Refrigeration – With indicator or tester – Condition sensing
Reexamination Certificate
1999-12-30
2002-04-16
Tapolcal, William E. (Department: 3744)
Refrigeration
With indicator or tester
Condition sensing
C236S094000
Reexamination Certificate
active
06370891
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to vehicle heating ventilation, and air conditioner systems, and more particularly to systems, components, and methods for testing for proper operation of such systems.
BACKGROUND
Most passenger vehicles are built with heating, ventilation, and air conditioner systems (HEVAC). As is well known, the purpose of a HEVAC system is to introduce temperature adjusted air into the passenger compartment of a vehicle in order to provide a more comfortable environment for the vehicle occupants. Present HEVAC systems have become more sophisticated and may include climate controls, front and rear vents, and vehicle zone controls.
Although HEVAC systems have become more sophisticated, methods of testing a HEVAC system installed in a vehicle during vehicle assembly have remained relatively unsophisticated. With particular respect to an air conditioner AC system, in many assembly plants, operators use a meat thermometer placed in the center instrument panel vent. The operator then switches the blower to high speed, moves the AC temperature control to a cold setting, and monitors the temperature for a period of approximately two minutes. The operator monitors the temperature drop from the initial temperature in order to determine if the AC system passes or fails this test. The operator then may go to a remote, off-line terminal or keyboard to enter such information into a quality control system. Similar test methods are employed to test the heater portion of a HEVAC system.
The present system is inherently inaccurate due to the use of meat thermometers or similar instruments which measure temperature over such a wide range. The temperature drop monitored by the operator is a very small portion of the entire scale of the thermometer, thereby reducing accuracy. While some test systems utilize a digital thermometer, the quality and accuracy of such digital thermometers is approximately the same as the meat thermometer, and the digital thermometers also rely on battery levels which can adversely affect accuracy of the readings. The dial or digital thermometers presently utilized having a very small viewing area and are difficult to see during the assembly operation without being relatively close to the viewing scale. The dial type thermometers further require that the operator read the location of a pointer on a relatively fine scale to determine initial and end readings. Operators often misread the scale or wait until the temperature has dropped more than the drop which the operator actually seeks in order to ensure that the vehicle has passed. Digital and analog thermometers both require that the operator perform a calculation to determine the end temperature, which is based on subtracting the initial desired drop from the initial temperature. Such calculations require additional process time.
The test operation also typically fails to include any time marking device so that the operator can measure the time over which temperature drop occurs. Therefore, the operator cannot certify that the temperature drop occurred within a predetermined time period. Further, the test process typically is a manual process and depends upon the operator following the procedures correctly in order to ensure consistency and quality of the test procedure. Inconsistencies may also be introduced if the operator chooses to use a feel test with a hand and/or if estimating the time rather than properly measuring the time. A manual process also requires that the operator commit a series of steps to memory and perform these steps repeatedly without prompting. Such systems require that new operators receive sufficient training before performing the test.
Because many vehicles are now equipped with dual zone systems, manually testing a dual zone system often proves difficult. The operator must monitor and remember test temperatures for one or two zones, times for both zones, and end temperatures at two different time periods. Such a complex test procedure often proves difficult to follow and often results in the operator concentrating on one zone, rather than two.
Present systems also do not provide sufficient verification that a proper test has occurred for a particular vehicle, as such testing often depends upon the operator properly reviewing build information for the vehicle. The present systems also provide inconsistent reporting and data tracking for each test. In particular, present systems record only a pass/fail indication, even if the pass/fail indication is entered into a database. Present systems also do not track the actual ambient temperature and humidity and drop times so that process performance can be properly documented. If the ambient temperature and/or the vehicle compartment temperature is not determined prior to the test, the test could be inaccurate for extreme vehicle temperatures, which can often occur in assembly plants.
Thus, there is a need for an improved air conditioning test system, method, and components in order to address the above-described issues.
SUMMARY OF THE INVENTION
This invention is directed to an automated system for testing a vehicle heating, ventilation, air conditioner (AC) unit. The system includes an ambient test unit. The ambient test unit includes an ambient temperature sensor placed in proximity to the vehicle. The ambient temperature sensor generates an ambient temperature signal that varies in accordance with the ambient temperature. An AC temperature sensor is placed in proximity to an AC vent. The AC temperature sensor generates an AC temperature signal that varies in accordance with the temperature of air exhausted from the AC vent. An AC test controller varies operation of the AC unit. An AC test unit which receives the AC temperature signal and the ambient temperature signal and determines if the AC temperature is within predefined limits in accordance with the ambient temperature and the operation of the AC unit.
This invention is also directed to a method for testing a vehicle heating, ventilation, air conditioner (HEVAC) unit. The method includes placing an HEVAC temperature probe in proximity to an exhaust vent of the HEVAC unit. The HEVAC temperature probe generates an HEVAC temperature signal that varies in accordance with an HEVAC temperature of air exhausted from the first exhaust vent. The method also includes determining an ambient temperature of air in proximity to the vehicle and operating the HEVAC unit to cause the exhaust air to exhaust from the first exhaust vent. The HEVAC temperature and the ambient temperature are compared and the time period over which the HEVAC temperature drops by a predetermined temperature value is determined. The time period over which the HEVAC temperature drops is compared to a predetermined time period to determine if the HEVAC system is operating properly.
The invention is also directed to an apparatus for sensing a temperature of air exhausted from an air conditioner (HEVAC) vent. The apparatus includes a temperature sensor having a body and a sensing section for receiving the air exhausted from the HEVAC vent. A holder receives the body of the temperature sensor, and a head receives the sensing section of the temperature sensor. The head has a window for enabling the HEVAC exhaust air to pass through the head and in proximity the sensing section. A fastener fastens the head in proximity to the exhaust vent and is arranged to maintain a predetermined orientation of the head with respect to the exhaust vent.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood however that the detailed description and specific examples, while indicating preferred embodiments of the invention, are intended for purposes of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
REFERENCES:
patent: 3686954 (1972-08-01), Motl
patent: 4770044 (1988-09-01
Currier, Jr. Ray E
Marshall Maureen L
Rideout Dennis K
Vudrag Djura
Ali Mohammad M
Bacon, Jr. Edwin W.
DaimlerChrysler Corporation
Tapolcal William E.
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