. This dispenses with the need for a conventional starter motor that works on the flywheel of the crank assembly. In conjunction with slightly modified gear ratios, this strategy leads to a fuel saving of approximately 8 percent in the New European Driving Cycle (NEDC). The standard consumption is reduced by approximately 0.4 litres per 100 kilometres – from 4.7 litres to around 4.3 litres. Depending on the traffic situation (heavy slow traffic), this can lead to a fuel saving of approximately 13 percent. There is also a corresponding reduction in CO2 emissions from 112 grams to approximately 103 g/km.
The system was developed by smart in cooperation with Valeo GmbH and the Gates Corporation. The mechanical assembly comprises the starter generator StARS 137 from Valeo. This generator delivers torque of 42 Newton metres or current of maximum 120 Ampere at 14 Volts - enough to guarantee a reliable engine start, even at a temperature of minus 25 degrees Celsius. To ensure a low-slip and durable connection of the crank assembly and the starter generator, both components were given wider belt pulleys, as was the water pump that is also driven. A six-rib poly-V-belt from Gates transmits the power.
Belt tension is particularly important because of the changing loads in start/stop operation. A coaxial spring-and-shock absorber unit that is hinged to the starter generator is supported by the engine block. The starter generator is pivoted so that it can apply the tension force to the belt drive. This ensures that both the belt section pulled by the combustion engine when it is running and the complementary belt section pulled by the starter during the start are able to reliably transmit the torque needed.
Control unit with integrated power electronics
The operation of the system is controlled by a separate control unit with integrated power electronics that is installed behind the battery recess. It communicates with the vehicle's other control units via CAN bus. An AGM battery stores the energy for the on-board electrics. Its physical properties make it more resistant to varying loaded and unloaded conditions, more cycle resistant, than conventional flooded lead-acid batteries. In the next generation 14+X StARS Valeo plans Maxwell Technologies' ultracaps which will enable brake energy regeneration and probably can also provide enough zap to extend automatic stop-start to the smart fortwo cdi turbodiesel, as diesels are usually a bit harder to start than gasoline engines.
The power electronics of the belt-driven starter generator switch off the combustion engine in idling phases, for example at traffic lights, level crossings or in stop-and-go traffic. In view of fuel economy and comfort, the electronics switch off the engine at a speed of below 8 km/h when the driver presses the brake pedal, signalising that he or she wants to stop. The engine starts as soon as the driver releases the brake pedal again. This guarantees an immediate response. The start/stop function can be deactivated if required with a switch on the centre console - until the next starting procedure (ignition off/ignition on).
The most important technical data on the new smart fortwo micro hybrid drive at a glance:
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Cylinders/valves |
R3, 4 valves per cylinder |
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Engine capacity |
999 cc |
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Bore/stroke |
72 x 81.8 mm |
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Rated output |
52 kW/71 hp at 5,800 rpm |
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Max. torque |
92 Nm/68 lb-ft at 4,500 rpm |
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0-100 km/h |
13.3 s |
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Maximum speed |
145 km/h |
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Combined fuel consumption, NEDC* |
4.3 l/100 km - 55 MPG US (preliminary figure) |
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Fuel saving |
On average approx. 8 %, |
CO2 emissions |
103 g/km |
July 11, 2007
DaimlerChrysler releases new smart fortwo cdi with 71.3 MPG
From the press release: "with fuel consumption of just 3.3 litres
per 100 kilometres, (NEDC, combined) and emissions of 88 grams of carbon
dioxide per kilometre
the new smart fortwo cdi is the most economical production car
worldwide. A full tank of fuel costs around EU38.00 and 33 litres
of fuel will take the 33 kW/45 bhp two-door car approximately
1,000 kilometres - for example theoretically from central Berlin
to the outskirts of Paris without refuelling. With an annual mileage
of 15,000 kilometres drivers of a new smart fortwo cdi would only
have to refuel 15 times a year. In other words: the smart fortwo cdi
is the right small car at the right time.- The world's most economical
production car with the lowest CO2 emissions."
The smart engineers have improved the successful cdi engine from the predecessor model and equipped it for the future. The power and torque have each increased by ten percent, whilst the fuel consumption has decreased by around 13 percent. In figures this means power of 33 kW/45 bhp and maximum torque of 110 Newton metres that is delivered between 2,000 and 2,500 rpm. The new smart fortwo cdi thus offers a combination of agility, economy and environmental compatibility that is unique in this class and that adds up to all-round driving fun.
