Heidelberg, a place where the great poet Goethe kept his heart, a place where Mark Twain praised as the most beautiful place ever. On the banks of this Neckar River, countless German Romantic ideas flowed, witnessing the changes of the German Renaissance and giving birth to our protagonist today , the rotor engine. It's just that the rotor engine born in the river and river valley may not have thought that its real stage does not merge into the Rhine like the Neckar. Although there is also a Ota River there, more importantly, its stage faces the sea and faces Hiroshima Bay.
After marrying Mazda, the rotor engine may have experienced what is called "the lover's eyes out of the West". High fuel consumption? Faced with the oil crisis, it was time for Mazda to start mass-producing it. Severe wear? There are "rotors forty-seven men" to study overcoming. Even at Le Mans on the opposite side of the world of reciprocating piston engines, Mazda did not "betray". So later there was also a "Mazda has no money to sell cars, and to make money to study the rotor" stem. Although romantic, can the rotor engine really only be reduced to a Don Quixote-like existence?
Rotor to do "charging treasure"? Not for the first time, nor for Mazda's first
Over time, Mazda's plans to return rotor engines as range extenders have become increasingly clear. However, using a rotor engine as a "charging treasure" is not a completely innovative idea. As early as 10 years ago, Audi had developed an Audi A1 e-tron extended range electric vehicle. The PQ25 platform of the fifth-generation Volkswagen Polo now looks antique, but as part of the range extender, is a rotor engine from the German Wankel.
This rotor engine with a displacement of only 0.254 liters is arranged in the rear axle position, while the generator is in the front axle, which is an alternative "rear-facing front-drive" layout. Coupled with the lithium battery pack that supports the vehicle's pure electric endurance of about 50km, plus the extended range of 200km in the state of full fuel (12L fuel tank), it is still very advanced in the environment at that time. However, at that time, Audi came up with a variety of hybrid models with a variety of technical paths, which was an early technical test. Coupled with the insistence on using the Wankel rotor engine instead of knocking on Mazda's door, Volkswagen has also been burdened with more pressure on research and development costs.
Audi could see the value of the rotor engine in the range extender, and Mazda could not fail to see it, so the Mazda 2 with the rotor range extender engine was born. The rear range extender, the mid-mounted battery, the front motor, Mazda and Audi are more heroic and slightly the same, the more regrettable it is that the two did not cooperate at that time. Mazda's rotor engine displacement is 0.33L, which is not much larger than the Audi model, and the displacement is smaller than many motorcycles. However, the total cruising range can reach about 380km, and the comprehensive fuel consumption can be controlled at about 5L/100km, which already has certain practical significance. However, neither Audi nor Mazda had the conditions for mass production and commercialization of such models at that time. But not then, can it be now?
It doesn't have to be a rotor, but the rotor is the most suitable
Before explaining this problem, it is necessary to borrow Coach Anxi's famous quote "The team does not exist because of you, it is the team that needs you so you exist.". The same is true of the rotor engine, not that Mazda is necessarily obsessed with it, but that it is best suited to the upcoming Mazda. With the help of Mazda's recently published patent diagram, Mazda's hybrid system will ideally use a front-mounted four-wheel drive structure. The drive system consists of two front-wheel hub motors and a rear-mounted drive motor. The engine is only used as a range extender (theoretically, it is also possible for the engine to directly output power to the rear axle).
Although the main power output is in the rear axle, the situation on the front axle is more interesting. First of all, from the patent diagram, the front axle part needs to integrate 2 inverters and hub motors, plus capacitors and high and low voltage converters. The focus is mainly on capacitors and hub motors. In terms of capacitance, Mazda's four-wheel drive system must be a timely four-wheel drive based on the rear drive, and the front wheel motor only intervenes in the drive under special working conditions, and realizes energy recovery in the braking or coasting state. From this working state, it can be found that the pressure of the capacitor is not small, and there is a feeling of "flash charge and flash release".
In addition, the pressure comes from the hub motor. Judging from the current news, the two front wheel motors may use a high voltage of 120V, due to the reduction of the motor volume. In fact, the use of capacitor structure itself is also the use of its advantages to reduce the weight of the front axle and the pressure of the wiring harness. Secondly, as a Mazda that pays attention to driving pleasure, in addition to reducing the weight of the front of the car as much as possible, it is also necessary to ensure the suspension structure and brake heat dissipation. From the patent drawing, we can also see that the drawing is drawn in a double wishbone suspension structure, which in itself is a structure that occupies quite a lot of space.
Where can the space of the front axle and the control of the front and rear counterweights of the vehicle squeeze out of the space? That's just the engine, so in the news we got earlier, it was all Mazda's sound of doing longitudinal rear-drive. The longitudinal position can of course meet the above conditions, but the longitudinal rotor engine is more "perfect". The situation of the engine part cannot be seen from the patent drawings exposed last year, but the structure of the longitudinal three-rotor engine has been clearly drawn on the latest exposure drawings. Of course, there is a high probability that this structure can be adapted to a rotor or a longitudinal reciprocating engine, just as it was speculated earlier that it is compatible with fuel (48V light mix) and extender electric drive.
But when we incorporate the advantages of the rotor engine, you can understand why the most suitable choice for this structure is the rotor engine. First of all, the rotor engine structure is relatively simple, in the absence of a crank slider mechanism, it is more compact than a reciprocating piston engine. This corresponds to the aforementioned front axle structure, and can also save valuable space for the wheel motors and suspension on both sides.
Secondly, in a unit volume, the power output of the rotor engine is much higher than that of the conventional piston engine. Due to the characteristics of the triangular rotor, its triangular speed and spindle speed are 1 to 3 ratio, so the high piston speed can be achieved without the need for high piston speed. Simply put, every time the triangular rotor rotates, the engine will ignite 3 times. This is compared to the average four-stroke engine that only does work once every two turns, which obviously has a huge advantage in terms of power output and smoothness. Thanks to the output advantages of the rotor engine, Mazda can also carry a smaller capacity battery pack to flexibly layout its rear axle part, reduce manufacturing costs, and so on. Since the battery capacity of the current patent figure cannot distinguish between the 48V light hybrid structure and the extended range structure, it is not too much discussion.
In terms of details, due to the simpler structure of the rotor engine, the small size and weight, coupled with the unique rotation work mode, the vibration in the working state is also smaller. This is for the current electric drive trend, all kinds of extended range or hybrid structure of the model, can further avoid the noise gap when the engine intervenes, to create a better passenger environment. At the same time, the lower center of gravity further strengthens Mazda's pursuit of handling characteristics.
In turn, the return to mass production in the form of a range extender also avoids the defects of the rotor engine as much as possible. For example, the low speed torque of the rotor engine is insufficient, the life is short, etc., in the case of electric drive, naturally do not have to worry about the linearity of the driving force. As for the life span, the rotor engine can be used as a range extender to stabilize the power generation in the appropriate working range. Moreover, the extended range model does not need the engine to run all the time, which is naturally a protection for the life of the rotor engine.
Write at the end:
The news released by Mazda in recent years has always been fragmented, but only a little news that is occasionally exposed can still get the attention of riders and the association of imagination. As the information becomes clearer, we can basically speculate that Mazda is building a set of basic modules with front and rear drives. It is then compatible with traditional reciprocating piston engines (or 6-cylinder + 48V light mix), rotor engine range extender systems (electric four-wheel drive), and even in the future can cover the structure of plug-in hybrid systems. This may also be the last and best chance for the rotor engine to get rid of its own feelings, totems, and even Mazda's bottomless pit of burning money.