Refrigeration – Automatic control – Responsive to vehicle body motion or traction
Reexamination Certificate
2000-01-12
2001-10-09
Tanner, Harry B. (Department: 3744)
Refrigeration
Automatic control
Responsive to vehicle body motion or traction
C062S157000, C062S323400, C123S19800E
Reexamination Certificate
active
06298675
ABSTRACT:
FIELD OF THE INVENTION
The field of the invention relates generally to estimation and control of air conditioning system operation.
BACKGROUND OF THE INVENTION
Vehicles are typically equipped with an air conditioning system to provide cabin cooling and to dry air for dehumidifying functions. Air conditioning systems typically include a compressor driven by a vehicle's internal combustion engine. The compressor can be either engaged, fully or partially, or disengaged to the engine via an electronically controlled clutch.
During air conditioning system operation under certain operating conditions, the compressor cycles between an engaged and disengaged state. Cycling is typically controlled based on refrigerant pressure in the air conditioning system. When the engine and clutch are coupled, pressure decreases and significantly cooled cabin air is circulated through the vehicle. Such operation continues until pressure reaches a minimum value where the clutch is controlled to disengage the engine and compressor. If air circulation is continued, pressure increases until it reaches a maximum value. At this maximum value, the compressor is then re-engaged via the clutch and cycling repeats.
The inventors herein have proposed engaging the compressor at time other than when pressure reaches a maximum value. However, a potential disadvantage with this approach is that the compressor could be engaged too soon after it was previously disengaged. If this occurred the compressor could only be engaged a short duration and excessive cycling could result.
SUMMARY OF THE INVENTION
An object of the present invention is to provide methods for estimating air conditioning compressor cycling durations.
The above object is achieved and disadvantages of prior approaches overcome by a method for determining an air conditioning compressor cycle engaged duration and disengaged duration of an air conditioning compressor. The method comprises indicating a compressor cycle in which the compressor is engaged and disengaged based on an air conditioning parameter has been completed when the compressor is engaged based on said air conditioning parameter and subsequently disengaged based on said air conditioning parameter; and determining the engaged duration and the disengaged duration in response to said indication.
By determining the engaged duration and the disengaged duration of compressor cycles, it is possible to prevent excessive cycling. In particular, enabling engagement of the compressor based on the determined engaged and disengaged durations prevents excessive cycling, even when operating conditions change. For example, consider that cycling durations are a function cabin conditions or exterior conditions. By learning cycling durations in real time, variations in these operating conditions are included.
An advantage of the above aspect of the invention is potential for improved compressor durability.
Another advantage of the above aspect of the invention is that improved drive feel is achieved.
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Blaha George
Cullen Michael John
Dage Gerhard A.
Kotwicki Allan Joseph
Russell John David
Ford Global Technologies Inc.
Russell John D.
Tanner Harry B.
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