This is thanks to the world's smallest direct-injection diesel engine - a masterpiece of engine development - that boasts technology previously only found in larger capacity engines, despite its extremely compact dimensions. For example the latest generation common-rail direct injection which builds up high injection pressure of up to 1,600 bar (previously: 1,350 bar) even at low revs, and injects the fuel into the combustion chambers with newly developed six-hole injectors, enabling an even more efficient combustion process.
A turbo-charger, charge-air cooling, electrically controlled and cooled exhaust gas recirculation, hydraulic compensation of valve clearance and a state-of-the-art light alloy construction are further features that identify the cdi engine as a high-tech package.
The smallest direct-injection diesel engine with state-of-the-art technology
The three-cylinder engine has also adopted two-phase fuel injection from the CDI engines of its sister brand Mercedes-Benz. A few milliseconds before the main injection a small quantity of diesel is injected into the combustion chambers where it ignites and preheats the cylinders. This results in a noticeably quieter combustion noise level than an engine without this pilot injection. The electronic "brain" of the cdi engine - a high-performance micro-computer that controls the whole engine-transmission system - calculates how much fuel is needed and the interval at which pilot injection and main injection take place.
The most important data on the new smart fortwo cdi at a glance:
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Cylinders/valves |
R3, 2 valves per cylinder |
Engine capacity |
799 cc |
Bore/stroke |
65.5 x 79 mm |
Power output |
33 kW/45 bhp |
Max. torque |
110 Nm at 2,000-2,500 rpm |
0-100 km/h |
19.8 s |
Maximum speed |
135 km/h |
Combined fuel consumption, NEDC |
3.3 l/100 km - 71.3 MPG US |
CO2 emissions |
88 g/km |
The quick response of the cdi engine is first and foremost thanks to the compact yet extremely effective turbocharger that is housed in the exhaust manifold. Its compressor wheel has a diameter of just 31 millimetres, yet it rotates at up to 290,000 rpm and builds up maximum charge pressure of approximately 1,150 millibars. This gives the three-cylinder engine more air to "breathe" and enables it to develop impressive torque: 85 Newton metres are available even from 1,500 rpm - more than three quarters of the maximum torque.
smart CDI turbocharger with up to 290,000 rpm
This torque curve plays an important part in the fun behind the wheel that drivers experience with every kilometre driven in a smart fortwo cdi. The smart fortwo cdi accelerates from 0-100 km/h in 19.8 seconds and reaches a top speed of 135 km/h.
As before, the engines of the smart fortwo are fitted transversally in space-saving mode in front of the rear axle and they are inclined at an angle of 45 degrees towards the rear. The consistent use of lightweight materials means that the diesel engine weighs in at just 86 kilograms. The crankcase features a state-of-the-art diecast aluminium bedplate design and the cylinder head and cylinder head cover are likewise made of aluminium.
Exhaust gas recirculation, catalytic converter and particle filter as standard
The three-cylinder diesel engine controls emissions in two stages. The high-tech common-rail injection and the extremely efficient combustion process inside the engine provide for a low level of untreated emissions. Depending on the driving situation and the engine load, up to 60 percent of the previously cooled exhaust gas is returned to the combustion chambers where it is combusted once again thus greatly reducing nitrogen oxide emissions. The exhaust gas recirculation works with an electropneumatic actuator which enables it to react quickly to changes. An oxidation catalytic converter and an open diesel particle filter are responsible for the aftertreatment of the exhaust gases. These are housed together with the exhaust silencer in a stainless steel case.
Automated manual transmission with kick-down function
The three-cylinder diesel engine works with a newly developed automated manual five-speed transmission which the driver operates by briefly tapping the shift lever on the centre console. When briefly pushed forwards the transmission shifts to the next highest gear. Gently pulling the shift lever backwards is sufficient to shift down. Shift paddles on the steering wheel are optionally available and come as standard in the pulse model line. An automatic transmission mode is also available for all equipment variants. This is a standard feature for the passion model.
The clutch is opened and closed by an electric motor which means that there is no clutch pedal in the new smart fortwo cdi. To enable quick intermediate spurts the smart engineers have developed a kick-down function that is activated with the accelerator pedal. This enables the driver to spontaneously change down by one or two gears and to make even better use of the engine's low-speed torque. One of the safest cars in its class
It is not just the three-cylinder diesel engine that is unique feature in this vehicle class; the new smart fortwo cdi also boasts other technical innovations as standard. For example: the anti-lock braking system (ABS) with electronic brake-force distribution, the electronic stability programme (ESP®), brake assist, full-size airbags for driver and passenger, seat belts with belt tensioners and belt-force limiters, safety seats with integral seat belts and the sturdy tridion safety cell of which 50 percent consists of high-strength steel alloys and that has proved itself in the toughest crash tests.
