SCANIA OPTICRUISE : Introduction to Scania Opticruise - Fully automated gearchanging

The new Scania Opticruise for buses and coaches is fully automated, relieving the driver of all work related to gearchanging en route. Electro-hydraulic clutch control is used for maximum smoothness and precision. The new gearchanging strategy is fine-tuned to give passengers a relaxed ride and several new functions are integrated to further ameliorate comfort.

An automated gearchanging system benefits drivers, passengers and operators in several ways. Besides improving comfort and eliminating the need to watch revs and change gears, it enables the driver to devote more attention to handling the vehicle and to other traffic. Familiarisation is quick and safe and economical driving is easy and consistent. Wear-and-tear is reduced on the clutch and other powertrain components, increasing service life.

SCANIA CAB INTERIOR : OPTICRUISE AND RETARDER LEVEL

SCANIA OPTICRUISE : FULLY AUTOMATED ELECTRO - HYDRAULIC CLUTCH 

Scania Opticruise, one of the first automated gearchanging systems in the market, has been refined in many steps over the years. After four years of development, the concept of a standard mechanical gearbox remains, but the system has been extensively modified, with improved mechanical components and entirely new software.

• A new automatic clutch control system replaces the system with a clutch pedal.
• The automatic clutch has a high-precision electro-hydraulic control system, which is an industry first.
• Manoeuvring mode provides extra fine clutch control, accelerator resolution and smoother engine control, for example during sightseeing or precision manoeuvring on a ferry.
• The automatic clutch is disengaged briefly during gearchanges, making shifts faster and smoother.
• Comprehensive electronic protection keeps clutch wear to a minimum.
• Scania Opticruise is introduced on Scania’s 8- and 12-speed gearboxes, starting in combination with Euro 5 and EEV engines. The 12-speed can be specified with overdrive for extra relaxed cruising.
• Hill-hold is standard.
• A new shift strategy strives to maintain speed uphill with early downchanges, if needed.
• Gearchanging adapts to the individual driving style, the load and the inclination of the road.
• A new Power mode is available for extra performance.
• The driver interface remains the same, with all gearchanging and retarder control functions integrated in the RH steering wheel lever, leaving the floor and driver seat uncluttered.
• Several parameters can be adjusted by any Scania workshop to customise the functionality.

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All controls in one lever

Scania Opticruise

• Mode selector: R-N-D. Power mode has a spring-back position.
• Automatic/manual gearchanging: Switch at tip of lever.
• Upchanging/downchanging: Pull lever towards or push away from steering wheel.
• Manoeuvring mode: Push lever away from steering wheel for 0.8 s at low speed or stationary.
• Floor switch: Triggers downchanging for maximum engine and exhaust braking without engaging retarder.

GEAR INDICATOR IN CENTRAL DISPLAY 

• R, Reverse
• A, Automatic
• M, Manual
• AP, MP, Automatic/Manual Power mode
• Letter followed by current gear in display, e.g. A12, M12, AP9, MP9.
• N, Neutral
• Next gear indicated in A and P modes.
• Manoeuvring mode indicated by ‘m’ after gear in display, e.g. A1m.

Scania Retarder

• Pull the lever downwards (five positions) for retarder braking. Exhaust brake engaged in the fifth position.
• Automatic application via brake pedal: Set the AUT switch on the lever to 1 (see illustration).
• In automatic retarder mode, brake blending is used to give the expected braking power also during downchanges. The wheel brakes are automatically applied to maintain smooth and even braking.

Hill-hold

• Works uphill and downhill.
• When stationary, the wheel brakes will remain applied for around three seconds while lifting the foot from the brake pedal (audio and visual warning activated).
• When depressing the accelerator, the hill-hold will not release until torque is sufficient to prevent the vehicle from rolling back.

New software

The gearchanging strategy has been re-developed from scratch to provide improved functionality, comfort and convenience, as well as capacity for future refinements.

Strategy and hill performance

• Automatic, Manual, Power and manoeuvring modes.
• Automatic mode is programmed to change down early on hills to maintain speed without wasting fuel. This is sensible because of the high efficiency of Scania engines at high load, irrespective of engine revs.
• Power mode is adapted for maximum engine performance and has a spring-back position for engagement and disengagement.
• The gearchanging strategy is continually adapted to the position of the accelerator pedal and the response is matched to the speed of pedal movement to suit the driver’s mood.
• Skip-shifts are made whenever possible to save fuel.
• Lower engine revs are used to save fuel with a light load.
• Kickdown additionally provides immediate access to maximum power. A downchange is made if this gives access to more power, including when running against the speed limiter.
• Downchanges are avoided if the downhill speed can be maintained by the retarder.
• Radar information from ACC (adaptive cruise control) is used to adapt gearchanges to the speed of the vehicle in front.

Manoeuvring and low-speed driving

• High-precision manoeuvring is possible in standard driving mode thanks to the electro-hydraulic control of the automatic clutch.
• The manoeuvring mode provides extra precision for example for sightseeing and in other exceptional situations.
• Manoeuvring mode is disengaged automatically in high range or if the lever is pulled towards the steering wheel.
• The clutch is disengaged when braking from low speed, e.g. for a junction, roundabout or stoplight. The system continuously prepares for the most suitable gear, which is immediately engaged when the accelerator is depressed.
• Running the vehicle at idling speed is possible in normal mode, interrupted by depression of the brake pedal. Running at idling speed is disabled in manoeuvring mode.

