Heat exchange – With timer – programmer – time delay – or condition responsive... – Having heating and cooling capability
Reexamination Certificate
2003-02-26
2004-08-31
Wayner, William (Department: 3744)
Heat exchange
With timer, programmer, time delay, or condition responsive...
Having heating and cooling capability
C236S049300, C236S09100C, C454S258000
Reexamination Certificate
active
06782945
ABSTRACT:
BACKGROUND OF THE INVENTION
An example of a climate control system of the prior art is seen in FIG.
1
. The system comprises an electronic microprocessor controller
26
which receives a temperature signal from an interior air temperature sensor
28
. It also receives signals from a solar heat sensor
30
and an ambient air temperature sensor
32
. The controller
26
will develop a voltage, as shown at
34
, for controlling the speed of the blower
36
as air is passed by the blower over an evaporator
38
and a heater core
40
. In a conventional fashion, the air flow that passes over the heater core
40
can be controlled by a blend door
42
, the opening of which is controlled by an air mix controller
44
. The processor
26
in a conventional fashion will activate the blend door as indicated schematically at
46
.
Air is distributed to the upper control panel area as shown at
48
or to the lower floor area of the vehicle as shown at
50
, depending upon the position of door
52
, which is under the control of an air mode controller
54
. The controller
26
activates the air mode controller
54
as shown at
56
.
The vehicle operator may set the desired temperature with a conventional control head, the output of which is distributed to the controller as an input.
Intake air mass flow is also determined by the electronic controller
26
, as indicated by control line
60
.
The electronic controller may be one of a variety of known digital microprocessors (e.g., an 8-bit, single-chip microcomputer). It includes a read-only memory (ROM) in which the heat flux control equation is stored. It has the usual random-access memory registers (RAM) that receive information from the sensors before it is looked upby the central processor unit (CPU) and used by the CPU logic to act upon the stored equation in ROM to produce an output for the driver circuits. In known fashion, the processor monitors the sensor information during successive control loops as it performs sequentially the process steps.
The interior heat content for an automotive vehicle is affected by a number of variables including but not limited to the sun load heat flux (kW/m
2
), the effective glass area capable of transmitting a solar heat load, the heat generated by passengers and electronic devices within the vehicle passenger compartment, the ambient temperature of the air surrounding the vehicle, the mass air flow rate (enthalpy rate per degree), the average outlet temperature of the air conditioning system, and the heat transfer coefficient for heat transfer between the passenger compartment and the ambient air. An automotive temperature control system should take the thermodynamic interaction of these variables into account in an attempt to maintain a target interior temperature in the most effective way.
U.S. Pat. No. 5,832,990, which was awarded to the present inventor, is an example of an automatic climate control system for vehicles that respond to the above mentioned variables, including airflow. The '990 patent teaches an automatic interior temperature control system for an automotive vehicle capable of controlling heat flux in response to changes in (but not limited to) ambient temperature, outlet temperature, sun load and air flow by taking into account the relationship between these four variables in accordance with thermodynamic principles wherein an adjustment in heat flux corrects an interior temperature error. U.S. Pat. Nos. 6,272,871 and 6,272,873 are examples of prior art air conditioning systems, the content of which is incorporated herein by reference.
SUMMARY OF THE INVENTION
There is a desire to automatically control the temperature in two zones inside a vehicle while an adjustment in heat flux corrects an interior temperature error. Some climate control algorithms calculate two separate outlet temperatures that are based on empirically determined factors or gains applied to various sensor inputs that depend on expensive trial and error vehicle level testing. These algorithms do not take into account heat flow considerations, or at best minimize the heat flow considerations due to the absence of the direct influence of system airflow in the calculation method. This omission creates error and considerable compromise in the task of achieving an appropriate climate for each zone, particularly when the target zone temperatures differ.
This is a problem because in a typical operating environment, for example, either more or less cooling is required depending upon whether the vehicle is unshaded or shaded. The previous dual zone climate control systems attempt to adjust the outlet temperatures to achieve a target interior temperature without taking into account the effect of air flow in the control of total heat load. They are designed to affect adjustment in the temperature of the system outlet, but they do not provide a quantifiable and significant change in the total heat flux itself as the system attempts to achieve a target interior temperature.
The present inventor has discovered a dual zone automatic climate control algorithm utilizing a heat flux analysis that overcomes the deficiencies in the prior art. The present inventor has discovered a set of control equations for a dual zone (by way of example and not by limitation: left-right) using energy balance considerations for the thermal influence in the vehicle cabin. The factor of airflow is included directly in the calculations of the two outlet temperatures. This considerably simplifies the development process and often inherently corrects errors that are generated by neglecting the direct influence of airflow. A logic system utilizing the equations addresses thermal balance of two zones that may have a single interior temperature sensor (for low cost reasons) to ones with multiple interior sensors. Further, the present invention can provide for a single airflow source for the system, but is not limited to such a design. In such a scenario, a primary zone and a secondary zone is defined for the purpose of control priority. The primary zone can be used to govern the transient (overall cabin temperature correction) and set up the total system airflow. The secondary zone can be provided with a stabilization enhancement logic that may provide increases to the system airflow, only when the full cold or full hot outlet temperatures are not sufficient for that zone's temperature achievement. In addition, the secondary zone can be provided with transient enhancement logic, which creates a temporary outlet temperature overshoot that depends on the rate of this zone's temperature target adjustment.
In one embodiment of the present invention, there is a method for automatically controlling the climate in a plurality of climate control zones of a cabin of an automobile comprising at least a first zone and a second zone having a temperature sensor located in the first zone and a conditioned air outlet vent in each of the zones, the method comprising, obtaining a target temperature value for the first zone and the second zone; obtaining a first zone temperature value estimate from the sensor in the first zone; obtaining an ambient air temperature value; obtaining a sun load heat flux value for at least one of the first zone and the second zone; obtaining a first zone gain factor value based at least on the first zone temperature value estimate; automatically determining the outlet temperatures and the mass flow rates of the first zone outlet and the second zone outlet based at least on the above obtained values and on a conduction/convection heat transfer coefficient between the cabin and the ambient air, an effective glass area for solar load transmission, a zone air crossover influence factor, and predetermined constraints on the relationship of the outlet temperatures and air flow, wherein the zone air crossover influence factor is a factor based on blending of the air in the cabin; and providing conditioned air to the cabin from the first zone outlet and the second zone outlet at outlet temperatures and mass flow rates correlating t
Nissan Technical Center North America, Inc.
Wayner William
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