Electrical resistors – Mechanically variable – Resistance value varied by removing or adding material
Reexamination Certificate
2000-03-03
2001-03-27
Easthom, Karl D. (Department: 2832)
Electrical resistors
Mechanically variable
Resistance value varied by removing or adding material
C338S232000, C338S276000, C338S234000, C338S236000, C338S226000
Reexamination Certificate
active
06208233
ABSTRACT:
TECHNICAL FIELD
The present invention relates to calibration of automotive sensor circuitry, and more particularly to a trim resistor connector assembly for mechanical and electrical coupling into the output circuitry of a sensor element provided in an automotive electronic control system.
BACKGROUND OF THE INVENTION
With the steady growth in recent years of vehicle electronic systems, the number of sensors used in automobiles has also risen dramatically. Current vehicles can contain forty to fifty of such sensors. Among the types of sensors commonly provided are pressure sensors in the vehicle fuel systems, air bag sensors, over-current and over temperature-protection sensors, oxygen sensors for exhaust gas systems, catalyst temperature sensor, etc. With most if not all of such sensors, signal conditioning will be necessary for most sensor elements. Raw sensors exhibit some level of offset voltage in output signal level when no stimulus is applied to the sensor. Typically, a potentiometer or a trim resistor branch circuit that is laser trimmed for calibration is employed to calibrate the output signal from the sensor.
For example, in the case of exhaust sensors the trim resistor is used in the automotive oxygen sensor output to ECU circuitry connection system. Hitherto, this trim resistor has been provided as an integral part of the sensor wiring output connector assembly. In one commercially provided connector assembly six male blade terminals are provided and four of the terminals are crimped to wires coming from the sensor. The remaining two terminals are insert molded into the connector assembly and one end of each terminal is soldered to a contact pad on the trim resistor substrate. An opening is provided on the side of the connector assembly to install the trim resister and allow access for the laser trimming operation. The opening is then closed and sealed with a cover and gasket.
In this prior art construction currently in use the ceramic substrate and terminals are pre-molded parts that are inserted as a pre-molded part into the connector assembly mold and then secured therein as a mold-over part. Hence the connector assembly construction must be designed to match the connector assembly family currently used in the given wiring system of the vehicle design. This current practice is thus limited in flexibility and adaptability when it is desired to provide resistance trim capability as an add-on to exhaust system sensors in automotive vehicle electronic systems. Mold tooling costs are also a problem when system design changes are mandated.
There is thus a need to provide a trim resistor connector assembly construction that can be economically manufactured, assembled and installed to be operably coupled as an add-on to new as well as existing sensor wiring assemblies. In addition, there is the continuing need to improve exhaust sensor performance by enhancing calibration circuit construction. There is also the ongoing need to reduce the expense of the calibrating means for the sensor, and one that can be employed to calibrate the sensor prior to installing in the vehicle.
OBJECTS OF THE INVENTION
Accordingly, among the objects of the present invention are to provide an improved trim resistor connector assembly and improved system coupling of the same that provides a solution to the aforementioned problems and overcomes the aforementioned disadvantages of existing trim resistor constructions employed in conjunction with various automotive sensors in vehicle electronic systems.
SUMMARY OF THE INVENTION
In general, and by way of summary description and not by way of limitation, the present invention fulfills one or more of the foregoing objects by providing an improved IDC trim resistor connector assembly characterized by a connector of generally open top cup shape having a bottom wall and a peripheral side wall with side wall slots and with an interior first array of terminal posts arranged to accommodate passage therethrough of a first lead wire of sensor circuitry. A first stamped metal IDC terminal is push-on mounted to the terminal posts and adapted to IDC cradle and connect to the first lead wire. A trim resistor substrate is mounted on the bottom wall of the connector and has an “E” pattern of resistive material thereon adapted for laser trimming for calibration of circuitry to be associated with the trim resistor connector assembly. The first IDC terminal has a spring arm overlapping one side leg of the Dim resistor E-pattern and spring clamping the resistor substrate in place on the connector bottom wall. A cover is snap-latch mounted on the connector and has an access opening in registry with the trim resistor substrate to enable laser trimming and resultant circuit calibration by access through the cover opening. A second IDC metal terminal is similarly mounted in the connector on a second array of terminal posts for electrically connecting a second lead wire via its spring leg to the other side leg of the E-pattern to provide a conductive laser-trimmable resistance path between the first and second lead wires in assembly and operation of the connector assembly in an electrical system. The IDC terminals have spring barbs cooperative with the terminal posts to anchor the same once fully inserted downwardly onto the terminal posts. The associated terminal spring aims mechanically clamp the trim substrate in position on the connector bottom wall to at least initially hold the same in place for subsequent processing, including the laser trimming operation.
Preferably the connector assembly includes a cap for covering the cover opening. The cover and connector have cooperative locking tangs and locking ears to provide snap-on retention of the cover on the connector during push-down assembly of the cover on the connector. The cap and cover likewise have cooperative locking tangs and latching ears adapted to provide snap-together locking of the cap on the cover when the cap is pushed down and assembled on the cover opening after laser trimming and in filling of the covered container with a sealant gel.
A second embodiment provides a crimped terminal that is, in place of the second IDC terminal, fastened to the second lead wire and has a mounting strap with mounting barbs to hold the crimped terminal in place along with the end of the second lead when fully installed on a modified second terminal post array.
REFERENCES:
patent: 2859318 (1958-11-01), Ohlheiser
patent: 2892250 (1959-06-01), Bartels
patent: 3768157 (1973-10-01), Buie
patent: 4298855 (1981-11-01), Mills
patent: 4481497 (1984-11-01), Kurtz et al.
patent: 4850227 (1989-07-01), Leuttgen et al.
patent: 5209122 (1993-05-01), Matly et al.
patent: 5798685 (1998-08-01), Katsuki et al.
Loutzenhiser Rick
McCall Mark D.
Stein, Sr. William L.
Delphi Technologies Inc.
Easthom Karl D.
Jones Richard A.
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