Green Patent Blog

Utah vehicle engineering company Raser Technologies recently announced that it has entered into an agreement with international vehicle technology developer FEV in an effort to integrate Raser’s electric motor and electronic drivetrain technology with traditional internal combustion engines.  (read the article here)  The goal of the project is a plug-in hybrid electric vehicle having 100 mpg fuel economy.

Raser owns one U.S. patent and several pending patent applications relating to AC induction electric motor systems.  Such systems typically include an electric motor and a “drive” or “controller” to provide an AC waveform to drive the motor.  Many AC motors are made to run from a DC power source with the drive acting as an interface between the two types of electrical energy.  However, complex and inefficient switching devices are necessary for the drive to convert DC power to an AC waveform.   U.S. Patent No. 6,847,186 seeks to solve this problem by eliminating the need for those switching devices. 

A rotary motor has a rotating part, or rotor, and a stationary part called a stator, with an air gap between them.  In an AC system, the stator has coils supplied with AC current to produce a rotating magnetic field to power the rotor.  Raser’s patented system widens the gap between the stator and the rotor, which has the effect of increasing inductance - the ratio of magnetic flux to current (changes in current create changes in magnetic flux, which generate electromotive force).  Thus, the motor itself is transformed into an inductor.  The inductance is connected in series with a capacitor, generating alternating current between the motor and the capacitor.  The result is a resonant circuit formed by the motor (inductor) and the capacitor.  When power is applied, the circuit oscillates and produces AC waveform without the need for complex devices to convert DC to AC.

Though not an intellectual property matter, California’s recent battles with automakers and the U.S. Environmental Protection Agency (EPA) are worth a post because of the potential impact on clean vehicle technology. 

The federal Clean Air Act preempts state regulation of motor vehicle emissions but provides that California may apply to the EPA for a waiver to impose rules more stringent than the federal regulations.  Other states cannot apply for a waiver, but they may adopt any California standards enacted pursuant to its waiver.  In 2002 California passed Assembly Bill 1493, which required the California Air Resources Control Board (CARB) to enact regulations to achieve maximum reduction of greenhouse gas emissions from motor vehicles.  In 2004, CARB completed the regulations, which provide strict emissions standards for passenger cars and light duty trucks starting with the 2009 model year. 

Central Valley Chrysler-Jeep and the Association of International Automobile Manufacturers sued to block the regulations from taking effect.  The automakers’ main argument was based on the doctrine of preemption, which holds that a federal law trumps a conflicting or inconsistent state law.  Specifically, the automakers contended that even if California were granted a waiver by the EPA, its emissions standards would still be state regulations subject to preemption.  The court disagreed and held, consistent with the outcome of a similar case in Vermont, that state regulations enacted in accordance with the Clean Air Act’s waiver scheme become “federalized” and are therefore not subject to federal preemption.  Thus, California’s vehicle emissions standards were legally viable; the state just needed the green light from the EPA.

Unfortunately, the EPA denied California’s request for a waiver to enact its emissions regulations.  (read the story here)  The agency’s rationale is that greenhouse gases are not a local or regional air quality issue, but are “global in nature” so separate state standards are not needed.  The EPA pointed to the energy bill just signed by President Bush as part of a national solution to emissions problems.  It seems California has lost the latest battle over its emissions standards, but future litigation seems likely - the chair of the California Air Resources Board plans to “sue and sue again” until the EPA lets the state go forward.

The University of California-Davis has licensed plug-in hybrid vehicle technology to a Palo Alto start-up called Efficient Drivetrains. (read the story here and here) The licensed technology includes a fuel efficient “parallel” hybrid powertrain and a continuously variable transmission (CVT) control system that automatically selects the optimal power ratio and eliminates the need for gear shifting.  Efficient Drivetrains plans to partner with auto manufacturers to develop cars that can be recharged using a domestic power supply.  The license agreement was negotiated by the UC-Davis InnovationAccess Unit, which manages the University’s patent portfolio. 

The licensed technology was developed by Andrew Frank, a professor of mechanical and aeronautical engineering.  Dr. Frank is the named inventor on several U.S. patents relating to drive train system designs and energy management systems for hybrid electric vehicles and plug in hybrid vehicles and has published many articles on the subject. (see Dr. Frank’s publications here) 

An example of the CVT control system is disclosed in U.S. Patent No. 7,261,672.  The invention increases the efficiency of a vehicle’s acceleration and deceleration by controlling the rate of change of the gear ratio in a continuously variable transmission.  The system includes a controller that maps and relates various operational characteristics such as torque, speed, oil temperature, differential pressure between pulleys or clamping pressure to the level of each needed to achieve an optimal rate of change of ratio.  Once the optimum rate is selected, the characteristic is controlled to achieve that rate.  This system can be used in both traditional automobiles and hybrid electric vehicles.

