Major refresh on 2015 Honda CR-V with new Earth Dreams powertrain provides fuel economy gain of up to 12%
|2015 Honda CR-V. Click to enlarge.|
Honda has given its 2015 CR-V compact SUV, which launched in US dealerships on 1 October, the most significant mid-model cycle refresh in the 17-year history of the model. The 2015 CR-V offers a new direct-injected Earth Dreams Technology i-VTEC engine and new continuously variable transmission (CVT); a new suite of “Honda Sensing” safety and driver assistance systems (DAS); significantly enhanced exterior and interior styling; as well a long list of new standard and available features and a new premium Touring trim.
The 2015 CR-V features increased EPA fuel economy ratings of 27/34/29 mpg (8.7/6.9/8.1 l/100 km) (city/highway/combined) for front-wheel-drive models and 26/33/28 mpg (9.0/7.1/8.4 l/100 km) for Real Time AWD models, both increasing +4/+3/+3 mpg over 2014 models—i.e., an increase in the combined rating of 11.5% and 12%, respectively, compared to the 2014 models.
The 2015 CR-V’s new Earth Dreams Technology 2.4-liter direct-injected DOHC i-VTEC inline 4-cylinder engine produces 181 lb-ft (245 N·m) of torque, an 11% increase over the previous engine’s 163 lb-ft (221 N·m) while making the same 185 horsepower (138 kW).
|Under the hood. Click to enlarge.|
Cylinder block, crankshaft and pistons. The CR-V’s 2.4-liter engine has a lighter-weight die-cast aluminum cylinder block with a main-bearing single cradle design that creates a rigid assembly to help minimize noise and vibration. Cast-in iron cylinder liners provide long-lasting durability. Each journal on the forged-steel crankshaft is micro-polished to reduce internal friction. To improve smoothness throughout the rpm range and help lower noise levels, the CR-V is fitted with an internal balancer unit. Consisting of a pair of chain-driven counter-rotating shafts located in the oil pan, the balancing system helps quell the inherent second-order harmonic vibrations that normally impact inline 4-cylinder engines.
To reduce piston-sliding friction, the cylinder bores are offset by 8.0 mm from the crankshaft. This gives the connecting rods a more favorable angle during each power stroke, which reduces side loading on the pistons and in turn, improves efficiency. The engine also features a forged crankshaft for high rigidity and low friction. With four smaller-diameter counterweight and four larger-diameter counterweights, the crankshaft offers optimized flywheel effect while minimizing total weight.
|The Honda CR-V was the best-selling compact SUV with individual American buyers in 2013, according to new-vehicle registration data compiled by IHS Polk. CR-V sold 303,904 units in 2013 (+7.9%), joining Accord and Civic as Honda’s above-300K unit sellers.|
Lightweight pistons have a carefully optimized skirt design to minimize reciprocating mass, and reduced weight minimizes vibration and increases operating efficiency. The piston crowns are dished to help maintain stable combustion and to optimize distribution of the stratified fuel charge from the direct injector in each cylinder. This close control over the combustion process boosts overall operating efficiency.
Cylinder head and valvetrain. A lightweight cylinder head made of pressure-cast aluminum alloy uses front-located exhaust ports that provide greater freedom in the layout of the close-coupled catalytic converter which mounts directly to the cylinder head. With exhaust passages cast directly into the cylinder head, the need for a traditional separate exhaust manifold is eliminated.
A silent-chain drives dual overhead cams and four valves per cylinder, and features a double-arm tensioner design that reduces operating friction. The cam drive is designed to be maintenance free throughout the life of the engine. To further reduce friction, the finish of the camshaft journals has been improved.
