A COMPOUND
ELECTRIC HYBRID SOLUTION
IN-LINE
The Compound Electric Hybrid is a straightforward concept similar to the well-known Serial Hybrid or Parallel Hybrid systems featured in many mass-produced cars. However, with a Compound Hybrid, the fuel engine and electric motor are positioned in-line and their shafts are connected to one another through a clutch mechanism that controls engagement. As a result, the shafts turn in unison when the clutch is engaged, while only the electric motor output is transmitted to the "transmission" when the clutch is disengaged.
The fuel engine and electric motor together constitute the Primary Power Source package (or prime mover). To allow for this link-up and compounding, the Electric Motor features a double-ended through shaft that serves to connect the Primary Power Source to the Transmission. This setup enables all the Primary Power Source output to be channeled directly into an Infinitely Variable Hydrostatic Transmission (IV/HST), which is discussed in more detail upcoming.
INFINITELY VARIABLE
For the Primary Power Source to function as a compounded system, it must be able to adjust RPMs continuously, from a minimum idle or neutral, up to the maximum most efficient RPM point for the requested power output, independently and regardless of the RPMs at the vehicle's drive axles. Therefore, this Compound Hybrid configuration requires the use of an Infinitely Variable Transmission, as it allows for low RPM linking up as well as detaching/unlinking between the power source components during vehicle travel at any speed. A geared transmission, on the other hand, has fixed ratios that tie the vehicle axle RPM to the power source engine(s) RPM, making it impossible to adjust the ratios moment to moment or have infinitely variable ratios, which are needed for compounding to work.
An IV/HST provides the necessary flexibility to link the in-line Power Source components and compound them or unlink them seamlessly. The infinitely variable dynamics enable complete and continuous RPM flexibility between the power source and vehicle axles, allowing for independent mode selection and computerized engine loading at any desired ratio and at any given moment in time. Consequently, the RPMs of the engine(s) are not directly limited or impacted by the speed of the load being moved – even when the load is hardly moving or not yet moving.
SMALL BUT MIGHTY
An Electric motor of only 150KW (like one out of a Tesla Model 3) if put in a long-haul Semi-Truck with a Compound Electric Hybrid – can by itself, through the IV/HST final drive, develop 86,000 lb./ft. of torque at the axles! This is right from a standstill to the start of rolling the vehicle load, and even while doing a super slow crawl. On level pavement this 150KW motor can also by itself maintain the load at highway speed. Additionally the electric motor can reduce its rpm’s while the load is in motion and start the fuel engine once the clutch is engaged.
Many high-efficiency Fuel Engines are smaller and lighter - while using higher RPM’s. Such as the 1.6-liter Formula 1 race engines that produces 700hp with 52% efficiency. By focusing solely on efficiency, the typical 15L Semi-Truck engine weighing over 3,000 lbs. can be reduced to around 700 lbs. while achieving the total horsepower & torque goals with the Compound Electric Hybrid. This weight reduction allows for the addition of batteries without adversely impacting the total vehicle GVW availability. In this way, engine designers can make high efficiency truck engines unleashed rather than tethered to the demand for high torque at low RPM’s.
SWEET SPOT
This compound hybrid application handles all combinations of torque and RPM requirements through the infinitely variable transmission, freeing up the power source package to focus solely on efficiency. The IV/HST transmits torque and RPMs independently of the engine, eliminating the need for a specific torque curve from the engine. This means that engines of any type or fuel can then operate at their most efficient RPM, known as the "Sweet Spot," allowing for greatly improved efficiency. Rather than designing engines with a specific torque curve, designers can focus on creating engines with the best efficiency curve possible (or efficiency area on a fuel consumption map) .
This Sweet Spot on the map (or curve) is also referred to as the "best efficiency point" (BEP), which can lead to achieving over 50% engine efficiency, even in heavy truck applications. Additionally, any engine, including turbines, can be adapted to this compound hybrid, making it a versatile solution. Neither parallel hybrid nor serial hybrid applications can accommodate all BEP possibilities and the incredibly high startup axle torque offered by the Compound Electric Hybrid in all selected drive modes of operation.
MAKING HISTORY
Hydrostatic transmissions can be found abundantly over the past century - used in farming and off road equipment, as well as construction equipment, where they are exceedingly valuable for continuously variable speed control while maintaining the power output. They have showcased their effectiveness in tackling many challenging tasks with great precision and efficiency, but they have yet to find their place in highway freight truck applications. Previous integration of hydrostatics into trucks do not utilize them as the primary transmission pathway from the prime mover to the axle for continuous torque control while traveling on roads.
