Vehicle engine cooling apparatus

Transversely mounted engine cooling fan in parallel with vehicle engine mechanically driven by straight drive and having blades whose pitch is varied in accordance with engine speed and load for optimized cooling performance. The fan has small radial dimension and extended width to match low and wide engine cooling radiator so that the front hood can be aerodynamically streamlined.

This invention relates to vehicle engine cooling and more particularly to a 
transverse engine and cooling fan arrangement providing for low hood 
profile, straight mechanical fan drive from the engine and improved engine 
cooling efficiency. 
Many vehicles with front wheel drive employ transversely mounted engines to 
provide increased space for the transmission, differential, front 
suspension struts and other components. Cooling of such transverse engines 
is generally accomplished with a forward mounted radiator and an 
electrically driven axial flow fan which eliminates requirement for right 
angle mechanical drive from the engine to the fan. While such axial flow 
fans and electric fan drives have met engine cooling requirements, new and 
improved fans and mechanical fan drive arrangements are desired. 
To this end, the present invention employs a transverse (cage type) engine 
cooling fan which can be simply and directly mechanically driven from the 
engine by belt, chain or gear train to replace the electrically driven fan 
so that load on the vehicle electrical system is sharply reduced. The 
transverse fan of this invention has variable pitch blading and is 
positioned ahead of the radiator for more efficient cooling. This 
invention also allows improved streamlining of the vehicle with low hood 
lines since the air intake can be below the bumper and the fan has reduced 
diameter and increased width to match a low and wide radiator. The fan can 
be mounted downstream of the heat exchanger in a more conventional fashion 
if desired. In the preferred embodiment of this invention, the transverse 
fan has blading whose pitch is automatically varied in accordance with fan 
speed or with load conditions for an optimized air flow rate through the 
radiator to thereby provide improved cooling over a broad operating range. 
The pitch of the fan blades is preferably centrifugally controlled by 
pendulum units which move outwardly in response to centrifugal force to 
simultaneously turn the blades of the fan to an infinite number of 
positions between a closed and a fully open position in accordance with 
fan speed. Maximum pitch and maximized air pumping of the fan is 
established at high operating engine speeds.

Turning now in greater detail to the drawings, there is shown in FIG. 1 a 
portion of an automobile 10 having an internal combustion engine 12 
transversely mounted in a front engine compartment for driving front drive 
wheels 14. A hood 15 having a low and aerodynamically streamlined hood 
line for the vehicle provides a closure for the engine compartment. The 
engine crank has a conventional viscous clutch 16 mounted on the end 
thereof which operates to transmit torque when the temperature of the 
engine coolant exceeds a predetermined temperature to drive a pulley 18 
mounted on the output side of the clutch. Pulley 18 drives an endless belt 
20 that extends around and drives a drive pulley 22 of a transverse fan 
assembly 24 operatively mounted in the engine compartment forwardly of and 
in parallel relationship to the transverse mounted engine 12. The fan 
assembly 24 has an enlarged sheet metal housing mounted in the engine 
compartment with laterally spaced side walls 28 and 30 connected by a 
curved outer shell 32 and further has an air inlet opening 34 and an air 
discharge opening 36. A sheet metal inlet-outlet divider 37 extends 
laterally between the side walls to separate the inlet and outlet openings 
and thereby provide an optimized air path through the fan assembly. A 
radiator 38 through which engine coolant is circulated is mounted in the 
engine compartment adjacent to the discharge opening 36 so that the fan 
assembly can pump air therethrough to dissipate heat energy developed by 
the engine during engine operation. Operatively mounted within the sheet 
metal housing 26 is a bladed fan rotor 39. This rotor is formed as a 
generally cylindrical cage with annular side plates 40, 42 laterally 
spaced from one another and secured to a centralized drive shaft 44 
extending laterally from drive connection with the pulley 22. The drive 
shaft 44 is journaled for rotation in the side walls 28, 30 by bearings 
46, 48. In addition to the side plates 40, 42 the bladed fan rotor 39 
further comprises a plurality of equally-spaced, variable-pitch blades or 
air foils 50 extending between the side plates 40, 42. These blades are 
preferably identical and each is pivoted to the side plates 40, 42 by 
aligned pivot pins 52 extending laterally outwardly from trailing end 
thereof. Suitable helical torsion springs 56 (FIG. 6) are mounted around 
each pivot pin 52 and have opposite ends connected to the associated side 
plate and to the blade respectively to yieldably bias the blades toward a 
closed position as will be further discussed below. The nose or forward 
end of said fan blade 50 has aligned and outwardly extending guide pins 60 
which ride in arcuate slots 62 formed in the side plates 40, 42 as best 
shown in FIG. 6 which stabilize the blades as their pitch is varied and 
establishes the degree of maximum pitch. The guide pins 60 further project 
through radial slots 64 formed in a flat washer-like guide plate 65, 
mounted for limited turning movement on the annular shoulder portion 66 of 
the side plates 40, 42. With this guide plate construction the blades 
pivot in unison with guide plate turning so that each blade is identically 
pitched during fan operation. 
As best shown in FIGS. 4-7, a plurality of small weights 68 are pivotally 
mounted by torsion bars 70 to the associated side plates 40 and 42. This 
torsional spring connection yieldably urges each associated weight 68 to 
an inboard position (FIG. 6) when there is no rotational drive of the fan 
assembly. Each of the weights has a camming surface 74 which engages the 
associated guide pin 60 on operation of this invention. 
During engine operation and low engine coolant temperatures viscous clutch 
16 has maximized slip so that blades 50 of the stationary or slowly 
rotating fan and the weights 68 are respectively biased by their 
associated springs toward their closed position. When engine coolant 
temperature increases, viscous clutch 16 fills with drive fluid and 
transmits torque for accelerating the fan rotor 39. Centrifugal forces 
pivot the weights 68 outwardly against the progressively increasing and 
yielding resistance of torsion bars 70 mounting weights 68 and of the 
springs acting on blades 50. This action varies the pitch of blades to a 
degree determined by the engine and fan speeds. As the blades 
progressively open, larger quantities of air are pumped from the inlet 34 
through the discharge 36 and through the associated heat exchanger 38 so 
that the temperature of engine coolant is maintained in a recommended 
range. When coolant temperatures are reduced to a point at which the 
clutch disengages, the drive of the fan is interrupted and the radiator is 
primarily cooled by ram air. 
In the preferred embodiment, the radiator has the height and width to match 
the fan which may extend laterally across the front of the vehicle. The 
cooling capacity of the radiator is high in view of its large area and its 
ability to be matched with the fan. The small radial dimension of the fan 
allows improved streamlining of the vehicle with small frontal areas and 
low front hood lines. 
The blade setting of this invention can also be utilized to adjust fan 
performance to suit a specific job by properly setting the blade 
angularity and then securing the blades with a suitable locking device. In 
this manner, the performance of one fan can be optimized for several 
applications. Inlet and outlet blade angle, inner and outer diameter, 
blade camber line and speed are carefully selected in each case. 
While a preferred embodiment of this invention has been shown and described 
to illustrate the invention, the scope of the invention is limited by the 
following claims.