CNG-Powered Bajaj on Way

[Admin]

Bajaj’s design illustrations show how the single-cylinder engine is laid flat to make room for the compressed natural gas cylinder and backup gasoline reserve tank. (Bajaj/)

India’s Bajaj is one of the world’s biggest motorcycle manufacturers with ties to big name brands including Triumph and KTM, and this year it will launch the first production model to be powered by Compressed Natural Gas (CNG).

CEO Rajiv Bajaj confirmed plans for a range of CNG bikes earlier this year, with a launch scheduled for June, and prototypes have been spotted on test in India. Now new patent applications from the company reveal more detail of the bikes, showing two distinct designs that are under development.

Bajaj already has plenty of experience with CNG. It manufactures several three-wheelers—the sort of auto-rickshaws and three-wheeled trucks that are commonplace in India—with the option of CNG power instead of gasoline, diesel, or LPG, with production numbers as high as 60,000 to 70,000 per month. CNG is widely available in India, and relatively cheap, so transferring the same tech to its motorcycles makes a lot of sense.

A view of the bike with the airbox and reserve fuel tank in place. (Bajaj/)

CNG is mainly methane, making it significantly less polluting than gasoline or diesel with large reductions in carbon monoxide, unburned hydrocarbons, nitrogen oxides, and particulates. All good, then, except it’s a gas, which makes storing it on board a motorcycle something of a challenge.

That’s where the Bajaj patents come into play. They illustrate how large CNG cylinders can be incorporated into a conventional-looking bike, extending almost the full length of the chassis from just behind the steering head to underneath the rider’s seat. It’s a layout that requires a low-profile engine to fit below the CNG cylinder, and the Bajaj designs both use a single-cylinder engine lying almost horizontally to make space for it.

The more sophisticated design, which closely resembles prototypes that have been seen on test, has a trellis-style steel-tube chassis and is the main focus of Bajaj’s patents. As well as requiring the frame to be specially designed to house the gas cylinder, the switch to CNG adds extra demands in other areas. There has to be a gas filling system, for instance, and the bikes also have a small auxiliary fuel tank, to be filled with gasoline, as a reserve. Meanwhile, the bulk of the cylinder also means components like the airbox have to be repositioned and redesigned.

On the main design, the airbox wraps around the left-hand side of the gas cylinder, behind bodywork that looks like a relatively conventional “tank” and side panel. On the right-hand side, the auxiliary gasoline tank does the same. The result is a bike with a slightly bulbous front section because components that are normally tucked away are forced to the outside. The CNG filler and the cap for the auxiliary gasoline tank are both in the normal spot, just ahead of the rider, sitting side by side. The CNG tank also has a pressure gauge and regulator.

The lower performance bike has further difficulty packing the CNG and fuel tanks. Note how the reserve tank is moved back under the right side panel. (Bajaj/)

The second design shown in the Bajaj patent appears to be a simpler, lower-cost bike. Like the first it has the CNG cylinder mounted horizontally under the rider’s seat and extending forward below the space where you’d normally have the fuel tank. On this design, the reserve gasoline tank is actually in the right-hand side panel underneath the rider’s seat, and the airbox is in the same position on the left-hand side. The part that looks like a conventional tank in front of the rider is actually luggage space or—according to the patent—can be an optional child seat.

Performance isn’t going to be the target of these machines. The CNG tank is likely to add weight and the engines, running on CNG, aren’t expected to be as powerful as gasoline equivalents. They will, however, be cheaper to operate, and in India where there’s a ready supply of CNG at filling stations the bikes are likely to be tempting low-cost transport.

View the full article