Heat exchange – With timer – programmer – time delay – or condition responsive... – Temperature responsive or control
Reexamination Certificate
1998-12-30
2001-04-17
Ford, John K. (Department: 3743)
Heat exchange
With timer, programmer, time delay, or condition responsive...
Temperature responsive or control
C165S041000, C165S051000, C165S122000, C165S140000, C165S916000, C123S041490, C123S041640, C123S041120, C123S041310, C123S1960AB
Reexamination Certificate
active
06216778
ABSTRACT:
FILED OF THE INVENTION
This invention relates generally to motor vehicles and, more particularly, to such vehicles having means to guide and control air for power plant cooling.
BACKGROUND OF THE INVENTION
Liquid-cooled internal combustion engines used to power motorized land vehicles, e.g., passenger autos, construction machines and the like, use an engine block of the type having a multi-passage cooling “jacket.” Coolant, usually a mix of water and ethylene glycol, is pumped through the jacket passages and absorbs heat resulting from engine operation. The heated coolant is delivered to a heat exchanger (often referred to as a “radiator”) where it is cooled as it gives up heat to the atmosphere. Such coolant is then recirculated back to the cooling jacket.
To function most efficiently and effectively, it is required that air flow across the heat exchanger at a relatively high volumetric rate. While passenger autos are equipped with radiator fans, it is not unusual to automatically disable the fan at highway speeds; the ram-urged air through the heat exchanger is sufficient to remove heat from the coolant. And it is also noteworthy that engine rotational speed and vehicle speed over-the-road are roughly proportional to one another; a slower-running vehicle usually requires less engine cooling. Exemplary cooling systems for over-the-road vehicles are disclosed in U.S. Pat. Nos. 4,969,421 (Haner et al.); 5,046,554 (Iwasaki et al.) and 5,495,909 (Charles).
On the other hand, cooling the engine of an off-highway vehicle presents a different set of technical problems. There are at least three reasons why this is true. One is that even if the heat exchanger is mounted at the front of the vehicle, there is little ram-urged air available to remove heat from the coolant flowing through the heat exchanger—most off-highway vehicles are stationary or move at low ground speed when working. Therefore, some sort of air-moving apparatus must be relied upon to provide a sufficient volumetric flow rate of cooling air.
Another is that when working, the engine is often set to run continuously at full throttle to make available high engine horsepower. It is not unusual to run the engine of an off-highway at 2300-2700 rpm. Implement and vehicle speeds are controlled by, e.g., hydraulic valves and torque-converter-type automatic transmissions. When running at high speed, engines and cooling fans of the types commonly used in off-highway vehicles produce a good deal of noise. While quieter fans with forwardly-turned blades are known, they have not been used on off-highway vehicles, insofar as is known.
Yet another reason relates to the first. Often, the engine is mounted at the rear of the vehicle behind the operator and forward vehicle motion results in no ram-urged cooling air whatsoever.
Exemplary cooling systems for off-highway vehicles are disclosed in U.S. Pat. Nos. 3,921,603 (Bentz et al.); 4,377,203 (Ejima) and 4,815,550 (Mather et al.). The system disclosed in the Mather et al. patent seemingly presents some problems. One is that such system uses, in one embodiment, a double-bladed fan and in any event, uses two opposed inlets. Any openings in the housing around a fan provide a path for fan noise to escape and be heard by the operator and bystanders.
Another is that the double-outlet exhaust is directed to either side of the vehicle. This could present a modest hazard for persons passing near the vehicle while it is in operation.
An improved off-highway-vehicle cooling system which addresses some of the problems and shortcomings of earlier work in this field would be an important technological advance.
OBJECTS OF THE INVENTION
It is an object of the invention to provide an off-highway-vehicle cooling system which addresses some of the problems and shortcomings of the prior art.
Another object of the invention is to provide such a cooling system which helps reduce system noise.
Another object of the invention is to provide such a cooling system which, in a specific embodiment, helps draw exhaust gas through the engine muffler, thereby reducing muffler back pressure.
Yet another object of the invention is to provide such a cooling system which, in a particular embodiment, helps cool the engine compartment.
Another object of the invention is to provide such a cooling system which, in yet other embodiments, provide thermostatic control of fan speed to help reduce system noise. How these and other objects are accomplished will become apparent from the following descriptions and from the drawings.
SUMMARY OF THE INVENTION
An off-highway-vehicle cooling system includes a heat exchanger for removing heat from, e.g., the engine coolant, hydraulic oil, automatic transmission fluid or the like. A fan mechanism flows air along a flow path through the heat exchanger. In the improvement, the fan mechanism is a centrifugal fan mechanism and includes a scroll-shaped housing and a fan in the housing. The fan has forward curved blades, thereby to reduce system noise. Such fan is preferred in the invention even though its efficiency is less than the efficiencies of fans with radial tips or backward curved blades. And such fan is preferred (for reasons relating to sound reduction) even though it requires about twice as much torque as other fan types to provide a given volumetric flow rate.
In other aspects of the invention, the fan rotates in a plane and has an upstream portion (i.e., upstream of the plane) toward the flow path and a downstream portion away from the flow path. The fan is in a housing having a shroud covering the downstream portion. Because most off-highway vehicles are stationary or move at very low ground speed when working, there is little if any ram-urged air contributing to cooling. In other words, the fan mechanism is substantially the sole means for flowing air along the flow path.
The housing includes a single inlet port which is adjacent to the upstream portion of the fan. In a specific embodiment, the inlet port is circular and concentric with the fan axis of rotation. The housing also includes a discharge portion from which heat-entraining air is discharged from the cooling system.
In other aspects of the invention, the fan has a diameter and an axially-measured depth, i.e., a “thickness” measured parallel to the axis of rotation. The ratio of the depth to the diameter is not in excess of about 0.4 and, most preferably, is not in excess of about 0.25.
In particular embodiments, the new cooling system has yet other features which reduce system noise. The engine heat exchanger has engine coolant flowing through it and the fan is powered by a hydraulic motor having a thermostatic controller coupled in speed-controlling relationship to such motor. The thermostatic controller controls the speed of the hydraulic motor as a function of the temperature of the engine coolant.
Assuming that the vehicle is equipped with some sort of hydraulic system, the cooling system may also include a second heat exchanger for removing heat from hydraulic oil. The thermostatic controller controls the speed of the hydraulic motor as a function of the temperature of the hydraulic oil. And such thermostatic controller may be arranged to control hydraulic motor speed as a function of either the hydraulic oil or the engine coolant, depending upon which liquid is exceeding a temperature limit.
And that is not all. The new cooling system has yet other beneficial features. In an off-highway vehicle, the cooling system is mounted adjacent to an engine compartment having the engine within it. The cooling-air flow path has an entry opening at the rear of such vehicle and is substantially free of ram-urged air. The fan mechanism preferably urges fan discharge air upwardly away from the vehicle.
In a particular embodiment, the fan housing has an upwardly pointing discharge mouth and the vehicle includes an air receiving structure, sometimes referred to as a diffuser, in air flow communication with such discharge mouth and vented to ambient air. The housing and the receiving structure are spaced apart somewhat and define
Corwin Russell V.
Wagner Edward L.
Case Corporation
Ford John K.
Jansson, Sharpe, Munger & Stomma, Ltd.
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