Geometrical instruments – Distance measuring – Single contact with a work engaging support
Reexamination Certificate
1999-01-28
2001-09-18
Bennett, G. Bradley (Department: 2859)
Geometrical instruments
Distance measuring
Single contact with a work engaging support
C033SDIG001
Reexamination Certificate
active
06289602
ABSTRACT:
BACKGROUND OF THE PREFERRED EMBODIMENT(S)
1. Field of the Preferred Embodiment(s)
This invention generally relates to position sensing and to a position sensor which is compact, durable and precise. More specifically, the invention relates to an exhaust gas recirculation valve sensor.
2. Description of the Related Art
Position sensing is used to allow an electrical circuit to gain information about an event or a continuously varying condition. There are a variety of known techniques for position sensing. For example, optical, electrical, electrostatic, and magnetic fields are all used in a sensor to measure position. There are many known sensors such as resistive contacting networks, inductively coupled ratio sensors, variable reluctance devices, capacitively coupled ratio detectors, optical detectors using the Faraday effect, photo-activated ratio detectors, and electrostatic ratio detectors.
There are many applications for sensors, and a wide variety of technologies to fill these needs. Each of these technologies offers a unique set of advantages and limitations. Of these applications, exhaust gas recirculation (EGR) valve sensing, is known to have its own unique requirements. An EGR valve sensor must be compact and rugged to resist the severe vibration, temperature and chemical exposure when mounted on an internal combustion engine.
Description of Related Art
Examples of patents related to the present invention are as follows, wherein each patent is herein incorporated by reference for related and supporting teachings:
U.S. Pat. No. 5,811,967 is a EGR valve linear position sensor having variable coupling transformer.
The foregoing patents reflect the state of the art of which the applicant is aware and are tendered with the view toward discharging applicants' acknowledged duty of candor in disclosing information that may be pertinent in the examination of this application. It is respectfully stipulated, however, that none of these patents teach or render obvious, singly or when considered in combination, applicants' claimed invention.
Problems with the Prior Art
There are several problems that exist with the prior art that are addressed by the preferred embodiment. One problem with the prior art contacting EGR sensors is wear. As the valve moves, over time the contacting parts of the sensor can wear out and fail. Further, due to the harsh environment, environmental contaminants can accelerate the failure of the contacting resistance system. Engine compartments are becoming more cramped due to more engine functions being added. A more compact sensor is desired. Other approaches such a magnetic sensors are susceptible to reversible performance degradation during high temperatures which require costly electronics to compensate for these temperature effects.
This and other problems will be solved by the preferred embodiments of the invention. A review of the specification, drawings, and claims will more clearly teach a skilled artisan of other problems that are solved by the preferred embodiments.
SUMMARY OF THE PREFERRED EMBODIMENT(S)
It is a feature of the invention to provide a linear position sensor operable to sense the movement of an object, including a housing having a cavity. A shaft is located in the cavity and extends out of the cavity into contact with the object. A sensor mechanism is located in the cavity, for sensing force and for generating an electrical signal proportional to the amount of force applied to the sensor mechanism. A spring mechanism is located between the shaft and the sensor mechanism, for translating movement of the shaft into a variable force on the sensor mechanism. The spring mechanism is compressed and decompressed as the object moves. The variable force on the sensor mechanism causes the electrical signal to change. An electrical connector extends through the housing and is connected to the sensor mechanism. The sensor mechanism includes a substrate and a strain gage resistor that is mounted on the substrate. The spring mechanism includes a sleeve attached to the shaft and a coil spring that has a first end and a second end. The first end is disposed in the sleeve and the second end is disposed adjacent the substrate.
The invention resides not in any one of these features per se, but rather in the particular combination of all of them herein disclosed and claimed. Those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. Further, the abstract is neither intended to define the invention of the application, which is measured by the claims, neither is it intended to be limiting as to the scope of the invention in any way.
REFERENCES:
patent: 2018777 (1935-10-01), Edwards
patent: 4622751 (1986-11-01), Berg
patent: 5077909 (1992-01-01), Cranor
patent: 5535631 (1996-07-01), Paine
patent: 5811967 (1998-09-01), Shank et al.
Bennett G. Bradley
Borgman Mark W.
Bourgeois Mark P.
CTS Corporation
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