This extensive safety equipment makes the new smart fortwo one of the safest cars in its class.
The body is 195 millimetres and the wheelbase 55 millimetres longer than that of the predecessor. This, together with the wider track (front: 7 millimetres; rear: 33 millimetres) greatly enhance the ride comfort and spaciousness. The luggage compartment capacity has increased from 150 to 220 litres or even from 260 to 340 litres when loaded to the roof (in accordance with the VDA measuring method). This means that six drinks crates fit into the luggage compartment of the new smart fortwo. The level loading area and the twin-section tailgate facilitate loading and unloading.
The new smart fortwo cdi is available as a coupé and a cabrio. The prices range from 11,200 to 16,240 euros (ex works) depending on the model and the equipment variant.
June 6, 2007
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smart fortwo to get stop-start technology; smart fortwo hybrid?
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New smart diesel engines start production
A 45 hp (33 kW) common rail direct injection turbodiesel with
799 cc displacement for the new smart cdi started production on
a new line in Kölleda, Thüringen. The smart cdi was certified
to consume 3.3 liters per 100 kilometers which translates to 71.3
MPG in US numbers emitting only 88 grams of carbon dioxide per kilometer.
Mar 20, 2007
smart fortwo ed (electric drive)
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well-to-wheel energy efficiency
Gasoline combustion engine: 93 Honda CIVIC VX, 51 MPG combined (source EPA). It drives 0.52 kilometers per MJ. Gasoline electric hybrid: Toyota Prius, 55 MPG combined (source EPA). It drives 0.56 kilometers per MJ. Diesel combustion engine: smart cdi, 4.2 liters per 100 km combined (source smart Canada). It drives 0.57 kilometers per MJ. Diesel electric hybrid: smart hybrid cdi, 15% more efficient than cdi in Euro cycle (source smart). It drives 0.66 kilometers per MJ. Electric car: smart ed, drives 100 kilometers with 12 kWh of electric energy (source smart) It drives 1.05 kilometers per MJ.
Thus the smart ed is about twice as efficient as the gasoline combustion vehicle.
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The Zytek brushless electric motor with rare earth permanent magnets simply replaces the combustion engine and is mounted in the same space. The gearbox is locked to 2nd gear, with one forward, one reverse and neutral and drives the fortwo's De Dion rear axle.
The brown enclosure across the lower rear houses the Zebra battery supplied by MES-DEA. This sodium nickel chloride battery was selected due to its high specific energy compared to other batteries. It was developed for the smart to fit under the floor. It's rated at 13.6 kilo Watt hours (kWh) with 264 cells in 3 modules of 88 each with a nominal 227 Volts overall.
The compact Zytek electric drivetrain simply bolts on instead of the
internal combustion engine.
Zytek IDT 120-55 specs
Overnight the smart ev plugs into the grid. The plug is behind the fuel filler flap.
10 AM and fully charged. Ready to head out to the office on London's Piccadilly Circus?
The charger with the cooling fan on top on the lower right converts grid AC to DC to recharge the battery. The smart ev can drive 100 kilometers with 12 kWh of electric energy. The running costs are only 0.02 EURO per kilometer compared to 0.06 EURO per kilometer for the standard gasoline version. The top speed was limited to 110 kilometers per hour.
The smart fortwo ev is exempt from congestion charging in the central zone of London of up to 8 pounds sterling per day and also exempt from registration duties.
smart fortwo ed trial to debut at British Motor show
About 100 smart fortwo ev will be offered for lease to select
corporate customers in London for a trial starting in November.
There are no plans for further production at present.
