Toyota Motor will enterthe ENEOS Super Taikyu Series 2024 Empowered by BRIDGESTONE Round 2 NAPAC Fuji SUPER TEC 24 Hours Race, to be held from May 24 to 26, with the #32 ORC ROOKIE GR Corolla H2 Concept, a hydrogen-powered GR Corolla running on liquid hydrogen. (Earlier post.)

The durability of the pump which boosts the pressure of liquid hydrogen before sending it to the engine has been greatly improved in the hopes of completing the 24 Hours Race without the need for replacement. The pump was replaced twice during last year’s 24 Hours Race.

The liquid hydrogen-powered engine generates power by injecting hydrogen, the fuel, directly into the engine for combustion. The liquid hydrogen-powered GR Corolla uses a reciprocating pump that pumps the fuel, through the reciprocating motion of a piston when transferring hydrogen from the fuel tank to the engine.

Because of the high pressure range this pump generates, the bearings which allow smooth rotation of the shaft and gears on one side of the crank, which transfers torque to the motor by converting reciprocating motion into rotational motion, were unevenly loaded, causing them to wear out and degrade quickly.

This time, a dual-drive crank mechanism has been implemented to improve the pump’s durability. The application of motor torque from both ends of the crank enables the boosting piston to move in a well-balanced manner, thereby significantly increasing pump durability.

Dual-drive crank mechanism

The shape of the liquid hydrogen tank mounted to the vehicle has been changed from a cylindrical shape to a custom oval shape, increasing the amount of liquid hydrogen that can be carried and extending the cruising range.

Cylindrical tanks are used for gaseous hydrogen fuel to evenly distribute high pressure, but since liquid hydrogen is lower pressure than gaseous hydrogen, custom-shaped tanks are possible. For this race, the tank has been changed to an oval to make more efficient use of cabin space. As a result, the tank has a capacity 1.5 times higher than that of the cylindrical tank. This doubles the hydrogen volume, and thus cruising range, over the 70 MPa compressed gaseous hydrogen tanks used until 2022.

Custom-shaped (oval) tank (left) and cylindrical tank (right)

CO₂ capture technology uses the large-volume air intake and heat generated by internal combustion engines to capture CO₂ from the atmosphere through a CO₂ capture device installed in the engine compartment.

More specifically, a CO₂ absorption device is installed at the inlet to the air cleaner, and a CO₂ separation device that uses heat from engine oil is installed next to the air cleaner. The separated CO₂ is then captured in a small tank filled with an absorbent.

In the final round of the Fuji race in 2023, mechanics manually switched the CO₂ absorption and separation processes. However, this time, a mechanism was implemented that automatically switches them by slowly rotating the CO₂ absorption filter while driving.