Volvo Cars introduces Twin Engine technology in world’s most powerful and cleanest SUV
Volvo Cars introduces Twin Engine technology in world’s most powerful and cleanest SUV
The first Volvo designed from the ground up for plug-in/electrification compatibility, the XC90 T8 delivers all the performance of a luxury SUV, but with emission levels that even small hybrid cars struggle to match.
When designing the XC90 T8, Volvo Cars chose not to compromise on performance, driving pleasure, efficiency or even luggage space. By building on the new modular Scalable Product Architecture (SPA) platform and successful Drive-E petrol powertrain, the company has created a uniquely roomy 7-seater SUV that delivers 400hp/640Nm combined with ultra-low emissions (59g/km) and high fuel efficiency (2.5 l/100km). The fuel economy according to the U.S. driving cycle is 59 MPGe.
“The XC90 T8 is a plug-in electric car, hybrid car and high-performance car rolled into one,” says Dr Peter Mertens, Senior Vice President Research and Development of Volvo Car Group. “The Drive-E engines already offer highly competitive performance versus the competition. The T8 takes it further into a leading position.”
A driving mode for every need
The XC90 T8 can go from 0 to 100km/h (62 mph) in 5.9 seconds, delivering all the driving pleasure customers have come to expect from a Volvo SUV. But driving pleasure is only a fraction of what the XC90 T8 offers: the car has five different driving modes that deliver a range of performance and efficiency-enhancing characteristics. Using either a scroll wheel on the center console or a touchscreen on the dashboard, drivers can choose from:
Hybrid: This is the default mode, suitable for everyday use. Here, the vehicle will automatically alternate between drawing power from the 2-liter, 4-cylinder Drive-E engine and the electric motor to deliver the best overall fuel consumption.
Pure electric: In this mode, when the high-voltage battery is fully charged, it serves as the car’s sole energy source, powering the electric motor over the rear axle. The XC90 T8 has a range of more than 40km using just electricity, which covers the total distance most people drive in one day. And thanks to the regenerative braking system, this mode is super-efficient in the stop-and-go traffic of city environments. If more power is needed, the Drive-E combustion engine starts up automatically.
Power mode: Here, drivers get the combined performance of the combustion engine and the electric motor. On start-up, the SUV takes advantage of the electric motor’s superior response and instant torque curve, while the combustion engine gets up to speed. This combination offers better torque at lower revs, equivalent to that of a large displacement engine like the V8.
AWD: This mode offers constant all-wheel drive on demand. The advantage of being able to select AWD manually is that the driver can use it when needed, or choose to save energy for later.
Save: If the battery is charged, this mode allows the driver to “freeze” the battery level and save it for later use with Pure Electric drive. On the other hand, if the battery is low, the driver can use the combustion engine to charge the battery to a certain level for later use with Pure Electric drive.
Under the shell
Many of the XC90 T8’s powertrain features have been optimized specifically for hybrid technology. Here are the main components of the system:
A specially modified version of the 4-cylinder Drive-E gasoline engine is under the hood. Already known for its ability to more efficiently deliver the power of an engine twice its size, the Drive-E engine is enhanced in the XC90 T8 by a supercharger and a turbocharger for a total power output of 318hp and 400Nm torque.
The 8-speed automatic gearbox has also been specially adapted for the hybrid: shift-by-wire technology allows drivers to control the transmission electrically (a luxurious touch is the gearshift as made of handmade Swedish crystal). A larger oil pump provides the necessary lubrication during electric drive and enables quicker pressure build-up when seamlessly going from electric to combustion drive.
The crankshaft-mounted starter generator (CISG), located between the engine and the gearbox, performs three important functions: it is a powerful, 34kW starter motor that allows the car to go from pure electric drive to combination combustion drive seamlessly, so drivers can experience the car’s petrol engine and electric motor as one unit; it is also a powerful electric generator; and finally, it acts as an electric engine booster, working with the supercharger and turbocharger when extra power is needed, providing up to 150 Nm of extra torque.
The high-voltage (270–400V) battery, delivering 65kW of power, is an excellent example of Volvo’s success with the XC90 T8. While other carmakers have struggled to combine the bulk of a battery pack with a luxurious and spacious interior, Volvo has managed to overcome this challenge by placing the battery centrally in the tunnel of the car. There are several advantages to this position. For example, the battery does not impact the amount of available space inside the car. This means that there is room for three rows of seats – plenty of space for people and luggage. Furthermore, the battery placement gives the SUV a low and central center of gravity, making the XC90 T8 easier to handle and safer to drive.
Rear electric motor
Delivering 82hp (60kW) and 240Nm torque, the large electric motor sits on the rear axle and drives the back wheels in electric and power-boost modes. The rear placement is significant because it allows for a larger motor, which is useful for following stop-and-go city traffic rhythms. This placement also makes efficient all-wheel drive possible because each axle has its own power source.
Two-step braking system
The XC90 T8 blended braking system partly uses brake-by-wire technology to recover and transmit energy back into the car, either to recharge the battery or for immediate use. The system is also equipped with a unique stability function that controls the amount of energy that may be safely regenerated.