|CR-V in Europe: new diesel and 9-speed|
|The refreshed European version of the CR-V, currently being showcased at the Paris Motor Show and due on the market in 2015, offers a more powerful diesel engine as well as an optional efficient nine-speed automatic transmission.|
|A higher powered 1.6-liter i-DTEC four-cylinder diesel engine from Honda’s Earth Dreams Technology series replaces the previous 2.2 liter i-DTEC diesel.|
|When matched to the six-speed manual transmission the new higher powered diesel engine produces 160 PS (118 kW) and 350 N·m (258 lb-ft), while emitting a class-leading sub-130 g/km of CO2—an 11% improvement compared to the previous unit. With the new nine-speed automatic transmission, CO2 emissions are less than 135 g/km—20% better than its predecessor.|
|The two-wheel drive diesel CR-V, available with a manual transmission, will continue to be equipped with the 120 PS 1.6 liter i-DTEC diesel engine, now with emissions as low as 117 g/km.|
The combustion chamber shape and valve angles have been optimized to boost fuel efficiency and power. The previous-generation CR-V engine had a 51˚ included angle between the intake and exhaust valves; the new engine features an included valve angle of 35˚. The narrower valve angle decreases the surface-to-volume ratio and helps create a flatter, more compact combustion chamber that reduces unburned hydrocarbon emissions. With this new combustion chamber shape and the precise control of direct injection, the compression ratio has been increased to 11.1:1 (up from 10.5:1 on the previous port-injected engine), yet the engine still operates on regular unleaded fuel.
The cylinder head features a new high-tumble intake-port design. In combination with the new combustion chamber and piston crown shape, the design’s high level of airflow tumble helps create a homogenous fuel mixture for low fuel consumption and high airflow for high power output.
Friction-reducing technologies. The CR-V’s engine makes use of new friction-reducing technologies designed to improve engine efficiency. The outer skirts of the lightweight aluminum pistons feature a low-friction molybdenum coating applied in a unique dot-pattern. The result is reduced overall friction as the pistons move within the cylinder bores.
A process called “plateau honing” further lowers the friction level between the pistons and the cylinders by creating an ultra-smooth surface. Plateau honing is a 2-stage machining procedure that uses two grinding processes instead of the more conventional single honing process. This also enhances the long-term wear characteristics of the engine. Due to the ultra-smooth cylinder surface, low tension piston rings could be utilized, which reduce friction while maintaining sealing efficiency.
A low-friction cam chain and double-arm tensioner, improvement in the camshaft journal finish, and the use of low viscosity engine oil (0W-20) further reduce friction.
Weight savings. To increase overall vehicle efficiency, significant efforts were made to reduce the weight of the 2015 CR-V’s engine. Multiple components were redesigned to be lighter while still providing Honda’s renowned durability and efficiency. Chief among the changes is a more rigid yet lighter cylinder block.
Block weight was shaved by reducing the mismatched mating surface areas and deleting the breather passage; the cam chain chamber is used for breathing instead. Optimizing the shape of its skirt helped to remove weight from the pistons. A reduction in the diameter of four crankshaft counterweights, while increasing the diameter of the other four provides the same level of balancing while reducing weight.
A high efficiency accessory belt design saves weight with the elimination of the idler pulley, decreased diameter of the other pulleys, the adoption of a hydraulic auto tensioner, a resin tensioner pulley and decreased belt length.
The oil filter and fuel injector bases, oil gallery cap and compressor bracket were all eliminated with the components being mounting directly. Having one of the catalytic converters mounted directly to the cylinder head and integrated into the exhaust pipe shed further weight.
The utilization of a resin cylinder head cover, a press-fit water pump pulley, the secondary balancer being integrated with the oil pump, a compact high-output ACG (alternating current generator) and wire harness routing efficiencies and length reduction also reduced the overall weight of the new engine.
i-VTEC valve control system. The CR-V’s direct-injected 2.4-liter DOHC 16-valve i-VTEC engine uses an advanced valve-control system to combine high power output with high fuel efficiency and low emissions. The CR-V system combines Variable Valve Timing and Lift Electronic Control (VTEC), which varies valve lift, timing and duration of the intake valves, with VTC (Variable Timing Control), which continuously adjusts the intake camshaft phase. At low rpm, the VTEC intake valve timing and lift are optimized for rapid swirl-pattern cylinder filling. As engine rpm builds past 4800 rpm, the VTEC system transitions to a high-lift, long-duration intake cam profile for superior high-rpm engine power.
The “intelligent” portion of the system is its ability to continuously vary the timing (phasing) of the intake cam relative to that of the exhaust camshaft. This helps boost power and also provides a smoother idle (allowing idle speed to be reduced). The intake cam timing is varied based on input from sensors that monitor rpm, timing, throttle opening, cam position and exhaust air-fuel ratio. The result is increased fuel efficiency and lower NOx emissions.
