The Toyota C-HR is equipped with an engine-range that is designed to deliver exactly the fluent, engaging driving behaviour that its customers are looking for. This is most powerfully expressed by the segment-unique, range-topping, full hybrid version, the intrinsic characteristics of which guarantee a smooth, jolt-free ride.
Fitted with the latest-generation
hybrid power plant, the Toyota C-HR generates CO2 emissions as low as 82 g/km – a figure unrivalled within its segment – and returns combined fuel consumption of only 3.6 l/100 km.
Delivering 90 kW/122 DIN hp, this new hybrid powertrain is not only more efficient and lighter than the previous system, but also offers sharper performance. Detailed design changes to the engine have resulted in a thermal efficiency of 40% – a world-beating performance for a petrol unit.
Other hybrid system components have been made lighter and smaller, and have been repositioned for optimum packaging, further contributing to the car’s low centre of gravity.
This new hybrid powertrain offers the response and the fluidity of a dynamic driving style that particularly suits the Toyota C-HR’s dynamic design philosophy.
The Toyota C-HR is also available with a new 1.2 litre turbo engine, which debuted in the Auris. Delivering 85 kW/116 DIN hp and 185 Nm of torque, this unit generates CO2 emission from 125 g/km and returns combined fuel consumption from 5.5 l/100 km. It may be mated to either a 6-speed manual gearbox or a Continuously Variable Transmission. CVT equipped versions are available with either front- or all-wheel drive.
And finally, a 2-litre 144 DIN hp/107 kW, 188 Nm CVT-only model will be available for certain markets (Ukraine and Caucasus).
NEW HYBRID SYSTEM
The Toyota C-HR is equipped with the new generation of Toyota’s signature hybrid powertrain.
Toyota has focused its efforts on making this next generation of hybrids even easier and more intuitive to drive. The system has been set up so that it gives a natural, immediate, but smooth response to any accelerator pedal input. Refined and confident, it delivers the right level of performance.
But of course, fuel economy has been improved as well, as demonstrated in new Toyota C-HR’s combined cycle economy starting from just 3.6 l/100 km. The new hybrid system comes in a more compact package that is lighter in weight and lower in cost. It reflects significant advances in battery, electric motor and petrol engine technologies.
The new hybrid battery offers higher energy density. Whilst its total power was maintained, its size could be reduced by 10%. And what’s more, it can now absorb 28% more energy in the same amount of time, which means that it charges faster than before. The electric motors are smaller in size, yet also provide a better power-to-weight ratio. And the thermal efficiency of the petrol engine reaches more than 40 per cent, a world’s best for a petrol unit.
Improved petrol engine
The Toyota C-HR’s hybrid system features a 1.8-litre VVT-i Atkinson cycle petrol engine. Compared to the third generation Prius, the unit has been completely re-engineered to deliver significantly better fuel economy. The gas flow, combustion, cooling and knock control have all been improved and much more effective use is made of exhaust gas recirculation.
Toyota has developed a heat recovery system that uses spent exhaust gas to speed the warming up of engine coolant. This means fuel can be saved because the hybrid system is able to stop the engine earlier and more often when it isn’t needed to power the vehicle. The engine is also helped to reach its optimum operating temperature more quickly thanks to a new dual-passage cooling system that can reduce the volume of coolant flowing into the engine, when required. This helps improving efficiency during cold weather.
Further work has been done to reduce energy losses, particularly through eliminating friction. Measures include the use of thin-section, resin-coated connecting rod bearings and a low-friction camshaft chain. Friction created by the piston skirts, rotating parts and oil pump has been reduced and a new electric water pump has helped cut the level of losses.
Conical “beehive”-type springs have been adopted to reduce the valvetrain load. And, to ensure comprehensive improvement, the entire engine underwent CAE analysis to achieve the best rigidity and to reduce noise and vibration.
The intake and exhaust systems came under particular scrutiny, resulting in an engine that enjoys better breathing, air filtration, packaging efficiency, reliability and quietness. The air filter has been made smaller and reduced in height, which helped the designers bring down the line of the hood. The new intake system has a resonator that creates less noise at noticeable frequencies and the intake duct is made of a porous material that suppresses resonance.
A fresh air inlet duct has been added to make sure ample air volume is obtained at motorway speeds and a clever air/fluid separating structure has been added to keep water and snow from mixing with the intake air. Should the fresh air duct fill with water or snow, a secondary inlet serves as the air intake.