However, by pursuing innovation in this domain and solving the internal limitations of the rotating parts, there is renewed potential for the promise of Infinitely Variable Hydrostatic Transmissions (IV/HST) to emerge as a promising solution for Hybrid technology in trucks. With their incredible provision of immediate and sustained high torque during startup and breakaway (even surpassing the capabilities of electric motors).
This IV/HST Compound Hybrid approach allows even a smaller Electric Motor as a component of the Primary Power Source, to deliver & easily maintain by itself an incredible full high torque through the final drivetrain in heavily loaded trucks while crawling at a very slow pace, or even before starting to move. Remarkably, this feat can be accomplished without impeding the primary power source's functionality (i.e., lugging an engine) or causing adverse effects on its operation.
HYBRID EXAMPLE TRIP
From the Spokane Valley to Port of Seattle, Washington…
SPOKANE VALLEY
The journey from the Spokane Valley to Port of Seattle spans 290 miles on I-90, encompassing a diverse range of elevation changes that total 2,915 feet to climb. Numerous trucks undertake this trip in a day and then back the following day, exchanging loaded trailers carrying various goods and products. Imagine a fully loaded 80,000 lb GVW semi-truck equipped as a Compound Electric Hybrid (CEH) embarking from Spokane Valley with its batteries fully charged. It deftly navigates beyond the city limits using just the sheer power of its 150KW electric motor.
AIRWAY HEIGHTS
As the ascent begins, the truck activates its smaller, high efficiency Bio-Diesel engine (ICE) to conquer the 6% grade leading to Airway Heights, where the airports and air base are located. The truck synchronizes the 300KW ICE power with the electric motor. The key distinction here is that the ICE engine consistently runs at an optimal 5,000 RPM, its operating “Sweet Spot”. As power requirements vary at the axle, the electric motor reduces or increases its power output, allowing the ICE to maintain this ideal RPM. All thanks to the Compound Electric Hybrid’s infinitely variable transmission.
RITZVILLE
Having conquered the grade, the ICE engine continues to operate in its sweet spot, channeling power both to the axles (for maintaining cruising speed), and the balance of power available at any moment goes toward recharging the batteries to their full specification. The rolling hills of farmland enroute to Ritzville along I-90's westward path are now easily managed shifting over to using electric power almost exclusively. Occasionally, the ICE engine is engaged to conquer hills and simultaneously recharge the batteries. Throughout this routine, the ICE maintains its sweet spot until disengaged, then allowing the electric motor to operate independently.
COLUMBIA RIVER AND
THE VANTAGE GRADE
Having journeyed over rolling farmlands, passing Moses Lake, and approaching George Washington, the truck reaches the pinnacle of the Columbia River Gorge. Here, the proactive ‘Grade anticipating Smart GPS’, has been planning on how to capture all the power available from the upcoming decent. Up to now utilizing battery power often (and operating the ICE at Sweet Spot for travel and recharging needs), it has so planned at this point for the batteries to have been drawn down enough for available room to capture the many kilowatts of power from the upcoming descent. This smart planning ensures recharge battery capacity for the steep descent down the Columbia River gorge, with this descending brake energy (as generated kilowatts) to be stored in the batteries
ELLENSBURG
With now fully charged batteries, both the electric motor and the ICE engine collaborate to ascend the 7% grade of the Vantage hill on the way to Ellensburg. Following this uphill climb at a good pace, the ICE engine continues to operate solely as needed for axle power and battery charging. The Compound Electric Hybrid dynamic power distribution sustains cruise speed as well as enabling extra power channeled to charge the batteries.
SNOQUALMIE PASS
The climb from Ellensburg to cross over Snoqualmie Pass, encompasses an elevation change of 2,300 feet, and demands more frequent ICE engine activation while also keeping that Sweet Spot higher efficiency advantage. However, as with previous trip segments, the ‘Grade Smart GPS’ anticipates and plans battery usage effectively. So later when descending the other side of the pass, the truck batteries have already been drawn down enough to capitalize on all the regenerative braking and recharge the batteries fully during the descent.
