Development of the Electronically Controlled Hydraulic Cooling Fan System

A new engine cooling fan system has been developed, in which the fan is driven by a hydraulic pump and motor and controlled electronically by a computer. By utilizing the hydrostatic power under precise control, the fan generates not only high airflow volume but also optimum flow rate for the various engine conditions. Also in this system, a relatively high efficiency is gained because the clearance between the tip of the fan blade and a shroud designed to be short, thanks to the installation of the fan on the radiator.

As the result of these functions, the following features have been obtained which are superior to conventional fan systems like a engine-driven fan with fluid coupling or an electric-motor fan.

1. (1)
   Reduced fan noise
2. (2)
   Improved fuel economy
3. (3)
   Small size and light weight