Unique cooling and climate system
The unique cooling system is composed of two extra circuits. The first cools the CISG and the large electric motor on the rear axle, while the second cools the battery in one of two ways: either passively, via the radiator, or actively through integration with the car’s climate system.
For convenience and efficiency, drivers can pre-condition the XC90 T8’s drivetrain, battery and cabin, either directly from within the car or by using the Volvo On Call mobile app. This ensures that, whether it’s freezing or hot and humid outside, the car will be heated or cooled as necessary and ready to go by the time the driver enters. Pre-conditioning can be done while the car is plugged in, which is beneficial from a CO2 perspective since it ensures that the battery will last as long as possible in Pure Electric Drive mode.
A heritage of innovation
As the world’s most powerful and cleanest SUV, the XC90 T8 joins a long list of Volvo Cars innovations designed to create a more comfortable driving experience, a cleaner environment and safer roads.
City Safety by Volvo Cars – outstanding crash prevention that is standard in the all-new XC90
Starting with the all-new Volvo XC90, City Safety becomes the umbrella name for all of Volvo Cars’ auto brake functions. The continuously enhanced collision-avoidance and mitigation technologies, which are standard in the XC90, include yet another Volvo world first: automatic braking if the driver turns in front of an oncoming vehicle.
“City Safety is one of the most advanced standard crash prevention offers you can find in a modern car. It addresses vehicles, cyclists and pedestrians in certain situations, day and night,” explains Prof. Lotta Jakobsson, Senior Technical Specialist Safety at Volvo Cars Safety Centre.
As the leader in automotive safety, Volvo Cars has been pioneering auto brake technologies since the first-generation standard brake support was introduced in 2006. Among the groundbreaking technologies is the first-generation City Safety, which was introduced as a low-speed auto brake solution in 2008.
Now, City Safety takes on an extended, all-new role as the umbrella name for all Volvo Cars’ auto brake functions. The system is active at all speeds from 4 km/h (2.5 mph).
Auto brake at intersections – a world first
The auto brake at intersections is a world first that deals with a situation that is a common scenario at busy city crossings as well as highway crossings, where the speed limits are higher.
“Our studies of accident data from this accident type show that an important number of these crashes could have been avoided or mitigated if the turning vehicle had been equipped with auto brake. The solution is yet another example of how our new technologies target substantial real-life traffic problems. This strategy moves us closer and closer to our ambition that by 2020 no one should be killed or seriously injured in a new Volvo,” says Lotta Jakobsson.
City Safety auto braking functions
The purpose of the advanced crash avoidance system is to assist the driver through an intuitive warning strategy and a brake support system. If a collision is imminent, the system will provide automatic braking when the driver fails to respond to the imminent threat. The focus is on avoiding the collision entirely or reducing the car’s speed as much as possible prior to the impact. City Safety addresses:
• Oncoming vehicles, including motorcycles and cycles, when the driver turns left (or right in left-hand traffic). City Safety detects a potential crash and brakes automatically in order to avoid a collision or mitigate the consequences of a crash.
• Vehicles, including motorcycles, travelling in the same direction. City Safety is able to avoid a collision if the relative speed difference between the two vehicles is up to 50 km/h (31 mph). At higher speeds, the automatic braking helps to reduce the consequences of the collision.
• Cyclists crossing the path of the car or suddenly swerving out in front it. Depending on the situation, City Safety is able to avoid a collision if the relative speed difference is up to 45 km/h (28 mph). At higher speeds, the automatic braking can mitigate the consequences of the collision.
• Pedestrians walking out in front of the car. City Safety is able to avoid a collision at speeds up to 45 km/h (28 mph). At higher speeds, the automatic braking can help mitigate the consequences of the collision.
Detection also in darkness
City Safety is based on a combined camera and radar unit integrated at the top of the windscreen, in front of the interior rear-view mirror. The latest technology upgrade is a smarter and faster high-sensitive, megapixel image camera combined with advanced exposure control. This makes the detection and auto brake technology work effectively also when driving in darkness.
The radar’s task is to detect objects in front of the car and to determine their position and movement, and the distance to them. The camera identifies what type of object it is. The technology continuously monitors the object – and a central control unit uses the camera and radar data to evaluate the risk of a collision and to initiate the most efficient counteraction.
In an emergency situation, the driver receives an audible alert combined with a haptic warning in the shape of a short braking pulse and a light flashing on the lower part of the windscreen.
If the driver reacts to the warning and starts braking, the system is programmed to automatically ‘fill up’ with more braking power if necessary. If the driver does not react at all, the auto brake is activated. Full braking power is applied approximately 1.0 seconds before impact.
Avoiding real-life accidents
“Statistics show that about 90 percent of all accidents are caused by distracted drivers. Since City Safety remains alert even if the driver is distracted or tired, it helps to bring collision figures down considerably. We have, for instance, seen a documented reduction in frontal collisions in low-speed car-following situations by over 20 percent*,” says Lotta Jakobsson. She concludes: “Our aim is of course to continuously extend the City Safety auto brake technologies to cover more objects and traffic situations.”