PRESTON, WASHINGTON, TO SEATTLE: (ZERO EMISSIONS ROUND TRIP)
Having descended from the mountains, the truck proceeds with a full battery charge to pass the city of Preston, located 22 miles outside Seattle. Now switching to electric-only mode and proceeding into the greater Seattle area – it traverses Seattle being a ‘Zero Emissions’ truck. Even during loading and unloading, all the while adhering to an electric-only mode. This emissions-free journey continues until the next day after passing Preston again to climb back up the mountain pass. Then for the climb again with the ICE engine operating solely at its Sweet Spot rpm’s for exceptional efficiency while heading up to the top of the pass.
THE COMPOUND ELECTRIC HYBRID TRUCK PRIMARY
OBJECTIVE IS THREE-FOLD
Operating at zero emissions within the cities, and zero emissions in lieu of idling elsewhere when stopped, or when slowed down in a traffic jams, or while at a loading dock … this is the first objective.
The secondary objective focuses on running the ICE engine exclusively at its sweet spot RPMs. By varying the electric motor power output as needed, this constant Sweet Spot can be maintained to have greater efficiency and yielding much higher MPG. And while charging, also significantly reducing GHG emissions per generated kilowatt output when compared to most grid-based “plug-in-your-charger” alternatives.
The third objective centers on harnessing all the potential of downhill stretches to capture the maximum energy from rolling forces while descending. While the ICE engine is off, the electric drive captures downhill energy and stores it in the battery, capitalizing on regenerative braking this way.
TOUTING BENEFITS
The Big Idea: Enable Hybrid Zero Emissions in long-haul semi-trucks, as well as generate electricity with much higher efficiency and a significantly lower carbon footprint than what can be obtained using the average grid, all for a 2,800+ mile range.
As the dawn of Zero Emissions for Heavy Trucks has arrived, the best part per the Transportation Energy Institute is that it would demand no upheaval in the existing infrastructure. In the freight hauling world it is shown that an electric drive semi-truck consumes around 2.2 KWh per mile. Then for the 75 mile range to achieve the status of a Zero Emissions Vehicle (ZEV), a battery with an operating range of 165 KWh’s is needed to supply this 75-mile "Electric Only" mode of operation. That battery pack would then be a lot like two of the batteries in the basic Tesla Model 3 and weighing around 2,600 lbs.
Picture a Semi Truck thoughtfully equipped with this lighter battery pack, (a slight heft over one ton), and realize as the weight of this system dwindles, so does its environmental footprint from inception to finality. (From the cradle to the grave as the analysis is often labeled.)
As shown in the prior “Example Trip”, the Compound Electric Hybrid (CEH) uses this battery pack in combination with the other Hybrid components to achieve fantastic efficiency, extremely lower carbon footprint, and the Zero Emissions impact where it counts most.
The conventional Series and Parallel hybrids have limitations that the Compound Electric Hybrid can overcome. The measures currently being taken to enhance efficiency and reduce emissions of modern diesel engines are compromised by idling and frequent cycling of the engine rpm’s. The Compound Hybrid Electric would have more flexibility in its operation - and more metrics, like pressure and flow, for real drive time analytics along with the data implemented during travel from upcoming grade smart Topographical GPS. So, this Hybrid would intelligently harmonize all operating parameters and thereby facilitate a more efficient operation of the engine and batteries to work in concert and within the coveted “Sweet Spot” ranges of optimum RPM’s for both the electric and fuel motors. In addition to enabling the greatest amount of highway “down-speeding” for engine rpms ever imagined. Thus, orchestrating a smart equilibrium within the ensemble of energy use and its distribution to the load.
It is not only about having a very efficient engine – you must also enable high efficiency with very limited high/low rpm cycling, and ‘smart load balancing’ of the fuel engine to keep it in its “sweet spot”. All of which can be done with a Compound Electric Hybrid and the smart controls easily adaptable in its operation.
All the while - no changes to existing infrastructure are needed to start Zero Emissions now with the Compound Electric Hybrid.
IN SUMMARY
THE COMPOUND ELECTRIC HYBRID:
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Electric-only operation is always available. But whenever the Fuel Engine is running, ensure it consistently operates at the Best Efficiency Point (BEP) rpm.
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Dynamically manage the Fuel Engine’s power distribution to simultaneously generate electricity and propel the axles, precisely in the required proportions, whenever needed.
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Equally important, when increased power is needed, add electric power to propel the axles along with the fuel engine.
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Ensure all these dynamics occur seamlessly, moment to moment, at any speed, on-the-fly while traveling down the road, with no gears to shift.
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And consistently use the Hybrid technology here to capture braking & downhill energy, storing it in the batteries for emissions-free propulsion or uphill assistance.
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