Load sensing and starting

• Load and inclination sensors automatically adapt the choice of starting gear. No action is required from the driver.
• Interaction between Scania Opticruise, launch control and clutch protection systems will maximise clutch life.

Rocking

• Rocking is possible in forward or reverse gears.
• The system identifies the need for rocking by comparing the rotation of the drive wheels with that of the front wheels.
• In rocking mode, quickly releasing the accelerator will immediately disengage the clutch, enabling the vehicle to roll back for a new attempt.
• Extra smooth rocking is available in manoeuvring mode (useful in ultra-slippery conditions), as well as extra smooth power delivery once the vehicle gets underway.

Clutch control system

The electro-hydraulic actuator for the automatic clutch is mounted on the gearbox. The unit consists of an electrical motor that pushes the piston of a hydraulic master cylinder. The hydraulic fluid moves a slave cylinder that actuates the fork inside the clutch housing. The clutch itself is completely standard, so is the gearbox.

Inside the actuator, an electric motor drives a ball-bearing spindle, which positions the hydraulic master cylinder. The ball-bearing spindle mechanism provides high controllability and extreme precision.

The automatic clutch operates independently of driver skills and is programmed to engage at the lowest possible engine revs. Clutch actuation is also adapted to the information from the inclination sensor and to the required starting gear.Hence, the engine speed is raised if needed to pull away cleanly.

The engine management system ensures that the clutch is never slipped during gearchanges, only used to disconnect the gearbox from the engine. These functions will effectively protect the clutch and other powertrain components from mechanical abuse.

Hill-hold, which engages briefly after depression of the brake pedal when stationary, makes starting even more convenient.

The electro-hydraulic control of the automatic clutch is unique in the industry, offering the benefit of particularly precise clutch actuation.

Adaptations

The functionality of Scania Opticruise can be altered by the driver via the instrument cluster or using the electronic diagnostics tool used by all Scania service workshops.

The driver can programme the following parameters:

• Enable/disable adaptive starting gear.
• Programme default starting gear.

Scania workshops can adjust the following parameters:

• Maximum permitted starting gear.
• Manual override of programmed starting gear enabled/disabled.
• Power mode enabled/disabled.
• Kickdown enabled/disabled.
• Reversing at low idling speed enabled/disabled.

Service aspects

Scania Opticruise is integrated in the gearbox cover of a completely standard 8- or 12-speed Scania gearbox, with or without the Scania Retarder.

The clutch is also a standard unit. Only the external actuation system differs from that of a standard clutch.

This philosophy will secure parts and service availability wherever a vehicle is working. Workshop staff will be fully familiar with the components and have all tools needed. The only items that are special with Opticruise are the gearbox cover with pneumatic shift controls and the electric actuator for the automatic clutch with integrated inclination sensor.

In case of clutch failure, a limp-home facility is provided. Automatic gearchanges are then made without using the clutch (normal operating mode of the system with a clutch pedal). Starting is possible using the ignition key and starter motor. The vehicle is brought to a standstill by turning off the ignition.

Milestones – automated gearchanging

Scania Opticruise is an in-house development that automates gearchanging using a standard mechanical gearbox. The only unique component on the gearbox is a special gearbox cover that incorporates pneumatic shift cylinders and position sensors. This concept has far-reaching benefits in terms of chassis installation (which is identical to a manual gearbox), bodybuilding and power take-off installation. Extensive parts commonality facilitates servicing and repairs, and makes trucks, buses and coaches with Scania Opticruise familiar to any Scania service technician.

Since it was originally unveiled for trucks in 1994, close to 150,000 trucks, buses and coaches worldwide have been delivered with Scania Opticruise, making it the pioneer and one of the most widespread automated gearchanging systems in the market.

1970s: Pneumatic gearchanging in laboratory test rigs. New computer-controlled gearchanging test rigs were developed. The idea was born: “Why not put it in a truck?”

1980s: Computer-Aided Gearchanging (CAG) launched in 1984, breaking new ground. Best gear calculated, engaged automatically when driver declutched. In the late 1980s, computerised gearchanging experiments were initiated. These trials also included the Scania Retarder, which was then under development. Control of the retarder was integrated. Some tests were made with an automated clutch, as well as with torque converter.

1990s: In the early 1990s, Scania applied for a large number of patents on two in-house developments: an auxiliary braking system (retarder) and an automated mechanical gearchanging system. The patents included a large number of software features, indicating the strong potential of electronic control systems.

The Scania Retarder was introduced in 1993, becoming the first system of its kind with automated downhill speed control and with the retarder function integrated in the brake pedal.

In 1994, large-scale field tests on trucks started on Scania Opticruise. The automated gearchanging system was presented to the press at an event in Angers, France in December. The public launch took place one year later in conjunction with the introduction of the Scania 4-series trucks. The 8-speed version was introduced on the bus and coach range launched in 1997.

2000s: By the turn of the millennium, Scania Opticruise had established itself as the best-selling automated gearchanging system in the market. Continuous improvements were made, with significant steps taken to refine the gearchanging strategy in conjunction with the introduction of the R-series in 2004, the new gearbox generation and Euro 4 engine range in 2005 and the new Euro 5 EGR engine platform in 2007. A 12-speed version for buses and coaches followed on the new bus and coach generation introduced in 2006, including optional overdrive. The fully automated version became the only option from the introduction of new Scania Opticruise in late 2009.

Pic and Info courtesy / Excerpts from : www.scania.com