Bosch 48V mild hybrid system to be production-ready by 2017; Gen 2 prototype integrated in transmission for all-electric driving
04 September 2015
Bosch is developing a 48V entry-level hybrid system that will be production-ready by 2017. “The boost recuperation system is the hybrid for everyone,” says Dr. Rolf Bulander, member of the board of management of Robert Bosch GmbH and chairman of the Mobility Solutions business sector.
Bosch says that the low-cost system, which enables start-stop functionality and braking energy recuperation, will deliver about a 15% improvement in fuel consumption, not only in controlled tests, but also in everyday driving situations. An electric boost feature also enables more dynamic acceleration; the motor generator provides the combustion engine with an additional 150 N·m of support during acceleration.
Unlike conventional ~400-volt full hybrids, the 48V system can utilize less expensive components. Instead of using a large electric traction motor, Bosch enhanced the generator to output four times as much power.
The motor generator uses a belt to support the combustion engine with up to 10 kW. The power electronics form the link between the additional low-voltage battery and the motor generator. A DC/DC converter supplies the car’s 12-volt on-board network from the 48-volt vehicle electrical system. The newly developed lithium-ion battery is also significantly smaller.
Bosch expects some 4 million new vehicles worldwide to be equipped with this type of hybrid powertrain in 2020.
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| 48-volt hybrid: Second generation. In this second generation, the electric motor is integrated into the transmission. The electric motor and the internal-combustion engine are separable via a coupler, which means that they can provide power to the wheels independently. This enables parking in full-electric mode. Click to enlarge. |
Second-generation prototype. At the IAA 2015, Bosch will also be presenting a new second-generation of the entry-level hybrid that is currently still in development. In the prototype, the more powerful motor generator is integrated into the transmission and connected directly to the powertrain rather than to the combustion engine.
Both the electric motor and the internal-combustion engine are separable via a coupler, which means that they can provide power to the wheels independently. This allows the entry-level hybrid to provide all-electric driving even at low speeds—such as in stop-and-go traffic—in addition to immediate electric support for a short period of time.
The new hybrid also makes it possible to include in compact cars a function that will celebrate its debut in premium vehicles at this year’s IAA: a remote-controlled parking assistant that allows drivers to direct the parking maneuver from the curbside. The fully automatic parking assistant steers the vehicle into even the tightest parking spaces and garages safely and conveniently, without any stress or hassle.
The assistant uses ultrasonic sensors and is based on the fully automatic parking system found in vehicles with an automatic transmission. With the built-in electric motor, the system is capable of accelerating by itself and independently shifting between forward and reverse gears. Because the parking process is started by pressing a button on the ignition key, drivers do not even have to be in the vehicle. Bosch has also developed a smartphone app that allows drivers to operate the parking assistant from outside the vehicle.
This looks pretty good, if you could add stop/start / roll to a bunch of cars for a 15% efficiency improvement, and in particular, allowing them to be "engine off" in stationary / slow traffic. (or am I reading too much into this?)
As long as it is cheap and easy to integrate.
Posted by: mahonj | 04 September 2015 at 08:10 AM
Evolute last week now Bosch.
God there is so much wrong here I don't know where to start.
Unlike conventional ~400-volt full hybrids, the 48V system can utilize less expensive components.
So first, what are these full hybrids that run on ~400V ? I personally don't know of any full hybrids on 400V but if they meant full electrics then Model S from Tesla fits that bill. They certainly can't be referring to the Prius because from 2004 that vehicle has been employing 500V with a 650v Sport upgrade arriving in 2010. So you could say that Toyota's collective experience has not made them averse to the use of high voltage semicons when over the years they have manufactured more than 8 million Prius. That last million being produced in the past eight months, or so I believe.
That said, I would think that the adoption of 48V by Bosch probably has a lot to do with the powering of other ancillary equipment on board that could benefit from a higher voltage than 12V.
History has not been kind to belt-assisted hybrids. The Malibu hybrid lasted just two model years being marketed mostly to rental fleets at the end. It didn't produce the expected fuel savings and the driving experience was was also less than stellar.
