One of my neighbours has a horrible, yappy little dog that, when it's not barking at its own shadow, travels everywhere on the rear parcel shelf of her silver Honda Civic. I should dearly love to make toast of the dog but I guess I shall have to hope she upscales to a Civic Hybrid and let that do the job for me.
If she does, and the dog lays where it does now, I should soon be able to butter it. Beneath the Civic Hybrid's parcel shelf are the batteries and control unit incorporated into the so-called Intelligent Power Unit (IPU), which, because it gets hot, is cooled by a fan drawing air through vents in the shelf. Obstruct the vents and....woof! - or not, as the case may be.
It is the IPU that makes the Civic Hybrid what it is - a car powered by a combination of calories and current. The calories are derived from petrol, and the current is delivered by an electric traction motor - built into the engine. Unlike the Toyota Prius, which has a separate engine and motor connected to a common output shaft, the Honda Civic Hybrid's electric motor is sandwiched between the four-cylinder petrol engine and the CVT gearbox, with the rotor comprising a section of the crankshaft.
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Just six centimetres wide, the motor delivers a hefty boost of torque when the engine is at its least efficient - namely below 2500 rpm. As the engine speeds up, so the torque assist - which, because of the motor's construction, is applied directly to the crankshaft - begins to tail off, although to some degree it is always present. And under the right driving conditions and throttle opening, the electric motor does all the work - albeit only for brief periods. But get it right, and the Civic Hybrid will cruise along at moderate speeds powered only by the electric motor. It won't last long, but meanwhile the engine does diddly squat.
This torque-assist function gives rise to the term Integrated Motor Assist - with the Integrated bit referring to the fact that the motor is built into the engine rather than separate from it, as is the case with the Prius.
When the traction motor alone powers the car, all four cylinders are de-activated: all the valves are closed and the fuel supply cut off. The same thing happens when the car is stationary, and also during braking and overrun, when the electric motor turns itself into a generator to charge the batteries in the IPU. (You don't need to plug in a Civic Hybrid - it recharges itself.) The hydraulically operated, 3-position camshaft, as well as having a 'stationary' position, also has a high- and low-lift function for fast or slow engine speeds, respectively.
When the motor assumes its alter ego and becomes a generator, it also acts as a brake - and this so-called 'regenerative braking' supplements the normal hydraulic brakes, although a special electronic control unit ensures that the driver feels the same amount of pedal pressure as if the hydraulic brakes were doing all the work.
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