A thinner silencer secures optimum performance and noise reduction, while also improving the underbody aerodynamics and avoiding any intrusion on the space available in the trunk.
The engine block has V-shaped drilled paths that reduce losses in water jacket pressure. There is also a new water jacket spacer which helps control cylinder wall temperatures in the combustion chamber, reducing friction and preventing engine knock, which in turn supports optimum ignition timing.
Engine cooling has been improved with a new cooling module structure and attachment, and a redesign that accommodates a lower hood line and helps reduce the car’s centre of gravity. There is a new grille shutter behind the radiator which automatically closes when full airflow isn’t required, improving aerodynamic performance and saving fuel.
While engine cooling helps improve anti-knock performance, it can lead to an increase in cooling heat loss. To help counter this, Toyota engineers have developed a new water jacket spacer to control temperature on the surface of the cylinder. This keeps engine oil warmer with lower viscosity and reduces the temperature fluctuation. This helps reduce friction and allows more engine torque to be generated. At the top end of the temperature scale it reduces temperatures in the combustion chamber.
The engine’s maximum output of 98 DIN hp/72 kW is delivered at 5,200 rpm, with peak torque of 142 Nm at 3,600 rpm.
World-best thermal efficiency
Thermal efficiency is a measurement of how well an engine converts the energy available in its fuel into usable energy to power the vehicle.
As a result of the large-volume exhaust gas recirculation system, improvements in combustion efficiency and innovative ways of managing heat and reducing friction, the new engine has a maximum 40 per cent thermal efficiency, the highest level in the world for a mass-produced petrol engine. This surpasses the 37 per cent of the first Prius’ 1.5-litre unit and the 38.5 per cent level of the 1.8-litre engine in the third generation Prius.
Improved exhaust gas recirculation
The exhaust gas recirculation system has an EGR cooler which lowers the temperature of the gas being circulated, thereby reducing the temperature of the intake mixture and reducing risk of engine knock. This allows ignition timing to be fully optimized, which contributes to better thermal efficiency.
Multi-shaft transaxle – a hybrid first
The new generation hybrid system has a redesigned transaxle that offers more efficient performance and packaging and reduced weight. A gear train with the two electric motor-generators placed on multiple axes has been adopted to shorten the overall length by 47 mm compared to the previous generation hybrid system.
The transaxle houses four components: two electric motor-generators (MG1 and MG2); a single planetary gear; and a reduction gear to the final drive. MG1 serves primarily as a generator, converting any surplus power from the petrol engine into electricity, which can be stored in the HV battery. It also serves as the engine’s starter motor. MG2 is the electric drive motor, which also acts as a generator when the car is in regenerative braking mode. It drives the car from start-up, at low speed and in EV (electric vehicle) mode and is the sole propulsion method when the vehicle is in reverse.
Improved hybrid software
Updates to the hybrid system software allow the Toyota C-HR to draw more on its electric drivetrain, allowing it to accelerate in a low engine rev range. It also has permitted the speed range of the electric motor (the range in which the electric motor can be used exclusively) to be increased by 60 per cent, compared to the third generation Prius. This means there is less dependency on the petrol engine at higher speeds, improving fuel economy.
Smaller, better electric motors
The two motor-generators are all-new and are smaller and lighter than before to suit the new multi-shaft transaxle design, with no negative affect on fuel economy.
Higher motor speed and new forced water-convection cooling in place of air cooling improve the efficiency of the electric-drive motor (MG2), which delivers 53 kW of power and 163 Nm of torque.
Fully redesigned power control unit
The power control unit (PCU) has been totally redesigned, resulting in a 33 per cent reduction in size, a six per cent weight saving and a 20 per cent reduction in electrical losses.
The PCU is the multi-purpose electrical heart of the vehicle, housing the inverter/voltage booster, a DC/DC converter for auxiliary power and the electronic control for the motor-generators.
In place of a belt-driven alternator the Toyota C-HR uses a DC/DC converter to recharge the 12-volt auxiliary battery by using the HV battery energy.
Nickel-metal Hydride HV battery
The nickel-metal hydride (NiMH) battery is more compact, and is located entirely beneath the rear seats, avoiding any intrusion in the load space. It has increased cooling efficiency and a wider regeneration range.
