A bit of history - how did Toyota's hybrid drive develop?

We've been running C-HR in the newsroom for a while now. Every day we appreciate the benefits of hybrid drive in the city, but for a while we were wondering how far Hybrid Synergy Drive went before it came to the latest model? If you are also interested, read on.

Have you ever wondered how far the history of hybrid drives has come? Contrary to appearances, this type of invention is not the domain of the last decades or so. The first patent for a drive system using an internal combustion engine and an electric motor belonged to William H. Patton, and it appeared ... before 128 years ago! This patent developed the Patton Motor Car, a hybrid powertrain that was used to power streetcars and small locomotives. In 1889, a prototype was created, and eight years later the serial version of the locomotive was sold to the railway company.

A year earlier, the Phaeton rolled out onto the roads before Patton's cable car production. No, not this Volkswagen-Bentley. Armstrong Phaeton. Probably the first hybrid car, or rather a wheelchair, in history. On board was a 6,5-liter 2-cylinder internal combustion engine, as well as an electric motor. The flywheel also acted as a dynamo that charged the battery. Armstrong Phaeton already recovered energy from braking, but in a slightly different way than today's hybrids. The electric motor was used to power lamps and start the internal combustion engine, and perhaps this would not have been surprising if not for the fact that it outstripped Cadillac's automatic starter by 16 years.

Interested? How about a 3-speed semi-automatic transmission? Gears did not have to be changed completely by hand. Long before synchronizers were invented and the double clutch technique was forgotten, an electric motor actuated the clutch automatically when changing gears. However, the Armstrong Phaeton engine was… too powerful. He constantly damaged the wooden wheels, which was subsequently eliminated by adding reinforcements to the wheels.

Ferdinand Porsche also had his merit in the history of cars. The Lohner-Porsche Mixte Hybrid was a vehicle that, in later versions, was powered by electric motors, one for each wheel. These motors were powered by batteries and the torque of an internal combustion engine. This vehicle could carry up to four people and move only through the power of electricity or only using an internal combustion engine.

Sounds great? Not completely. Mixte batteries consisted of 44 80-volt cells and weighed 1,8 tons. The links were not very strong, so they were closed in a suitable case and hung on springs. However, this is the battery itself, and let's add a lot of electric motors to it. The invention of Lohner and Porsche weighed more than 4 tons. Although from today's point of view it looks like a complete misfire, Mixte got many engineers thinking. For example, those from Boeing and NASA, who studied this apparatus very carefully. With effects, because the LRV that the Apollo 15, 16, and 17 missions used to get around the moon had many solutions taken from the Lohner-Porsche Mixte hybrid.

The history of hybrids is quite long, so let's go straight to the present from the very beginning. Hybrids as we know them only became popular in the late 90s when the Toyota Prius entered the Japanese market. It was then that for the first time - in 1997 - the name "Toyota Hybrid System" was used, which later became "Hybrid Synergy Drive". What did the individual generations look like?

First Toyota Prius - Toyota Hybrid System

We already know that the idea of ​​a hybrid car is not new. However, it took more than 100 years for this concept to become really popular. Toyota Prius became the first mass-produced hybrid car. Perhaps that is why all hybrids are clearly associated with the Prius. But let's look at the technical solutions.

Although production of the Prius began in 1997, this portion of sales was for the Japanese market only. Exports to other markets, mainly the US, only began in 2000. However, the export model NHW11 has been slightly upgraded from its predecessor (NHW10).

Under the hood of the Japanese hybrid was a 1.5 VVT-i engine with variable valve timing, operating on the Atkinson cycle. The assumptions were more or less the same as they are now - the gasoline engine was supported by two electric motors - one working as a generator, and the other driving the wheels. The planetary gear, which served as a continuously variable CVT transmission, was responsible for the correct distribution of the work of the engines.

It was not a very fast car, with a power output of 58 hp. and 102 Nm at 4000 rpm. Therefore, the acceleration was rather modest, as was the maximum speed of 160 km / h. What pleased me was the low fuel consumption, which on average could fall below 5 l / 100 km.

In the NHW11 version, most of the components have been improved to provide better performance. The power of the electric motor has been increased by 3 kW and the torque by 45 Nm. Mechanical losses have been reduced and noise has been reduced. The maximum engine speed has also been increased by 500 rpm.

