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7. History of the HYBRID System - Racing (THS-R)

2005: Development Starts on Hybrid Systems for Racing In December of 2005, the decision was made to investigate the possibilities of race activities using cars with hybrid systems. Since there were no existing racing cars with hybrid systems at that time, there were no race competitions that hybrid cars could compete in. Therefore, the initial points for investigation were what direction hybrid system development for racing should take and what competition such cars should compete in.

2006: The first race participation. Finishing the Tokachi 24 Hours race

LEXUS GS450h First, an image for a hybrid race system was created, not only by the Motorsport Division but also with the cooperation of other divisions within Toyota. The race that was chosen for the first entry attempt was the Tokachi 24 Hours race held at the Tokachi Speedway in Hokkaido.

With an eye to a coming era of eco-racing, a special production group “P- 1” class had been newly established for hybrids and other eco-cars in the Tokachi 24 Hours race that year (2006). Provisions had been made for such cars to also compete officially in the Super-endurance “ST-1” class under a special regulation as well. In light of this situation, it was decided to attach a capacitor to the nickelhydrogen battery of one model of the latest production hybrid model, the Lexus GS450h, for entry in this class. This decision was made based on the assumption that a capacitor, which has the advantage of faster charging/discharging potential than a battery as the system’s energy storage apparatus, would be better suited for a racing hybrid system. With this, the hybrid system’s maximum power output was increased to 254kW (345PS). The resulting model was then entered in the Tokachi race and, suffering no real trouble at all, managed to complete the full 24 hours and finish in 17th place overall, while rendering a significant amount of new development data in the process.

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2007: Overall win at Tokachi 24 Hours race. A world’s first achievement

TOYOTA SUPRA HV-R Based on the knowhow gained from the 2006 entry in the Tokachi 24 Hours race with a modified production model Lexus GS450h, the development team succeeded in developing a further advanced race-specific hybrid system in 2007 and entered it in the 2007 running of the Tokachi 24 Hours race.

The base car for this race machine was the Supra model competing at the time in the SUPER GT GT500 class, the pinnacle of GT racing in Japan. The Supra mounted a modified version of the 3UZ-FE naturally aspirated 4500cc V8 engine with a max. output of 353kW (480PS), and this engine was fitted with a transaxle. In the hybrid system, a major modification fitted a 150kW motor generator unit (MGU) in front of the transaxle and two 10kW in-wheel MGUs were also mounted on the backsides of the right and left front wheel brake rotors (total 230PS). A capacitor was also added as the energy storage apparatus to make this the first experience of racing-specific hybrid system ever used in an actual race for us, and it became the origin of the racing hybrid system that later came to be known as the Toyota Hybrid System – Racing (THS-R).

This Supra HV-R was entered in the Tokachi 24h-Special group of the TP-1 Class/GT Class, and amid the worst of conditions with intermittent rain, it succeeded in winning the race overall against a field of 36 competing cars by completing 616 laps (3,136 km) in 24 hours. This became a memorable achievement as the first overall victory in the world for a hybrid car in a semi- international-certified race. Furthermore, due to the effect of the hybrid system, fuel consumption was improved by more than 10%, and it was also discovered that the effect of the front-wheel regenerating - powering system limited the front brake wear to less than half that originally anticipated.

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2008-2011: Goal shifts to participation. Taking on difficult hurdles

After winning the Tokachi 24 Hours race, a search revealed no other races in the world where a car with a racing hybrid system could compete seriously. Also, when the possibilities of competing in the 24 Hours of Le Mans as a car with a gasoline engine plus a racing hybrid system were investigated, it was calculated that in order to match the running performance of the other cars competing in the race, the weight of the system would have to be increased to more than 600 kg. It became clear that winning at the 24 Hours of Le Mans would require the seemingly impossible task of reducing that system weight to less than 1/6th the calculated weight necessary, namely less than 100 kg.

2012: WEC/Le Mans participation begins with the TS030 HYBRID

TS030 HYBRID When the regulations concerning hybrid cars participating in the LMP1 class of the World Endurance Championship / Le Mans race were relaxed, Toyota announced that it would enter its TS030 HYBRID car in the 24 Hours of Le Mans and the World Endurance Championship in 2012.