July 13, 2006
smart ev presented in Geneva
smart sounding out alternative drive concepts: Prospects for the electric engine Investigating and developing alternative engine concepts is a must for all car manufacturers. smart adopts a slightly different approach here: Apart from the various types of hybrid drives and natural-gas engines, the company is also focusing its attention on the electric engine. With an efficient electric engine and a powerful Zebra battery, the smart fortwo has a range of no less than 110 kilometres with a fully charged battery – more than enough for most trips in town. The battery of the smart ev (electric vehicle) can be charged from 20 to 80 per cent in four hours, and from empty to 100 per cent in no more than eight hours. The battery has a service life of at least 1000 charging cycles or ten years. The additional costs continue to raise questions as to the viability of this drive technology. The Zebra battery alone costs around half the price of an entire car with a standard engine. However, the running costs are only a third as high as those for a conventional petrol engine. In special cases, a smart ev could already be financially viable today – in inner-city areas such as London, for example, where particularly environment-friendly vehicles, including electric cars, are exempted from the toll charge which otherwise applies. The toll charge for London amounts to eight pounds sterling a day, for example. For those with a particular interest in the technical aspects: The storage battery in the prototype is the stated Zebra or sodium-nickel-chloride battery. It fits under the floor, weighs 60 kilograms and stores 12 kilowatt hours (kWh) of electricity. The smart fortwo ev cruises along much like its counterpart fitted with a combustion engine – but virtually without a sound. It moves at a sprightly pace with its 30 kW / 41 bhp, its acceleration from 0 to 60 km/h on a par with the petrol variant. No gear changing is necessary, apart from “forward” and “reverse”. The maximum speed is limited to 120 km/h. When the accelerator is released and during gentle braking, the drive engine is operated as a generator, thus replenishing its store of electric power. Other drive concepts Two prototypes of the smart ev put in a fine showing at the recent smart Technology Forum, at which all the possibilities offered by alternative drive concepts were demonstrated in practice. This underlines smart’s role as a pioneer in the field of individual mobility with a special focus on the environment. The other drive concepts include above all natural gas and mild and full hybrid. A natural-gas drive could be realised immediately for the smart fortwo, in the face of corresponding demand. The two-seater actually offers particularly favourable conditions for this alternative, as the natural-gas tanks could be installed under the floor of the vehicle, without claiming any space from the interior or the luggage compartment. The additional (smaller) petrol tank provides reserve mobility to ensure that the nearest natural-gas filling station can be reached, as the number of such stations remains limited as yet. automatic stop-start On the smart fortwo mild hybrid a belt-driven starter generator serves as both starter and alternator. It enables the engine to be started in a fraction of a second without the occupants noticing – an ideal basis for an automatic stop-start system. This system enables the engine to be shut down automatically whenever it would otherwise be idling unnecessarily – when waiting at a red traffic light, for example. As soon as the driver releases the brake pedal, the engine starts up again. A mild hybrid can be combined with both petrol and diesel engines. Prototypes of the smart fortwo mild hybrid achieve savings of up to 15 per cent over conventional petrol engines in urban traffic. The smart fortwo cdi diesel hybrid offers even more possibilities. Instead of the flywheel, the combustion engine is equipped with an electric machine. In addition to functioning as a starter and alternator, this machine is also able to support the engine during acceleration, for example, and to “recuperate”, or recharge itself, when the accelerator is released. smart has combined a diesel with an electric engine for the first time in the prototype of the fortwo cdi hybrid. 30 diesel kW plus 20 electric kW result in even better acceleration – particularly in the upper speed range. The combination also leads to enhanced shifting comfort, as the electric engine bridges the shifting delays. The most important aspect is the low fuel consumption, however, which drops by around 15 per cent on the fortwo cdi hybrid to as little as around 2.9 litres per 100 kilometres under standard conditions. Diesel drive remains the best alternative Increased driving pleasure and reduced fuel consumption – music to the ears of the development engineers at smart. And they have really done their homework to come up with this result. In the smart fortwo cdi, they unveiled a diesel engine back at the end of 1999 that was soon to evolve into the most successful “three-litre car” ever. 30 kW / 41 bhp of engine power, a top speed of 135 km/h and a fuel consumption of 3.8 litres of diesel per 100 kilometres under standard conditions. To date, this engine has been fitted in over 140,000 cars – several times the figures attained by competitors with similar models. The secret behind the success of the smart fortwo cdi is the way in which it excels in terms of both ecology and economy. In other words, its attractive purchase price means that cutting fuel costs does not entail a costly investment up-front. The diesel engine remains the best alternative in economic terms. [...] smart is capable of evolving and marketing drives such as electric, gas or hybrid. It is first and foremost the economic efficiency of these alternatives which will determine when they might be introduced onto the market. The technology is available, and rest assured that smart will utilise it as soon as the appropriate underlying conditions apply.
©1998-2006 DaimlerChrysler. All rights reserved.
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