11/7/2006 | 5 MINUTE READ

Present at the Creation

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Dr. George Gelb and his colleagues created a device called the "Electro-Mechanical Transmission." You may know it better as "Hybrid Drive."


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Contrary to popular opinion, hybrids were not created in Japan. Nor were they created by an automobile company. The hybrid drive system we know today was created in the late 1960s by three researchers—Dr. Baruch Berman, Dr. George Gelb, and Dr. Neal Richardson—working for the Power Systems Div. of TRW Inc. (a predecessor to today’s TRW Automotive Inc. that also was a major aerospace and defense contractor) under the leadership of Bob Bromberg. “Bob was always asking probing questions like: ‘Why can’t we violate the second law of thermodynamics?’,” says George Gelb. “He was firmly convinced that batteries and electrical storage devices really made sense because of their thermodynamic advantages.” This led to an investigation of all known battery technologies, driving emissions, what a car has to do under various conditions, and what the power supply must do under those circumstances. “We came to the conclusion very quickly,” says Gelb, “that battery power alone would never fly in a commercially viable electric automobile.”

That didn’t stop the trio, or their boss, because there was more to this quest than a pure technical exercise. “Even back then some of us were wondering about the long-term emission and geopolitical ramifications of using so much gas and oil for transportation,” Gelb claims. However, an alternative needed to be found. “We theorized that, somewhere in the future, there would be a different type of powertrain, and that there would need to be a transitional technology to get us from here—the late 1960s—to there. To us, the hybrid was an evolutionary path to that future.” They postulated that running an engine at a constant speed and driving the output into a planetary gearset where one part of that gearset would rotate at a variable speed in response to what was required at the wheels would do the trick. So they developed what they eventually called the “Electro-Mechanical Transmission” (EMT).



To make up the difference between the road demand and engine output, the design team inserted an electrical path that would supply power on demand. The output shaft also was attached to a traction motor known as the “torquer” that could operate bimodally by either adding torque or subtracting it through regenerative braking. The speed difference was made up by a device appropriately called the “speeder” that acted as a constant-torque electrical generator. Gelb and his associates modeled the EMT on a computer and “drove” it for the equivalent of several hundred thousand miles. “We used those simulations to vary the size of the battery pack and the weight of the vehicle, and drove it over the precursor to the driving cycle the EPA uses to this day,” says Gelb. From this simulation work, they determined the ideal system would encompass a 150-lb. to 200-lb. lead-acid or NiCad battery, a 100 in.3 gasoline engine producing 100 hp, a 30-hp traction motor, and a 10-kW to 15-kW electric generator. The TRW patent lawyers said the device was patentable, but that the U.S. Patent Office would require a working version before they issued any paperwork. It was time to go from theory to practice.



“We got hold of a 1600 cc VW Beetle engine because we could independently control its air-fuel ratio, added a 10-kW synchronous Westinghouse generator rated to 10,000 rpm, a 27-hp DC motor from GE, and gutted a Chrysler Torqueflite automatic transmission for its planetary gearset,” recounts Gelb. To this they added a small gearbox so they could match the ratios of these disparate pieces. Cast steel flywheels warranted to a maximum speed of 900 rpm—which corresponded with a 65 mph road speed—were driven by V-belts to simulate the vehicle mass, and dynamometer dynamic braking was used to simulate road loads. Remember, this took place during the late 1960s and early 1970s. Men were going to the moon with computers that had less power than today’s handheld calculators. “We had to handle thousands of amperes and voltages in the neighborhood of 300 volts,” says Gelb, “and we were forced to use thyristors in place of today’s power transistors.” The group created the circuits that allowed the torquer to run as both a motor and generator, as well as circuits that would let the control system interface with the battery pack and pull and return power in a controlled fashion. Another circuit was created that would allow the speeder to run as a constant-torque, variable-speed generator. They used a potentiometer as the accelerator pedal, and included a neutral position that commanded zero torque. 

“It took the better part of a year to build, and we drove it on the dyno for another year,” recounts Gelb. This, however, wasn’t enough for the people at the patent office. They wanted a working EMT-equipped vehicle before they would process the paperwork. “So we found a beat-up 1962 Pontiac Tempest —the one with the rear transaxle and ‘rope drive’—and fitted our system to it. The engine was up front with the torquer and speeder, while the batteries were placed in the trunk. We drove it around until the patent people were happy, and then put the pieces back on the dynamometer.”



Not long after, folks who would form the nucleus of the Environmental Protection Agency contacted the team. Tasked with coming up with an emissions drive cycle and curious about the magnitude of a problem known as “cold start,” they asked the EMT’s inventors to drive the device on the dyno and report back. “We told them that, without a catalyst, the first 30 seconds of cold-start driving blew through the proposed hydrocarbon and carbon monoxide standards, even with the EMT,” says Gelb. They later received funding from the EPA to investigate future automotive battery technologies. This funding included a program to demonstrate the EMT’s fuel saving potential. Paired with a 1974 Dodge Dart running the federal driving cycle, the device showed a 30% increase in fuel economy, and a reduction in overall emissions. “And that’s what we did through about the mid-1970s,” says Gelb. The EMT was taken around to the domestic as well as the major foreign manufacturers, but all turned it down because of its cost and complexity. “After that, the whole project was mothballed,” he says, and the pieces were scattered to the wind.

According to Gelb, Toyota didn’t infringe in TRW’s patents to create its Synergy Drive as they had expired (the first was issued in 1970 with the final revision made in 1974) by the time the Toyota Prius hit the market. In reality, he says, the Toyota system takes advantage of today’s technology, inverted the EMT’s input and output shaft drive, and added NiMH batteries and a utility Gelb and his associates once considered: the ability to turn the engine off and drive only on electric power at low speeds. Gelb also adds this: In the 1990s, under the auspices of TRW’s Center for Automotive Technology, they visited a domestic automaker with an updated EMT design, only to be told it would never use the TRW system in place of its planned electric motor-assist design. Ironically, claims Gelb, that same automaker “now licenses Toyota’s technology for its small SUV, a design based on our original work.”


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