Direct injection system. The CR-V’s engine incorporates direct-injection (DI) for 2015. The CR-V’s system features a compact high-pressure direct-injection pump that allows both high fuel flow and pulsation suppression, and variable pressure control optimizes injector operation. A multi-hole injector delivers fuel directly into each cylinder.
The multi-hole injectors create an optimized fuel/air mixture in the cylinders and also create a weak stratified combustion effect that maximizes fuel efficiency at lower power conditions. The stratified charge puts a mixture that’s richer near the spark plug for easy ignition, while other areas on the combustion chamber have a leaner fuel/air ratio.
Based on the operating conditions, the direct injection system alters its function for best performance. Upon cold engine startup, fuel is injected into the cylinders on the compression stroke. This creates a weak stratified charge effect that improves engine start-up and reduces exhaust emissions before normal operating temperature is reached.
Once the engine is fully warm for maximum power and fuel efficiency, fuel is injected during the intake stroke, creating a more homogeneous fuel/air mix in the cylinder that is aided by the high-tumble intake port design. This improves volumetric efficiency, and the cooling effect of the incoming fuel improves anti-knock performance.
Drive-by-wire throttle control. An electronic drive-by-wire system helps enhance the driving character of the CR-V. With smart electronics connecting the throttle pedal to the throttle butterfly valve in the intake manifold, the engine response can be optimized to suit the driving conditions and to better match the driver's expectations.
By eliminating the direct throttle cable connection to the engine, the ratio between pedal movement and the DC motor-controlled throttle butterfly can be continuously optimized. To determine the current driving conditions, the system monitors pedal position, throttle position, vehicle speed, engine speed and engine vacuum. This information is then used to define the throttle control sensitivity.
High-efficiency catalytic converters. Key contributors to the CR-V engine’s emissions performance are its high-efficiency catalytic converters. One converter mounts directly to the front of the cylinder head, close-coupled for fast activation after the engine is started. A second converter is positioned slightly downstream, beneath the passenger compartment floor. Both converters use a thin-wall design that increases internal reaction area and improves efficiency. A high-efficiency exhaust system and high-density catalytic converters help the CR-V engine meet LEV2-ULEV emissions certifications in California and Federal BIN5 certifications.
Multi-stage alternator control. To improve battery life and help reduce fuel consumption, the CR-V has a new multi-stage alternator control system. By closely monitoring the battery’s charge state, the system can adjust alternator output more precisely than the previous high/low mode system. This fine control reduces excessive charge or discharge and can help increase battery life by up to 30%. By inhibiting surplus power generation, the multistage alternator control along with other electrical system efficiencies contributes to an improvement in fuel efficiency.
Fuel system. The 15.3-gallon fuel tank is molded of high-density polyethylene for low weight, corrosion elimination and impact resistance. It is positioned immediately ahead of the rear wheels to help guard against collision damage. The corners of the tank are rounded and the inside of the tank is baffled to diminish the likelihood of sloshing-fuel noise. A lightweight and efficient fuel pump is housed inside the fuel tank. The fuel system also incorporates a returnless fuel supply system that helps reduce vapor generation, and a lifetime fuel-filter that requires no regular maintenance. The CR-V's minimum fuel grade requirement is regular unleaded.
Torque-rod engine mount system. A torque-rod engine-mount system enhances the CR-V’s quiet and vibration-free operation. The system resists the engine’s rotational torque inputs to the chassis, reducing idle vibration and mid- and high-frequency engine noise during acceleration.
Continuously variable transmission (CVT). The CR-V’s new Continuously Variable Transmission (CVT) offers seamless gear ratio transitions and excellent acceleration matched with efficient low-rpm cruising. The CVT has a 33% wider overall ratio spread than the 5-speed automatic transmission it replaces. This change results in strong acceleration performance coupled with reduced engine rpm at high road speeds. The highly efficient operation of the CVT contributes a significant improvement in overall fuel efficiency compared to the prior 5-speed automatic transmission.