At the time, the race-specific THS-R hybrid system on the TS030 HYBRID car was designed with motor generator units (MGUs) for regeneration and powering (drive force). One was located in the rear inside the gearbox and two at the front wheels. However, after that the regulation was revised to allow only two MGUs and only in the front or rear, and only on the same . This meant that, after consideration, the two MGUs at the front wheels had to be removed to compete in the actual debut race. For the capacitor, a new “electric doublelayer capacitor” with increased electric storage capacity was adopted and a form of "super-capacitor.”

Revisions were also made in the technical regulation regarding the engine, with the displacement for a naturally aspirated gasoline engine set at 3.4 liters and for a turbocharged diesel engine at 3.7 liters, while a turbocharged

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gasoline engine was limited to a maximum of 2 liters. For the TS030 HYBRID car, a 3.4-liter naturally aspirated gasoline engine was chosen. In the 13.629 km/lap at the Le Mans Sarthe Circuit, seven specific zones where the cars could transmit the energy recuperated under braking were established and the regulation specified that energy release per sector was limited to a maximum of 0.5kJ, and limited to 3.5kJ for one lap.

2013: Introduction of a further developed TS030 HYBRID

TS030 HYBRID 2013 version The THS-R racing hybrid system on the 2013 model TS030 HYBRID inherited the same basic specifications of the 2012 powertrain, but compared to that system the efficiency was improved, while at the same time the braking control systems were made more precise. However, the elimination of the need for space for the MGUs at the front wheels enabled a re-designing of the and suspensions, while the line from the to the nose was also reshaped to a smoother form and the aerodynamics were improved. The revised THS-R system produced an output of 300 horsepower that was added to the 530 hp V8 engine.

This 2013 model TS030 HYBRID barely missed winning the 24 Hours of Le Mans race, ending up with a 2nd-place podium finish.

2014: Regulation revisions create the TS040 HYBRID

TS040 HYBRID For 2014, big changes were made in the car regulation. Limitations on the displacement of gasoline engines and the requirement for intake restrictors

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were eliminated. Meanwhile, changes were also made in the regulation concerning hybrid systems. The limits on energy release per sector of the circuit were eliminated and replaced by a choice of four levels of maximum energy release (2MJ/4MJ/6MJ/8MJ) for one lap of the Sarthe Circuit.

When thinking solely in terms of energy release, the larger values would seem attractive, but they also meant added system weight that would negatively affect performance. Also, because of the increased energy recovery, a new limit was placed on fuel and fuel flow in the technical regulation. Based on the fact that the hybrid system performance, its weight and its weight distribution affect the car’s running performance, the development team sought the best balance, and in the end they decided to go with a released energy level of 6MJ per lap. In accordance with this decision, a further evolution of the super-capacitor structure was made. As a result, to the 520 hp of the 3.7-liter V8 engine the hybrid system added another 480 hp to bring the output total up to an awesome level of more than 1,000 hp.

2015: Further progress in stability and durability. Technological returns for production models too

TS040 HYBRID 2015 version Improvement of the THS-R system focused on how to make full use of the awesome power unit with its more than 1,000 hp in a way that was smooth as well as efficient. The key component in the THS-R system was the super- capacitor that could regenerate lots of energy quickly during deceleration and then release it instantly when needed. In 2015, with the aim of getting even better performance out of the 2014 model’s super-capacitor, its structure was reviewed and revised and ended up delivering strong hybrid power with greater stability than in 2014.

The year 2015 brought improvement in the Toyota TS040 HYBRID for the 24 Hours of Le Mans with greater refinement of the hybrid system and review and improvement of the suspension geometry. In pre-season tests the TS040

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HYBRID piled up some 30,000 km of tests with no major problems. It also successfully completed a 6,000-km test simulating the Le Mans race.