History has not been kind to non belt-assisted hybrids either. Honda produced an inline-assist with 15Kw motor for the Honda Civic and the V6 Accord to take on the Prius which has two motor/generators. If they had just released the Civic with its specialised 1.3L engine without the battery assist it would have done fine IMO. However the inadequate battery charge management system hardware including insufficient battery insulation and of course the lack of battery temperature environmental control meant that oft times the Civic was operating as a Hybrid in name only. Amost inevitably in early 2012 a court case was won by an owner whose car did not provide the advertised savings and by 2015 Honda dropped their hybrid owing to the poor showing in sales.
The future for the Malibu now includes mechanical solutions in the form of 6-speed transmissions.
The future for the Civic Hybrid is that Honda is going to re-introduce their hybrid with a downsized version of the two motor configuration as equipped by the 2014 Accord Hybrid.
Posted by: T2 | 04 September 2015 at 10:53 AM
The light dawns in Germany; small electric motors are good for filling in the low rpm torque that is missing in an ICE car. You only need about 12 to 20 hp from the ICE to sustain the steady state equilibrium of cruising. However, based on T2's post, the Bosch approach may also be a failure.
Can't wait to watch what happens to all these interim ideas when the battery we have been wishing for is finally available. I suspect they will be blown away by the 'Wind of Progress.'
Posted by: Lad | 04 September 2015 at 12:23 PM
Good points from T2 and Lad.
Is it too late for another interim solution, when the arrival of affordable extended range BEVs (like the $35K TESLA III) and lower cost full PHEVs are around the corner?
Posted by: HarveyD | 04 September 2015 at 05:33 PM
I wouldn't use the GM examples to judge the merits of a belt-driven system. For both BAS generations, they integrated with prev-gen engine/transmission combos, making the benefits seems smaller than they actually were. First gen BAS was limited by 4-speed auto and second gen by older 2.4 (when newer 2.5 with 2-stage lift was out).
Would have been interesting to see latest BAS with new, lighter 2016 Malibu with 1.5 turbo.
Posted by: alpha1847 | 07 September 2015 at 09:07 AM
I second alpha1847's comment about judging the merits of this Bosch development on past failures with similar systems.
You can always botch up any technology or concept.
I have quite high confidence in Bosch ability to innovate and develop practical solutions that stand the test of time.
I see no reason why a belt-driven assist from the (beefed up) starter motor/generator should not work. I do, however, acknowledge the need for a higher strength and quality belt over what is used today. But that's just engineering.
There are a number of derived possible benefits from a system such as this:
- Feasible engine downsizing without sacrificing acceleration (standard 'hybrid-argument')
- Motor-assisted acceleration from zero can allow a higher 1st gear and thus a higher overall gear ratio with the same gear spread. Gear spread is a limiting factor in gear boxes
- Transient torque assist allows higher top gear for manual gear boxes without sacrificing drivability/comfort/performance
- ICE engineers can worry slightly less about low-rev performance of the engine and focus on efficiency at cruise-rpm and, for small down-sized engines, peak power (for top speed). Basically, putting a bigger turbo on that gives higher peak power, but poor low-rpm torque.
- Instant throttle response with turbo ICEs. Many OEMs sacrifice peak torque of turbo charged engines in order to keep a reserve for faster acceleration (and possibly to reduce NOx formation...)
- ICE off all the time in traffic jams with walk-paced stop'n'go
- No belt-driven ancillaries - higher engine output to gearbox (Mazda concept)
This was just to pick the main benefits off the top of my head. I probably missed some, even important ones.
I am sure BEVs are coming. But change takes time. In the mean time, all tech to reduce oil consumption and emissions is welcome in my book.
Posted by: Thomas Pedersen | 08 September 2015 at 03:01 AM
48 V is fine for safety in case of car crash, fire, maintenance and repair. In addition, it is cost effective.
Nevertheless, stop and start system has some draw backs:
•15 % efficiency improvement might be based on test cycles which have a lot of idle periods very far from the real world (25 % in NEDC cycle!),
•Only one machine means that the electricity energy has to be stored in a battery and reused after many energy transformations and associated losses,
•At each stop and start, the engine gets chocks: mechanical, thermal, lubrication, chemical (NOx).
