Power plants – Pressure fluid source and motor – Having distinct cooling or lubricating structure
Reexamination Certificate
2000-01-26
2001-12-18
Tapolcai, William E. (Department: 3744)
Power plants
Pressure fluid source and motor
Having distinct cooling or lubricating structure
C060S468000
Reexamination Certificate
active
06330799
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates in general to cooling systems, and more particularly to an adaptive cooling control system for use primarily in association with cooling operating fluids of heavy construction equipment. The invention is not however limited thereto, and may be adapted for use in association with the cooling systems of different equipment and machinery.
2. Background Art
The use of cooling systems for internal combustion engines and the like has long been known in the art. The engine and transmission are cooled by the circulation of fluids. Such fluids generally include engine coolant, oil, transmission fluid, steering fluid, and hydraulic fluid, among others. Generally, fans are used to cool heat exchangers (radiators) which carry the various fluids. The fans can be operated in many different manners, such as through an electric motor, a hydraulic motor or the fan may be driven directly by the engine crankshaft.
While these solutions have proved successful, they do have certain drawbacks. For example, electric fans generally place large loads upon the alternator and are rather expensive solutions. Fans driven by the crankshaft are in constant rotation—even when not needed—rendering them inefficient. Furthermore, in certain cold climates, with a directly driven fan the operating fluids may not even reach the proper elevated operating temperatures.
To solve such problems, variable speed fans have been utilized. Such fans have been powered by hydraulic pumps associated with the engine. In particular, the pump that rotates with the crankshaft powers the fan motor. Such a solution, while an improvement over the above-identified solutions, nevertheless suffers from certain drawbacks. For example, since pump speed is directly associated with engine speed, such fans include continuously variable thermostatic control devices to control the speed of the fan independently from the speed of the engine and pump. As a result these complex systems require frequent maintenance and are quite expensive to produce and maintain.
It is therefore an object of the invention to provide an improved control system for a hydraulic cooling fan that overcomes the shortcomings of the prior art.
It is another object of the invention to provide a control system which can utilize commercially available components so as to enhance durability and to minimize cost.
These and other objects of the invention will become apparent in light of the specification and claims appended hereto.
SUMMARY OF THE INVENTION
The invention comprises an adaptive cooling system control system for controlling fluid delivery from a pump to a fan motor. The system includes an inlet, an outlet and primary speed controlling means. The inlet receives fluid from a pump. The outlet delivers fluid to a fan motor. The primary control means comprises a bypass valve which includes a first passage which is in fluid communication with the inlet and the outlet. In addition, a bypass passage is selectively communicable with the inlet. The bypass passage is placed into fluid communication with the inlet upon receiving fluid from a pump which in excess of a predetermined desired quantity of such fluid.
In a preferred embodiment, the bypass valve further includes means for altering the quantity of excess fluid flow required to place the bypass passage into communication with the inlet.
In another preferred embodiment, the bypass valve includes a flow control float and means for biasing same. The flow control float is slidably positionable relative to the inlet. The biasing means biases the flow control float between the inlet and the bypass passage, wherein a predetermined flow rate is capable of overcoming the biasing means, in turn, placing the inlet into fluid communication with the bypass passage. In such a preferred embodiment, the biasing means may further provide for means for adjusting the biasing means to alter the quantity of fluid flow required to place the bypass passage into fluid communication with the inlet.
In yet another preferred embodiment, the system further includes a pressure relief valve to preclude undesirable elevated fluid pressure within the system.
In another embodiment, the system further includes means for minimizing cavitation of the fan after fluid delivery from the pump ceases. In such an embodiment, wherein the system further includes a return passage from the outlet of the fan motor, the cavitation minimizing means comprises means for circulating fluid from the return passage into the inlet until the pressure in the return passage falls below a predetermined pressure.
In another such preferred embodiment, the circulating means further comprises a first check valve and a second check valve. The first check valve includes a first rating, an open position and a closed position. The first check valve is associated with the return passage and provides a fluid conduit from the return passage to a fluid outlet when in the open position. The second check valve includes a second rating, an open position and a closed position. The second check valve is associated with the return passage, wherein the second check valve provides a fluid conduit between the return passage and the inlet when in the open position. In this embodiment, the second rating is a pressure higher than the first rating. Upon cessation of fluid delivery from a pump, and decrease in flow of fluid in the inlet, the second check valve returns to the closed position, and the first check valve is prompted into the open position. In turn, circulation of fluid from the return passage through the first check valve into the inlet is facilitated until the pressure within the return passage falls below a predetermined pressure.
In such an embodiment, the first rating is less than 5 psi, and the second rating is less than 30 psi. In another such embodiment, the fluid outlet is associated with a fluid reservoir.
In a preferred embodiment, the system further comprises secondary means for controlling the fluid flow to a fan motor. In such an embodiment, the secondary means comprises a second valve positioned between the inlet and the outlet. The second valve is selectively positionable so as to selectively provide a conduit between the inlet and the outlet.
In such a preferred embodiment, the second valve includes at least one sensor and means associated with the at least one sensor for activating the selective positioning of the valve. In another such embodiment, the at least one sensor comprises at least one of a temperature sensor, a pressure sensor and a manually activated switch.
Preferably, the activating means of such an embodiment comprises a solenoid associated with the at least one sensor. Upon energization of the solenoid the valve is positioned such that the inlet and the outlet are in fluid communication.
In another such preferred embodiment, the secondary means further includes means for adjusting the fluid flow capacity of the conduit between the inlet and the outlet. In such a preferred embodiment, the adjusting means comprises a selectively positionable plunger positioned within the conduit.
In another embodiment, the adjusting means comprises means for automatically adjusting the quantity of fluid directed through the conduit based on predetermined sensed conditions.
In such an embodiment, the automatic adjusting means comprises a selectively positionable plunger, a logic controller, at least one sensor and a stepper motor. The plunger is positioned within the conduit of the secondary means. The at least one sensor is associated with the controller. The stepper motor is associated with the controller and the plunger. Rotation of the stepper motor which is controlled by the controller in response to an input received from the at least one sensor, operably alters the position of the plunger to facilitate one of greater or lesser fluid flow through the conduit.
In a preferred embodiment, the secondary flow control means further includes means for bypassing the outlet, to in turn, substantially precl
Ali Mohammad M.
Factor & Partners LLC
Tapolcai William E.
LandOfFree
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