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Antonov Applying Dual-Speed Drives to Engine Accessories

The Antonov dual-speed front end accessory drive uses a planetary gear set to enable either a direct of step-up ratio. Click to enlarge.

Antonov Automotive Technologies, which is currently offering a simple dual-speed supercharger for downsizing engines to reduce fuel consumption and CO2 emissions (earlier post), is developing other applications of the dual-speed drive unit for alternators, water and air-conditioning pumps, and other engine ancillaries to allow them to operate more often in their most efficient speed range.

The dual-speed technology is based on a simple mechanical shift for an automatic transmission system invented 20 years ago by Roumen Antonov. The principle is to control the shift with the use of centrifugal force and axial thrust generated by helical gears under load. The systems can work as autonomous self-adapting modules without the need for more expensive hydraulic actuation or electronic control.

The company expects that the highest volume application for the technology is in engine accessory drive systems. Antonov has integrated its dual-speed drive unit into the pulley located at the front end of an engine crankshaft, which drives auxiliary units such as the water and air-conditioning pumps and electrical alternator.

The ability for the drive unit to operate as a passive device without the need for external electronic controls or hydraulic systems is a major cost-reducing benefit. There is also no need to modify the base engine, making the drive unit easy to apply to existing powertrain systems.

An Antonov dual-speed front end accessory drive employs a planetary gear set to enable either a direct or step-up ratio. In this configuration, smaller and less expensive alternators, water and air-conditioning pumps can be fitted. These ancillaries achieve their required output at engine idle by being driven through the pulley system at up to twice their normal speed. Once the engine itself speeds up a clutch in the dual-drive unit is automatically closed and the pulley system reverts to direct drive. In this mode it has no mechanical losses as all the internal elements are locked giving in effect a solid pulley.

The benefit of a two-speed drive is the efficiency gain by not running the alternator, water and air-conditioning pumps faster than is needed for effective operation. The impact of this on vehicle fuel consumption depends on vehicle size, but independent studies have shown between 4 and 5 per cent improvements. This is more than sufficient to justify the expected $100 additional cost of a two-speed pulley. Further benefits will unfold as geared pulley systems are more widely adopted and when powertrain engineers start to design the front end accessory drive incorporating dual-drive units.

—Philippe Echardour, program director
The dual-speed alternator. Click to enlarge.

Antonov has similarly developed a standalone dual-speed alternator. This is targeted at a specific client application where insufficient current can be generated by the alternator at engine idle speed to meet the high demand from the vehicle. The vehicle currently has to have two alternators fitted which adds cost, package complexity and adds to losses at higher engine speeds. Antonov is now looking for other applications for this unit to assess if there is sufficient production demand to justify the development and tooling investment to take this to production.

The dual-speed pulley unit. Click to enlarge.

In addition to the dual-speed supercharger, Antonov recently launched a self-contained two-speed pulley unit—the Antonov dual pulley unit (DPU)—to make available the benefits of dual speed drives to any belt-driven application. The initial target market is US aftermarket supercharger installations where the relay pulley in the standard installation can be replaced by an Antonov DPU to provide two speed supercharger operations.

Three dual-speed supercharger studies are currently being pursued by Antonov. This includes an engine downsizing application for a typical family car (Chevrolet Lacetti); an aftermarket application already in production for high performance vehicles (Ford Mustang); and a performance enhancement application for off-road vehicles with relatively poor class performance (Hummer H3).



Could a similar unit increase the overall efficiency of the small onboard genset used in PHEVs?



It couldn't.

The reason should be obvious.

Seems to me that all the accessories for ICE cars can be driven by electric motors except the alternator that must be engine driven. That includes A/C, the cooling fan, the water pump and power steering. So I don't see the reason for two speed accessories for ICEs especially if the trent is toward building PHEV and BEVs.


Thanks Helen, but could you take a little time to point out the obvious to those of us who might not be as "up to speed" as you clearly are.

Seems like I remember once reading about some world renowned intellects making a similar argument supporting the "fact" that the earth is flat.


Oops... teach me not to look back before I post.

Sorry Helen, my previous post was meant for HarveyD


Are you sure that direct drive is the most efficient mechanical link for an onboard genset? Couldn't the ICE driving engine efficiency be optimized while ensuring the best electrical generator output vs demand with an automated variable speed coupling between the two units?

Recent heat pumps use invertor type variable speed units to double the overall system efficiency.


The ICE for a PHEV can run on the "Burn and Coast" schedule as used by super high mileage teams. So there is no need for this.

This could be cheaper and more efficient than running things with electrical motors. For example a number of years ago a super efficient water pump was invented that has not been used so far because of cost.


Using a similar unit to increase the overall efficiency of the small onboard genset used in PHEVs is not a benefit because by genset we mean an ICE driving a generator - no mechanical drive whatsoever, from the ICE to the wheels. In this case the ICE should operate at a CONSTANT speed that is optimum for it's efficiency. The ICE should never idle (just turn it off).
You are probably thinking of one of the NON-genset systems that has the electric motor/generators connected to the ICE and the wheels, like the Honda, Prius and GM 2 mode; all are quite different but all already have transmissions in various arrangements, regardless of whether they are HEV or PHEV.

This would appear to be a great invention for about 1980. Since idle/stop is probably going to become standard on all cars within a few years, and electrification of accessories is gaining traction, including even water pumps, oil pumps, etc, the need for efficient accessory drive at idle is going to diminish rapidly.


I mention couple time on this website Constantinesco inertia transmission. That so fare the best and most efficient CVT solution if transmission have to be used in the system. The characteristic of that transmission always keep the engine at lowest rpm for the required power and torque. It will be perfect for the PHEV.

The two stage transmission that Antonov invented is interesting but not exactly the bests solution.
Someone above mention electric systems are better to drive all subsystems.


Can these be used as a two speed transmission for lightweight vehicles, with the speed sensor side attached to the axle and the other attached to an electric motor. When the wheel speed exceeds a certain value it shifts into the higher gear.

I noticed the story references a simple mechanical shift for an automatic transmission system invented 20 years ago by Roumen Antonov. This sounded like something we should have seen offered on cars so I checked it out.

Once more when looking into the history of development of a cheaper, better, more fuel efficient technology, I find GM took an option to develop it and then blocked it's development.

I'm getting to really dislike the business practices history of GM.


Conserning this story:

Antonov has the future supercharger en automatic transmission technoly for today:
About fuelsaving, making small engines even powerfull as big engines, six-speed automatic transmission technoloy and many more.

If you what to see this propducts in action a to read and see (lot of video’s) and pictures go to:

Conserning the Antonov supercharger (making smal engines very powerfull).
See some movies with the antonov dual speed supercharger.
Movie Antonov dual speed in full action:
Antonov supercharger laungh at SEMA:
Many photo’s

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