1.2T ENGINE: GOOD PERFORMANCE AND LOW CONSUMPTION
The 1.2T engine uses advanced technologies that allow the engine to change from the Otto-cycle to the Atkinson cycle under low loads, it has vertical vortex high tumble air flow intake ports, an exhaust manifold integrated in the cylinder-head and advanced heat management. To this, the 1.2T adds a direct injection system, as well as a water-cooled turbo and heat-exchanger. Furthermore, the VVT-i (Variable Valve Timing – intelligent) system known from the Aygo and Yaris 1.0 engine, is upgraded to a VVT-iW (Variable Valve Timing - intelligent Wide) system, which allows even more flexibility in the valve-timing.
The combination of these technologies results in outstanding performance and efficiency. For a displacement of 1.197cm3, the engine delivers 116 DIN hp (85kW) and a constant torque of 185 Nm between 1.500 and 4.000 rpm. It will push the Toyota C-HR from 0 to 100 km/h in 10.9 seconds and the top speed is set at 190 km/h. All of this is achieved despite a strong focus on fuel consumption and CO2 – the car achieves 5.5/100 km on the combined cycle, and delivers just 125g/km of CO2.
Advanced heat management
The key to achieving outstanding fuel consumption without compromising performance, is to apply a higher compression. But generally, as the compression increases, so does the risk of uncontrolled combustion, also known as knocking.
The 1.2T’s high compression ratio of 10:1 was made possible thanks to the adoption of a series of key technologies that improve control over the combustion process. That way, the risk of knocking could be avoided.
First of all, the intake ports have been designed to generate a more intense flow and a ‘vertical vortex’, and also the shape of the piston has been optimized to improve in-cylinder turbulence. As a result, fuel and intake air mix faster, and a more homogeneous mixture is formed. This leads to a higher combustion speed – which helps prevent knocking.
Advanced heat-management is in itself a great way to improve fuel economy, but it is also another way of reducing the risk of knocking. The engine was designed in such a way, that the temperature of each individual part can be optimized. For example, the bottom of the pistons is cooled by oil-jets and the cooling of the cylinder head is separated from that of the engine block. This allows to reduce the temperature in the combustion chamber, whilst keeping the block itself hot enough to reduce friction.
Direct injection contributes as well, as it helps to dissipate the heat in the combustion chamber. And the charge air passes through the intercooler, which uses an independent low temperature cooling circuit.
Low-end torque and quick response
A low-inertia turbocharger, the VVT-iW valve system and the D-4T direct injection system work hand in hand to ensure excellent torque delivery from the lowest engine speeds. Together with the limited volume intake system, this ensures an immediate response to the accelerator pedal.
The injection system has been newly developed for the 1.2T engine. Compact in design, it is perfect for utilisation in a small displacement engine. It allows multiple injections per cycle, and the optimized width and reduced length of the fuel spray ensure the quality of the combustion, regardless of the engine regime and load.
From Otto to Atkinson
The VVT-i (Variable Valve Timing - intelligent) system operates on both the intake and the exhaust side, and allows maximizing torque at all engine speeds. In addition, the new VVT-iW (Variable Valve Timing - intelligent Wide) allows for the intake valve closing to be delayed, which means that the engine can operate in both the Otto and the Atkinson cycle. The latter is used in extremely low load conditions, when the intake valve remains open for a fraction of time, after the compression stroke has set in, allowing part of the gas charge to be pushed back into the intake. As a result, the effective compression stroke is shortened. Pumping losses are reduced, since the pressure on the piston is lower, and also the throttle valve can be opened wider.
Quick and smooth Stop & Start
A new start control was developed to ensure a quick and smooth engine restart. When the system shuts down the engine, it controls the stop position to leave the piston half way in the compression stroke. Then, upon restart, it applies stratified injection in the first compressed cylinder to counter vibrations. And by retarding the ignition, torque increase is kept in check, preventing the engine from revving excessively, hence ensuring a confident and tranquil take-off.
Like a heel/toe master:
Intelligent Manual Transmission
For the first time in the Toyota range a new system called “Intelligent Manual Transmission” is fitted to the Toyota C-HR 1.2T. Just like a heel/toe master, the system automatically increases the engine revs when downshifting ensuring a smooth gear shift. The system also works when shifting up in order to improve comfort for driver and passengers by reducing clutch shock. A smooth start is also ensured and the risk of stalling is almost null – particularly good news for all the learner-drivers out there.