An example of Dr. Frank’s “parallel” hybrid powertrain is described in U.S. Patent No. 6,809,429, which incorporates the idea of inserting an electric motor and its battery and controls between the vehicle’s engine and its transmission.  The electric motor is coupled to the input shaft of the CVT so it injects power in parallel with the vehicle’s drive train.   The system varies motor torque and rate of change of ratio to reduce the amount of power cycled by the batteries and maximize efficiency and vehicle performance.

Toyota is the acknowledged hybrid leader in the automotive industry and has sold more Priuses than all other hybrids combined. Last year, the Prius accounted for more than 40% of hybrid sales in the U.S. But it turns out this international icon of clean energy uses infringing drive train technology, and it looks like Toyota will be paying a royalty on every Prius sold in the U.S. through 2011.

In October, the U.S. Court of Appeals for the Federal Circuit (the appellate court that hears appeals of all lawsuits arising under the patent laws and final decisions from the U.S. Patent & Trademark Office) affirmed a jury verdict that three of Toyota’s hybrid vehicles – the Prius, the Highlander and the Lexus RX 400h – infringe a patent owned by Paice, a company that holds several patents relating to hybrid vehicle drive train technology.  This case is interesting because Toyota’s drive train was found to infringe despite seemingly significant differences between its structure and the patented system and because the court imposed an ongoing royalty on Toyota’s infringing vehicles.

In conventional cars, the wheels are driven by torque (rotational force) supplied only by an internal combustion engine (ICE). In hybrid vehicles, torque is supplied by an internal combustion engine (ICE), an electric motor, or a combination of the two. A hybrid drive train must be able to combine and control the relative torque contributions of an ICE and an electric motor. One of Paice’s patents, 5,343,970, claims a hybrid electric vehicle in which the drive train uses a microprocessor and a controllable torque transfer unit (CTTU) that accepts torque input from both the ICE and the electric motor. The microprocessor controls the amount of torque provided by the ICE and the electric motor by locking or releasing a bevel gear assembly and holding torque inputs constant.

The Toyota drive train also combines torque from an ICE with torque from an electric motor but instead of bevel gears the Toyota system has a “planetary” gear unit having a central “sun” gear that meshes with several planetary gears, which in turn mesh with a peripheral ring gear. The output shaft from the ICE is connected to the planetary gears, but the output shaft from the electric motor is connected to the ring gear, instead of both output shafts being connected to the same structure. The transfer of torque through Toyota’s planetary gear system can’t be varied; 72% of the torque provided by the ICE is always transferred to the ring gear and is combined with 100% of the torque provided by the electric motor.

The Federal Circuit upheld the jury verdict of no literal infringement because Toyota lacks the literal elements of Paice’s CTTU. But despite the distinctions between the systems, the Federal Circuit found there was enough evidence that Toyota has infringing equivalent structure because it accepts inputs from multiple sources, i.e., input at the planetary gears from the ICE output shaft and input at the ring gear from the electric motor output shaft, and it is controlled to transfer variable amounts of torque, i.e., the microprocessor dictates the amount of torque sent from each input, and ultimately the amount of torque output to the drive shaft.

The district court denied Paice’s motion for a permanent injunction, but imposed an “ongoing royalty” of $25 per infringing vehicle sold during the remaining term of the patent. The Federal Circuit vacated the royalty and instructed the district court to reevaluate the rate because the district court’s decision provided no reasoning as to how it arrived at that sum. (The royalty rate does seem low considering the importance of the drive train to the vehicles and the vehicles’ sticker prices).

Meanwhile, Nissan got an issued patent last week for a device to protect a vehicle fuel cell system from the detrimental effects of water clogging. Moisture is important for ion transfer in fuel cell stacks and to keep the systems cool, but excessive moisture can reduce efficiency. Nissan’s patented device estimates and predicts water-clogging by taking into account coolant temperature, the speed of the vehicle and the ambient temperature. When water clogging conditions are detected, a fuel gas exhaust valve opens to allow condensed water to exit the fuel gas flow passage.