The all-new Volvo XC90 addresses dangerous run-off road crashes with world-first solution (video)
The standard safety package in the all-new Volvo XC90 includes a world-first run-off road protection package. Addressing these common and complex situations will take Volvo Cars another step closer to its vision that no one will be killed or seriously injured in a new Volvo car by 2020.
“Our solution focuses on keeping the occupants firmly in position and introducing unique ‘energy-absorbing’ functionality in the seat. This counteracts spine injuries, which are serious and relatively frequent consequences of run-off road scenarios,” says Prof. Lotta Jakobsson, Senior Technical Specialist Safety at Volvo Cars Safety Centre.
Run-off road is a common accident type with different causes, such as driver inattentiveness, fatigue or poor weather conditions. For example, half of all traffic fatalities in the United States are road departure crashes, while in Sweden, single-vehicle accidents involve one-third of all fatal and severe injury crashes with passenger cars.
Run-off road crashes are also very complex situations in which occupants often move in random directions – which puts high demands on the interior restraints.
Not covered by any rating program
There are not yet any regulatory or rating tests to examine a car’s ability to handle run-off road crashes. “Committing to safety is not about passing a test or getting a ranking,” says Lotta Jakobsson. “It is about finding out how and why crashes and injuries occur and then developing the technology to prevent them. To reach our Vision 2020, we have to cover all accident types that occur in real-life traffic.”
Spine injuries common in run-off road scenarios
Injury trends in car accidents have changed over the years. A continuous development of car structure and implementation of different specialized safety systems have resulted in significant improvements in car safety over the past few decades. The risk of being seriously injured or killed in a new Volvo has been reduced by more than two-thirds compared with cars designed in the 1970s.
However, in contrast to this significant overall injury risk reduction, the frequency of thoracic and lumbar spine injuries has not been reduced to the same extent – and these injuries are over represented in run-off road scenarios, multiple impacts and multiple events.
“Studying our own extensive accident data, we discovered that the occupant’s posture during the load transfer through the spine is an important factor. In several of the cases, great occupant flexion was seen as an influencing factor. Anterior wedge fractures, resulting from a combination of axial load and flexion, are the most common spine injury in run-off road events together with compression fractures,” says Lotta Jakobsson.
Tightening belts and cushioning impact
The run-off road protection solution in the all-new XC90 includes two vital parts:
• Using input from the car’s advanced sensor system, the technology is able to detect a run-off road scenario. The front safety belts are electrically tightened as much as possible to retract and keep the occupants in position. The pulling capacity of the safety belt retractor is 1 mm/ms – which means it can retract 100 mm safety belt in only 0.1 seconds. The belts are firmly tightened as long as the car is in motion.
• To help prevent spine injuries, energy-absorbing functionality between the seat and seat frame deforms mechanically to cushion the vertical forces that can arise when the car encounters a hard landing in the terrain.
“By keeping the occupant in an upright posture while cushioning the impact, the vertical forces he or she is exposed to can be reduced by up to one-third. This helps to considerably lower the risk of the most serious and frequent spine injuries in these situations,” says Lotta Jakobsson.
Three complete vehicle test methods
Based on real-life data, Volvo Cars has developed three complete vehicle crash test track methods, called ‘Ditch’, ‘Airborne’ and ‘Rough terrain’, for evaluating the consequences of various run-off road scenarios.
During the ‘Airborne’ method the vehicle runs off the road at, e.g., 80 km/h. After the initial free flight, the car lands on a smooth surface and continues onwards. The height difference is 80 cm, resulting in a hard impact on the wheels. This causes massive vertical forces of the same level as a fighter pilot is subjected to when using his ejection seat in an emergency.
The ‘Ditch’ test is designed to replicate the bouncing movement when driving into an 80 cm deep ditch and impacting an embankment, which causes high vertical forces. The ‘Rough road’ test creates a bumpy ride in the terrain, producing substantial lateral rolling motions in combination with vertical and longitudinal vehicle motions.
Crash test dummies are used to represent humans in the tests. The most advanced dummy is ‘Thor’, which is equipped with an enhanced flexible shoulder area to create more human-like movement in a run-off road scenario.
Unique test rig
In addition to complete vehicle crash testing, Volvo Cars has also developed a flexible and multi-purpose test rig to evaluate occupant positioning and occupant retention. A vehicle seat and restraint system is mounted on a multi-axial industrial robot. The robot, which is used together with a crash test dummy, can be programmed to simulate the occupant kinematics in each of the three test track methods, or any other variation of a run-off road crash. (The robot is described in a separate press release.)
Helping the driver avoid run-off road scenarios
“Of course, we are also focusing on supporting the driver with technologies that help prevent run-off road crashes from happening. Two specific systems in the all-new XC90, Lane Keeping Aid and Driver Alert Control, are targeting these situations,” says Lotta Jakobsson.
Lane Keeping Aid helps the driver stay on track by applying extra steering torque if the car is about to leave the lane unintentionally. Driver Alert Control detects and warns tired or inattentive drivers. In the all-new XC90, it is enhanced with a new Rest Stop Guidance, which directs the driver to the nearest rest area.