But, races can’t be competed with reliable system performance alone. When considering the 24 Hours of Le Mans regulation, the change in regulation from 2014 when there were limits on energy release for each sector of the course to the 2015 regulation where the limit was for an entire lap, meant more strain on the capacitor as an energy storage device, which despite its advantage in quicker charging and discharging was at a disadvantage in terms of charging capacity per unit of weight. Porsche had entered the WEC with a car mounting a lithium-ion battery and it was beginning to exert its performance potential effectively. Despite the fact that the system of the TS040 HYBRID had become more refined, the competition it faced was now stronger, and although Toyota had gone to the 24 Hours of Le Mans with a must-win stance, the race didn’t go as hoped. In the WEC competition as well, it turned out to be a disappointing season with the only podium finishes coming with two 3rd places at the opening round at Silverstone and the final round at Bahrain, leaving Toyota 3rd in the Manufacturers Championship.

2016: Full-scale improvements based on the latest regulation

TS050 HYBRID After thorough investigation of the implications of the change in the charging/ discharging regulation from 2014, the development team reached the decision that they should introduce a new engine, which had been under development during the race season and a new energy storage apparatus. Whereas the previous year they had decided to go with a 6MJ max. energy release per lap out of concern for system weight, with the success of an exclusively developed lightweight, compact high-power lithium-ion battery that could handle 8MJ energy release, it was adopted to replace the existing . Furthermore, development of a V6 direct injection twin turbo engine that would be easier to tune to fit different conditions during the WEC series was accelerated to make it available in time. The result was a completely new and

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improved power train.

Since the time Toyota had begun competing in WEC with hybrid cars, the trend in international motorsport had shifted from trying to increase horsepower in conventional internal combustion engines by building higher-revving engines to the same direction that was being pursued in production cars of limiting the amount of fuel used and increasing thermal efficiency in order to boost horsepower. What the THS-R system on the 2016 model TS050 HYBRID represented was nothing less than advanced-development effort to use the race circuit as a fast-track proving ground to pioneer the next generation of Toyota hybrid systems (THS/THS-II).

By making big changes in the main components, the 2016 model TS050 HYBRID was reborn with a highly competitive power train but went into the season’s opening round at Silverstone with much of the fine tuning still to be done, where amid upsets like the dropping out of some rivals it manages to take 2nd place overall. In round two at Spa-Francorchamps, despite having to drop out late in the race due to machine trouble, it showed impressive performance in leading the race in run-away fashion until the late stages.

By the time of this 24 Hours of Le Mans race that had been the season’s biggest target, the power train with its vastly improved potential had finally been tuned to fine degree, and reliability in actual race conditions had been proven. Once the race got underway, the machine was performing to expectations and leading the race until 23 hours and 57 minutes. It was then, just as the victory goal was before the team’s very eyes that the machine suddenly lost power and began to slow. Finally, in an incredible twist of fate, the car came to a stop with just one lap remaining. The TS050 HYBRID with its aerodynamics developed specifically for the Le Mans course had had trouble competing at some other circuits, but at its home circuit it won the Fuji 6 Hours race in magnificent form.

Shortly after the end of the 24 Hours of Le Mans, development had already begun to further boost power train performance and the hybrid system for the 2017 machine with a goal of next time winning the Le Mans race for certain.

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2017: Improved performance with newly-developed technology

TS050 HYBRID 2017 version The 2017-specification TS050 HYBRID improved its performance after the frustrating WEC season of the previous year. The name and monocoque may have been the same, but the engineers worked very hard to improve its performance with newly-developed technology.

The FIA and ACO changed the regulations to reduce cornering speeds by raising certain key aerodynamic parts such as the front splitter, and reducing the size of rear diffuser. As a result the TS050 HYBRID should have suffered a significant loss of but the determination of the team’s aerodynamicists found solutions to recover the performance while powertrain engineers made a significant upgrade on the engine and hybrid system to regain the lost lap time.

The powertrain of the TS050 HYBRID is a combination of engine and hybrid system, with the engine still the key component. A 2.4 litre V6 direct injection engine with twin turbochargers produced significant power but fuel flow restrictions, by regulation, limited the available power so engineers worked to increase thermal efficiency. One of the solutions was to increase the size of turbocharger to take more air for lean combustion. However, increasing the size of a turbocharger normally creates a turbo lag, where power is delivered only after a short delay. To solve this problem software engineers adjusted the hybrid system to compensate.