The first Prius, however, was not without flaws - it wasn't as reliable as today's models, there were issues with batteries overheating, and some electrical components (such as the electric motor) were too loud.

Prius II, or Hybrid Synergy Drive

In 2003, another Prius appeared with a second generation THS engine. It was first called Hybrid Synergy Drive. Before we get into the drive, it's worth mentioning the iconic shape. It did not arise from scratch and even has its own name - "Kammbak". It was developed in the 30s by aerodynamic engineer Wunibald Kamm. The body with a high, cut back is more streamlined, there is no turbulence behind the car.

While working on the second generation Prius, Toyota registered as many as 530 patents. Although the concept as such was similar to the THS drive, it was only in the HSD that the capabilities of the disk system were properly used. The potential of the electric motor and the internal combustion engine was equalized, in contrast to the earlier idea, which was to increase the power of the internal combustion engine to increase productivity. The second Prius started and accelerated partly with the help of an electric motor. The power of the electrical part of the drive is increased by 50%.

This generation also saw the introduction of an electric air conditioning compressor that did not require an internal combustion engine to cool or heat the interior. It has remained so to this day. The Prius also received lighter NiMH batteries in 2003. The number of cells has been reduced and the density of the electrolyte has been increased. Also, it was in this model that the EV mode was first introduced, which allows you to drive only on the electric motor.

Lexus developed its own variants of this generation's powertrain. In 2005, he applied another electric motor to the rear axle and thus created an all-wheel drive hybrid. The third engine worked independently of the command to the front axle - although, of course, it was controlled by a controller that regulates torque and speed differential.

The first Lexus GS 450h and LS 600h showed how HSD can work together with powerful engines and rear wheel drive. This system was even more complex - especially in the field of transmission. Ravigneaux planetary gearbox with four shafts, two clutches that change the gear ratio of the second engine relative to the wheels - it was not clear to go into details. This should be explained by the mechanical engineer.

Hybrid Synergy Drive III

We reach the penultimate generation of the hybrid drive. This is where a real revolution took place. Replaced 90% of parts. The internal combustion engine increased the working volume to 1.8 liters, but the electric motors were reduced. Power increased to 136 hp, while fuel consumption decreased by 9%. In this generation, we were able to select a driving mode - normal, eco and dynamic.

The HSD has a fixed gear ratio, so the planetary gear, while similar to a CVT, is something completely different. The outer ring of the gearing is the MG2 motor, the sun gear is the MG1 motor, and the ICE is connected by "planets". The driver can somehow influence the operation of the internal combustion engine and electric motor, but the accelerator pedal is only used to communicate with the computer. We say how we would like to accelerate, and the computer will calculate what the road conditions are and how to most effectively combine the work of the electric motor and the internal combustion engine.

Toyota C-HR or HSD IV

The fourth generation of the drive appeared ... in the fourth generation of the Prius. However, he has already managed to take root in other models - for example, in the C-HR. The Quartet leans heavily on the HSD III, but squeezes even more out of it with less fuel consumption. However, "more" does not mean power, as it has been reduced to 122 hp.

First of all, the charging characteristics of the batteries have been improved - new hybrids are able to absorb large doses of energy in a shorter time. The inverter has a separate cooling system and takes up 30% less space. The planetary gear is replaced by a cylindrical one. The entire gearbox has been redesigned so it generates 20% less wastage.

Summation

We've seen parts of Toyota's journey to cars that combine the benefits of electric motors with the versatility of internal combustion engines. However, it is not the disk itself that changes. The concept of a hybrid car is also changing. This one has long since ceased being a Prius and is making its way into cars that look a little more conventional. Hybrids are gradually becoming part of everyday life. We see them everywhere in big cities. 

One of them is the Toyota C-HR, which will appeal to those who want to move around the city in an interesting crossover, but appreciate low fuel consumption and noiselessness. There is also a growing awareness of the need to reduce pollution - and while cars are not the source of all evil here, they are part of it, so something needs to be done about it. Toyota records significant growth in hybrid vehicle sales year on year. Not thanks to the Prius - thanks to cars like the Auris or the C-HR - still available on the wallet, in the usual packaging, but with improved drivetrain, the added value of which is proven reliability.

When is the next generation? We don't know. We'll probably wait a few more years. However, the powertrain of the latest Toyota hybrids is already reaching an incredibly high level of sophistication.