The CVT comprises a torque converter which drives the variable-width drive pulley that is connected by a steel belt to the variable-width driven pulley. With its angled inner faces, the belt can circle the angled pulley faces at varying diameters depending on the pulley width, which alters the effective ratio between the pulleys. Since there are no steps in the pulley faces, the range of possible gear ratios is nearly infinite.
This ultra-fine control of the gear ratio is the key to the CVT’s greater efficiency over a conventional automatic transmission with a limited number of discrete gear ratios. Instead of approximating the correct ratio for the conditions as a conventional automatic does, the CR-V’s CVT can precisely select the optimum ratio from moment to moment without steps or slippage. To increase the efficiency of the interface of belt to pulleys, the coefficient of friction was improved by 10% with optimized metal contact allowing for less belt tension.
Computer control of the transmission allows the ratio between the pulleys to be altered almost instantly to best suit the driving conditions and accelerator pedal use.
A planetary gear set allows the transmission to shift between forward and reverse directions with the operation of a multi-plate clutch, with plates that have a 10% increase in surface friction. A variable-flow oil pump optimizes oil flow to the transmission’s moving parts while minimizing the load on the engine.
The CR-V’s CVT is more compact and lighter compared to a conventional CVT by utilizing metal gaskets, having a unit-type body construction and fewer parts through integration, such as the parking gear being integrated with the driven pulley and a function-consolidated stator. Compared to the previous generation’s 5-speed automatic transmission, the CVT has more compact dimensions (24 mm shorter) and has a higher torque capacity (up by 17%).
G-Design Shift. Honda announced the G-Design Shift along with a new CVT for mid-size vehicles in 2011. The G-Design Shift is a coordinated control system for gearing, throttle and hydraulic control that responds quickly to driver input, maintains strong and smooth acceleration G and helps realize an exhilarating and sporty driving feel. (Earlier post.)
The CR-V CVT is designed to provide the optimum gear ratio for the driving conditions and to offer a more natural driving feel than some previous CVT transmissions that have a disconnected “rubber-band” feel compared to a conventional automatic transmission; the CR-V also offers stronger acceleration response with a linear build in engine rpm that avoids much of the “slipping” feeling some drivers notice with other CVTs. The G-design Shift logic gives the CR-V a more linear and sporty driving feel.
The CR-V CVT’s G-design Shift logic is designed to offer more immediate acceleration response than either conventional automatics or other CVT designs. When abruptly applying power from a steady-state cruising speed, the CR-V CVT immediately sends power to the drive wheels while simultaneously adjusting the gear ratio (seamlessly and progressively downshifting) to smoothly bring the engine to its horsepower peak in a linear way.
By comparison, a conventional automatic is slower to respond and loses time making multiple downshifts. Since the automatic transmission has a limited number of separate, discrete ratios, even when fully downshifted, it can only approximate the optimum engine rpm as speed increases, which reduces acceleration efficiency.
CVT automatic modes. The transmission can be operated in three different fully automatic modes with the console-mounted straight-gate shifter. The D mode is ideal for most driving situations, and combines fuel efficiency with smooth operation and responsive power when needed. The S mode is for more performance-oriented driving, and features more aggressive transmission mapping to keep engine rpm higher for greater acceleration and response. The L mode is for lower speeds and provides additional engine braking.
ECON mode. All CR-V models are equipped with an ECON button on the left side of the instrument panel as part of the Eco Assist system. When activated, ECON mode alters the Drive-by-Wire throttle system response curve in the range from about 10% of pedal movement to 80%. With less gain, the throttle opening in this range increases more gradually to reduce a potentially excessive peak input for better fuel efficiency. ECON mode also alters the operation of the cruise control system and the air conditioning system, allowing for slightly increased variances with the set speed or the set temperature in order to conserve fuel whenever possible.
Real Time AWD with Intelligent Control System. The 2015 CR-V is offered with Real Time AWD with Intelligent Control System. System operation is completely automatic and virtually transparent in smoothness. Unlike some four-wheel-drive systems that require the driver to select a drive mode based on the perceived need, Real Time AWD’s automatic operation means the system is always ready to transfer torque to the rear wheels, allowing the driver to focus more on driving when situations are demanding.
