Valeo's Steering-Integrated Hydraulic Fan System Boosts Performance

23 November 2000

Valeo's Steering-Integrated Hydraulic Fan System Boosts Overall Vehicle Performance

    AUBURN HILLS, Mich.--Nov. 22, 2000--Valeo (PA:VLOF), a leading supplier of automotive motors and actuators, has introduced a new, steering system-integrated, hydraulically driven engine cooling fan system (HDFS) that substantially improves fuel economy, air conditioning performance and towing capacities, while reducing engine compartment operating temperatures.
    HDFS is being used in the 2001 Jeep(R) Grand Cherokee.
    The industry has long known that hydraulic systems can meet all cooling fan needs. However, these systems were previously too costly and heavy for practical application. By integrating the HDFS with the power steering pump, the Valeo design eliminates the cost, weight and parasitic losses of a separate hydraulic circuit with its own pump.
    "Our hydraulic team worked closely with the engineers from Valeo to make this system standard on our V-8 WJ," said Steve Johnston, supervisor of DaimlerChrysler's Jeep(R) cooling systems. "The HDFS reduces the consumption of horsepower as compared to current engine-driven fan cooling systems -- up to 19 horsepower -- and returns that power to the rear wheels. This power savings will be seen in both fuel economy and performance. This new fan, which runs only on demand, allows us to reduce heat exchanger sizes for the transmission, power steering and engine while also allowing the grille area size to decrease."
    "The biggest market for our steering-integrated HDFS is light trucks and SUVs," said James Neville, general manager of the Air Flow Division of Valeo's Motors and Actuators. "Our system is much quieter and more efficient than traditional fans that connect directly to the engine through a clutch. Vehicles with engine-driven fans lack the refined aerodynamic features we see in passenger cars that use electric fans. But electric fans are seldom an option in trucks because their low air flow hampers towing capacity, underhood cooling and air conditioning performance. Our system permits improved aerodynamic designs in the truck and SUV markets."
    In the Valeo design, a common pump powers both the fan and the hydraulic assist to the power steering system. It is driven by the engine accessory belt. A dual displacement motor drives the fan and efficiently transfers power levels greater than 10 horsepower from the pump. The maximum air moving power is 20 to 30 times higher than is typically available from electrically driven fans. An electronic link to the engine controller closely matches fan speed to the vehicle's cooling demands, thereby minimizing noise and power draw. A special valve feature gives the steering system priority during brief periods when both systems demand high power.
    Valeo's HDFS provides much higher airflow at idle and low speeds than a traditional engine-driven fan. This gives the engine cooling system a cushion of safety for long, heavy towing. Thus, engine cooling requirements are no longer the limiting factor in determining trailer capacities. HDFS also allows much better heat dissipation for the air conditioning condenser. This results in improved air conditioning performance in comparison to traditional engine-driven fan systems whose lower air flow often result in poor air conditioning performance under severe high temperature. It also results in improved compressor durability due to reduced heat and refrigerant pressures. The ultimate benefit is that temperatures sensed by the driver and passengers can be up to ten degrees cooler than with clutch-driven systems.
    A vehicle equipped with the HDFS delivers better fuel economy and more horsepower to the wheels. Another feature of Valeo's HDFS is that it temporarily reduces fan power draw during rapid vehicle acceleration. In contrast, drivers of vehicles equipped with clutch-driven fans often find that up to 25 Hp is unavailable for acceleration when the fan clutch is engaged. Even when the clutch is disengaged, these fans waste about one horsepower through parasitic losses under normal loading. HDFS also improves water pump durability because a mechanical fan and fan drive are no longer attached.