Subaru has a strong history with turbines. Okay, so they didn’t make turbines directly, but its parent company, Subaru Corporation (formerly Fuji Heavy Industries), manufactures aviation vehicles both on its own and under license. Present-day Subaru Corporation is also a development and manufacturing partner to both Boeing and Lockheed Martin.
- Founded
-
1953
- Founder
-
Chikuhei Nakajima and Kenji Kita
- Headquarters
-
Shibuya, Japan
- Current CEO
-
Tomomi Nakamura
- Status
-
Active
- Total Vehicles Sold In 2022
-
860,311
But what does aviation have to do with today’s article? Well, that’s because our friends from CarBuzz have recently discovered that Subaru has a patent filing for a turbine engine being used in extended-range electric vehicles (EREVs). Also known as range-extended electric vehicles (REEVs), these vehicles are another type of plug-in hybrid. Today’s patent discovery gives the world yet another application of what kind of engine can power an REEV, and what are the chances that Subaru will indeed push through with the technology?
To give you the most up-to-date and accurate information possible, the data used to compile this article was sourced from various manufacturers and other authoritative sources.
How Subaru’s Turbine Engine Works
Unlike a piston engine, which is what’s fitted to most cars today, a turbine works by simply sucking in air through a series of blades, and then compressing it to an extremely high pressure that, when mixed with fuel, generates power.
The Product Is Small In Size, But Big On Power
From a power-to-size standpoint, a turbine can create high amounts of power relative to how big (or small) it is. Just imagine the jet engines of commercial airplanes and the power they generate relative to a similarly-sized piston engine. Apply that same logic to a car and you can yield the same packaging results.
Furthermore, unlike in a piston engine, it has cleaner emissions due to turbine engines having a more complete combustion process. Oh, and with piston engines, the oscillations of the pistons firing are what cause vibrations and shakes. Since a turbine engine spins, there are fewer or no vibrations as a result. Lastly, turbine engines have fewer moving parts than piston engines.
It Won’t Power The Wheels Like A Traditional Hybrid
In Subaru’s case, the turbine engine won’t power the wheels. As the REEV application suggests, it will only charge the battery. Since an engine for REEV use can simply operate at a specific rev range or power band, a turbine engine would be perfect. The major reason why piston engines are used for ICE cars is the linearity and ease of management of their power delivery, especially when meshed together with a gearbox.
But There Are Challenges To Overcome
There’s a reason why jet or turbine engines never became mainstream in automotive use. Some of these issues are related to the associated high costs due to the fact that barely any automaker has ventured into the technology, while others revolve around its operation.
Why These Are Best Suited For Planes
For one, there are major challenges when it comes to heat management of the exhaust, and, as you’ll probably notice when you board a plane and as it gets pushed back from the gate, turbine or jet engines take a lot of time to start up. They’re also quite noisy—once again, going back to our commercial jet example. They’re also not that efficient at idling, but Subaru’s patent filing, which our friends from CarBuzz found at the WIPO, has a few solutions for these challenges.
Electrical Assistance Aims To Cure Downsides
What Subaru has thought of is the same thing that piston-powered hybrids already implement today—a second electric motor-generator. Most hybrid cars have two electric motors; the first one powers the wheels, while the second motor is directly hooked up to the engine. In a piston engine, this second electric motor instantly fires up the engine, unlike the slower startup of a starter motor hooked to a 12-volt battery. When the engine is running to charge the battery, the second electric motor runs in reverse to generate a charge for the battery. Remember, electric motors become generators when spinning the other way around, when the flow of current is reversed.
This same principle of having a second electric motor to instantly fire up the turbine engine is what Subaru hopes will solve the constraints of a turbine engine. Once it’s turned on, the turbine engine won’t be running for short bursts. Instead, the turbine engine aims to charge the battery at a significant rate. However, Subaru is still adding a secondary 12-volt battery for the second electric motor, and it’s where the second electric motor will draw power in start-up mode. The reason for this is that if the main battery pack of the REEV is too low, it won’t be able to start up the turbine. The electric motor solves the long startup times, the idle speed issues, and the noise problems, but the high exhaust gas temperatures remain.
Chrysler’s Previous Attempt At Turbine Engines
But did you know that Chrysler made bold progress with turbine engines? Though they never reached mass production, Chrysler is the brand that has made the most impactful development, due to a few vehicles that actually reached a few customers.
The Turbine Car Has Roots In American Automobiles
It was simply called the Chrysler Turbine Car, wherein 55 were produced from 1963 to 1964. All models came in a “Turbine Bronze” paint, and all came with a futuristic jet engine sound from their A-831 turbine engine. The engine did not require antifreeze, a cooling system, a radiator, connecting rods, or crankshafts; heck, it could even combust diesel, gasoline, and, surprisingly, leaded gasoline damaged it.
Today, only nine survive, and all but one of them are in museums. Where is the sole customer-owned model, you ask? Well, Jay Leno purchased one of the three that Chrysler still had in 2009, and the great thing here is that Jay Leno’s Turbine Car is in running condition.
Here’s Chrysler’s Turbine Car Drove
If you’re curious about what it was like to drive one, the best person to ask is, therefore, Jay Leno. One of the key traits he loves about the Chrysler Turbine Car is its distinct jet engine noise. It’s futuristic, and actually, from the inside, the sound insulation of the jet engine is copious, which is why it was so quiet inside. And yes, while a jet engine exhaust is usually hotter than that of a piston engine, Chrysler solved this by creating regenerators. Basically, the exhaust went back and forth and recirculated the hot gases until it was cool enough to exit from the back of the vehicle.
And then there are the distinct characteristics of a turbine engine. The engine usually spun at 22,000 RPM, which is unheard of in a piston engine. It also has a three-speed TorqueFlite automatic, and it didn’t need a torque converter because the jet engine already did that job. These have contributed to the engine feeling very smooth, though it isn’t necessarily as fast as it took the Turbine Car 12 seconds to accelerate from zero to 60 mph. Other advantages that this engine had were its far lower maintenance needs, but what really killed it was that, by 1978, Chrysler was encountering significant financial challenges. A government deal was reached in 1979 that the gas turbine program should be abandoned because they thought it was “too risky” for Chrysler to remain afloat whilst pursuing its turbine engine ambitions.
Sources: WIPO