Some projects aim to reduce power of the two machines systems (like Prius) so their voltage and battery size to the level of the start and stop system. Refer to the following link and the good comments from T2:
http://contest.techbriefs.com/2015/entries/sustainable-technologies/5453
Posted by: Vupilla | 08 September 2015 at 05:40 AM
Good post Vupilla;
As an aside;
Converted my garden tractor to electric three years ago using 48 volts of Pb batteries; the downside...the heavy lead acid batteries and their short life....been waiting for lithium battery prices to come down. Perhaps a good supply of mass production 48V lithium batteries will help.
Posted by: Lad | 08 September 2015 at 12:16 PM
@Vupilla,
I went to the link you posted, a hybrid drivetrain system. Actually it is US patent 8845469, went there too to get more info.
I guess you are familiar with details of the invention (Perhaps the inventor homself?), and I have some questions.
Given the example in patent description, 1000 kg car, Thermal Engine: 53 KW at 4000 rpm, 1000-5000 rpm,
Electric motor and generator: 17 KW, 0-7000 rpm, 70 mN, 400V\
Battery: 0.5 KWh+0.2 KWh capacitor..
1. All electric driving:
if you have 2 e-mootors of 2x 17 KW (as above), how much max power can they deliver to the wheels when ICE is turned off?
2. These 17 kW for motors - is it continuous power or peak power?
3. When braking from 50 kph to zero (using brake pedal), at what speed will the ICE be turned off?
4. Max electric braking power - with ICE on and with ICE off?
5. How are capacitor and battery connected - in parallel, via a DC-DC converter or some other way?
6. Compared with Prius and Chevy Volt 2016 hybrid systems (or new GM HEV in Malibu, ie without big battery), what are the advantages od this system?
Posted by: Alex_C | 11 September 2015 at 11:20 AM
@Alex C
Thanks for your comments. Please find some answers.
Q1 All electric driving: if you have 2 e-mootors of 2x 17 KW (as above), how much max power can they deliver to the wheels when ICE is turned off?
A1 In e-mode, the Generator can work as a motor to support the Motor, so 34 KW is available. It is sufficient up to 30 km/h in a hyper-city center. If an extra power is required, the ICE can easily and quickly restart as described in another patent. The limit 30 km/h is based upon the fact that the efficiency and CO2 emission, from the pit to the wheel through a power plant, are not good even for an EV. To run in electrical mode the above limit is not so interesting in today conditions.
Q2 This 17 kW for motors - is it continuous power or peak power?
A2 17 KW is peak power; my target is 10 KW continuous to decrease hybrid extra costs and to decrease voltage for more safety. In addition (around 150 KJ), I use the inertia of the generator rotor to store some kinetic energy, which is directly available through the gearing system, mainly to boost vehicle performances.
Q3 When braking from 50 kph to zero (using brake pedal), at what speed will the ICE be turned off?
A3 The ICE is turnoff according the power requirement and, of course, according the speed diagram. Note that the ICE power can be accurately calculated from the behavior of the high inertia generator. This reference does not change during vehicle life and according to external conditions. Another patent.
Q4 Max electric braking power - with ICE on and with ICE off?
A4 The kinetic energy stored in the generator rotor can be used as the energy stored in a battery but, almost, without power limit
Q5 How are capacitor and battery connected - in parallel, via a DC-DC converter or some other way?
A5 As far as possible, the Generator and the Motor work at the electrical balance. So basically, we do not need a huge battery except for plug in operation. In that case, we use the Motor remaining capacity. In a good hybrid concept, the electric power is decreased as soon as the ICE gets its best working point, so plenty of capacities are available for the plug-in energy.
Q6 Compared with Prius and Chevy Volt 2016 hybrid systems (or new GM HEV in Malibu, ie without big battery), what are the advantages od this system?
