Electricity: motive power systems – Plural diverse motor controls – Motor-reversing
Reexamination Certificate
2002-12-17
2004-06-15
Masih, Karen (Department: 2837)
Electricity: motive power systems
Plural diverse motor controls
Motor-reversing
C318S280000
Reexamination Certificate
active
06750623
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to a reversible fan associated with a radiator of a machine and, more particularly, to a reversible automatic fan control system and process.
BACKGROUND
Many types of machines that use an engine for motive power also include a radiator to supply a coolant, such as water, anti-freeze, or the like, to the engine to ensure that the engine does not overheat. The radiator is generally associated with a fan that supplies cooling air to the radiator. The radiator is normally positioned in front of the fan, and the fan normally draws air through the radiator to cool the liquid coolant for the engine.
In many types of applications, the machine is working or traveling in a dirty and/or trashy environment. As a result, debris such as dirt, insects, trash, and the like, becomes lodged in the radiator because the fan pulls air into the machine across the radiator. Thus, any debris included in the air that passes across the radiator may become, and often does become, lodged in the radiator.
It some machines, a hydraulic circuit, electrical circuit, or the like may be used to selectively switch the mode of operation of the cooling fan so that the cooling fan may be stopped, rotated forward, or rotated in reverse. For example, U.S. Pat. No. 6,076,488, to Yamagishi discloses a control device that may be used to rotate the cooling fan in reverse based on the temperature of the coolant. In particular, the control device rotates the cooling fan in reverse when the temperature of the coolant is not lower than a given temperature while the temperature of hydraulic oil is lower than a given temperature. This causes the back flow of air to discharge debris lodged in the radiator.
In this operation, however, the control device only rotates the cooling fan in reverse when the temperature of the cooling water is not lower than a given temperature of the hydraulic oil. While the fan reversal may discharge debris lodged in the radiator, this operation does not allow for automatic regular intervals of reversing the fan to dislodge debris in the radiator.
SUMMARY OF THE INVENTION
In accordance with an exemplary aspect of the invention, a method of operating a fan control system associated with a radiator may include rotating a fan in a first direction at an operating speed to direct air toward the radiator for a first predetermined period of time and, after expiration of the first predetermined period of time, decelerating rotation of the fan in the first direction. The method may also include accelerating rotation of the fan in a second direction to a predetermined speed, wherein the second direction is opposite to the first direction, rotating the fan in the second direction at the predetermined speed for a second predetermined period of time, and, after expiration of the second predetermined period of time, decelerating rotation of the fan in the second direction. The method may further include accelerating rotation of the fan in the first direction to the operating speed.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention.
REFERENCES:
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patent: 3786891 (1974-01-01), Vogelaar et al.
patent: 4160487 (1979-07-01), Kunze et al.
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patent: 5364332 (1994-11-01), Gray, Jr.
patent: 5820352 (1998-10-01), Gunn et al.
patent: 6067489 (2000-05-01), Letang et al.
patent: 6076488 (2000-06-01), Yamagishi
patent: 6109871 (2000-08-01), Nelson et al.
McCauley Thomas A.
Morrison James A.
Vogt Bryan A.
Caterpillar Inc.
Finnegan Henderson Farabow Garrett & Dunner
Masih Karen
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