The capabilities of the system are prioritized to further support high fuel efficiency and all-around drivability on-road as well as off-road. Assisting the front wheels when it is beneficial, Real Time AWD instantly powers the rear wheels when starting from a stop, even on dry pavement, working in cooperation with Vehicle Stability Assist (VSA) and the Motion-Adaptive Electric Power Steering (EPS).
The Real Time AWD system can operate at all speeds when needed. When torque transfer to the rear wheels is not required such as when cruising, drive to the rear wheels is decoupled for reduced drag.
The CR-V’s all-wheel drive system consists of the conventional front-wheel-drive system, a compact transfer case that distributes torque to a propeller shaft running the length of the vehicle; the rear differential; an electronically-controlled hydraulic pump; a multi-plate clutch; and left and right rear-wheel driveshafts.
The multi-plate clutch connects the propeller shaft to the rear differential and is operated by an electric motor driving a hydraulic pump. The electric motor is controlled by the Intelligent Control System, which means that the system can actively apportion power based on the conditions. The system doesn’t merely react to front wheel spin; it minimizes wheel spin before it happens by sending power to the rear wheels accordingly. For efficiency, the electric motor activating the hydraulic pump is idled when not required, further reducing drag within the system and helping to reduce energy consumption.
When starting on snow for example, the system sends power to the rear wheels right from the start, minimizing the potential for front wheel spin. The system can also detect when the CR-V is climbing a hill and sends a greater amount of power to the rear wheels in cooperation with the Hill Start Assist feature. Hill Start Assist maintains brake pressure briefly after the brake pedal is released, giving the driver time to accelerate and smoothly resume motion. The Intelligent Control System instantly assesses the road’s slope angle using a G-sensor and the level of grip as detected by VSA allowing added initial apportioning of torque to the rear wheels for smooth starts.
Suspension. An updated suspension design, and features such as Vehicle Stability Assist (VSA) and Motion-Adaptive Electric Power Steering (EPS) all contribute to the 2015 CR-V’s quality driving experience, which is enhanced further on the EX and above trims with wider front and rear track dimensions due to wider wheels (+0.5 inches).
The CR-V uses front MacPherson strut and rear multi-link suspension systems that benefit from tuning changes. The rear multi-link system helps maximize rear seating and cargo space while providing stable and comfortable handling and ride quality. Newly revised shock absorber tuning helps deliver a refined driving feel.
Safety and Driver-Assistive Technology. The CR-V’s next-generation Advanced Compatibility Engineering (ACE) body structure helps make the CR-V highly effective at absorbing and dispersing the energy of a frontal collision crash. Overall, the body received more than 60 changes to improve stiffness and collision performance. Honda is targeting the 2015 CR-V is targeted to achieve top safety ratings, including a TOP SAFETY PICK+ rating from the Insurance Institute for Highway Safety (IIHS) (it will need to improve its small overlap front score) and an NCAP 5-Star Overall Vehicle Score from the National Highway Traffic Safety Administration (NHTSA).
|Honda Sensing. Click to enlarge.|
Standard safety equipment on all models include Vehicle Stability Assist (VSA) electronic stability control system; Anti-lock Braking System (ABS) with Brake Assist; frontal airbags; side-curtain airbags; SmartVent front-side airbags; and a front seat design that can help reduce the severity of neck injury in the event of a rear collision.
The newly available Honda Sensing suite of safety and driver assistive features includes Honda LaneWatch; Forward Collision Warning (FCW); Collision Mitigation Braking System (CMBS); Lane Keeping Assist System (LKAS); and Lane Departure Warning (LDW).
These systems benefit from the adoption of new sensor fusion technology that integrates the capabilities of a windshield-mounted monocular camera and millimeter wave radar to provide enhanced sensing with ability to identify and anticipate multiple collision scenarios, including a pedestrian collision, and initiate warnings and, in some cases, emergency braking.
The CR-V is enhanced with multiple functionality upgrades, including a new configurable center console; new rear console heat/air ventilation ducts; and an available 7-inch touchscreen Display Audio telematics interface. For 2015, the CR-V includes a longer list of standard features on all trims. The CR-V EX, for example, adds 7-inch Display Audio, a 10-way power driver’s seat, heated front seats, Honda LaneWatch, Smart Entry/Push-Button Start and LED daytime running lights.