A6 Usually, I never comment competitors. My strategy is basically to increase the efficiency regarding the complete energy cycle (from the pit to the wheels) and to decrease the power of the electric power chain. In addition, the transmission architecture gets five innovations and even opens the way to a new technology (pulsatile cycles at low power). Please refer to the following links:
http://contest.techbriefs.com/2013/entries/transportation-and-automotive/3519
http://contest.techbriefs.com/2015/entries/sustainable-technologies/5453
http://contest.techbriefs.com/2015/entries/automotive-transportation/5116
http://contest.techbriefs.com/2014/entries/automotive-transportation/by-views/4139
I am available for more information: [email protected]
Posted by: Vupilla | 14 September 2015 at 11:43 AM
@Vupilla,
Thanks for the answers. From the patent text (mentioned above) it wasn't clear to me if both e-motors can participate in all electric mode (in Prius only MG2 can do it).
Unfortunately I cannot help you sell the invention to a carmaker, but I wish you success in selling/licencing it.
Usually in most US patent texts there is significantly more description how system works, and also advantages of the proposed solution.
In the texts from the links from your latest email, there is not enough text to conclude how exactly it works, how it handles various scenarios (say high speed, uphill low speed, acceleration, braking, all electric drive). Planetary systems have non linear relations, a lot depends of selected gear ratios, image itself usually is not enough.
Mentioned peak motor(s) power of 17 KW is somewhat above peak power that 48 Volt provide, that I saw. Highest I saw was 15 KW peak, below 7 KW continuous. I think it was a Continental system. Limitations are due to cable thickness.
You are trying to minimize battery size. With expected battery prices going down in years to come, you may need to reconsider the optimal values for battery size, and motor power too, so it can either be powered by 48 Volt, if not increase its power to better satisfy other design goal (every design is a result of various compromises, total system price is very important ).
BTW do you have any details on Renault hybrid system, announced near the end of 2014, a 3 speed system?
Posted by: Alex_C | 17 September 2015 at 10:26 AM
@ Alex C
It’s difficult to explain in few words. Usually, I have slides for supporting my presentations.
I don’t use the same quadrants as the Prius. So both electric machines can participate in electrical mode in my configuration.
Thank you for your encouraging wishes but for the moment, I only look for a feasibility study on an existing vehicle in an existing environment.
Patents take time before to be accessible. In addition, their reading is not always easy.
I am sorry; a planetary system is linear relations starting from the Willis formula. I know at least one project of a major car maker which has failed for forgetting this fact.
You are right about voltage versus performances but performances depend on many parameters such as water cooling, distances between the machines, etc.
My target is mainly to improve the complete energy chain. To use a battery multiplies the energy conversions and associated losses, whatsoever its price.
I am also interested by information about Renault project.
Posted by: Vupilla | 26 September 2015 at 02:52 PM
The second generation Bosch 48V system sounds far better than a Belt-Alternator-Starter.
"In the second-generation of the entry-level hybrid, the more powerful motor generator is integrated into the transmission and connected directly to the powertrain rather than to the combustion engine.
Both the electric motor and the internal-combustion engine are separable via a coupler, which means that they can provide power to the wheels independently. This allows the entry-level hybrid to provide all-electric driving at low speeds"
I see this as becoming mainstream in markets with emissions controls as a replacement for ICE-only or stop-start systems for cars that are not full hybrids or plug-ins.
If the Bosch 48v system delivers 80% of the fuel savings for 20% of the cost of a full hybrid, it will be cost effective for most car buyers. Modern cars have large electrical loads that are better served by a 48v system too.
Posted by: Chip | 12 October 2015 at 12:42 PM
@Lad -
Lad said: "converted my garden tractor to electric three years ago using 48 volts; ....been waiting for lithium battery prices to come down".
I have found that the lead-acid golf-cart batteries in my robot mower fail over the winter, so I am also looking for a lithium-ion solution.
I bought some used laptop battery packs and I have found that most packs have one or a pair of dead cells while the others are ok. Some packs had all six cells still working. I guess those came from unsold stock or discarded laptops.
Have you experimented with cells from used laptop batteries?
On YouTube there are several people who have built DIY battery packs. For example, 'Rinoa Super-Genius' has ridden more than 1000 miles on his trike powered by recycled laptop cells.
https://www.youtube.com/watch?v=NVJNol7jq0M
Posted by: Chip | 12 October 2015 at 01:00 PM