US patent application published for radical new Mazda rotary tech that could power new RX sports car

Mazda has filed a US patent application for a radical new rotary engine that could power the production version of its RX 2020 VISION concept.

Published on March 24, the patent application outlines in minute detail a “Rotary piston engine mounted on vehicle”, which is rotated 180 degrees so the exhaust port is now on top of engine and the intake is at the bottom.

This configuration is believed to allow a long lower intake manifold to boost performance, while the top-mounted exhaust port allows for shorter, more direct exhaust gas passage into a turbocharger housing mounted directly to the upper exhaust port, improving both intake and exhaust flow.

“The engine includes a rotary piston engine body mounted on the vehicle in an orientation where an output shaft of the rotary piston engine body extends substantially horizontally, an intake passage connected with an intake port formed in the rotary piston engine body, and an exhaust passage connected with an exhaust port formed in the rotary piston engine body,” said the patent filing.

Although this is not definitive evidence of the engine that will power Mazda’s born-again RX rotary sports car by 2020, it shows the company continues to develop innovative solutions for its new-generation rotary, which will feature a number of ‘SKYACTIV’ technologies.

As we’ve reported, among them could be diesel-style compression-ignition petrol engine technology. Indeed, just a week earlier on March 17, Mazda file a US patent application for a “Start control device of homogeneous-charge compression ignition engine”.

Mazda previewed a 1.6-litre twin-rotor 16X concept engine as long ago as 2007, and has also developed a small-capacity single-rotor unit that could act as a range extender in a plug-in hybrid vehicle.

We’ve written before about the potential of twin turbos pumping out more than 300kW from a twin 800cc (1.6-litre) rotary.

Whatever eventuates, in its long-winded description of its latest rotary engine technology, Mazda says the improved efficiency and power density of the design allows it to be more compact.

“As described in JP2009-085116A, conventionally, in a case where a rotary piston engine is mounted on a vehicle in an orientation where an output shaft of the rotary piston engine extends horizontally, when the rotary piston engine is seen along the output shaft, an intake port is formed in an upper part of the rotary piston engine and an exhaust port is formed in a lower part of the rotary piston engine.

“On the other hand, with the above configuration according to the present invention, the intake port is formed in the lower part of the rotary piston engine body and the exhaust port is formed in the upper part of the rotary piston engine body.

“That is, in the rotary piston engine with this configuration, the rotary piston engine body is mounted on the vehicle in a state corresponding to the conventional rotary piston engine rotated by 180 degrees centering on the output shaft so that the disposition of the intake port and the exhaust port becomes opposite in the up-and-down direction from the conventional rotary piston engine.



“In the conventional rotary piston engine, since the intake port is formed in the upper part, the intake passage disposed in an upper part inside an engine room has a comparatively short length and is connected with the intake port.

“On the other hand, in the rotary piston engine with the above configuration according to the present invention, the intake port is formed in the lower part, and accordingly, the intake passage is disposed to extend downward from above at a position on one side of the rotary piston engine body and then be connected with the intake port.

“Note that the “intake passage” referred to here includes an intake manifold having a common passage and independent passages. Therefore, a length of the intake passage becomes longer than that of the conventional configuration.

“Such a length, as a result, can be advantageous in obtaining a dynamic forced-induction effect caused by an inertia effect.

“Moreover, in the rotary piston engine with the above configuration according to the present invention, the exhaust port is formed in the upper part and the exhaust passage is disposed above the rotary piston engine body.

“Note that the “exhaust passage” referred to here includes an exhaust manifold having independent passages and a manifold passage. A length of the exhaust passage becomes comparatively short, and thus, a passage resistance in the exhaust passage can be decreased.

“Since the dynamic forced-induction effect can be obtained on the intake side and the passage resistance can be decreased on the exhaust side as above, the performance of the rotary piston engine can be improved.

“Moreover, the intake passage disposed near the engine body is not provided with any large-size devices. Therefore, the entire size of the rotary piston engine can be reduced even if the intake passage is disposed on one side of the rotary piston engine body. Thus, the mountability of the rotary piston engine in a small engine room can be improved.”