The TS050 HYBRID uses two kinetic energy recovery systems, converting energy which would otherwise be lost under braking into energy for additional power, as opposed to exhaust gas recovery alternatives which cost some engine power to create energy. Toyota selected the maximum hybrid class, 8MJ, for a system which uses two motor generators; an AW unit at the front and a unit at the rear. The size of the front motor has been

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reduced over years of WEC participation which gives designers more freedom when conceiving the front area of the bodywork. The TS050 HYBRID has used Toyota-developed high-powered lithium-ion battery since 2016.

With this high performance hybrid system three TS050 HYBRIDs competed at Le Mans in 2017 but this effort didn’t bear fruit. , in the #7 car, astonished onlookers with a new lap record of 3m14.781s in qualifying to earn pole position but retired due to trouble after 10 hours at the front. Car #8 finished 8th after a long to replace the front motor while car #9 retired due to damaged rear suspension after being hit by an LMP2 car.

Despite a bitterly disappointing result at Le Mans, the TS050 HYBRID proved its performance and the success of its aerodynamic upgrades, winning five of the nine races.

2018-2019: Strengthening reliability combined with high heat resistance and efficiency of the battery

TS050 HYBRID 2019 version

TS050 HYBRID 2019 Hybrid System

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In response to the issues affecting its cars at the 2017 Le Mans 24 Hours, TOYOTA GAZOO Racing switched its focus away from outright performance towards an improvement in reliability, and procedures for minimising the effect of any issue, for 2018-2019 season.

The root cause of the front motor problem on the #8 TS050 HYBRID at Le Mans in 2017 was that the screw was not secured with threadlocker. Why was the process completed without using threadlocker? We repeatedly looked into the background behind such issues, as well as checking even more thoroughly the parts delivered, before use on track. We worked with suppliers and together asked “Was there any difficulty to assemble parts?”, “Was there any point to improve?” Then, we instituted a thorough action to improve the quality of each part.

However, that provides no guarantee of a trouble-free race, so the team also worked on a more robust system of ‘get-home’ modes to maximise the chances of the car returning to the pit after an incident. It is not enough to have a ‘get- home’ mode, as such possibilities did exist in the past and did not prevent the retirements experienced in 2017; communication and processes had to be strengthened as well. All parts of the team worked together to explore solutions for a range of possible issues, eventually implementing a process which quickly enables the correct ‘get home’ mode to be selected and communicated.

Only creating a robust process is not enough; to be ready for the worst-case scenario, it is necessary to practice and perfect the use of ‘get home’ modes. Therefore the pre-season endurance tests took on a different look, with many simulated problems used to test the readiness of team and driver, as well as the effectiveness of the ‘get home’ solution.

All that preparation paid off when, late in the 2018 Le Mans 24 Hours, Kamui Kobayashi missed the pit lane entrance for a regular fuel stop in his #7 TS050 HYBRID. This was exactly the kind of scenario the team had trained for and they stayed calm, selected the appropriate response, and brought the car back to pit lane with only a small amount of time lost.

In addition to those process and reliability efforts, TOYOTA GAZOO Racing further developed the battery in the TS050 HYBRID, targeting higher temperature resistance and efficiency. In 2016, the upper temperature threshold was 60°C, increasing to 85°C for the following season when improvements also eliminated performance degradation over 10,000km thanks to its high efficiency.

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In 2018, the cooling system could be simplified, and overall weight reduced, thanks to a further improvement in temperature resistance, which increased to 95°C.

The 2018-2019 season began with a one-two at Spa-Francorchamps prior to the same result at Le Mans following a remarkable race without a single mechanical problem on either car. The two TS050 HYBRIDs crossed the line first and second at Silverstone as well following a fierce battle, but damage to the floor saw both cars disqualified for a technical infringement. That proved to be the only race without a TOYOTA winner, as the TS050 HYBRIDs earned one-two finishes at Fuji, Shanghai and Sebring. A hybrid issue for the #7 prevented another one-two at Spa, although the #8 did earn victory. The season finished with a repeat win at Le Mans, the #8 again winning from the #7 which was very unfortunate to suffer a tyre puncture late in the race when leading comfortably.

After over a year of competition, in eight races, TOYOTA GAZOO Racing was crowned teams’ World Champions, with the #8 crew of Sébastien Buemi, , Fernando Alonso winning the drivers’ crown. The #7 line-up of , Kamui Kobayashi and José María López were second in the championship.

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